// SPDX-License-Identifier: GPL-2.0 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "misc.h" #include "extent_io.h" #include "extent-io-tree.h" #include "extent_map.h" #include "ctree.h" #include "btrfs_inode.h" #include "bio.h" #include "check-integrity.h" #include "locking.h" #include "rcu-string.h" #include "backref.h" #include "disk-io.h" #include "subpage.h" #include "zoned.h" #include "block-group.h" #include "compression.h" #include "fs.h" #include "accessors.h" #include "file-item.h" #include "file.h" #include "dev-replace.h" #include "super.h" #include "transaction.h" static struct kmem_cache *extent_buffer_cache; #ifdef CONFIG_BTRFS_DEBUG static inline void btrfs_leak_debug_add_eb(struct extent_buffer *eb) { struct btrfs_fs_info *fs_info = eb->fs_info; unsigned long flags; spin_lock_irqsave(&fs_info->eb_leak_lock, flags); list_add(&eb->leak_list, &fs_info->allocated_ebs); spin_unlock_irqrestore(&fs_info->eb_leak_lock, flags); } static inline void btrfs_leak_debug_del_eb(struct extent_buffer *eb) { struct btrfs_fs_info *fs_info = eb->fs_info; unsigned long flags; spin_lock_irqsave(&fs_info->eb_leak_lock, flags); list_del(&eb->leak_list); spin_unlock_irqrestore(&fs_info->eb_leak_lock, flags); } void btrfs_extent_buffer_leak_debug_check(struct btrfs_fs_info *fs_info) { struct extent_buffer *eb; unsigned long flags; /* * If we didn't get into open_ctree our allocated_ebs will not be * initialized, so just skip this. */ if (!fs_info->allocated_ebs.next) return; WARN_ON(!list_empty(&fs_info->allocated_ebs)); spin_lock_irqsave(&fs_info->eb_leak_lock, flags); while (!list_empty(&fs_info->allocated_ebs)) { eb = list_first_entry(&fs_info->allocated_ebs, struct extent_buffer, leak_list); pr_err( "BTRFS: buffer leak start %llu len %lu refs %d bflags %lu owner %llu\n", eb->start, eb->len, atomic_read(&eb->refs), eb->bflags, btrfs_header_owner(eb)); list_del(&eb->leak_list); kmem_cache_free(extent_buffer_cache, eb); } spin_unlock_irqrestore(&fs_info->eb_leak_lock, flags); } #else #define btrfs_leak_debug_add_eb(eb) do {} while (0) #define btrfs_leak_debug_del_eb(eb) do {} while (0) #endif /* * Structure to record info about the bio being assembled, and other info like * how many bytes are there before stripe/ordered extent boundary. */ struct btrfs_bio_ctrl { struct btrfs_bio *bbio; enum btrfs_compression_type compress_type; u32 len_to_oe_boundary; blk_opf_t opf; btrfs_bio_end_io_t end_io_func; struct writeback_control *wbc; }; static void submit_one_bio(struct btrfs_bio_ctrl *bio_ctrl) { struct btrfs_bio *bbio = bio_ctrl->bbio; if (!bbio) return; /* Caller should ensure the bio has at least some range added */ ASSERT(bbio->bio.bi_iter.bi_size); if (btrfs_op(&bbio->bio) == BTRFS_MAP_READ && bio_ctrl->compress_type != BTRFS_COMPRESS_NONE) btrfs_submit_compressed_read(bbio); else btrfs_submit_bio(bbio, 0); /* The bbio is owned by the end_io handler now */ bio_ctrl->bbio = NULL; } /* * Submit or fail the current bio in the bio_ctrl structure. */ static void submit_write_bio(struct btrfs_bio_ctrl *bio_ctrl, int ret) { struct btrfs_bio *bbio = bio_ctrl->bbio; if (!bbio) return; if (ret) { ASSERT(ret < 0); btrfs_bio_end_io(bbio, errno_to_blk_status(ret)); /* The bio is owned by the end_io handler now */ bio_ctrl->bbio = NULL; } else { submit_one_bio(bio_ctrl); } } int __init extent_buffer_init_cachep(void) { extent_buffer_cache = kmem_cache_create("btrfs_extent_buffer", sizeof(struct extent_buffer), 0, SLAB_MEM_SPREAD, NULL); if (!extent_buffer_cache) return -ENOMEM; return 0; } void __cold extent_buffer_free_cachep(void) { /* * Make sure all delayed rcu free are flushed before we * destroy caches. */ rcu_barrier(); kmem_cache_destroy(extent_buffer_cache); } void extent_range_clear_dirty_for_io(struct inode *inode, u64 start, u64 end) { unsigned long index = start >> PAGE_SHIFT; unsigned long end_index = end >> PAGE_SHIFT; struct page *page; while (index <= end_index) { page = find_get_page(inode->i_mapping, index); BUG_ON(!page); /* Pages should be in the extent_io_tree */ clear_page_dirty_for_io(page); put_page(page); index++; } } void extent_range_redirty_for_io(struct inode *inode, u64 start, u64 end) { struct address_space *mapping = inode->i_mapping; unsigned long index = start >> PAGE_SHIFT; unsigned long end_index = end >> PAGE_SHIFT; struct folio *folio; while (index <= end_index) { folio = filemap_get_folio(mapping, index); filemap_dirty_folio(mapping, folio); folio_account_redirty(folio); index += folio_nr_pages(folio); folio_put(folio); } } /* * Process one page for __process_pages_contig(). * * Return >0 if we hit @page == @locked_page. * Return 0 if we updated the page status. * Return -EGAIN if the we need to try again. * (For PAGE_LOCK case but got dirty page or page not belong to mapping) */ static int process_one_page(struct btrfs_fs_info *fs_info, struct address_space *mapping, struct page *page, struct page *locked_page, unsigned long page_ops, u64 start, u64 end) { u32 len; ASSERT(end + 1 - start != 0 && end + 1 - start < U32_MAX); len = end + 1 - start; if (page_ops & PAGE_SET_ORDERED) btrfs_page_clamp_set_ordered(fs_info, page, start, len); if (page_ops & PAGE_START_WRITEBACK) { btrfs_page_clamp_clear_dirty(fs_info, page, start, len); btrfs_page_clamp_set_writeback(fs_info, page, start, len); } if (page_ops & PAGE_END_WRITEBACK) btrfs_page_clamp_clear_writeback(fs_info, page, start, len); if (page == locked_page) return 1; if (page_ops & PAGE_LOCK) { int ret; ret = btrfs_page_start_writer_lock(fs_info, page, start, len); if (ret) return ret; if (!PageDirty(page) || page->mapping != mapping) { btrfs_page_end_writer_lock(fs_info, page, start, len); return -EAGAIN; } } if (page_ops & PAGE_UNLOCK) btrfs_page_end_writer_lock(fs_info, page, start, len); return 0; } static int __process_pages_contig(struct address_space *mapping, struct page *locked_page, u64 start, u64 end, unsigned long page_ops, u64 *processed_end) { struct btrfs_fs_info *fs_info = btrfs_sb(mapping->host->i_sb); pgoff_t start_index = start >> PAGE_SHIFT; pgoff_t end_index = end >> PAGE_SHIFT; pgoff_t index = start_index; unsigned long pages_processed = 0; struct folio_batch fbatch; int err = 0; int i; if (page_ops & PAGE_LOCK) { ASSERT(page_ops == PAGE_LOCK); ASSERT(processed_end && *processed_end == start); } folio_batch_init(&fbatch); while (index <= end_index) { int found_folios; found_folios = filemap_get_folios_contig(mapping, &index, end_index, &fbatch); if (found_folios == 0) { /* * Only if we're going to lock these pages, we can find * nothing at @index. */ ASSERT(page_ops & PAGE_LOCK); err = -EAGAIN; goto out; } for (i = 0; i < found_folios; i++) { int process_ret; struct folio *folio = fbatch.folios[i]; process_ret = process_one_page(fs_info, mapping, &folio->page, locked_page, page_ops, start, end); if (process_ret < 0) { err = -EAGAIN; folio_batch_release(&fbatch); goto out; } pages_processed += folio_nr_pages(folio); } folio_batch_release(&fbatch); cond_resched(); } out: if (err && processed_end) { /* * Update @processed_end. I know this is awful since it has * two different return value patterns (inclusive vs exclusive). * * But the exclusive pattern is necessary if @start is 0, or we * underflow and check against processed_end won't work as * expected. */ if (pages_processed) *processed_end = min(end, ((u64)(start_index + pages_processed) << PAGE_SHIFT) - 1); else *processed_end = start; } return err; } static noinline void __unlock_for_delalloc(struct inode *inode, struct page *locked_page, u64 start, u64 end) { unsigned long index = start >> PAGE_SHIFT; unsigned long end_index = end >> PAGE_SHIFT; ASSERT(locked_page); if (index == locked_page->index && end_index == index) return; __process_pages_contig(inode->i_mapping, locked_page, start, end, PAGE_UNLOCK, NULL); } static noinline int lock_delalloc_pages(struct inode *inode, struct page *locked_page, u64 delalloc_start, u64 delalloc_end) { unsigned long index = delalloc_start >> PAGE_SHIFT; unsigned long end_index = delalloc_end >> PAGE_SHIFT; u64 processed_end = delalloc_start; int ret; ASSERT(locked_page); if (index == locked_page->index && index == end_index) return 0; ret = __process_pages_contig(inode->i_mapping, locked_page, delalloc_start, delalloc_end, PAGE_LOCK, &processed_end); if (ret == -EAGAIN && processed_end > delalloc_start) __unlock_for_delalloc(inode, locked_page, delalloc_start, processed_end); return ret; } /* * Find and lock a contiguous range of bytes in the file marked as delalloc, no * more than @max_bytes. * * @start: The original start bytenr to search. * Will store the extent range start bytenr. * @end: The original end bytenr of the search range * Will store the extent range end bytenr. * * Return true if we find a delalloc range which starts inside the original * range, and @start/@end will store the delalloc range start/end. * * Return false if we can't find any delalloc range which starts inside the * original range, and @start/@end will be the non-delalloc range start/end. */ EXPORT_FOR_TESTS noinline_for_stack bool find_lock_delalloc_range(struct inode *inode, struct page *locked_page, u64 *start, u64 *end) { struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree; const u64 orig_start = *start; const u64 orig_end = *end; /* The sanity tests may not set a valid fs_info. */ u64 max_bytes = fs_info ? fs_info->max_extent_size : BTRFS_MAX_EXTENT_SIZE; u64 delalloc_start; u64 delalloc_end; bool found; struct extent_state *cached_state = NULL; int ret; int loops = 0; /* Caller should pass a valid @end to indicate the search range end */ ASSERT(orig_end > orig_start); /* The range should at least cover part of the page */ ASSERT(!(orig_start >= page_offset(locked_page) + PAGE_SIZE || orig_end <= page_offset(locked_page))); again: /* step one, find a bunch of delalloc bytes starting at start */ delalloc_start = *start; delalloc_end = 0; found = btrfs_find_delalloc_range(tree, &delalloc_start, &delalloc_end, max_bytes, &cached_state); if (!found || delalloc_end <= *start || delalloc_start > orig_end) { *start = delalloc_start; /* @delalloc_end can be -1, never go beyond @orig_end */ *end = min(delalloc_end, orig_end); free_extent_state(cached_state); return false; } /* * start comes from the offset of locked_page. We have to lock * pages in order, so we can't process delalloc bytes before * locked_page */ if (delalloc_start < *start) delalloc_start = *start; /* * make sure to limit the number of pages we try to lock down */ if (delalloc_end + 1 - delalloc_start > max_bytes) delalloc_end = delalloc_start + max_bytes - 1; /* step two, lock all the pages after the page that has start */ ret = lock_delalloc_pages(inode, locked_page, delalloc_start, delalloc_end); ASSERT(!ret || ret == -EAGAIN); if (ret == -EAGAIN) { /* some of the pages are gone, lets avoid looping by * shortening the size of the delalloc range we're searching */ free_extent_state(cached_state); cached_state = NULL; if (!loops) { max_bytes = PAGE_SIZE; loops = 1; goto again; } else { found = false; goto out_failed; } } /* step three, lock the state bits for the whole range */ lock_extent(tree, delalloc_start, delalloc_end, &cached_state); /* then test to make sure it is all still delalloc */ ret = test_range_bit(tree, delalloc_start, delalloc_end, EXTENT_DELALLOC, 1, cached_state); if (!ret) { unlock_extent(tree, delalloc_start, delalloc_end, &cached_state); __unlock_for_delalloc(inode, locked_page, delalloc_start, delalloc_end); cond_resched(); goto again; } free_extent_state(cached_state); *start = delalloc_start; *end = delalloc_end; out_failed: return found; } void extent_clear_unlock_delalloc(struct btrfs_inode *inode, u64 start, u64 end, struct page *locked_page, u32 clear_bits, unsigned long page_ops) { clear_extent_bit(&inode->io_tree, start, end, clear_bits, NULL); __process_pages_contig(inode->vfs_inode.i_mapping, locked_page, start, end, page_ops, NULL); } static bool btrfs_verify_page(struct page *page, u64 start) { if (!fsverity_active(page->mapping->host) || PageUptodate(page) || start >= i_size_read(page->mapping->host)) return true; return fsverity_verify_page(page); } static void end_page_read(struct page *page, bool uptodate, u64 start, u32 len) { struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb); ASSERT(page_offset(page) <= start && start + len <= page_offset(page) + PAGE_SIZE); if (uptodate && btrfs_verify_page(page, start)) btrfs_page_set_uptodate(fs_info, page, start, len); else btrfs_page_clear_uptodate(fs_info, page, start, len); if (!btrfs_is_subpage(fs_info, page)) unlock_page(page); else btrfs_subpage_end_reader(fs_info, page, start, len); } /* lots and lots of room for performance fixes in the end_bio funcs */ void end_extent_writepage(struct page *page, int err, u64 start, u64 end) { struct btrfs_inode *inode; const bool uptodate = (err == 0); int ret = 0; ASSERT(page && page->mapping); inode = BTRFS_I(page->mapping->host); btrfs_writepage_endio_finish_ordered(inode, page, start, end, uptodate); if (!uptodate) { const struct btrfs_fs_info *fs_info = inode->root->fs_info; u32 len; ASSERT(end + 1 - start <= U32_MAX); len = end + 1 - start; btrfs_page_clear_uptodate(fs_info, page, start, len); ret = err < 0 ? err : -EIO; mapping_set_error(page->mapping, ret); } } /* * after a writepage IO is done, we need to: * clear the uptodate bits on error * clear the writeback bits in the extent tree for this IO * end_page_writeback if the page has no more pending IO * * Scheduling is not allowed, so the extent state tree is expected * to have one and only one object corresponding to this IO. */ static void end_bio_extent_writepage(struct btrfs_bio *bbio) { struct bio *bio = &bbio->bio; int error = blk_status_to_errno(bio->bi_status); struct bio_vec *bvec; struct bvec_iter_all iter_all; ASSERT(!bio_flagged(bio, BIO_CLONED)); bio_for_each_segment_all(bvec, bio, iter_all) { struct page *page = bvec->bv_page; struct inode *inode = page->mapping->host; struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); const u32 sectorsize = fs_info->sectorsize; u64 start = page_offset(page) + bvec->bv_offset; u32 len = bvec->bv_len; /* Our read/write should always be sector aligned. */ if (!IS_ALIGNED(bvec->bv_offset, sectorsize)) btrfs_err(fs_info, "partial page write in btrfs with offset %u and length %u", bvec->bv_offset, bvec->bv_len); else if (!IS_ALIGNED(bvec->bv_len, sectorsize)) btrfs_info(fs_info, "incomplete page write with offset %u and length %u", bvec->bv_offset, bvec->bv_len); btrfs_finish_ordered_extent(bbio->ordered, page, start, len, !error); if (error) { btrfs_page_clear_uptodate(fs_info, page, start, len); mapping_set_error(page->mapping, error); } btrfs_page_clear_writeback(fs_info, page, start, len); } bio_put(bio); } /* * Record previously processed extent range * * For endio_readpage_release_extent() to handle a full extent range, reducing * the extent io operations. */ struct processed_extent { struct btrfs_inode *inode; /* Start of the range in @inode */ u64 start; /* End of the range in @inode */ u64 end; bool uptodate; }; /* * Try to release processed extent range * * May not release the extent range right now if the current range is * contiguous to processed extent. * * Will release processed extent when any of @inode, @uptodate, the range is * no longer contiguous to the processed range. * * Passing @inode == NULL will force processed extent to be released. */ static void endio_readpage_release_extent(struct processed_extent *processed, struct btrfs_inode *inode, u64 start, u64 end, bool uptodate) { struct extent_state *cached = NULL; struct extent_io_tree *tree; /* The first extent, initialize @processed */ if (!processed->inode) goto update; /* * Contiguous to processed extent, just uptodate the end. * * Several things to notice: * * - bio can be merged as long as on-disk bytenr is contiguous * This means we can have page belonging to other inodes, thus need to * check if the inode still matches. * - bvec can contain range beyond current page for multi-page bvec * Thus we need to do processed->end + 1 >= start check */ if (processed->inode == inode && processed->uptodate == uptodate && processed->end + 1 >= start && end >= processed->end) { processed->end = end; return; } tree = &processed->inode->io_tree; /* * Now we don't have range contiguous to the processed range, release * the processed range now. */ unlock_extent(tree, processed->start, processed->end, &cached); update: /* Update processed to current range */ processed->inode = inode; processed->start = start; processed->end = end; processed->uptodate = uptodate; } static void begin_page_read(struct btrfs_fs_info *fs_info, struct page *page) { ASSERT(PageLocked(page)); if (!btrfs_is_subpage(fs_info, page)) return; ASSERT(PagePrivate(page)); btrfs_subpage_start_reader(fs_info, page, page_offset(page), PAGE_SIZE); } /* * after a readpage IO is done, we need to: * clear the uptodate bits on error * set the uptodate bits if things worked * set the page up to date if all extents in the tree are uptodate * clear the lock bit in the extent tree * unlock the page if there are no other extents locked for it * * Scheduling is not allowed, so the extent state tree is expected * to have one and only one object corresponding to this IO. */ static void end_bio_extent_readpage(struct btrfs_bio *bbio) { struct bio *bio = &bbio->bio; struct bio_vec *bvec; struct processed_extent processed = { 0 }; /* * The offset to the beginning of a bio, since one bio can never be * larger than UINT_MAX, u32 here is enough. */ u32 bio_offset = 0; struct bvec_iter_all iter_all; ASSERT(!bio_flagged(bio, BIO_CLONED)); bio_for_each_segment_all(bvec, bio, iter_all) { bool uptodate = !bio->bi_status; struct page *page = bvec->bv_page; struct inode *inode = page->mapping->host; struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); const u32 sectorsize = fs_info->sectorsize; u64 start; u64 end; u32 len; btrfs_debug(fs_info, "end_bio_extent_readpage: bi_sector=%llu, err=%d, mirror=%u", bio->bi_iter.bi_sector, bio->bi_status, bbio->mirror_num); /* * We always issue full-sector reads, but if some block in a * page fails to read, blk_update_request() will advance * bv_offset and adjust bv_len to compensate. Print a warning * for unaligned offsets, and an error if they don't add up to * a full sector. */ if (!IS_ALIGNED(bvec->bv_offset, sectorsize)) btrfs_err(fs_info, "partial page read in btrfs with offset %u and length %u", bvec->bv_offset, bvec->bv_len); else if (!IS_ALIGNED(bvec->bv_offset + bvec->bv_len, sectorsize)) btrfs_info(fs_info, "incomplete page read with offset %u and length %u", bvec->bv_offset, bvec->bv_len); start = page_offset(page) + bvec->bv_offset; end = start + bvec->bv_len - 1; len = bvec->bv_len; if (likely(uptodate)) { loff_t i_size = i_size_read(inode); pgoff_t end_index = i_size >> PAGE_SHIFT; /* * Zero out the remaining part if this range straddles * i_size. * * Here we should only zero the range inside the bvec, * not touch anything else. * * NOTE: i_size is exclusive while end is inclusive. */ if (page->index == end_index && i_size <= end) { u32 zero_start = max(offset_in_page(i_size), offset_in_page(start)); zero_user_segment(page, zero_start, offset_in_page(end) + 1); } } /* Update page status and unlock. */ end_page_read(page, uptodate, start, len); endio_readpage_release_extent(&processed, BTRFS_I(inode), start, end, uptodate); ASSERT(bio_offset + len > bio_offset); bio_offset += len; } /* Release the last extent */ endio_readpage_release_extent(&processed, NULL, 0, 0, false); bio_put(bio); } /* * Populate every free slot in a provided array with pages. * * @nr_pages: number of pages to allocate * @page_array: the array to fill with pages; any existing non-null entries in * the array will be skipped * * Return: 0 if all pages were able to be allocated; * -ENOMEM otherwise, and the caller is responsible for freeing all * non-null page pointers in the array. */ int btrfs_alloc_page_array(unsigned int nr_pages, struct page **page_array) { unsigned int allocated; for (allocated = 0; allocated < nr_pages;) { unsigned int last = allocated; allocated = alloc_pages_bulk_array(GFP_NOFS, nr_pages, page_array); if (allocated == nr_pages) return 0; /* * During this iteration, no page could be allocated, even * though alloc_pages_bulk_array() falls back to alloc_page() * if it could not bulk-allocate. So we must be out of memory. */ if (allocated == last) return -ENOMEM; memalloc_retry_wait(GFP_NOFS); } return 0; } static bool btrfs_bio_is_contig(struct btrfs_bio_ctrl *bio_ctrl, struct page *page, u64 disk_bytenr, unsigned int pg_offset) { struct bio *bio = &bio_ctrl->bbio->bio; struct bio_vec *bvec = bio_last_bvec_all(bio); const sector_t sector = disk_bytenr >> SECTOR_SHIFT; if (bio_ctrl->compress_type != BTRFS_COMPRESS_NONE) { /* * For compression, all IO should have its logical bytenr set * to the starting bytenr of the compressed extent. */ return bio->bi_iter.bi_sector == sector; } /* * The contig check requires the following conditions to be met: * * 1) The pages are belonging to the same inode * This is implied by the call chain. * * 2) The range has adjacent logical bytenr * * 3) The range has adjacent file offset * This is required for the usage of btrfs_bio->file_offset. */ return bio_end_sector(bio) == sector && page_offset(bvec->bv_page) + bvec->bv_offset + bvec->bv_len == page_offset(page) + pg_offset; } static void alloc_new_bio(struct btrfs_inode *inode, struct btrfs_bio_ctrl *bio_ctrl, u64 disk_bytenr, u64 file_offset) { struct btrfs_fs_info *fs_info = inode->root->fs_info; struct btrfs_bio *bbio; bbio = btrfs_bio_alloc(BIO_MAX_VECS, bio_ctrl->opf, fs_info, bio_ctrl->end_io_func, NULL); bbio->bio.bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT; bbio->inode = inode; bbio->file_offset = file_offset; bio_ctrl->bbio = bbio; bio_ctrl->len_to_oe_boundary = U32_MAX; /* Limit data write bios to the ordered boundary. */ if (bio_ctrl->wbc) { struct btrfs_ordered_extent *ordered; ordered = btrfs_lookup_ordered_extent(inode, file_offset); if (ordered) { bio_ctrl->len_to_oe_boundary = min_t(u32, U32_MAX, ordered->file_offset + ordered->disk_num_bytes - file_offset); bbio->ordered = ordered; } /* * Pick the last added device to support cgroup writeback. For * multi-device file systems this means blk-cgroup policies have * to always be set on the last added/replaced device. * This is a bit odd but has been like that for a long time. */ bio_set_dev(&bbio->bio, fs_info->fs_devices->latest_dev->bdev); wbc_init_bio(bio_ctrl->wbc, &bbio->bio); } } /* * @disk_bytenr: logical bytenr where the write will be * @page: page to add to the bio * @size: portion of page that we want to write to * @pg_offset: offset of the new bio or to check whether we are adding * a contiguous page to the previous one * * The will either add the page into the existing @bio_ctrl->bbio, or allocate a * new one in @bio_ctrl->bbio. * The mirror number for this IO should already be initizlied in * @bio_ctrl->mirror_num. */ static void submit_extent_page(struct btrfs_bio_ctrl *bio_ctrl, u64 disk_bytenr, struct page *page, size_t size, unsigned long pg_offset) { struct btrfs_inode *inode = BTRFS_I(page->mapping->host); ASSERT(pg_offset + size <= PAGE_SIZE); ASSERT(bio_ctrl->end_io_func); if (bio_ctrl->bbio && !btrfs_bio_is_contig(bio_ctrl, page, disk_bytenr, pg_offset)) submit_one_bio(bio_ctrl); do { u32 len = size; /* Allocate new bio if needed */ if (!bio_ctrl->bbio) { alloc_new_bio(inode, bio_ctrl, disk_bytenr, page_offset(page) + pg_offset); } /* Cap to the current ordered extent boundary if there is one. */ if (len > bio_ctrl->len_to_oe_boundary) { ASSERT(bio_ctrl->compress_type == BTRFS_COMPRESS_NONE); ASSERT(is_data_inode(&inode->vfs_inode)); len = bio_ctrl->len_to_oe_boundary; } if (bio_add_page(&bio_ctrl->bbio->bio, page, len, pg_offset) != len) { /* bio full: move on to a new one */ submit_one_bio(bio_ctrl); continue; } if (bio_ctrl->wbc) wbc_account_cgroup_owner(bio_ctrl->wbc, page, len); size -= len; pg_offset += len; disk_bytenr += len; /* * len_to_oe_boundary defaults to U32_MAX, which isn't page or * sector aligned. alloc_new_bio() then sets it to the end of * our ordered extent for writes into zoned devices. * * When len_to_oe_boundary is tracking an ordered extent, we * trust the ordered extent code to align things properly, and * the check above to cap our write to the ordered extent * boundary is correct. * * When len_to_oe_boundary is U32_MAX, the cap above would * result in a 4095 byte IO for the last page right before * we hit the bio limit of UINT_MAX. bio_add_page() has all * the checks required to make sure we don't overflow the bio, * and we should just ignore len_to_oe_boundary completely * unless we're using it to track an ordered extent. * * It's pretty hard to make a bio sized U32_MAX, but it can * happen when the page cache is able to feed us contiguous * pages for large extents. */ if (bio_ctrl->len_to_oe_boundary != U32_MAX) bio_ctrl->len_to_oe_boundary -= len; /* Ordered extent boundary: move on to a new bio. */ if (bio_ctrl->len_to_oe_boundary == 0) submit_one_bio(bio_ctrl); } while (size); } static int attach_extent_buffer_page(struct extent_buffer *eb, struct page *page, struct btrfs_subpage *prealloc) { struct btrfs_fs_info *fs_info = eb->fs_info; int ret = 0; /* * If the page is mapped to btree inode, we should hold the private * lock to prevent race. * For cloned or dummy extent buffers, their pages are not mapped and * will not race with any other ebs. */ if (page->mapping) lockdep_assert_held(&page->mapping->private_lock); if (fs_info->nodesize >= PAGE_SIZE) { if (!PagePrivate(page)) attach_page_private(page, eb); else WARN_ON(page->private != (unsigned long)eb); return 0; } /* Already mapped, just free prealloc */ if (PagePrivate(page)) { btrfs_free_subpage(prealloc); return 0; } if (prealloc) /* Has preallocated memory for subpage */ attach_page_private(page, prealloc); else /* Do new allocation to attach subpage */ ret = btrfs_attach_subpage(fs_info, page, BTRFS_SUBPAGE_METADATA); return ret; } int set_page_extent_mapped(struct page *page) { struct btrfs_fs_info *fs_info; ASSERT(page->mapping); if (PagePrivate(page)) return 0; fs_info = btrfs_sb(page->mapping->host->i_sb); if (btrfs_is_subpage(fs_info, page)) return btrfs_attach_subpage(fs_info, page, BTRFS_SUBPAGE_DATA); attach_page_private(page, (void *)EXTENT_PAGE_PRIVATE); return 0; } void clear_page_extent_mapped(struct page *page) { struct btrfs_fs_info *fs_info; ASSERT(page->mapping); if (!PagePrivate(page)) return; fs_info = btrfs_sb(page->mapping->host->i_sb); if (btrfs_is_subpage(fs_info, page)) return btrfs_detach_subpage(fs_info, page); detach_page_private(page); } static struct extent_map * __get_extent_map(struct inode *inode, struct page *page, size_t pg_offset, u64 start, u64 len, struct extent_map **em_cached) { struct extent_map *em; if (em_cached && *em_cached) { em = *em_cached; if (extent_map_in_tree(em) && start >= em->start && start < extent_map_end(em)) { refcount_inc(&em->refs); return em; } free_extent_map(em); *em_cached = NULL; } em = btrfs_get_extent(BTRFS_I(inode), page, pg_offset, start, len); if (em_cached && !IS_ERR(em)) { BUG_ON(*em_cached); refcount_inc(&em->refs); *em_cached = em; } return em; } /* * basic readpage implementation. Locked extent state structs are inserted * into the tree that are removed when the IO is done (by the end_io * handlers) * XXX JDM: This needs looking at to ensure proper page locking * return 0 on success, otherwise return error */ static int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, struct btrfs_bio_ctrl *bio_ctrl, u64 *prev_em_start) { struct inode *inode = page->mapping->host; struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); u64 start = page_offset(page); const u64 end = start + PAGE_SIZE - 1; u64 cur = start; u64 extent_offset; u64 last_byte = i_size_read(inode); u64 block_start; struct extent_map *em; int ret = 0; size_t pg_offset = 0; size_t iosize; size_t blocksize = inode->i_sb->s_blocksize; struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree; ret = set_page_extent_mapped(page); if (ret < 0) { unlock_extent(tree, start, end, NULL); unlock_page(page); return ret; } if (page->index == last_byte >> PAGE_SHIFT) { size_t zero_offset = offset_in_page(last_byte); if (zero_offset) { iosize = PAGE_SIZE - zero_offset; memzero_page(page, zero_offset, iosize); } } bio_ctrl->end_io_func = end_bio_extent_readpage; begin_page_read(fs_info, page); while (cur <= end) { enum btrfs_compression_type compress_type = BTRFS_COMPRESS_NONE; bool force_bio_submit = false; u64 disk_bytenr; ASSERT(IS_ALIGNED(cur, fs_info->sectorsize)); if (cur >= last_byte) { iosize = PAGE_SIZE - pg_offset; memzero_page(page, pg_offset, iosize); unlock_extent(tree, cur, cur + iosize - 1, NULL); end_page_read(page, true, cur, iosize); break; } em = __get_extent_map(inode, page, pg_offset, cur, end - cur + 1, em_cached); if (IS_ERR(em)) { unlock_extent(tree, cur, end, NULL); end_page_read(page, false, cur, end + 1 - cur); return PTR_ERR(em); } extent_offset = cur - em->start; BUG_ON(extent_map_end(em) <= cur); BUG_ON(end < cur); if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) compress_type = em->compress_type; iosize = min(extent_map_end(em) - cur, end - cur + 1); iosize = ALIGN(iosize, blocksize); if (compress_type != BTRFS_COMPRESS_NONE) disk_bytenr = em->block_start; else disk_bytenr = em->block_start + extent_offset; block_start = em->block_start; if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) block_start = EXTENT_MAP_HOLE; /* * If we have a file range that points to a compressed extent * and it's followed by a consecutive file range that points * to the same compressed extent (possibly with a different * offset and/or length, so it either points to the whole extent * or only part of it), we must make sure we do not submit a * single bio to populate the pages for the 2 ranges because * this makes the compressed extent read zero out the pages * belonging to the 2nd range. Imagine the following scenario: * * File layout * [0 - 8K] [8K - 24K] * | | * | | * points to extent X, points to extent X, * offset 4K, length of 8K offset 0, length 16K * * [extent X, compressed length = 4K uncompressed length = 16K] * * If the bio to read the compressed extent covers both ranges, * it will decompress extent X into the pages belonging to the * first range and then it will stop, zeroing out the remaining * pages that belong to the other range that points to extent X. * So here we make sure we submit 2 bios, one for the first * range and another one for the third range. Both will target * the same physical extent from disk, but we can't currently * make the compressed bio endio callback populate the pages * for both ranges because each compressed bio is tightly * coupled with a single extent map, and each range can have * an extent map with a different offset value relative to the * uncompressed data of our extent and different lengths. This * is a corner case so we prioritize correctness over * non-optimal behavior (submitting 2 bios for the same extent). */ if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags) && prev_em_start && *prev_em_start != (u64)-1 && *prev_em_start != em->start) force_bio_submit = true; if (prev_em_start) *prev_em_start = em->start; free_extent_map(em); em = NULL; /* we've found a hole, just zero and go on */ if (block_start == EXTENT_MAP_HOLE) { memzero_page(page, pg_offset, iosize); unlock_extent(tree, cur, cur + iosize - 1, NULL); end_page_read(page, true, cur, iosize); cur = cur + iosize; pg_offset += iosize; continue; } /* the get_extent function already copied into the page */ if (block_start == EXTENT_MAP_INLINE) { unlock_extent(tree, cur, cur + iosize - 1, NULL); end_page_read(page, true, cur, iosize); cur = cur + iosize; pg_offset += iosize; continue; } if (bio_ctrl->compress_type != compress_type) { submit_one_bio(bio_ctrl); bio_ctrl->compress_type = compress_type; } if (force_bio_submit) submit_one_bio(bio_ctrl); submit_extent_page(bio_ctrl, disk_bytenr, page, iosize, pg_offset); cur = cur + iosize; pg_offset += iosize; } return 0; } int btrfs_read_folio(struct file *file, struct folio *folio) { struct page *page = &folio->page; struct btrfs_inode *inode = BTRFS_I(page->mapping->host); u64 start = page_offset(page); u64 end = start + PAGE_SIZE - 1; struct btrfs_bio_ctrl bio_ctrl = { .opf = REQ_OP_READ }; int ret; btrfs_lock_and_flush_ordered_range(inode, start, end, NULL); ret = btrfs_do_readpage(page, NULL, &bio_ctrl, NULL); /* * If btrfs_do_readpage() failed we will want to submit the assembled * bio to do the cleanup. */ submit_one_bio(&bio_ctrl); return ret; } static inline void contiguous_readpages(struct page *pages[], int nr_pages, u64 start, u64 end, struct extent_map **em_cached, struct btrfs_bio_ctrl *bio_ctrl, u64 *prev_em_start) { struct btrfs_inode *inode = BTRFS_I(pages[0]->mapping->host); int index; btrfs_lock_and_flush_ordered_range(inode, start, end, NULL); for (index = 0; index < nr_pages; index++) { btrfs_do_readpage(pages[index], em_cached, bio_ctrl, prev_em_start); put_page(pages[index]); } } /* * helper for __extent_writepage, doing all of the delayed allocation setup. * * This returns 1 if btrfs_run_delalloc_range function did all the work required * to write the page (copy into inline extent). In this case the IO has * been started and the page is already unlocked. * * This returns 0 if all went well (page still locked) * This returns < 0 if there were errors (page still locked) */ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode, struct page *page, struct writeback_control *wbc) { const u64 page_end = page_offset(page) + PAGE_SIZE - 1; u64 delalloc_start = page_offset(page); u64 delalloc_to_write = 0; /* How many pages are started by btrfs_run_delalloc_range() */ unsigned long nr_written = 0; int ret; int page_started = 0; while (delalloc_start < page_end) { u64 delalloc_end = page_end; bool found; found = find_lock_delalloc_range(&inode->vfs_inode, page, &delalloc_start, &delalloc_end); if (!found) { delalloc_start = delalloc_end + 1; continue; } ret = btrfs_run_delalloc_range(inode, page, delalloc_start, delalloc_end, &page_started, &nr_written, wbc); if (ret) return ret; /* * delalloc_end is already one less than the total length, so * we don't subtract one from PAGE_SIZE */ delalloc_to_write += (delalloc_end - delalloc_start + PAGE_SIZE) >> PAGE_SHIFT; delalloc_start = delalloc_end + 1; } if (wbc->nr_to_write < delalloc_to_write) { int thresh = 8192; if (delalloc_to_write < thresh * 2) thresh = delalloc_to_write; wbc->nr_to_write = min_t(u64, delalloc_to_write, thresh); } /* Did btrfs_run_dealloc_range() already unlock and start the IO? */ if (page_started) { /* * We've unlocked the page, so we can't update the mapping's * writeback index, just update nr_to_write. */ wbc->nr_to_write -= nr_written; return 1; } return 0; } /* * Find the first byte we need to write. * * For subpage, one page can contain several sectors, and * __extent_writepage_io() will just grab all extent maps in the page * range and try to submit all non-inline/non-compressed extents. * * This is a big problem for subpage, we shouldn't re-submit already written * data at all. * This function will lookup subpage dirty bit to find which range we really * need to submit. * * Return the next dirty range in [@start, @end). * If no dirty range is found, @start will be page_offset(page) + PAGE_SIZE. */ static void find_next_dirty_byte(struct btrfs_fs_info *fs_info, struct page *page, u64 *start, u64 *end) { struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private; struct btrfs_subpage_info *spi = fs_info->subpage_info; u64 orig_start = *start; /* Declare as unsigned long so we can use bitmap ops */ unsigned long flags; int range_start_bit; int range_end_bit; /* * For regular sector size == page size case, since one page only * contains one sector, we return the page offset directly. */ if (!btrfs_is_subpage(fs_info, page)) { *start = page_offset(page); *end = page_offset(page) + PAGE_SIZE; return; } range_start_bit = spi->dirty_offset + (offset_in_page(orig_start) >> fs_info->sectorsize_bits); /* We should have the page locked, but just in case */ spin_lock_irqsave(&subpage->lock, flags); bitmap_next_set_region(subpage->bitmaps, &range_start_bit, &range_end_bit, spi->dirty_offset + spi->bitmap_nr_bits); spin_unlock_irqrestore(&subpage->lock, flags); range_start_bit -= spi->dirty_offset; range_end_bit -= spi->dirty_offset; *start = page_offset(page) + range_start_bit * fs_info->sectorsize; *end = page_offset(page) + range_end_bit * fs_info->sectorsize; } /* * helper for __extent_writepage. This calls the writepage start hooks, * and does the loop to map the page into extents and bios. * * We return 1 if the IO is started and the page is unlocked, * 0 if all went well (page still locked) * < 0 if there were errors (page still locked) */ static noinline_for_stack int __extent_writepage_io(struct btrfs_inode *inode, struct page *page, struct btrfs_bio_ctrl *bio_ctrl, loff_t i_size, int *nr_ret) { struct btrfs_fs_info *fs_info = inode->root->fs_info; u64 cur = page_offset(page); u64 end = cur + PAGE_SIZE - 1; u64 extent_offset; u64 block_start; struct extent_map *em; int ret = 0; int nr = 0; ret = btrfs_writepage_cow_fixup(page); if (ret) { /* Fixup worker will requeue */ redirty_page_for_writepage(bio_ctrl->wbc, page); unlock_page(page); return 1; } bio_ctrl->end_io_func = end_bio_extent_writepage; while (cur <= end) { u64 disk_bytenr; u64 em_end; u64 dirty_range_start = cur; u64 dirty_range_end; u32 iosize; if (cur >= i_size) { btrfs_writepage_endio_finish_ordered(inode, page, cur, end, true); /* * This range is beyond i_size, thus we don't need to * bother writing back. * But we still need to clear the dirty subpage bit, or * the next time the page gets dirtied, we will try to * writeback the sectors with subpage dirty bits, * causing writeback without ordered extent. */ btrfs_page_clear_dirty(fs_info, page, cur, end + 1 - cur); break; } find_next_dirty_byte(fs_info, page, &dirty_range_start, &dirty_range_end); if (cur < dirty_range_start) { cur = dirty_range_start; continue; } em = btrfs_get_extent(inode, NULL, 0, cur, end - cur + 1); if (IS_ERR(em)) { ret = PTR_ERR_OR_ZERO(em); goto out_error; } extent_offset = cur - em->start; em_end = extent_map_end(em); ASSERT(cur <= em_end); ASSERT(cur < end); ASSERT(IS_ALIGNED(em->start, fs_info->sectorsize)); ASSERT(IS_ALIGNED(em->len, fs_info->sectorsize)); block_start = em->block_start; disk_bytenr = em->block_start + extent_offset; ASSERT(!test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)); ASSERT(block_start != EXTENT_MAP_HOLE); ASSERT(block_start != EXTENT_MAP_INLINE); /* * Note that em_end from extent_map_end() and dirty_range_end from * find_next_dirty_byte() are all exclusive */ iosize = min(min(em_end, end + 1), dirty_range_end) - cur; free_extent_map(em); em = NULL; btrfs_set_range_writeback(inode, cur, cur + iosize - 1); if (!PageWriteback(page)) { btrfs_err(inode->root->fs_info, "page %lu not writeback, cur %llu end %llu", page->index, cur, end); } /* * Although the PageDirty bit is cleared before entering this * function, subpage dirty bit is not cleared. * So clear subpage dirty bit here so next time we won't submit * page for range already written to disk. */ btrfs_page_clear_dirty(fs_info, page, cur, iosize); submit_extent_page(bio_ctrl, disk_bytenr, page, iosize, cur - page_offset(page)); cur += iosize; nr++; } btrfs_page_assert_not_dirty(fs_info, page); *nr_ret = nr; return 0; out_error: /* * If we finish without problem, we should not only clear page dirty, * but also empty subpage dirty bits */ *nr_ret = nr; return ret; } /* * the writepage semantics are similar to regular writepage. extent * records are inserted to lock ranges in the tree, and as dirty areas * are found, they are marked writeback. Then the lock bits are removed * and the end_io handler clears the writeback ranges * * Return 0 if everything goes well. * Return <0 for error. */ static int __extent_writepage(struct page *page, struct btrfs_bio_ctrl *bio_ctrl) { struct folio *folio = page_folio(page); struct inode *inode = page->mapping->host; const u64 page_start = page_offset(page); const u64 page_end = page_start + PAGE_SIZE - 1; int ret; int nr = 0; size_t pg_offset; loff_t i_size = i_size_read(inode); unsigned long end_index = i_size >> PAGE_SHIFT; trace___extent_writepage(page, inode, bio_ctrl->wbc); WARN_ON(!PageLocked(page)); pg_offset = offset_in_page(i_size); if (page->index > end_index || (page->index == end_index && !pg_offset)) { folio_invalidate(folio, 0, folio_size(folio)); folio_unlock(folio); return 0; } if (page->index == end_index) memzero_page(page, pg_offset, PAGE_SIZE - pg_offset); ret = set_page_extent_mapped(page); if (ret < 0) goto done; ret = writepage_delalloc(BTRFS_I(inode), page, bio_ctrl->wbc); if (ret == 1) return 0; if (ret) goto done; ret = __extent_writepage_io(BTRFS_I(inode), page, bio_ctrl, i_size, &nr); if (ret == 1) return 0; bio_ctrl->wbc->nr_to_write--; done: if (nr == 0) { /* make sure the mapping tag for page dirty gets cleared */ set_page_writeback(page); end_page_writeback(page); } if (ret) end_extent_writepage(page, ret, page_start, page_end); unlock_page(page); ASSERT(ret <= 0); return ret; } void wait_on_extent_buffer_writeback(struct extent_buffer *eb) { wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_WRITEBACK, TASK_UNINTERRUPTIBLE); } /* * Lock extent buffer status and pages for writeback. * * Return %false if the extent buffer doesn't need to be submitted (e.g. the * extent buffer is not dirty) * Return %true is the extent buffer is submitted to bio. */ static noinline_for_stack bool lock_extent_buffer_for_io(struct extent_buffer *eb, struct writeback_control *wbc) { struct btrfs_fs_info *fs_info = eb->fs_info; bool ret = false; btrfs_tree_lock(eb); while (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags)) { btrfs_tree_unlock(eb); if (wbc->sync_mode != WB_SYNC_ALL) return false; wait_on_extent_buffer_writeback(eb); btrfs_tree_lock(eb); } /* * We need to do this to prevent races in people who check if the eb is * under IO since we can end up having no IO bits set for a short period * of time. */ spin_lock(&eb->refs_lock); if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) { set_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags); spin_unlock(&eb->refs_lock); btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN); percpu_counter_add_batch(&fs_info->dirty_metadata_bytes, -eb->len, fs_info->dirty_metadata_batch); ret = true; } else { spin_unlock(&eb->refs_lock); } btrfs_tree_unlock(eb); return ret; } static void set_btree_ioerr(struct extent_buffer *eb) { struct btrfs_fs_info *fs_info = eb->fs_info; set_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags); /* * A read may stumble upon this buffer later, make sure that it gets an * error and knows there was an error. */ clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); /* * We need to set the mapping with the io error as well because a write * error will flip the file system readonly, and then syncfs() will * return a 0 because we are readonly if we don't modify the err seq for * the superblock. */ mapping_set_error(eb->fs_info->btree_inode->i_mapping, -EIO); /* * If writeback for a btree extent that doesn't belong to a log tree * failed, increment the counter transaction->eb_write_errors. * We do this because while the transaction is running and before it's * committing (when we call filemap_fdata[write|wait]_range against * the btree inode), we might have * btree_inode->i_mapping->a_ops->writepages() called by the VM - if it * returns an error or an error happens during writeback, when we're * committing the transaction we wouldn't know about it, since the pages * can be no longer dirty nor marked anymore for writeback (if a * subsequent modification to the extent buffer didn't happen before the * transaction commit), which makes filemap_fdata[write|wait]_range not * able to find the pages tagged with SetPageError at transaction * commit time. So if this happens we must abort the transaction, * otherwise we commit a super block with btree roots that point to * btree nodes/leafs whose content on disk is invalid - either garbage * or the content of some node/leaf from a past generation that got * cowed or deleted and is no longer valid. * * Note: setting AS_EIO/AS_ENOSPC in the btree inode's i_mapping would * not be enough - we need to distinguish between log tree extents vs * non-log tree extents, and the next filemap_fdatawait_range() call * will catch and clear such errors in the mapping - and that call might * be from a log sync and not from a transaction commit. Also, checking * for the eb flag EXTENT_BUFFER_WRITE_ERR at transaction commit time is * not done and would not be reliable - the eb might have been released * from memory and reading it back again means that flag would not be * set (since it's a runtime flag, not persisted on disk). * * Using the flags below in the btree inode also makes us achieve the * goal of AS_EIO/AS_ENOSPC when writepages() returns success, started * writeback for all dirty pages and before filemap_fdatawait_range() * is called, the writeback for all dirty pages had already finished * with errors - because we were not using AS_EIO/AS_ENOSPC, * filemap_fdatawait_range() would return success, as it could not know * that writeback errors happened (the pages were no longer tagged for * writeback). */ switch (eb->log_index) { case -1: set_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags); break; case 0: set_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags); break; case 1: set_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags); break; default: BUG(); /* unexpected, logic error */ } } /* * The endio specific version which won't touch any unsafe spinlock in endio * context. */ static struct extent_buffer *find_extent_buffer_nolock( struct btrfs_fs_info *fs_info, u64 start) { struct extent_buffer *eb; rcu_read_lock(); eb = radix_tree_lookup(&fs_info->buffer_radix, start >> fs_info->sectorsize_bits); if (eb && atomic_inc_not_zero(&eb->refs)) { rcu_read_unlock(); return eb; } rcu_read_unlock(); return NULL; } static void extent_buffer_write_end_io(struct btrfs_bio *bbio) { struct extent_buffer *eb = bbio->private; struct btrfs_fs_info *fs_info = eb->fs_info; bool uptodate = !bbio->bio.bi_status; struct bvec_iter_all iter_all; struct bio_vec *bvec; u32 bio_offset = 0; if (!uptodate) set_btree_ioerr(eb); bio_for_each_segment_all(bvec, &bbio->bio, iter_all) { u64 start = eb->start + bio_offset; struct page *page = bvec->bv_page; u32 len = bvec->bv_len; if (!uptodate) btrfs_page_clear_uptodate(fs_info, page, start, len); btrfs_page_clear_writeback(fs_info, page, start, len); bio_offset += len; } clear_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags); smp_mb__after_atomic(); wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK); bio_put(&bbio->bio); } static void prepare_eb_write(struct extent_buffer *eb) { u32 nritems; unsigned long start; unsigned long end; clear_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags); /* Set btree blocks beyond nritems with 0 to avoid stale content */ nritems = btrfs_header_nritems(eb); if (btrfs_header_level(eb) > 0) { end = btrfs_node_key_ptr_offset(eb, nritems); memzero_extent_buffer(eb, end, eb->len - end); } else { /* * Leaf: * header 0 1 2 .. N ... data_N .. data_2 data_1 data_0 */ start = btrfs_item_nr_offset(eb, nritems); end = btrfs_item_nr_offset(eb, 0); if (nritems == 0) end += BTRFS_LEAF_DATA_SIZE(eb->fs_info); else end += btrfs_item_offset(eb, nritems - 1); memzero_extent_buffer(eb, start, end - start); } } static noinline_for_stack void write_one_eb(struct extent_buffer *eb, struct writeback_control *wbc) { struct btrfs_fs_info *fs_info = eb->fs_info; struct btrfs_bio *bbio; prepare_eb_write(eb); bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES, REQ_OP_WRITE | REQ_META | wbc_to_write_flags(wbc), eb->fs_info, extent_buffer_write_end_io, eb); bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT; bio_set_dev(&bbio->bio, fs_info->fs_devices->latest_dev->bdev); wbc_init_bio(wbc, &bbio->bio); bbio->inode = BTRFS_I(eb->fs_info->btree_inode); bbio->file_offset = eb->start; if (fs_info->nodesize < PAGE_SIZE) { struct page *p = eb->pages[0]; lock_page(p); btrfs_subpage_set_writeback(fs_info, p, eb->start, eb->len); if (btrfs_subpage_clear_and_test_dirty(fs_info, p, eb->start, eb->len)) { clear_page_dirty_for_io(p); wbc->nr_to_write--; } __bio_add_page(&bbio->bio, p, eb->len, eb->start - page_offset(p)); wbc_account_cgroup_owner(wbc, p, eb->len); unlock_page(p); } else { for (int i = 0; i < num_extent_pages(eb); i++) { struct page *p = eb->pages[i]; lock_page(p); clear_page_dirty_for_io(p); set_page_writeback(p); __bio_add_page(&bbio->bio, p, PAGE_SIZE, 0); wbc_account_cgroup_owner(wbc, p, PAGE_SIZE); wbc->nr_to_write--; unlock_page(p); } } btrfs_submit_bio(bbio, 0); } /* * Submit one subpage btree page. * * The main difference to submit_eb_page() is: * - Page locking * For subpage, we don't rely on page locking at all. * * - Flush write bio * We only flush bio if we may be unable to fit current extent buffers into * current bio. * * Return >=0 for the number of submitted extent buffers. * Return <0 for fatal error. */ static int submit_eb_subpage(struct page *page, struct writeback_control *wbc) { struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb); int submitted = 0; u64 page_start = page_offset(page); int bit_start = 0; int sectors_per_node = fs_info->nodesize >> fs_info->sectorsize_bits; /* Lock and write each dirty extent buffers in the range */ while (bit_start < fs_info->subpage_info->bitmap_nr_bits) { struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private; struct extent_buffer *eb; unsigned long flags; u64 start; /* * Take private lock to ensure the subpage won't be detached * in the meantime. */ spin_lock(&page->mapping->private_lock); if (!PagePrivate(page)) { spin_unlock(&page->mapping->private_lock); break; } spin_lock_irqsave(&subpage->lock, flags); if (!test_bit(bit_start + fs_info->subpage_info->dirty_offset, subpage->bitmaps)) { spin_unlock_irqrestore(&subpage->lock, flags); spin_unlock(&page->mapping->private_lock); bit_start++; continue; } start = page_start + bit_start * fs_info->sectorsize; bit_start += sectors_per_node; /* * Here we just want to grab the eb without touching extra * spin locks, so call find_extent_buffer_nolock(). */ eb = find_extent_buffer_nolock(fs_info, start); spin_unlock_irqrestore(&subpage->lock, flags); spin_unlock(&page->mapping->private_lock); /* * The eb has already reached 0 refs thus find_extent_buffer() * doesn't return it. We don't need to write back such eb * anyway. */ if (!eb) continue; if (lock_extent_buffer_for_io(eb, wbc)) { write_one_eb(eb, wbc); submitted++; } free_extent_buffer(eb); } return submitted; } /* * Submit all page(s) of one extent buffer. * * @page: the page of one extent buffer * @eb_context: to determine if we need to submit this page, if current page * belongs to this eb, we don't need to submit * * The caller should pass each page in their bytenr order, and here we use * @eb_context to determine if we have submitted pages of one extent buffer. * * If we have, we just skip until we hit a new page that doesn't belong to * current @eb_context. * * If not, we submit all the page(s) of the extent buffer. * * Return >0 if we have submitted the extent buffer successfully. * Return 0 if we don't need to submit the page, as it's already submitted by * previous call. * Return <0 for fatal error. */ static int submit_eb_page(struct page *page, struct btrfs_eb_write_context *ctx) { struct writeback_control *wbc = ctx->wbc; struct address_space *mapping = page->mapping; struct extent_buffer *eb; int ret; if (!PagePrivate(page)) return 0; if (btrfs_sb(page->mapping->host->i_sb)->nodesize < PAGE_SIZE) return submit_eb_subpage(page, wbc); spin_lock(&mapping->private_lock); if (!PagePrivate(page)) { spin_unlock(&mapping->private_lock); return 0; } eb = (struct extent_buffer *)page->private; /* * Shouldn't happen and normally this would be a BUG_ON but no point * crashing the machine for something we can survive anyway. */ if (WARN_ON(!eb)) { spin_unlock(&mapping->private_lock); return 0; } if (eb == ctx->eb) { spin_unlock(&mapping->private_lock); return 0; } ret = atomic_inc_not_zero(&eb->refs); spin_unlock(&mapping->private_lock); if (!ret) return 0; ctx->eb = eb; ret = btrfs_check_meta_write_pointer(eb->fs_info, ctx); if (ret) { if (ret == -EBUSY) ret = 0; free_extent_buffer(eb); return ret; } if (!lock_extent_buffer_for_io(eb, wbc)) { free_extent_buffer(eb); return 0; } /* Implies write in zoned mode. */ if (ctx->zoned_bg) { /* Mark the last eb in the block group. */ btrfs_schedule_zone_finish_bg(ctx->zoned_bg, eb); ctx->zoned_bg->meta_write_pointer += eb->len; } write_one_eb(eb, wbc); free_extent_buffer(eb); return 1; } int btree_write_cache_pages(struct address_space *mapping, struct writeback_control *wbc) { struct btrfs_eb_write_context ctx = { .wbc = wbc }; struct btrfs_fs_info *fs_info = BTRFS_I(mapping->host)->root->fs_info; int ret = 0; int done = 0; int nr_to_write_done = 0; struct folio_batch fbatch; unsigned int nr_folios; pgoff_t index; pgoff_t end; /* Inclusive */ int scanned = 0; xa_mark_t tag; folio_batch_init(&fbatch); if (wbc->range_cyclic) { index = mapping->writeback_index; /* Start from prev offset */ end = -1; /* * Start from the beginning does not need to cycle over the * range, mark it as scanned. */ scanned = (index == 0); } else { index = wbc->range_start >> PAGE_SHIFT; end = wbc->range_end >> PAGE_SHIFT; scanned = 1; } if (wbc->sync_mode == WB_SYNC_ALL) tag = PAGECACHE_TAG_TOWRITE; else tag = PAGECACHE_TAG_DIRTY; btrfs_zoned_meta_io_lock(fs_info); retry: if (wbc->sync_mode == WB_SYNC_ALL) tag_pages_for_writeback(mapping, index, end); while (!done && !nr_to_write_done && (index <= end) && (nr_folios = filemap_get_folios_tag(mapping, &index, end, tag, &fbatch))) { unsigned i; for (i = 0; i < nr_folios; i++) { struct folio *folio = fbatch.folios[i]; ret = submit_eb_page(&folio->page, &ctx); if (ret == 0) continue; if (ret < 0) { done = 1; break; } /* * the filesystem may choose to bump up nr_to_write. * We have to make sure to honor the new nr_to_write * at any time */ nr_to_write_done = wbc->nr_to_write <= 0; } folio_batch_release(&fbatch); cond_resched(); } if (!scanned && !done) { /* * We hit the last page and there is more work to be done: wrap * back to the start of the file */ scanned = 1; index = 0; goto retry; } /* * If something went wrong, don't allow any metadata write bio to be * submitted. * * This would prevent use-after-free if we had dirty pages not * cleaned up, which can still happen by fuzzed images. * * - Bad extent tree * Allowing existing tree block to be allocated for other trees. * * - Log tree operations * Exiting tree blocks get allocated to log tree, bumps its * generation, then get cleaned in tree re-balance. * Such tree block will not be written back, since it's clean, * thus no WRITTEN flag set. * And after log writes back, this tree block is not traced by * any dirty extent_io_tree. * * - Offending tree block gets re-dirtied from its original owner * Since it has bumped generation, no WRITTEN flag, it can be * reused without COWing. This tree block will not be traced * by btrfs_transaction::dirty_pages. * * Now such dirty tree block will not be cleaned by any dirty * extent io tree. Thus we don't want to submit such wild eb * if the fs already has error. * * We can get ret > 0 from submit_extent_page() indicating how many ebs * were submitted. Reset it to 0 to avoid false alerts for the caller. */ if (ret > 0) ret = 0; if (!ret && BTRFS_FS_ERROR(fs_info)) ret = -EROFS; if (ctx.zoned_bg) btrfs_put_block_group(ctx.zoned_bg); btrfs_zoned_meta_io_unlock(fs_info); return ret; } /* * Walk the list of dirty pages of the given address space and write all of them. * * @mapping: address space structure to write * @wbc: subtract the number of written pages from *@wbc->nr_to_write * @bio_ctrl: holds context for the write, namely the bio * * If a page is already under I/O, write_cache_pages() skips it, even * if it's dirty. This is desirable behaviour for memory-cleaning writeback, * but it is INCORRECT for data-integrity system calls such as fsync(). fsync() * and msync() need to guarantee that all the data which was dirty at the time * the call was made get new I/O started against them. If wbc->sync_mode is * WB_SYNC_ALL then we were called for data integrity and we must wait for * existing IO to complete. */ static int extent_write_cache_pages(struct address_space *mapping, struct btrfs_bio_ctrl *bio_ctrl) { struct writeback_control *wbc = bio_ctrl->wbc; struct inode *inode = mapping->host; int ret = 0; int done = 0; int nr_to_write_done = 0; struct folio_batch fbatch; unsigned int nr_folios; pgoff_t index; pgoff_t end; /* Inclusive */ pgoff_t done_index; int range_whole = 0; int scanned = 0; xa_mark_t tag; /* * We have to hold onto the inode so that ordered extents can do their * work when the IO finishes. The alternative to this is failing to add * an ordered extent if the igrab() fails there and that is a huge pain * to deal with, so instead just hold onto the inode throughout the * writepages operation. If it fails here we are freeing up the inode * anyway and we'd rather not waste our time writing out stuff that is * going to be truncated anyway. */ if (!igrab(inode)) return 0; folio_batch_init(&fbatch); if (wbc->range_cyclic) { index = mapping->writeback_index; /* Start from prev offset */ end = -1; /* * Start from the beginning does not need to cycle over the * range, mark it as scanned. */ scanned = (index == 0); } else { index = wbc->range_start >> PAGE_SHIFT; end = wbc->range_end >> PAGE_SHIFT; if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) range_whole = 1; scanned = 1; } /* * We do the tagged writepage as long as the snapshot flush bit is set * and we are the first one who do the filemap_flush() on this inode. * * The nr_to_write == LONG_MAX is needed to make sure other flushers do * not race in and drop the bit. */ if (range_whole && wbc->nr_to_write == LONG_MAX && test_and_clear_bit(BTRFS_INODE_SNAPSHOT_FLUSH, &BTRFS_I(inode)->runtime_flags)) wbc->tagged_writepages = 1; if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) tag = PAGECACHE_TAG_TOWRITE; else tag = PAGECACHE_TAG_DIRTY; retry: if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) tag_pages_for_writeback(mapping, index, end); done_index = index; while (!done && !nr_to_write_done && (index <= end) && (nr_folios = filemap_get_folios_tag(mapping, &index, end, tag, &fbatch))) { unsigned i; for (i = 0; i < nr_folios; i++) { struct folio *folio = fbatch.folios[i]; done_index = folio->index + folio_nr_pages(folio); /* * At this point we hold neither the i_pages lock nor * the page lock: the page may be truncated or * invalidated (changing page->mapping to NULL), * or even swizzled back from swapper_space to * tmpfs file mapping */ if (!folio_trylock(folio)) { submit_write_bio(bio_ctrl, 0); folio_lock(folio); } if (unlikely(folio->mapping != mapping)) { folio_unlock(folio); continue; } if (!folio_test_dirty(folio)) { /* Someone wrote it for us. */ folio_unlock(folio); continue; } if (wbc->sync_mode != WB_SYNC_NONE) { if (folio_test_writeback(folio)) submit_write_bio(bio_ctrl, 0); folio_wait_writeback(folio); } if (folio_test_writeback(folio) || !folio_clear_dirty_for_io(folio)) { folio_unlock(folio); continue; } ret = __extent_writepage(&folio->page, bio_ctrl); if (ret < 0) { done = 1; break; } /* * The filesystem may choose to bump up nr_to_write. * We have to make sure to honor the new nr_to_write * at any time. */ nr_to_write_done = (wbc->sync_mode == WB_SYNC_NONE && wbc->nr_to_write <= 0); } folio_batch_release(&fbatch); cond_resched(); } if (!scanned && !done) { /* * We hit the last page and there is more work to be done: wrap * back to the start of the file */ scanned = 1; index = 0; /* * If we're looping we could run into a page that is locked by a * writer and that writer could be waiting on writeback for a * page in our current bio, and thus deadlock, so flush the * write bio here. */ submit_write_bio(bio_ctrl, 0); goto retry; } if (wbc->range_cyclic || (wbc->nr_to_write > 0 && range_whole)) mapping->writeback_index = done_index; btrfs_add_delayed_iput(BTRFS_I(inode)); return ret; } /* * Submit the pages in the range to bio for call sites which delalloc range has * already been ran (aka, ordered extent inserted) and all pages are still * locked. */ int extent_write_locked_range(struct inode *inode, u64 start, u64 end, struct writeback_control *wbc) { bool found_error = false; int first_error = 0; int ret = 0; struct address_space *mapping = inode->i_mapping; struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); const u32 sectorsize = fs_info->sectorsize; loff_t i_size = i_size_read(inode); u64 cur = start; struct btrfs_bio_ctrl bio_ctrl = { .wbc = wbc, .opf = REQ_OP_WRITE | wbc_to_write_flags(wbc), }; if (wbc->no_cgroup_owner) bio_ctrl.opf |= REQ_BTRFS_CGROUP_PUNT; ASSERT(IS_ALIGNED(start, sectorsize) && IS_ALIGNED(end + 1, sectorsize)); while (cur <= end) { u64 cur_end = min(round_down(cur, PAGE_SIZE) + PAGE_SIZE - 1, end); struct page *page; int nr = 0; page = find_get_page(mapping, cur >> PAGE_SHIFT); /* * All pages in the range are locked since * btrfs_run_delalloc_range(), thus there is no way to clear * the page dirty flag. */ ASSERT(PageLocked(page)); ASSERT(PageDirty(page)); clear_page_dirty_for_io(page); ret = __extent_writepage_io(BTRFS_I(inode), page, &bio_ctrl, i_size, &nr); if (ret == 1) goto next_page; /* Make sure the mapping tag for page dirty gets cleared. */ if (nr == 0) { set_page_writeback(page); end_page_writeback(page); } if (ret) end_extent_writepage(page, ret, cur, cur_end); btrfs_page_unlock_writer(fs_info, page, cur, cur_end + 1 - cur); if (ret < 0) { found_error = true; first_error = ret; } next_page: put_page(page); cur = cur_end + 1; } submit_write_bio(&bio_ctrl, found_error ? ret : 0); if (found_error) return first_error; return ret; } int extent_writepages(struct address_space *mapping, struct writeback_control *wbc) { struct inode *inode = mapping->host; int ret = 0; struct btrfs_bio_ctrl bio_ctrl = { .wbc = wbc, .opf = REQ_OP_WRITE | wbc_to_write_flags(wbc), }; /* * Allow only a single thread to do the reloc work in zoned mode to * protect the write pointer updates. */ btrfs_zoned_data_reloc_lock(BTRFS_I(inode)); ret = extent_write_cache_pages(mapping, &bio_ctrl); submit_write_bio(&bio_ctrl, ret); btrfs_zoned_data_reloc_unlock(BTRFS_I(inode)); return ret; } void extent_readahead(struct readahead_control *rac) { struct btrfs_bio_ctrl bio_ctrl = { .opf = REQ_OP_READ | REQ_RAHEAD }; struct page *pagepool[16]; struct extent_map *em_cached = NULL; u64 prev_em_start = (u64)-1; int nr; while ((nr = readahead_page_batch(rac, pagepool))) { u64 contig_start = readahead_pos(rac); u64 contig_end = contig_start + readahead_batch_length(rac) - 1; contiguous_readpages(pagepool, nr, contig_start, contig_end, &em_cached, &bio_ctrl, &prev_em_start); } if (em_cached) free_extent_map(em_cached); submit_one_bio(&bio_ctrl); } /* * basic invalidate_folio code, this waits on any locked or writeback * ranges corresponding to the folio, and then deletes any extent state * records from the tree */ int extent_invalidate_folio(struct extent_io_tree *tree, struct folio *folio, size_t offset) { struct extent_state *cached_state = NULL; u64 start = folio_pos(folio); u64 end = start + folio_size(folio) - 1; size_t blocksize = folio->mapping->host->i_sb->s_blocksize; /* This function is only called for the btree inode */ ASSERT(tree->owner == IO_TREE_BTREE_INODE_IO); start += ALIGN(offset, blocksize); if (start > end) return 0; lock_extent(tree, start, end, &cached_state); folio_wait_writeback(folio); /* * Currently for btree io tree, only EXTENT_LOCKED is utilized, * so here we only need to unlock the extent range to free any * existing extent state. */ unlock_extent(tree, start, end, &cached_state); return 0; } /* * a helper for release_folio, this tests for areas of the page that * are locked or under IO and drops the related state bits if it is safe * to drop the page. */ static int try_release_extent_state(struct extent_io_tree *tree, struct page *page, gfp_t mask) { u64 start = page_offset(page); u64 end = start + PAGE_SIZE - 1; int ret = 1; if (test_range_bit(tree, start, end, EXTENT_LOCKED, 0, NULL)) { ret = 0; } else { u32 clear_bits = ~(EXTENT_LOCKED | EXTENT_NODATASUM | EXTENT_DELALLOC_NEW | EXTENT_CTLBITS); /* * At this point we can safely clear everything except the * locked bit, the nodatasum bit and the delalloc new bit. * The delalloc new bit will be cleared by ordered extent * completion. */ ret = __clear_extent_bit(tree, start, end, clear_bits, NULL, NULL); /* if clear_extent_bit failed for enomem reasons, * we can't allow the release to continue. */ if (ret < 0) ret = 0; else ret = 1; } return ret; } /* * a helper for release_folio. As long as there are no locked extents * in the range corresponding to the page, both state records and extent * map records are removed */ int try_release_extent_mapping(struct page *page, gfp_t mask) { struct extent_map *em; u64 start = page_offset(page); u64 end = start + PAGE_SIZE - 1; struct btrfs_inode *btrfs_inode = BTRFS_I(page->mapping->host); struct extent_io_tree *tree = &btrfs_inode->io_tree; struct extent_map_tree *map = &btrfs_inode->extent_tree; if (gfpflags_allow_blocking(mask) && page->mapping->host->i_size > SZ_16M) { u64 len; while (start <= end) { struct btrfs_fs_info *fs_info; u64 cur_gen; len = end - start + 1; write_lock(&map->lock); em = lookup_extent_mapping(map, start, len); if (!em) { write_unlock(&map->lock); break; } if (test_bit(EXTENT_FLAG_PINNED, &em->flags) || em->start != start) { write_unlock(&map->lock); free_extent_map(em); break; } if (test_range_bit(tree, em->start, extent_map_end(em) - 1, EXTENT_LOCKED, 0, NULL)) goto next; /* * If it's not in the list of modified extents, used * by a fast fsync, we can remove it. If it's being * logged we can safely remove it since fsync took an * extra reference on the em. */ if (list_empty(&em->list) || test_bit(EXTENT_FLAG_LOGGING, &em->flags)) goto remove_em; /* * If it's in the list of modified extents, remove it * only if its generation is older then the current one, * in which case we don't need it for a fast fsync. * Otherwise don't remove it, we could be racing with an * ongoing fast fsync that could miss the new extent. */ fs_info = btrfs_inode->root->fs_info; spin_lock(&fs_info->trans_lock); cur_gen = fs_info->generation; spin_unlock(&fs_info->trans_lock); if (em->generation >= cur_gen) goto next; remove_em: /* * We only remove extent maps that are not in the list of * modified extents or that are in the list but with a * generation lower then the current generation, so there * is no need to set the full fsync flag on the inode (it * hurts the fsync performance for workloads with a data * size that exceeds or is close to the system's memory). */ remove_extent_mapping(map, em); /* once for the rb tree */ free_extent_map(em); next: start = extent_map_end(em); write_unlock(&map->lock); /* once for us */ free_extent_map(em); cond_resched(); /* Allow large-extent preemption. */ } } return try_release_extent_state(tree, page, mask); } /* * To cache previous fiemap extent * * Will be used for merging fiemap extent */ struct fiemap_cache { u64 offset; u64 phys; u64 len; u32 flags; bool cached; }; /* * Helper to submit fiemap extent. * * Will try to merge current fiemap extent specified by @offset, @phys, * @len and @flags with cached one. * And only when we fails to merge, cached one will be submitted as * fiemap extent. * * Return value is the same as fiemap_fill_next_extent(). */ static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo, struct fiemap_cache *cache, u64 offset, u64 phys, u64 len, u32 flags) { int ret = 0; /* Set at the end of extent_fiemap(). */ ASSERT((flags & FIEMAP_EXTENT_LAST) == 0); if (!cache->cached) goto assign; /* * Sanity check, extent_fiemap() should have ensured that new * fiemap extent won't overlap with cached one. * Not recoverable. * * NOTE: Physical address can overlap, due to compression */ if (cache->offset + cache->len > offset) { WARN_ON(1); return -EINVAL; } /* * Only merges fiemap extents if * 1) Their logical addresses are continuous * * 2) Their physical addresses are continuous * So truly compressed (physical size smaller than logical size) * extents won't get merged with each other * * 3) Share same flags */ if (cache->offset + cache->len == offset && cache->phys + cache->len == phys && cache->flags == flags) { cache->len += len; return 0; } /* Not mergeable, need to submit cached one */ ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys, cache->len, cache->flags); cache->cached = false; if (ret) return ret; assign: cache->cached = true; cache->offset = offset; cache->phys = phys; cache->len = len; cache->flags = flags; return 0; } /* * Emit last fiemap cache * * The last fiemap cache may still be cached in the following case: * 0 4k 8k * |<- Fiemap range ->| * |<------------ First extent ----------->| * * In this case, the first extent range will be cached but not emitted. * So we must emit it before ending extent_fiemap(). */ static int emit_last_fiemap_cache(struct fiemap_extent_info *fieinfo, struct fiemap_cache *cache) { int ret; if (!cache->cached) return 0; ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys, cache->len, cache->flags); cache->cached = false; if (ret > 0) ret = 0; return ret; } static int fiemap_next_leaf_item(struct btrfs_inode *inode, struct btrfs_path *path) { struct extent_buffer *clone; struct btrfs_key key; int slot; int ret; path->slots[0]++; if (path->slots[0] < btrfs_header_nritems(path->nodes[0])) return 0; ret = btrfs_next_leaf(inode->root, path); if (ret != 0) return ret; /* * Don't bother with cloning if there are no more file extent items for * our inode. */ btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); if (key.objectid != btrfs_ino(inode) || key.type != BTRFS_EXTENT_DATA_KEY) return 1; /* See the comment at fiemap_search_slot() about why we clone. */ clone = btrfs_clone_extent_buffer(path->nodes[0]); if (!clone) return -ENOMEM; slot = path->slots[0]; btrfs_release_path(path); path->nodes[0] = clone; path->slots[0] = slot; return 0; } /* * Search for the first file extent item that starts at a given file offset or * the one that starts immediately before that offset. * Returns: 0 on success, < 0 on error, 1 if not found. */ static int fiemap_search_slot(struct btrfs_inode *inode, struct btrfs_path *path, u64 file_offset) { const u64 ino = btrfs_ino(inode); struct btrfs_root *root = inode->root; struct extent_buffer *clone; struct btrfs_key key; int slot; int ret; key.objectid = ino; key.type = BTRFS_EXTENT_DATA_KEY; key.offset = file_offset; ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); if (ret < 0) return ret; if (ret > 0 && path->slots[0] > 0) { btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0] - 1); if (key.objectid == ino && key.type == BTRFS_EXTENT_DATA_KEY) path->slots[0]--; } if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) { ret = btrfs_next_leaf(root, path); if (ret != 0) return ret; btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY) return 1; } /* * We clone the leaf and use it during fiemap. This is because while * using the leaf we do expensive things like checking if an extent is * shared, which can take a long time. In order to prevent blocking * other tasks for too long, we use a clone of the leaf. We have locked * the file range in the inode's io tree, so we know none of our file * extent items can change. This way we avoid blocking other tasks that * want to insert items for other inodes in the same leaf or b+tree * rebalance operations (triggered for example when someone is trying * to push items into this leaf when trying to insert an item in a * neighbour leaf). * We also need the private clone because holding a read lock on an * extent buffer of the subvolume's b+tree will make lockdep unhappy * when we call fiemap_fill_next_extent(), because that may cause a page * fault when filling the user space buffer with fiemap data. */ clone = btrfs_clone_extent_buffer(path->nodes[0]); if (!clone) return -ENOMEM; slot = path->slots[0]; btrfs_release_path(path); path->nodes[0] = clone; path->slots[0] = slot; return 0; } /* * Process a range which is a hole or a prealloc extent in the inode's subvolume * btree. If @disk_bytenr is 0, we are dealing with a hole, otherwise a prealloc * extent. The end offset (@end) is inclusive. */ static int fiemap_process_hole(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo, struct fiemap_cache *cache, struct extent_state **delalloc_cached_state, struct btrfs_backref_share_check_ctx *backref_ctx, u64 disk_bytenr, u64 extent_offset, u64 extent_gen, u64 start, u64 end) { const u64 i_size = i_size_read(&inode->vfs_inode); u64 cur_offset = start; u64 last_delalloc_end = 0; u32 prealloc_flags = FIEMAP_EXTENT_UNWRITTEN; bool checked_extent_shared = false; int ret; /* * There can be no delalloc past i_size, so don't waste time looking for * it beyond i_size. */ while (cur_offset < end && cur_offset < i_size) { u64 delalloc_start; u64 delalloc_end; u64 prealloc_start; u64 prealloc_len = 0; bool delalloc; delalloc = btrfs_find_delalloc_in_range(inode, cur_offset, end, delalloc_cached_state, &delalloc_start, &delalloc_end); if (!delalloc) break; /* * If this is a prealloc extent we have to report every section * of it that has no delalloc. */ if (disk_bytenr != 0) { if (last_delalloc_end == 0) { prealloc_start = start; prealloc_len = delalloc_start - start; } else { prealloc_start = last_delalloc_end + 1; prealloc_len = delalloc_start - prealloc_start; } } if (prealloc_len > 0) { if (!checked_extent_shared && fieinfo->fi_extents_max) { ret = btrfs_is_data_extent_shared(inode, disk_bytenr, extent_gen, backref_ctx); if (ret < 0) return ret; else if (ret > 0) prealloc_flags |= FIEMAP_EXTENT_SHARED; checked_extent_shared = true; } ret = emit_fiemap_extent(fieinfo, cache, prealloc_start, disk_bytenr + extent_offset, prealloc_len, prealloc_flags); if (ret) return ret; extent_offset += prealloc_len; } ret = emit_fiemap_extent(fieinfo, cache, delalloc_start, 0, delalloc_end + 1 - delalloc_start, FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN); if (ret) return ret; last_delalloc_end = delalloc_end; cur_offset = delalloc_end + 1; extent_offset += cur_offset - delalloc_start; cond_resched(); } /* * Either we found no delalloc for the whole prealloc extent or we have * a prealloc extent that spans i_size or starts at or after i_size. */ if (disk_bytenr != 0 && last_delalloc_end < end) { u64 prealloc_start; u64 prealloc_len; if (last_delalloc_end == 0) { prealloc_start = start; prealloc_len = end + 1 - start; } else { prealloc_start = last_delalloc_end + 1; prealloc_len = end + 1 - prealloc_start; } if (!checked_extent_shared && fieinfo->fi_extents_max) { ret = btrfs_is_data_extent_shared(inode, disk_bytenr, extent_gen, backref_ctx); if (ret < 0) return ret; else if (ret > 0) prealloc_flags |= FIEMAP_EXTENT_SHARED; } ret = emit_fiemap_extent(fieinfo, cache, prealloc_start, disk_bytenr + extent_offset, prealloc_len, prealloc_flags); if (ret) return ret; } return 0; } static int fiemap_find_last_extent_offset(struct btrfs_inode *inode, struct btrfs_path *path, u64 *last_extent_end_ret) { const u64 ino = btrfs_ino(inode); struct btrfs_root *root = inode->root; struct extent_buffer *leaf; struct btrfs_file_extent_item *ei; struct btrfs_key key; u64 disk_bytenr; int ret; /* * Lookup the last file extent. We're not using i_size here because * there might be preallocation past i_size. */ ret = btrfs_lookup_file_extent(NULL, root, path, ino, (u64)-1, 0); /* There can't be a file extent item at offset (u64)-1 */ ASSERT(ret != 0); if (ret < 0) return ret; /* * For a non-existing key, btrfs_search_slot() always leaves us at a * slot > 0, except if the btree is empty, which is impossible because * at least it has the inode item for this inode and all the items for * the root inode 256. */ ASSERT(path->slots[0] > 0); path->slots[0]--; leaf = path->nodes[0]; btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY) { /* No file extent items in the subvolume tree. */ *last_extent_end_ret = 0; return 0; } /* * For an inline extent, the disk_bytenr is where inline data starts at, * so first check if we have an inline extent item before checking if we * have an implicit hole (disk_bytenr == 0). */ ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); if (btrfs_file_extent_type(leaf, ei) == BTRFS_FILE_EXTENT_INLINE) { *last_extent_end_ret = btrfs_file_extent_end(path); return 0; } /* * Find the last file extent item that is not a hole (when NO_HOLES is * not enabled). This should take at most 2 iterations in the worst * case: we have one hole file extent item at slot 0 of a leaf and * another hole file extent item as the last item in the previous leaf. * This is because we merge file extent items that represent holes. */ disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, ei); while (disk_bytenr == 0) { ret = btrfs_previous_item(root, path, ino, BTRFS_EXTENT_DATA_KEY); if (ret < 0) { return ret; } else if (ret > 0) { /* No file extent items that are not holes. */ *last_extent_end_ret = 0; return 0; } leaf = path->nodes[0]; ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, ei); } *last_extent_end_ret = btrfs_file_extent_end(path); return 0; } int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo, u64 start, u64 len) { const u64 ino = btrfs_ino(inode); struct extent_state *cached_state = NULL; struct extent_state *delalloc_cached_state = NULL; struct btrfs_path *path; struct fiemap_cache cache = { 0 }; struct btrfs_backref_share_check_ctx *backref_ctx; u64 last_extent_end; u64 prev_extent_end; u64 lockstart; u64 lockend; bool stopped = false; int ret; backref_ctx = btrfs_alloc_backref_share_check_ctx(); path = btrfs_alloc_path(); if (!backref_ctx || !path) { ret = -ENOMEM; goto out; } lockstart = round_down(start, inode->root->fs_info->sectorsize); lockend = round_up(start + len, inode->root->fs_info->sectorsize); prev_extent_end = lockstart; btrfs_inode_lock(inode, BTRFS_ILOCK_SHARED); lock_extent(&inode->io_tree, lockstart, lockend, &cached_state); ret = fiemap_find_last_extent_offset(inode, path, &last_extent_end); if (ret < 0) goto out_unlock; btrfs_release_path(path); path->reada = READA_FORWARD; ret = fiemap_search_slot(inode, path, lockstart); if (ret < 0) { goto out_unlock; } else if (ret > 0) { /* * No file extent item found, but we may have delalloc between * the current offset and i_size. So check for that. */ ret = 0; goto check_eof_delalloc; } while (prev_extent_end < lockend) { struct extent_buffer *leaf = path->nodes[0]; struct btrfs_file_extent_item *ei; struct btrfs_key key; u64 extent_end; u64 extent_len; u64 extent_offset = 0; u64 extent_gen; u64 disk_bytenr = 0; u64 flags = 0; int extent_type; u8 compression; btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY) break; extent_end = btrfs_file_extent_end(path); /* * The first iteration can leave us at an extent item that ends * before our range's start. Move to the next item. */ if (extent_end <= lockstart) goto next_item; backref_ctx->curr_leaf_bytenr = leaf->start; /* We have in implicit hole (NO_HOLES feature enabled). */ if (prev_extent_end < key.offset) { const u64 range_end = min(key.offset, lockend) - 1; ret = fiemap_process_hole(inode, fieinfo, &cache, &delalloc_cached_state, backref_ctx, 0, 0, 0, prev_extent_end, range_end); if (ret < 0) { goto out_unlock; } else if (ret > 0) { /* fiemap_fill_next_extent() told us to stop. */ stopped = true; break; } /* We've reached the end of the fiemap range, stop. */ if (key.offset >= lockend) { stopped = true; break; } } extent_len = extent_end - key.offset; ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); compression = btrfs_file_extent_compression(leaf, ei); extent_type = btrfs_file_extent_type(leaf, ei); extent_gen = btrfs_file_extent_generation(leaf, ei); if (extent_type != BTRFS_FILE_EXTENT_INLINE) { disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, ei); if (compression == BTRFS_COMPRESS_NONE) extent_offset = btrfs_file_extent_offset(leaf, ei); } if (compression != BTRFS_COMPRESS_NONE) flags |= FIEMAP_EXTENT_ENCODED; if (extent_type == BTRFS_FILE_EXTENT_INLINE) { flags |= FIEMAP_EXTENT_DATA_INLINE; flags |= FIEMAP_EXTENT_NOT_ALIGNED; ret = emit_fiemap_extent(fieinfo, &cache, key.offset, 0, extent_len, flags); } else if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) { ret = fiemap_process_hole(inode, fieinfo, &cache, &delalloc_cached_state, backref_ctx, disk_bytenr, extent_offset, extent_gen, key.offset, extent_end - 1); } else if (disk_bytenr == 0) { /* We have an explicit hole. */ ret = fiemap_process_hole(inode, fieinfo, &cache, &delalloc_cached_state, backref_ctx, 0, 0, 0, key.offset, extent_end - 1); } else { /* We have a regular extent. */ if (fieinfo->fi_extents_max) { ret = btrfs_is_data_extent_shared(inode, disk_bytenr, extent_gen, backref_ctx); if (ret < 0) goto out_unlock; else if (ret > 0) flags |= FIEMAP_EXTENT_SHARED; } ret = emit_fiemap_extent(fieinfo, &cache, key.offset, disk_bytenr + extent_offset, extent_len, flags); } if (ret < 0) { goto out_unlock; } else if (ret > 0) { /* fiemap_fill_next_extent() told us to stop. */ stopped = true; break; } prev_extent_end = extent_end; next_item: if (fatal_signal_pending(current)) { ret = -EINTR; goto out_unlock; } ret = fiemap_next_leaf_item(inode, path); if (ret < 0) { goto out_unlock; } else if (ret > 0) { /* No more file extent items for this inode. */ break; } cond_resched(); } check_eof_delalloc: /* * Release (and free) the path before emitting any final entries to * fiemap_fill_next_extent() to keep lockdep happy. This is because * once we find no more file extent items exist, we may have a * non-cloned leaf, and fiemap_fill_next_extent() can trigger page * faults when copying data to the user space buffer. */ btrfs_free_path(path); path = NULL; if (!stopped && prev_extent_end < lockend) { ret = fiemap_process_hole(inode, fieinfo, &cache, &delalloc_cached_state, backref_ctx, 0, 0, 0, prev_extent_end, lockend - 1); if (ret < 0) goto out_unlock; prev_extent_end = lockend; } if (cache.cached && cache.offset + cache.len >= last_extent_end) { const u64 i_size = i_size_read(&inode->vfs_inode); if (prev_extent_end < i_size) { u64 delalloc_start; u64 delalloc_end; bool delalloc; delalloc = btrfs_find_delalloc_in_range(inode, prev_extent_end, i_size - 1, &delalloc_cached_state, &delalloc_start, &delalloc_end); if (!delalloc) cache.flags |= FIEMAP_EXTENT_LAST; } else { cache.flags |= FIEMAP_EXTENT_LAST; } } ret = emit_last_fiemap_cache(fieinfo, &cache); out_unlock: unlock_extent(&inode->io_tree, lockstart, lockend, &cached_state); btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED); out: free_extent_state(delalloc_cached_state); btrfs_free_backref_share_ctx(backref_ctx); btrfs_free_path(path); return ret; } static void __free_extent_buffer(struct extent_buffer *eb) { kmem_cache_free(extent_buffer_cache, eb); } static int extent_buffer_under_io(const struct extent_buffer *eb) { return (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags) || test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)); } static bool page_range_has_eb(struct btrfs_fs_info *fs_info, struct page *page) { struct btrfs_subpage *subpage; lockdep_assert_held(&page->mapping->private_lock); if (PagePrivate(page)) { subpage = (struct btrfs_subpage *)page->private; if (atomic_read(&subpage->eb_refs)) return true; /* * Even there is no eb refs here, we may still have * end_page_read() call relying on page::private. */ if (atomic_read(&subpage->readers)) return true; } return false; } static void detach_extent_buffer_page(struct extent_buffer *eb, struct page *page) { struct btrfs_fs_info *fs_info = eb->fs_info; const bool mapped = !test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags); /* * For mapped eb, we're going to change the page private, which should * be done under the private_lock. */ if (mapped) spin_lock(&page->mapping->private_lock); if (!PagePrivate(page)) { if (mapped) spin_unlock(&page->mapping->private_lock); return; } if (fs_info->nodesize >= PAGE_SIZE) { /* * We do this since we'll remove the pages after we've * removed the eb from the radix tree, so we could race * and have this page now attached to the new eb. So * only clear page_private if it's still connected to * this eb. */ if (PagePrivate(page) && page->private == (unsigned long)eb) { BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)); BUG_ON(PageDirty(page)); BUG_ON(PageWriteback(page)); /* * We need to make sure we haven't be attached * to a new eb. */ detach_page_private(page); } if (mapped) spin_unlock(&page->mapping->private_lock); return; } /* * For subpage, we can have dummy eb with page private. In this case, * we can directly detach the private as such page is only attached to * one dummy eb, no sharing. */ if (!mapped) { btrfs_detach_subpage(fs_info, page); return; } btrfs_page_dec_eb_refs(fs_info, page); /* * We can only detach the page private if there are no other ebs in the * page range and no unfinished IO. */ if (!page_range_has_eb(fs_info, page)) btrfs_detach_subpage(fs_info, page); spin_unlock(&page->mapping->private_lock); } /* Release all pages attached to the extent buffer */ static void btrfs_release_extent_buffer_pages(struct extent_buffer *eb) { int i; int num_pages; ASSERT(!extent_buffer_under_io(eb)); num_pages = num_extent_pages(eb); for (i = 0; i < num_pages; i++) { struct page *page = eb->pages[i]; if (!page) continue; detach_extent_buffer_page(eb, page); /* One for when we allocated the page */ put_page(page); } } /* * Helper for releasing the extent buffer. */ static inline void btrfs_release_extent_buffer(struct extent_buffer *eb) { btrfs_release_extent_buffer_pages(eb); btrfs_leak_debug_del_eb(eb); __free_extent_buffer(eb); } static struct extent_buffer * __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start, unsigned long len) { struct extent_buffer *eb = NULL; eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS|__GFP_NOFAIL); eb->start = start; eb->len = len; eb->fs_info = fs_info; init_rwsem(&eb->lock); btrfs_leak_debug_add_eb(eb); spin_lock_init(&eb->refs_lock); atomic_set(&eb->refs, 1); ASSERT(len <= BTRFS_MAX_METADATA_BLOCKSIZE); return eb; } struct extent_buffer *btrfs_clone_extent_buffer(const struct extent_buffer *src) { int i; struct extent_buffer *new; int num_pages = num_extent_pages(src); int ret; new = __alloc_extent_buffer(src->fs_info, src->start, src->len); if (new == NULL) return NULL; /* * Set UNMAPPED before calling btrfs_release_extent_buffer(), as * btrfs_release_extent_buffer() have different behavior for * UNMAPPED subpage extent buffer. */ set_bit(EXTENT_BUFFER_UNMAPPED, &new->bflags); ret = btrfs_alloc_page_array(num_pages, new->pages); if (ret) { btrfs_release_extent_buffer(new); return NULL; } for (i = 0; i < num_pages; i++) { int ret; struct page *p = new->pages[i]; ret = attach_extent_buffer_page(new, p, NULL); if (ret < 0) { btrfs_release_extent_buffer(new); return NULL; } WARN_ON(PageDirty(p)); copy_page(page_address(p), page_address(src->pages[i])); } set_extent_buffer_uptodate(new); return new; } struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info, u64 start, unsigned long len) { struct extent_buffer *eb; int num_pages; int i; int ret; eb = __alloc_extent_buffer(fs_info, start, len); if (!eb) return NULL; num_pages = num_extent_pages(eb); ret = btrfs_alloc_page_array(num_pages, eb->pages); if (ret) goto err; for (i = 0; i < num_pages; i++) { struct page *p = eb->pages[i]; ret = attach_extent_buffer_page(eb, p, NULL); if (ret < 0) goto err; } set_extent_buffer_uptodate(eb); btrfs_set_header_nritems(eb, 0); set_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags); return eb; err: for (i = 0; i < num_pages; i++) { if (eb->pages[i]) { detach_extent_buffer_page(eb, eb->pages[i]); __free_page(eb->pages[i]); } } __free_extent_buffer(eb); return NULL; } struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info, u64 start) { return __alloc_dummy_extent_buffer(fs_info, start, fs_info->nodesize); } static void check_buffer_tree_ref(struct extent_buffer *eb) { int refs; /* * The TREE_REF bit is first set when the extent_buffer is added * to the radix tree. It is also reset, if unset, when a new reference * is created by find_extent_buffer. * * It is only cleared in two cases: freeing the last non-tree * reference to the extent_buffer when its STALE bit is set or * calling release_folio when the tree reference is the only reference. * * In both cases, care is taken to ensure that the extent_buffer's * pages are not under io. However, release_folio can be concurrently * called with creating new references, which is prone to race * conditions between the calls to check_buffer_tree_ref in those * codepaths and clearing TREE_REF in try_release_extent_buffer. * * The actual lifetime of the extent_buffer in the radix tree is * adequately protected by the refcount, but the TREE_REF bit and * its corresponding reference are not. To protect against this * class of races, we call check_buffer_tree_ref from the codepaths * which trigger io. Note that once io is initiated, TREE_REF can no * longer be cleared, so that is the moment at which any such race is * best fixed. */ refs = atomic_read(&eb->refs); if (refs >= 2 && test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) return; spin_lock(&eb->refs_lock); if (!test_and_set_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) atomic_inc(&eb->refs); spin_unlock(&eb->refs_lock); } static void mark_extent_buffer_accessed(struct extent_buffer *eb, struct page *accessed) { int num_pages, i; check_buffer_tree_ref(eb); num_pages = num_extent_pages(eb); for (i = 0; i < num_pages; i++) { struct page *p = eb->pages[i]; if (p != accessed) mark_page_accessed(p); } } struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info, u64 start) { struct extent_buffer *eb; eb = find_extent_buffer_nolock(fs_info, start); if (!eb) return NULL; /* * Lock our eb's refs_lock to avoid races with free_extent_buffer(). * When we get our eb it might be flagged with EXTENT_BUFFER_STALE and * another task running free_extent_buffer() might have seen that flag * set, eb->refs == 2, that the buffer isn't under IO (dirty and * writeback flags not set) and it's still in the tree (flag * EXTENT_BUFFER_TREE_REF set), therefore being in the process of * decrementing the extent buffer's reference count twice. So here we * could race and increment the eb's reference count, clear its stale * flag, mark it as dirty and drop our reference before the other task * finishes executing free_extent_buffer, which would later result in * an attempt to free an extent buffer that is dirty. */ if (test_bit(EXTENT_BUFFER_STALE, &eb->bflags)) { spin_lock(&eb->refs_lock); spin_unlock(&eb->refs_lock); } mark_extent_buffer_accessed(eb, NULL); return eb; } #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info, u64 start) { struct extent_buffer *eb, *exists = NULL; int ret; eb = find_extent_buffer(fs_info, start); if (eb) return eb; eb = alloc_dummy_extent_buffer(fs_info, start); if (!eb) return ERR_PTR(-ENOMEM); eb->fs_info = fs_info; again: ret = radix_tree_preload(GFP_NOFS); if (ret) { exists = ERR_PTR(ret); goto free_eb; } spin_lock(&fs_info->buffer_lock); ret = radix_tree_insert(&fs_info->buffer_radix, start >> fs_info->sectorsize_bits, eb); spin_unlock(&fs_info->buffer_lock); radix_tree_preload_end(); if (ret == -EEXIST) { exists = find_extent_buffer(fs_info, start); if (exists) goto free_eb; else goto again; } check_buffer_tree_ref(eb); set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags); return eb; free_eb: btrfs_release_extent_buffer(eb); return exists; } #endif static struct extent_buffer *grab_extent_buffer( struct btrfs_fs_info *fs_info, struct page *page) { struct extent_buffer *exists; /* * For subpage case, we completely rely on radix tree to ensure we * don't try to insert two ebs for the same bytenr. So here we always * return NULL and just continue. */ if (fs_info->nodesize < PAGE_SIZE) return NULL; /* Page not yet attached to an extent buffer */ if (!PagePrivate(page)) return NULL; /* * We could have already allocated an eb for this page and attached one * so lets see if we can get a ref on the existing eb, and if we can we * know it's good and we can just return that one, else we know we can * just overwrite page->private. */ exists = (struct extent_buffer *)page->private; if (atomic_inc_not_zero(&exists->refs)) return exists; WARN_ON(PageDirty(page)); detach_page_private(page); return NULL; } static int check_eb_alignment(struct btrfs_fs_info *fs_info, u64 start) { if (!IS_ALIGNED(start, fs_info->sectorsize)) { btrfs_err(fs_info, "bad tree block start %llu", start); return -EINVAL; } if (fs_info->nodesize < PAGE_SIZE && offset_in_page(start) + fs_info->nodesize > PAGE_SIZE) { btrfs_err(fs_info, "tree block crosses page boundary, start %llu nodesize %u", start, fs_info->nodesize); return -EINVAL; } if (fs_info->nodesize >= PAGE_SIZE && !PAGE_ALIGNED(start)) { btrfs_err(fs_info, "tree block is not page aligned, start %llu nodesize %u", start, fs_info->nodesize); return -EINVAL; } return 0; } struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start, u64 owner_root, int level) { unsigned long len = fs_info->nodesize; int num_pages; int i; unsigned long index = start >> PAGE_SHIFT; struct extent_buffer *eb; struct extent_buffer *exists = NULL; struct page *p; struct address_space *mapping = fs_info->btree_inode->i_mapping; u64 lockdep_owner = owner_root; int uptodate = 1; int ret; if (check_eb_alignment(fs_info, start)) return ERR_PTR(-EINVAL); #if BITS_PER_LONG == 32 if (start >= MAX_LFS_FILESIZE) { btrfs_err_rl(fs_info, "extent buffer %llu is beyond 32bit page cache limit", start); btrfs_err_32bit_limit(fs_info); return ERR_PTR(-EOVERFLOW); } if (start >= BTRFS_32BIT_EARLY_WARN_THRESHOLD) btrfs_warn_32bit_limit(fs_info); #endif eb = find_extent_buffer(fs_info, start); if (eb) return eb; eb = __alloc_extent_buffer(fs_info, start, len); if (!eb) return ERR_PTR(-ENOMEM); /* * The reloc trees are just snapshots, so we need them to appear to be * just like any other fs tree WRT lockdep. */ if (lockdep_owner == BTRFS_TREE_RELOC_OBJECTID) lockdep_owner = BTRFS_FS_TREE_OBJECTID; btrfs_set_buffer_lockdep_class(lockdep_owner, eb, level); num_pages = num_extent_pages(eb); for (i = 0; i < num_pages; i++, index++) { struct btrfs_subpage *prealloc = NULL; p = find_or_create_page(mapping, index, GFP_NOFS|__GFP_NOFAIL); if (!p) { exists = ERR_PTR(-ENOMEM); goto free_eb; } /* * Preallocate page->private for subpage case, so that we won't * allocate memory with private_lock hold. The memory will be * freed by attach_extent_buffer_page() or freed manually if * we exit earlier. * * Although we have ensured one subpage eb can only have one * page, but it may change in the future for 16K page size * support, so we still preallocate the memory in the loop. */ if (fs_info->nodesize < PAGE_SIZE) { prealloc = btrfs_alloc_subpage(fs_info, BTRFS_SUBPAGE_METADATA); if (IS_ERR(prealloc)) { ret = PTR_ERR(prealloc); unlock_page(p); put_page(p); exists = ERR_PTR(ret); goto free_eb; } } spin_lock(&mapping->private_lock); exists = grab_extent_buffer(fs_info, p); if (exists) { spin_unlock(&mapping->private_lock); unlock_page(p); put_page(p); mark_extent_buffer_accessed(exists, p); btrfs_free_subpage(prealloc); goto free_eb; } /* Should not fail, as we have preallocated the memory */ ret = attach_extent_buffer_page(eb, p, prealloc); ASSERT(!ret); /* * To inform we have extra eb under allocation, so that * detach_extent_buffer_page() won't release the page private * when the eb hasn't yet been inserted into radix tree. * * The ref will be decreased when the eb released the page, in * detach_extent_buffer_page(). * Thus needs no special handling in error path. */ btrfs_page_inc_eb_refs(fs_info, p); spin_unlock(&mapping->private_lock); WARN_ON(btrfs_page_test_dirty(fs_info, p, eb->start, eb->len)); eb->pages[i] = p; if (!btrfs_page_test_uptodate(fs_info, p, eb->start, eb->len)) uptodate = 0; /* * We can't unlock the pages just yet since the extent buffer * hasn't been properly inserted in the radix tree, this * opens a race with btree_release_folio which can free a page * while we are still filling in all pages for the buffer and * we could crash. */ } if (uptodate) set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); again: ret = radix_tree_preload(GFP_NOFS); if (ret) { exists = ERR_PTR(ret); goto free_eb; } spin_lock(&fs_info->buffer_lock); ret = radix_tree_insert(&fs_info->buffer_radix, start >> fs_info->sectorsize_bits, eb); spin_unlock(&fs_info->buffer_lock); radix_tree_preload_end(); if (ret == -EEXIST) { exists = find_extent_buffer(fs_info, start); if (exists) goto free_eb; else goto again; } /* add one reference for the tree */ check_buffer_tree_ref(eb); set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags); /* * Now it's safe to unlock the pages because any calls to * btree_release_folio will correctly detect that a page belongs to a * live buffer and won't free them prematurely. */ for (i = 0; i < num_pages; i++) unlock_page(eb->pages[i]); return eb; free_eb: WARN_ON(!atomic_dec_and_test(&eb->refs)); for (i = 0; i < num_pages; i++) { if (eb->pages[i]) unlock_page(eb->pages[i]); } btrfs_release_extent_buffer(eb); return exists; } static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head) { struct extent_buffer *eb = container_of(head, struct extent_buffer, rcu_head); __free_extent_buffer(eb); } static int release_extent_buffer(struct extent_buffer *eb) __releases(&eb->refs_lock) { lockdep_assert_held(&eb->refs_lock); WARN_ON(atomic_read(&eb->refs) == 0); if (atomic_dec_and_test(&eb->refs)) { if (test_and_clear_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags)) { struct btrfs_fs_info *fs_info = eb->fs_info; spin_unlock(&eb->refs_lock); spin_lock(&fs_info->buffer_lock); radix_tree_delete(&fs_info->buffer_radix, eb->start >> fs_info->sectorsize_bits); spin_unlock(&fs_info->buffer_lock); } else { spin_unlock(&eb->refs_lock); } btrfs_leak_debug_del_eb(eb); /* Should be safe to release our pages at this point */ btrfs_release_extent_buffer_pages(eb); #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS if (unlikely(test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags))) { __free_extent_buffer(eb); return 1; } #endif call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu); return 1; } spin_unlock(&eb->refs_lock); return 0; } void free_extent_buffer(struct extent_buffer *eb) { int refs; if (!eb) return; refs = atomic_read(&eb->refs); while (1) { if ((!test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags) && refs <= 3) || (test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags) && refs == 1)) break; if (atomic_try_cmpxchg(&eb->refs, &refs, refs - 1)) return; } spin_lock(&eb->refs_lock); if (atomic_read(&eb->refs) == 2 && test_bit(EXTENT_BUFFER_STALE, &eb->bflags) && !extent_buffer_under_io(eb) && test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) atomic_dec(&eb->refs); /* * I know this is terrible, but it's temporary until we stop tracking * the uptodate bits and such for the extent buffers. */ release_extent_buffer(eb); } void free_extent_buffer_stale(struct extent_buffer *eb) { if (!eb) return; spin_lock(&eb->refs_lock); set_bit(EXTENT_BUFFER_STALE, &eb->bflags); if (atomic_read(&eb->refs) == 2 && !extent_buffer_under_io(eb) && test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) atomic_dec(&eb->refs); release_extent_buffer(eb); } static void btree_clear_page_dirty(struct page *page) { ASSERT(PageDirty(page)); ASSERT(PageLocked(page)); clear_page_dirty_for_io(page); xa_lock_irq(&page->mapping->i_pages); if (!PageDirty(page)) __xa_clear_mark(&page->mapping->i_pages, page_index(page), PAGECACHE_TAG_DIRTY); xa_unlock_irq(&page->mapping->i_pages); } static void clear_subpage_extent_buffer_dirty(const struct extent_buffer *eb) { struct btrfs_fs_info *fs_info = eb->fs_info; struct page *page = eb->pages[0]; bool last; /* btree_clear_page_dirty() needs page locked */ lock_page(page); last = btrfs_subpage_clear_and_test_dirty(fs_info, page, eb->start, eb->len); if (last) btree_clear_page_dirty(page); unlock_page(page); WARN_ON(atomic_read(&eb->refs) == 0); } void btrfs_clear_buffer_dirty(struct btrfs_trans_handle *trans, struct extent_buffer *eb) { struct btrfs_fs_info *fs_info = eb->fs_info; int i; int num_pages; struct page *page; btrfs_assert_tree_write_locked(eb); if (trans && btrfs_header_generation(eb) != trans->transid) return; if (!test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) return; percpu_counter_add_batch(&fs_info->dirty_metadata_bytes, -eb->len, fs_info->dirty_metadata_batch); if (eb->fs_info->nodesize < PAGE_SIZE) return clear_subpage_extent_buffer_dirty(eb); num_pages = num_extent_pages(eb); for (i = 0; i < num_pages; i++) { page = eb->pages[i]; if (!PageDirty(page)) continue; lock_page(page); btree_clear_page_dirty(page); unlock_page(page); } WARN_ON(atomic_read(&eb->refs) == 0); } void set_extent_buffer_dirty(struct extent_buffer *eb) { int i; int num_pages; bool was_dirty; check_buffer_tree_ref(eb); was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags); num_pages = num_extent_pages(eb); WARN_ON(atomic_read(&eb->refs) == 0); WARN_ON(!test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)); if (!was_dirty) { bool subpage = eb->fs_info->nodesize < PAGE_SIZE; /* * For subpage case, we can have other extent buffers in the * same page, and in clear_subpage_extent_buffer_dirty() we * have to clear page dirty without subpage lock held. * This can cause race where our page gets dirty cleared after * we just set it. * * Thankfully, clear_subpage_extent_buffer_dirty() has locked * its page for other reasons, we can use page lock to prevent * the above race. */ if (subpage) lock_page(eb->pages[0]); for (i = 0; i < num_pages; i++) btrfs_page_set_dirty(eb->fs_info, eb->pages[i], eb->start, eb->len); if (subpage) unlock_page(eb->pages[0]); percpu_counter_add_batch(&eb->fs_info->dirty_metadata_bytes, eb->len, eb->fs_info->dirty_metadata_batch); } #ifdef CONFIG_BTRFS_DEBUG for (i = 0; i < num_pages; i++) ASSERT(PageDirty(eb->pages[i])); #endif } void clear_extent_buffer_uptodate(struct extent_buffer *eb) { struct btrfs_fs_info *fs_info = eb->fs_info; struct page *page; int num_pages; int i; clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); num_pages = num_extent_pages(eb); for (i = 0; i < num_pages; i++) { page = eb->pages[i]; if (!page) continue; /* * This is special handling for metadata subpage, as regular * btrfs_is_subpage() can not handle cloned/dummy metadata. */ if (fs_info->nodesize >= PAGE_SIZE) ClearPageUptodate(page); else btrfs_subpage_clear_uptodate(fs_info, page, eb->start, eb->len); } } void set_extent_buffer_uptodate(struct extent_buffer *eb) { struct btrfs_fs_info *fs_info = eb->fs_info; struct page *page; int num_pages; int i; set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); num_pages = num_extent_pages(eb); for (i = 0; i < num_pages; i++) { page = eb->pages[i]; /* * This is special handling for metadata subpage, as regular * btrfs_is_subpage() can not handle cloned/dummy metadata. */ if (fs_info->nodesize >= PAGE_SIZE) SetPageUptodate(page); else btrfs_subpage_set_uptodate(fs_info, page, eb->start, eb->len); } } static void extent_buffer_read_end_io(struct btrfs_bio *bbio) { struct extent_buffer *eb = bbio->private; struct btrfs_fs_info *fs_info = eb->fs_info; bool uptodate = !bbio->bio.bi_status; struct bvec_iter_all iter_all; struct bio_vec *bvec; u32 bio_offset = 0; eb->read_mirror = bbio->mirror_num; if (uptodate && btrfs_validate_extent_buffer(eb, &bbio->parent_check) < 0) uptodate = false; if (uptodate) { set_extent_buffer_uptodate(eb); } else { clear_extent_buffer_uptodate(eb); set_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags); } bio_for_each_segment_all(bvec, &bbio->bio, iter_all) { u64 start = eb->start + bio_offset; struct page *page = bvec->bv_page; u32 len = bvec->bv_len; if (uptodate) btrfs_page_set_uptodate(fs_info, page, start, len); else btrfs_page_clear_uptodate(fs_info, page, start, len); bio_offset += len; } clear_bit(EXTENT_BUFFER_READING, &eb->bflags); smp_mb__after_atomic(); wake_up_bit(&eb->bflags, EXTENT_BUFFER_READING); free_extent_buffer(eb); bio_put(&bbio->bio); } int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num, struct btrfs_tree_parent_check *check) { int num_pages = num_extent_pages(eb), i; struct btrfs_bio *bbio; if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags)) return 0; /* * We could have had EXTENT_BUFFER_UPTODATE cleared by the write * operation, which could potentially still be in flight. In this case * we simply want to return an error. */ if (unlikely(test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags))) return -EIO; /* Someone else is already reading the buffer, just wait for it. */ if (test_and_set_bit(EXTENT_BUFFER_READING, &eb->bflags)) goto done; clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags); eb->read_mirror = 0; check_buffer_tree_ref(eb); atomic_inc(&eb->refs); bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES, REQ_OP_READ | REQ_META, eb->fs_info, extent_buffer_read_end_io, eb); bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT; bbio->inode = BTRFS_I(eb->fs_info->btree_inode); bbio->file_offset = eb->start; memcpy(&bbio->parent_check, check, sizeof(*check)); if (eb->fs_info->nodesize < PAGE_SIZE) { __bio_add_page(&bbio->bio, eb->pages[0], eb->len, eb->start - page_offset(eb->pages[0])); } else { for (i = 0; i < num_pages; i++) __bio_add_page(&bbio->bio, eb->pages[i], PAGE_SIZE, 0); } btrfs_submit_bio(bbio, mirror_num); done: if (wait == WAIT_COMPLETE) { wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_READING, TASK_UNINTERRUPTIBLE); if (!test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags)) return -EIO; } return 0; } static bool report_eb_range(const struct extent_buffer *eb, unsigned long start, unsigned long len) { btrfs_warn(eb->fs_info, "access to eb bytenr %llu len %lu out of range start %lu len %lu", eb->start, eb->len, start, len); WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG)); return true; } /* * Check if the [start, start + len) range is valid before reading/writing * the eb. * NOTE: @start and @len are offset inside the eb, not logical address. * * Caller should not touch the dst/src memory if this function returns error. */ static inline int check_eb_range(const struct extent_buffer *eb, unsigned long start, unsigned long len) { unsigned long offset; /* start, start + len should not go beyond eb->len nor overflow */ if (unlikely(check_add_overflow(start, len, &offset) || offset > eb->len)) return report_eb_range(eb, start, len); return false; } void read_extent_buffer(const struct extent_buffer *eb, void *dstv, unsigned long start, unsigned long len) { size_t cur; size_t offset; struct page *page; char *kaddr; char *dst = (char *)dstv; unsigned long i = get_eb_page_index(start); if (check_eb_range(eb, start, len)) return; offset = get_eb_offset_in_page(eb, start); while (len > 0) { page = eb->pages[i]; cur = min(len, (PAGE_SIZE - offset)); kaddr = page_address(page); memcpy(dst, kaddr + offset, cur); dst += cur; len -= cur; offset = 0; i++; } } int read_extent_buffer_to_user_nofault(const struct extent_buffer *eb, void __user *dstv, unsigned long start, unsigned long len) { size_t cur; size_t offset; struct page *page; char *kaddr; char __user *dst = (char __user *)dstv; unsigned long i = get_eb_page_index(start); int ret = 0; WARN_ON(start > eb->len); WARN_ON(start + len > eb->start + eb->len); offset = get_eb_offset_in_page(eb, start); while (len > 0) { page = eb->pages[i]; cur = min(len, (PAGE_SIZE - offset)); kaddr = page_address(page); if (copy_to_user_nofault(dst, kaddr + offset, cur)) { ret = -EFAULT; break; } dst += cur; len -= cur; offset = 0; i++; } return ret; } int memcmp_extent_buffer(const struct extent_buffer *eb, const void *ptrv, unsigned long start, unsigned long len) { size_t cur; size_t offset; struct page *page; char *kaddr; char *ptr = (char *)ptrv; unsigned long i = get_eb_page_index(start); int ret = 0; if (check_eb_range(eb, start, len)) return -EINVAL; offset = get_eb_offset_in_page(eb, start); while (len > 0) { page = eb->pages[i]; cur = min(len, (PAGE_SIZE - offset)); kaddr = page_address(page); ret = memcmp(ptr, kaddr + offset, cur); if (ret) break; ptr += cur; len -= cur; offset = 0; i++; } return ret; } /* * Check that the extent buffer is uptodate. * * For regular sector size == PAGE_SIZE case, check if @page is uptodate. * For subpage case, check if the range covered by the eb has EXTENT_UPTODATE. */ static void assert_eb_page_uptodate(const struct extent_buffer *eb, struct page *page) { struct btrfs_fs_info *fs_info = eb->fs_info; /* * If we are using the commit root we could potentially clear a page * Uptodate while we're using the extent buffer that we've previously * looked up. We don't want to complain in this case, as the page was * valid before, we just didn't write it out. Instead we want to catch * the case where we didn't actually read the block properly, which * would have !PageUptodate and !EXTENT_BUFFER_WRITE_ERR. */ if (test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags)) return; if (fs_info->nodesize < PAGE_SIZE) { if (WARN_ON(!btrfs_subpage_test_uptodate(fs_info, page, eb->start, eb->len))) btrfs_subpage_dump_bitmap(fs_info, page, eb->start, eb->len); } else { WARN_ON(!PageUptodate(page)); } } void write_extent_buffer_chunk_tree_uuid(const struct extent_buffer *eb, const void *srcv) { char *kaddr; assert_eb_page_uptodate(eb, eb->pages[0]); kaddr = page_address(eb->pages[0]) + get_eb_offset_in_page(eb, offsetof(struct btrfs_header, chunk_tree_uuid)); memcpy(kaddr, srcv, BTRFS_FSID_SIZE); } void write_extent_buffer_fsid(const struct extent_buffer *eb, const void *srcv) { char *kaddr; assert_eb_page_uptodate(eb, eb->pages[0]); kaddr = page_address(eb->pages[0]) + get_eb_offset_in_page(eb, offsetof(struct btrfs_header, fsid)); memcpy(kaddr, srcv, BTRFS_FSID_SIZE); } void write_extent_buffer(const struct extent_buffer *eb, const void *srcv, unsigned long start, unsigned long len) { size_t cur; size_t offset; struct page *page; char *kaddr; char *src = (char *)srcv; unsigned long i = get_eb_page_index(start); WARN_ON(test_bit(EXTENT_BUFFER_NO_CHECK, &eb->bflags)); if (check_eb_range(eb, start, len)) return; offset = get_eb_offset_in_page(eb, start); while (len > 0) { page = eb->pages[i]; assert_eb_page_uptodate(eb, page); cur = min(len, PAGE_SIZE - offset); kaddr = page_address(page); memcpy(kaddr + offset, src, cur); src += cur; len -= cur; offset = 0; i++; } } void memzero_extent_buffer(const struct extent_buffer *eb, unsigned long start, unsigned long len) { size_t cur; size_t offset; struct page *page; char *kaddr; unsigned long i = get_eb_page_index(start); if (check_eb_range(eb, start, len)) return; offset = get_eb_offset_in_page(eb, start); while (len > 0) { page = eb->pages[i]; assert_eb_page_uptodate(eb, page); cur = min(len, PAGE_SIZE - offset); kaddr = page_address(page); memset(kaddr + offset, 0, cur); len -= cur; offset = 0; i++; } } void copy_extent_buffer_full(const struct extent_buffer *dst, const struct extent_buffer *src) { int i; int num_pages; ASSERT(dst->len == src->len); if (dst->fs_info->nodesize >= PAGE_SIZE) { num_pages = num_extent_pages(dst); for (i = 0; i < num_pages; i++) copy_page(page_address(dst->pages[i]), page_address(src->pages[i])); } else { size_t src_offset = get_eb_offset_in_page(src, 0); size_t dst_offset = get_eb_offset_in_page(dst, 0); ASSERT(src->fs_info->nodesize < PAGE_SIZE); memcpy(page_address(dst->pages[0]) + dst_offset, page_address(src->pages[0]) + src_offset, src->len); } } void copy_extent_buffer(const struct extent_buffer *dst, const struct extent_buffer *src, unsigned long dst_offset, unsigned long src_offset, unsigned long len) { u64 dst_len = dst->len; size_t cur; size_t offset; struct page *page; char *kaddr; unsigned long i = get_eb_page_index(dst_offset); if (check_eb_range(dst, dst_offset, len) || check_eb_range(src, src_offset, len)) return; WARN_ON(src->len != dst_len); offset = get_eb_offset_in_page(dst, dst_offset); while (len > 0) { page = dst->pages[i]; assert_eb_page_uptodate(dst, page); cur = min(len, (unsigned long)(PAGE_SIZE - offset)); kaddr = page_address(page); read_extent_buffer(src, kaddr + offset, src_offset, cur); src_offset += cur; len -= cur; offset = 0; i++; } } /* * eb_bitmap_offset() - calculate the page and offset of the byte containing the * given bit number * @eb: the extent buffer * @start: offset of the bitmap item in the extent buffer * @nr: bit number * @page_index: return index of the page in the extent buffer that contains the * given bit number * @page_offset: return offset into the page given by page_index * * This helper hides the ugliness of finding the byte in an extent buffer which * contains a given bit. */ static inline void eb_bitmap_offset(const struct extent_buffer *eb, unsigned long start, unsigned long nr, unsigned long *page_index, size_t *page_offset) { size_t byte_offset = BIT_BYTE(nr); size_t offset; /* * The byte we want is the offset of the extent buffer + the offset of * the bitmap item in the extent buffer + the offset of the byte in the * bitmap item. */ offset = start + offset_in_page(eb->start) + byte_offset; *page_index = offset >> PAGE_SHIFT; *page_offset = offset_in_page(offset); } /* * Determine whether a bit in a bitmap item is set. * * @eb: the extent buffer * @start: offset of the bitmap item in the extent buffer * @nr: bit number to test */ int extent_buffer_test_bit(const struct extent_buffer *eb, unsigned long start, unsigned long nr) { u8 *kaddr; struct page *page; unsigned long i; size_t offset; eb_bitmap_offset(eb, start, nr, &i, &offset); page = eb->pages[i]; assert_eb_page_uptodate(eb, page); kaddr = page_address(page); return 1U & (kaddr[offset] >> (nr & (BITS_PER_BYTE - 1))); } /* * Set an area of a bitmap to 1. * * @eb: the extent buffer * @start: offset of the bitmap item in the extent buffer * @pos: bit number of the first bit * @len: number of bits to set */ void extent_buffer_bitmap_set(const struct extent_buffer *eb, unsigned long start, unsigned long pos, unsigned long len) { u8 *kaddr; struct page *page; unsigned long i; size_t offset; const unsigned int size = pos + len; int bits_to_set = BITS_PER_BYTE - (pos % BITS_PER_BYTE); u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(pos); eb_bitmap_offset(eb, start, pos, &i, &offset); page = eb->pages[i]; assert_eb_page_uptodate(eb, page); kaddr = page_address(page); while (len >= bits_to_set) { kaddr[offset] |= mask_to_set; len -= bits_to_set; bits_to_set = BITS_PER_BYTE; mask_to_set = ~0; if (++offset >= PAGE_SIZE && len > 0) { offset = 0; page = eb->pages[++i]; assert_eb_page_uptodate(eb, page); kaddr = page_address(page); } } if (len) { mask_to_set &= BITMAP_LAST_BYTE_MASK(size); kaddr[offset] |= mask_to_set; } } /* * Clear an area of a bitmap. * * @eb: the extent buffer * @start: offset of the bitmap item in the extent buffer * @pos: bit number of the first bit * @len: number of bits to clear */ void extent_buffer_bitmap_clear(const struct extent_buffer *eb, unsigned long start, unsigned long pos, unsigned long len) { u8 *kaddr; struct page *page; unsigned long i; size_t offset; const unsigned int size = pos + len; int bits_to_clear = BITS_PER_BYTE - (pos % BITS_PER_BYTE); u8 mask_to_clear = BITMAP_FIRST_BYTE_MASK(pos); eb_bitmap_offset(eb, start, pos, &i, &offset); page = eb->pages[i]; assert_eb_page_uptodate(eb, page); kaddr = page_address(page); while (len >= bits_to_clear) { kaddr[offset] &= ~mask_to_clear; len -= bits_to_clear; bits_to_clear = BITS_PER_BYTE; mask_to_clear = ~0; if (++offset >= PAGE_SIZE && len > 0) { offset = 0; page = eb->pages[++i]; assert_eb_page_uptodate(eb, page); kaddr = page_address(page); } } if (len) { mask_to_clear &= BITMAP_LAST_BYTE_MASK(size); kaddr[offset] &= ~mask_to_clear; } } static inline bool areas_overlap(unsigned long src, unsigned long dst, unsigned long len) { unsigned long distance = (src > dst) ? src - dst : dst - src; return distance < len; } static void copy_pages(struct page *dst_page, struct page *src_page, unsigned long dst_off, unsigned long src_off, unsigned long len) { char *dst_kaddr = page_address(dst_page); char *src_kaddr; int must_memmove = 0; if (dst_page != src_page) { src_kaddr = page_address(src_page); } else { src_kaddr = dst_kaddr; if (areas_overlap(src_off, dst_off, len)) must_memmove = 1; } if (must_memmove) memmove(dst_kaddr + dst_off, src_kaddr + src_off, len); else memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len); } void memcpy_extent_buffer(const struct extent_buffer *dst, unsigned long dst_offset, unsigned long src_offset, unsigned long len) { size_t cur; size_t dst_off_in_page; size_t src_off_in_page; unsigned long dst_i; unsigned long src_i; if (check_eb_range(dst, dst_offset, len) || check_eb_range(dst, src_offset, len)) return; while (len > 0) { dst_off_in_page = get_eb_offset_in_page(dst, dst_offset); src_off_in_page = get_eb_offset_in_page(dst, src_offset); dst_i = get_eb_page_index(dst_offset); src_i = get_eb_page_index(src_offset); cur = min(len, (unsigned long)(PAGE_SIZE - src_off_in_page)); cur = min_t(unsigned long, cur, (unsigned long)(PAGE_SIZE - dst_off_in_page)); copy_pages(dst->pages[dst_i], dst->pages[src_i], dst_off_in_page, src_off_in_page, cur); src_offset += cur; dst_offset += cur; len -= cur; } } void memmove_extent_buffer(const struct extent_buffer *dst, unsigned long dst_offset, unsigned long src_offset, unsigned long len) { size_t cur; size_t dst_off_in_page; size_t src_off_in_page; unsigned long dst_end = dst_offset + len - 1; unsigned long src_end = src_offset + len - 1; unsigned long dst_i; unsigned long src_i; if (check_eb_range(dst, dst_offset, len) || check_eb_range(dst, src_offset, len)) return; if (dst_offset < src_offset) { memcpy_extent_buffer(dst, dst_offset, src_offset, len); return; } while (len > 0) { dst_i = get_eb_page_index(dst_end); src_i = get_eb_page_index(src_end); dst_off_in_page = get_eb_offset_in_page(dst, dst_end); src_off_in_page = get_eb_offset_in_page(dst, src_end); cur = min_t(unsigned long, len, src_off_in_page + 1); cur = min(cur, dst_off_in_page + 1); copy_pages(dst->pages[dst_i], dst->pages[src_i], dst_off_in_page - cur + 1, src_off_in_page - cur + 1, cur); dst_end -= cur; src_end -= cur; len -= cur; } } #define GANG_LOOKUP_SIZE 16 static struct extent_buffer *get_next_extent_buffer( struct btrfs_fs_info *fs_info, struct page *page, u64 bytenr) { struct extent_buffer *gang[GANG_LOOKUP_SIZE]; struct extent_buffer *found = NULL; u64 page_start = page_offset(page); u64 cur = page_start; ASSERT(in_range(bytenr, page_start, PAGE_SIZE)); lockdep_assert_held(&fs_info->buffer_lock); while (cur < page_start + PAGE_SIZE) { int ret; int i; ret = radix_tree_gang_lookup(&fs_info->buffer_radix, (void **)gang, cur >> fs_info->sectorsize_bits, min_t(unsigned int, GANG_LOOKUP_SIZE, PAGE_SIZE / fs_info->nodesize)); if (ret == 0) goto out; for (i = 0; i < ret; i++) { /* Already beyond page end */ if (gang[i]->start >= page_start + PAGE_SIZE) goto out; /* Found one */ if (gang[i]->start >= bytenr) { found = gang[i]; goto out; } } cur = gang[ret - 1]->start + gang[ret - 1]->len; } out: return found; } static int try_release_subpage_extent_buffer(struct page *page) { struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb); u64 cur = page_offset(page); const u64 end = page_offset(page) + PAGE_SIZE; int ret; while (cur < end) { struct extent_buffer *eb = NULL; /* * Unlike try_release_extent_buffer() which uses page->private * to grab buffer, for subpage case we rely on radix tree, thus * we need to ensure radix tree consistency. * * We also want an atomic snapshot of the radix tree, thus go * with spinlock rather than RCU. */ spin_lock(&fs_info->buffer_lock); eb = get_next_extent_buffer(fs_info, page, cur); if (!eb) { /* No more eb in the page range after or at cur */ spin_unlock(&fs_info->buffer_lock); break; } cur = eb->start + eb->len; /* * The same as try_release_extent_buffer(), to ensure the eb * won't disappear out from under us. */ spin_lock(&eb->refs_lock); if (atomic_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) { spin_unlock(&eb->refs_lock); spin_unlock(&fs_info->buffer_lock); break; } spin_unlock(&fs_info->buffer_lock); /* * If tree ref isn't set then we know the ref on this eb is a * real ref, so just return, this eb will likely be freed soon * anyway. */ if (!test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) { spin_unlock(&eb->refs_lock); break; } /* * Here we don't care about the return value, we will always * check the page private at the end. And * release_extent_buffer() will release the refs_lock. */ release_extent_buffer(eb); } /* * Finally to check if we have cleared page private, as if we have * released all ebs in the page, the page private should be cleared now. */ spin_lock(&page->mapping->private_lock); if (!PagePrivate(page)) ret = 1; else ret = 0; spin_unlock(&page->mapping->private_lock); return ret; } int try_release_extent_buffer(struct page *page) { struct extent_buffer *eb; if (btrfs_sb(page->mapping->host->i_sb)->nodesize < PAGE_SIZE) return try_release_subpage_extent_buffer(page); /* * We need to make sure nobody is changing page->private, as we rely on * page->private as the pointer to extent buffer. */ spin_lock(&page->mapping->private_lock); if (!PagePrivate(page)) { spin_unlock(&page->mapping->private_lock); return 1; } eb = (struct extent_buffer *)page->private; BUG_ON(!eb); /* * This is a little awful but should be ok, we need to make sure that * the eb doesn't disappear out from under us while we're looking at * this page. */ spin_lock(&eb->refs_lock); if (atomic_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) { spin_unlock(&eb->refs_lock); spin_unlock(&page->mapping->private_lock); return 0; } spin_unlock(&page->mapping->private_lock); /* * If tree ref isn't set then we know the ref on this eb is a real ref, * so just return, this page will likely be freed soon anyway. */ if (!test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) { spin_unlock(&eb->refs_lock); return 0; } return release_extent_buffer(eb); } /* * btrfs_readahead_tree_block - attempt to readahead a child block * @fs_info: the fs_info * @bytenr: bytenr to read * @owner_root: objectid of the root that owns this eb * @gen: generation for the uptodate check, can be 0 * @level: level for the eb * * Attempt to readahead a tree block at @bytenr. If @gen is 0 then we do a * normal uptodate check of the eb, without checking the generation. If we have * to read the block we will not block on anything. */ void btrfs_readahead_tree_block(struct btrfs_fs_info *fs_info, u64 bytenr, u64 owner_root, u64 gen, int level) { struct btrfs_tree_parent_check check = { .has_first_key = 0, .level = level, .transid = gen }; struct extent_buffer *eb; int ret; eb = btrfs_find_create_tree_block(fs_info, bytenr, owner_root, level); if (IS_ERR(eb)) return; if (btrfs_buffer_uptodate(eb, gen, 1)) { free_extent_buffer(eb); return; } ret = read_extent_buffer_pages(eb, WAIT_NONE, 0, &check); if (ret < 0) free_extent_buffer_stale(eb); else free_extent_buffer(eb); } /* * btrfs_readahead_node_child - readahead a node's child block * @node: parent node we're reading from * @slot: slot in the parent node for the child we want to read * * A helper for btrfs_readahead_tree_block, we simply read the bytenr pointed at * the slot in the node provided. */ void btrfs_readahead_node_child(struct extent_buffer *node, int slot) { btrfs_readahead_tree_block(node->fs_info, btrfs_node_blockptr(node, slot), btrfs_header_owner(node), btrfs_node_ptr_generation(node, slot), btrfs_header_level(node) - 1); }