494 lines
16 KiB
C
494 lines
16 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* include/linux/buffer_head.h
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*
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* Everything to do with buffer_heads.
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*/
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#ifndef _LINUX_BUFFER_HEAD_H
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#define _LINUX_BUFFER_HEAD_H
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#include <linux/types.h>
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#include <linux/blk_types.h>
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#include <linux/fs.h>
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#include <linux/linkage.h>
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#include <linux/pagemap.h>
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#include <linux/wait.h>
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#include <linux/atomic.h>
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#ifdef CONFIG_BLOCK
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enum bh_state_bits {
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BH_Uptodate, /* Contains valid data */
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BH_Dirty, /* Is dirty */
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BH_Lock, /* Is locked */
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BH_Req, /* Has been submitted for I/O */
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BH_Mapped, /* Has a disk mapping */
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BH_New, /* Disk mapping was newly created by get_block */
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BH_Async_Read, /* Is under end_buffer_async_read I/O */
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BH_Async_Write, /* Is under end_buffer_async_write I/O */
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BH_Delay, /* Buffer is not yet allocated on disk */
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BH_Boundary, /* Block is followed by a discontiguity */
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BH_Write_EIO, /* I/O error on write */
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BH_Unwritten, /* Buffer is allocated on disk but not written */
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BH_Quiet, /* Buffer Error Prinks to be quiet */
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BH_Meta, /* Buffer contains metadata */
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BH_Prio, /* Buffer should be submitted with REQ_PRIO */
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BH_Defer_Completion, /* Defer AIO completion to workqueue */
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BH_PrivateStart,/* not a state bit, but the first bit available
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* for private allocation by other entities
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*/
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};
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#define MAX_BUF_PER_PAGE (PAGE_SIZE / 512)
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struct page;
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struct buffer_head;
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struct address_space;
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typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
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/*
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* Historically, a buffer_head was used to map a single block
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* within a page, and of course as the unit of I/O through the
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* filesystem and block layers. Nowadays the basic I/O unit
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* is the bio, and buffer_heads are used for extracting block
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* mappings (via a get_block_t call), for tracking state within
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* a page (via a page_mapping) and for wrapping bio submission
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* for backward compatibility reasons (e.g. submit_bh).
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*/
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struct buffer_head {
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unsigned long b_state; /* buffer state bitmap (see above) */
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struct buffer_head *b_this_page;/* circular list of page's buffers */
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union {
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struct page *b_page; /* the page this bh is mapped to */
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struct folio *b_folio; /* the folio this bh is mapped to */
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};
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sector_t b_blocknr; /* start block number */
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size_t b_size; /* size of mapping */
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char *b_data; /* pointer to data within the page */
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struct block_device *b_bdev;
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bh_end_io_t *b_end_io; /* I/O completion */
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void *b_private; /* reserved for b_end_io */
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struct list_head b_assoc_buffers; /* associated with another mapping */
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struct address_space *b_assoc_map; /* mapping this buffer is
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associated with */
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atomic_t b_count; /* users using this buffer_head */
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spinlock_t b_uptodate_lock; /* Used by the first bh in a page, to
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* serialise IO completion of other
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* buffers in the page */
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};
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/*
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* macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
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* and buffer_foo() functions.
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* To avoid reset buffer flags that are already set, because that causes
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* a costly cache line transition, check the flag first.
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*/
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#define BUFFER_FNS(bit, name) \
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static __always_inline void set_buffer_##name(struct buffer_head *bh) \
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{ \
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if (!test_bit(BH_##bit, &(bh)->b_state)) \
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set_bit(BH_##bit, &(bh)->b_state); \
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} \
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static __always_inline void clear_buffer_##name(struct buffer_head *bh) \
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{ \
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clear_bit(BH_##bit, &(bh)->b_state); \
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} \
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static __always_inline int buffer_##name(const struct buffer_head *bh) \
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{ \
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return test_bit(BH_##bit, &(bh)->b_state); \
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}
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/*
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* test_set_buffer_foo() and test_clear_buffer_foo()
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*/
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#define TAS_BUFFER_FNS(bit, name) \
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static __always_inline int test_set_buffer_##name(struct buffer_head *bh) \
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{ \
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return test_and_set_bit(BH_##bit, &(bh)->b_state); \
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} \
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static __always_inline int test_clear_buffer_##name(struct buffer_head *bh) \
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{ \
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return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
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} \
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/*
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* Emit the buffer bitops functions. Note that there are also functions
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* of the form "mark_buffer_foo()". These are higher-level functions which
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* do something in addition to setting a b_state bit.
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*/
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BUFFER_FNS(Dirty, dirty)
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TAS_BUFFER_FNS(Dirty, dirty)
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BUFFER_FNS(Lock, locked)
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BUFFER_FNS(Req, req)
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TAS_BUFFER_FNS(Req, req)
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BUFFER_FNS(Mapped, mapped)
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BUFFER_FNS(New, new)
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BUFFER_FNS(Async_Read, async_read)
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BUFFER_FNS(Async_Write, async_write)
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BUFFER_FNS(Delay, delay)
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BUFFER_FNS(Boundary, boundary)
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BUFFER_FNS(Write_EIO, write_io_error)
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BUFFER_FNS(Unwritten, unwritten)
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BUFFER_FNS(Meta, meta)
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BUFFER_FNS(Prio, prio)
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BUFFER_FNS(Defer_Completion, defer_completion)
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static __always_inline void set_buffer_uptodate(struct buffer_head *bh)
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{
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/*
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* If somebody else already set this uptodate, they will
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* have done the memory barrier, and a reader will thus
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* see *some* valid buffer state.
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*
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* Any other serialization (with IO errors or whatever that
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* might clear the bit) has to come from other state (eg BH_Lock).
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*/
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if (test_bit(BH_Uptodate, &bh->b_state))
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return;
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/*
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* make it consistent with folio_mark_uptodate
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* pairs with smp_load_acquire in buffer_uptodate
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*/
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smp_mb__before_atomic();
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set_bit(BH_Uptodate, &bh->b_state);
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}
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static __always_inline void clear_buffer_uptodate(struct buffer_head *bh)
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{
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clear_bit(BH_Uptodate, &bh->b_state);
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}
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static __always_inline int buffer_uptodate(const struct buffer_head *bh)
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{
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/*
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* make it consistent with folio_test_uptodate
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* pairs with smp_mb__before_atomic in set_buffer_uptodate
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*/
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return test_bit_acquire(BH_Uptodate, &bh->b_state);
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}
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#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
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/* If we *know* page->private refers to buffer_heads */
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#define page_buffers(page) \
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({ \
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BUG_ON(!PagePrivate(page)); \
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((struct buffer_head *)page_private(page)); \
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})
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#define page_has_buffers(page) PagePrivate(page)
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#define folio_buffers(folio) folio_get_private(folio)
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void buffer_check_dirty_writeback(struct folio *folio,
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bool *dirty, bool *writeback);
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/*
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* Declarations
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*/
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void mark_buffer_dirty(struct buffer_head *bh);
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void mark_buffer_write_io_error(struct buffer_head *bh);
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void touch_buffer(struct buffer_head *bh);
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void set_bh_page(struct buffer_head *bh,
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struct page *page, unsigned long offset);
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void folio_set_bh(struct buffer_head *bh, struct folio *folio,
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unsigned long offset);
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bool try_to_free_buffers(struct folio *);
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struct buffer_head *folio_alloc_buffers(struct folio *folio, unsigned long size,
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bool retry);
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struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
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bool retry);
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void create_empty_buffers(struct page *, unsigned long,
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unsigned long b_state);
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void folio_create_empty_buffers(struct folio *folio, unsigned long blocksize,
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unsigned long b_state);
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void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
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void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
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void end_buffer_async_write(struct buffer_head *bh, int uptodate);
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/* Things to do with buffers at mapping->private_list */
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void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
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int inode_has_buffers(struct inode *);
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void invalidate_inode_buffers(struct inode *);
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int remove_inode_buffers(struct inode *inode);
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int sync_mapping_buffers(struct address_space *mapping);
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int generic_buffers_fsync_noflush(struct file *file, loff_t start, loff_t end,
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bool datasync);
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int generic_buffers_fsync(struct file *file, loff_t start, loff_t end,
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bool datasync);
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void clean_bdev_aliases(struct block_device *bdev, sector_t block,
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sector_t len);
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static inline void clean_bdev_bh_alias(struct buffer_head *bh)
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{
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clean_bdev_aliases(bh->b_bdev, bh->b_blocknr, 1);
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}
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void mark_buffer_async_write(struct buffer_head *bh);
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void __wait_on_buffer(struct buffer_head *);
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wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
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struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
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unsigned size);
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struct buffer_head *__getblk_gfp(struct block_device *bdev, sector_t block,
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unsigned size, gfp_t gfp);
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void __brelse(struct buffer_head *);
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void __bforget(struct buffer_head *);
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void __breadahead(struct block_device *, sector_t block, unsigned int size);
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struct buffer_head *__bread_gfp(struct block_device *,
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sector_t block, unsigned size, gfp_t gfp);
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void invalidate_bh_lrus(void);
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void invalidate_bh_lrus_cpu(void);
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bool has_bh_in_lru(int cpu, void *dummy);
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struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
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void free_buffer_head(struct buffer_head * bh);
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void unlock_buffer(struct buffer_head *bh);
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void __lock_buffer(struct buffer_head *bh);
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int sync_dirty_buffer(struct buffer_head *bh);
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int __sync_dirty_buffer(struct buffer_head *bh, blk_opf_t op_flags);
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void write_dirty_buffer(struct buffer_head *bh, blk_opf_t op_flags);
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void submit_bh(blk_opf_t, struct buffer_head *);
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void write_boundary_block(struct block_device *bdev,
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sector_t bblock, unsigned blocksize);
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int bh_uptodate_or_lock(struct buffer_head *bh);
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int __bh_read(struct buffer_head *bh, blk_opf_t op_flags, bool wait);
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void __bh_read_batch(int nr, struct buffer_head *bhs[],
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blk_opf_t op_flags, bool force_lock);
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extern int buffer_heads_over_limit;
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/*
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* Generic address_space_operations implementations for buffer_head-backed
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* address_spaces.
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*/
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void block_invalidate_folio(struct folio *folio, size_t offset, size_t length);
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int block_write_full_page(struct page *page, get_block_t *get_block,
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struct writeback_control *wbc);
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int __block_write_full_folio(struct inode *inode, struct folio *folio,
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get_block_t *get_block, struct writeback_control *wbc,
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bh_end_io_t *handler);
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int block_read_full_folio(struct folio *, get_block_t *);
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bool block_is_partially_uptodate(struct folio *, size_t from, size_t count);
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int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
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struct page **pagep, get_block_t *get_block);
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int __block_write_begin(struct page *page, loff_t pos, unsigned len,
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get_block_t *get_block);
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int block_write_end(struct file *, struct address_space *,
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loff_t, unsigned, unsigned,
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struct page *, void *);
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int generic_write_end(struct file *, struct address_space *,
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loff_t, unsigned, unsigned,
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struct page *, void *);
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void folio_zero_new_buffers(struct folio *folio, size_t from, size_t to);
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void clean_page_buffers(struct page *page);
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int cont_write_begin(struct file *, struct address_space *, loff_t,
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unsigned, struct page **, void **,
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get_block_t *, loff_t *);
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int generic_cont_expand_simple(struct inode *inode, loff_t size);
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int block_commit_write(struct page *page, unsigned from, unsigned to);
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int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
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get_block_t get_block);
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/* Convert errno to return value from ->page_mkwrite() call */
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static inline vm_fault_t block_page_mkwrite_return(int err)
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{
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if (err == 0)
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return VM_FAULT_LOCKED;
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if (err == -EFAULT || err == -EAGAIN)
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return VM_FAULT_NOPAGE;
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if (err == -ENOMEM)
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return VM_FAULT_OOM;
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/* -ENOSPC, -EDQUOT, -EIO ... */
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return VM_FAULT_SIGBUS;
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}
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sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
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int block_truncate_page(struct address_space *, loff_t, get_block_t *);
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#ifdef CONFIG_MIGRATION
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extern int buffer_migrate_folio(struct address_space *,
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struct folio *dst, struct folio *src, enum migrate_mode);
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extern int buffer_migrate_folio_norefs(struct address_space *,
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struct folio *dst, struct folio *src, enum migrate_mode);
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#else
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#define buffer_migrate_folio NULL
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#define buffer_migrate_folio_norefs NULL
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#endif
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void buffer_init(void);
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/*
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* inline definitions
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*/
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static inline void get_bh(struct buffer_head *bh)
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{
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atomic_inc(&bh->b_count);
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}
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static inline void put_bh(struct buffer_head *bh)
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{
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smp_mb__before_atomic();
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atomic_dec(&bh->b_count);
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}
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static inline void brelse(struct buffer_head *bh)
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{
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if (bh)
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__brelse(bh);
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}
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static inline void bforget(struct buffer_head *bh)
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{
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if (bh)
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__bforget(bh);
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}
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static inline struct buffer_head *
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sb_bread(struct super_block *sb, sector_t block)
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{
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return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
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}
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static inline struct buffer_head *
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sb_bread_unmovable(struct super_block *sb, sector_t block)
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{
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return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
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}
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static inline void
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sb_breadahead(struct super_block *sb, sector_t block)
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{
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__breadahead(sb->s_bdev, block, sb->s_blocksize);
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}
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static inline struct buffer_head *
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sb_getblk(struct super_block *sb, sector_t block)
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{
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return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
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}
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static inline struct buffer_head *
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sb_getblk_gfp(struct super_block *sb, sector_t block, gfp_t gfp)
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{
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return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, gfp);
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}
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static inline struct buffer_head *
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sb_find_get_block(struct super_block *sb, sector_t block)
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{
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return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
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}
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static inline void
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map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
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{
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set_buffer_mapped(bh);
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bh->b_bdev = sb->s_bdev;
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bh->b_blocknr = block;
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bh->b_size = sb->s_blocksize;
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}
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static inline void wait_on_buffer(struct buffer_head *bh)
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{
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might_sleep();
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if (buffer_locked(bh))
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__wait_on_buffer(bh);
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}
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static inline int trylock_buffer(struct buffer_head *bh)
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{
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return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
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}
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static inline void lock_buffer(struct buffer_head *bh)
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{
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might_sleep();
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if (!trylock_buffer(bh))
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__lock_buffer(bh);
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}
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static inline struct buffer_head *getblk_unmovable(struct block_device *bdev,
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sector_t block,
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unsigned size)
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{
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return __getblk_gfp(bdev, block, size, 0);
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}
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static inline struct buffer_head *__getblk(struct block_device *bdev,
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sector_t block,
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unsigned size)
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{
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return __getblk_gfp(bdev, block, size, __GFP_MOVABLE);
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}
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static inline void bh_readahead(struct buffer_head *bh, blk_opf_t op_flags)
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{
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if (!buffer_uptodate(bh) && trylock_buffer(bh)) {
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if (!buffer_uptodate(bh))
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__bh_read(bh, op_flags, false);
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else
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unlock_buffer(bh);
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}
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}
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static inline void bh_read_nowait(struct buffer_head *bh, blk_opf_t op_flags)
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{
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if (!bh_uptodate_or_lock(bh))
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__bh_read(bh, op_flags, false);
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}
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/* Returns 1 if buffer uptodated, 0 on success, and -EIO on error. */
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static inline int bh_read(struct buffer_head *bh, blk_opf_t op_flags)
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{
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if (bh_uptodate_or_lock(bh))
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return 1;
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return __bh_read(bh, op_flags, true);
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}
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static inline void bh_read_batch(int nr, struct buffer_head *bhs[])
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{
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__bh_read_batch(nr, bhs, 0, true);
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}
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static inline void bh_readahead_batch(int nr, struct buffer_head *bhs[],
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blk_opf_t op_flags)
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{
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__bh_read_batch(nr, bhs, op_flags, false);
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}
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/**
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* __bread() - reads a specified block and returns the bh
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* @bdev: the block_device to read from
|
|
* @block: number of block
|
|
* @size: size (in bytes) to read
|
|
*
|
|
* Reads a specified block, and returns buffer head that contains it.
|
|
* The page cache is allocated from movable area so that it can be migrated.
|
|
* It returns NULL if the block was unreadable.
|
|
*/
|
|
static inline struct buffer_head *
|
|
__bread(struct block_device *bdev, sector_t block, unsigned size)
|
|
{
|
|
return __bread_gfp(bdev, block, size, __GFP_MOVABLE);
|
|
}
|
|
|
|
bool block_dirty_folio(struct address_space *mapping, struct folio *folio);
|
|
|
|
#else /* CONFIG_BLOCK */
|
|
|
|
static inline void buffer_init(void) {}
|
|
static inline bool try_to_free_buffers(struct folio *folio) { return true; }
|
|
static inline int inode_has_buffers(struct inode *inode) { return 0; }
|
|
static inline void invalidate_inode_buffers(struct inode *inode) {}
|
|
static inline int remove_inode_buffers(struct inode *inode) { return 1; }
|
|
static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
|
|
static inline void invalidate_bh_lrus_cpu(void) {}
|
|
static inline bool has_bh_in_lru(int cpu, void *dummy) { return false; }
|
|
#define buffer_heads_over_limit 0
|
|
|
|
#endif /* CONFIG_BLOCK */
|
|
#endif /* _LINUX_BUFFER_HEAD_H */
|