linux-zen-desktop/fs/nfs/read.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * linux/fs/nfs/read.c
 *
 * Block I/O for NFS
 *
 * Partial copy of Linus' read cache modifications to fs/nfs/file.c
 * modified for async RPC by okir@monad.swb.de
 */

#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/pagemap.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_page.h>
#include <linux/module.h>

#include "nfs4_fs.h"
#include "internal.h"
#include "iostat.h"
#include "fscache.h"
#include "pnfs.h"
#include "nfstrace.h"

#define NFSDBG_FACILITY		NFSDBG_PAGECACHE

static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
static const struct nfs_rw_ops nfs_rw_read_ops;

static struct kmem_cache *nfs_rdata_cachep;

static struct nfs_pgio_header *nfs_readhdr_alloc(void)
{
	struct nfs_pgio_header *p = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL);

	if (p)
		p->rw_mode = FMODE_READ;
	return p;
}

static void nfs_readhdr_free(struct nfs_pgio_header *rhdr)
{
	kmem_cache_free(nfs_rdata_cachep, rhdr);
}

static int nfs_return_empty_folio(struct folio *folio)
{
	folio_zero_segment(folio, 0, folio_size(folio));
	folio_mark_uptodate(folio);
	folio_unlock(folio);
	return 0;
}

void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
			      struct inode *inode, bool force_mds,
			      const struct nfs_pgio_completion_ops *compl_ops)
{
	struct nfs_server *server = NFS_SERVER(inode);
	const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;

#ifdef CONFIG_NFS_V4_1
	if (server->pnfs_curr_ld && !force_mds)
		pg_ops = server->pnfs_curr_ld->pg_read_ops;
#endif
	nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops,
			server->rsize, 0);
}
EXPORT_SYMBOL_GPL(nfs_pageio_init_read);

static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
{
	struct nfs_pgio_mirror *pgm;
	unsigned long npages;

	nfs_pageio_complete(pgio);

	/* It doesn't make sense to do mirrored reads! */
	WARN_ON_ONCE(pgio->pg_mirror_count != 1);

	pgm = &pgio->pg_mirrors[0];
	NFS_I(pgio->pg_inode)->read_io += pgm->pg_bytes_written;
	npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> PAGE_SHIFT;
	nfs_add_stats(pgio->pg_inode, NFSIOS_READPAGES, npages);
}


void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
{
	struct nfs_pgio_mirror *mirror;

	if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
		pgio->pg_ops->pg_cleanup(pgio);

	pgio->pg_ops = &nfs_pgio_rw_ops;

	/* read path should never have more than one mirror */
	WARN_ON_ONCE(pgio->pg_mirror_count != 1);

	mirror = &pgio->pg_mirrors[0];
	mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize;
}
EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);

static void nfs_readpage_release(struct nfs_page *req, int error)
{
	struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
	struct folio *folio = nfs_page_to_folio(req);

	dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
		(unsigned long long)NFS_FILEID(inode), req->wb_bytes,
		(long long)req_offset(req));

	if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
		folio_set_error(folio);
	if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
		if (folio_test_uptodate(folio))
			nfs_fscache_write_page(inode, &folio->page);
		folio_unlock(folio);
	}
	nfs_release_request(req);
}

struct nfs_readdesc {
	struct nfs_pageio_descriptor pgio;
	struct nfs_open_context *ctx;
};

static void nfs_page_group_set_uptodate(struct nfs_page *req)
{
	if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
		folio_mark_uptodate(nfs_page_to_folio(req));
}

static void nfs_read_completion(struct nfs_pgio_header *hdr)
{
	unsigned long bytes = 0;
	int error;

	if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
		goto out;
	while (!list_empty(&hdr->pages)) {
		struct nfs_page *req = nfs_list_entry(hdr->pages.next);
		struct folio *folio = nfs_page_to_folio(req);