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ee4cdf7ba8
Improve the efficiency of buffered reads in a number of ways:
(1) Overhaul the algorithm in general so that it's a lot more compact and
split the read submission code between buffered and unbuffered
versions. The unbuffered version can be vastly simplified.
(2) Read-result collection is handed off to a work queue rather than being
done in the I/O thread. Multiple subrequests can be processes
simultaneously.
(3) When a subrequest is collected, any folios it fully spans are
collected and "spare" data on either side is donated to either the
previous or the next subrequest in the sequence.
Notes:
(*) Readahead expansion is massively slows down fio, presumably because it
causes a load of extra allocations, both folio and xarray, up front
before RPC requests can be transmitted.
(*) RDMA with cifs does appear to work, both with SIW and RXE.
(*) PG_private_2-based reading and copy-to-cache is split out into its own
file and altered to use folio_queue. Note that the copy to the cache
now creates a new write transaction against the cache and adds the
folios to be copied into it. This allows it to use part of the
writeback I/O code.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20240814203850.2240469-20-dhowells@redhat.com/ # v2
Signed-off-by: Christian Brauner <brauner@kernel.org>
201 lines
6.5 KiB
C
201 lines
6.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/* NFS filesystem cache interface definitions
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*
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* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#ifndef _NFS_FSCACHE_H
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#define _NFS_FSCACHE_H
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#include <linux/swap.h>
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#include <linux/nfs_fs.h>
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#include <linux/nfs_mount.h>
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#include <linux/nfs4_mount.h>
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#include <linux/fscache.h>
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#include <linux/iversion.h>
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#ifdef CONFIG_NFS_FSCACHE
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/*
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* Definition of the auxiliary data attached to NFS inode storage objects
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* within the cache.
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*
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* The contents of this struct are recorded in the on-disk local cache in the
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* auxiliary data attached to the data storage object backing an inode. This
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* permits coherency to be managed when a new inode binds to an already extant
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* cache object.
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*/
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struct nfs_fscache_inode_auxdata {
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s64 mtime_sec;
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s64 mtime_nsec;
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s64 ctime_sec;
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s64 ctime_nsec;
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u64 change_attr;
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};
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struct nfs_netfs_io_data {
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/*
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* NFS may split a netfs_io_subrequest into multiple RPCs, each
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* with their own read completion. In netfs, we can only call
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* netfs_subreq_terminated() once for each subrequest. Use the
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* refcount here to double as a marker of the last RPC completion,
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* and only call netfs via netfs_subreq_terminated() once.
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*/
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refcount_t refcount;
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struct netfs_io_subrequest *sreq;
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/*
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* Final disposition of the netfs_io_subrequest, sent in
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* netfs_subreq_terminated()
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*/
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atomic64_t transferred;
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int error;
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};
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static inline void nfs_netfs_get(struct nfs_netfs_io_data *netfs)
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{
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refcount_inc(&netfs->refcount);
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}
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static inline void nfs_netfs_put(struct nfs_netfs_io_data *netfs)
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{
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/* Only the last RPC completion should call netfs_subreq_terminated() */
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if (!refcount_dec_and_test(&netfs->refcount))
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return;
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/*
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* The NFS pageio interface may read a complete page, even when netfs
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* only asked for a partial page. Specifically, this may be seen when
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* one thread is truncating a file while another one is reading the last
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* page of the file.
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* Correct the final length here to be no larger than the netfs subrequest
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* length, and thus avoid netfs's "Subreq overread" warning message.
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*/
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netfs->sreq->transferred = min_t(s64, netfs->sreq->len,
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atomic64_read(&netfs->transferred));
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netfs_read_subreq_terminated(netfs->sreq, netfs->error, false);
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kfree(netfs);
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}
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static inline void nfs_netfs_inode_init(struct nfs_inode *nfsi)
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{
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netfs_inode_init(&nfsi->netfs, &nfs_netfs_ops, false);
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}
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extern void nfs_netfs_initiate_read(struct nfs_pgio_header *hdr);
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extern void nfs_netfs_read_completion(struct nfs_pgio_header *hdr);
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extern int nfs_netfs_folio_unlock(struct folio *folio);
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/*
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* fscache.c
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*/
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extern int nfs_fscache_get_super_cookie(struct super_block *, const char *, int);
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extern void nfs_fscache_release_super_cookie(struct super_block *);
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extern void nfs_fscache_init_inode(struct inode *);
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extern void nfs_fscache_clear_inode(struct inode *);
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extern void nfs_fscache_open_file(struct inode *, struct file *);
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extern void nfs_fscache_release_file(struct inode *, struct file *);
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extern int nfs_netfs_readahead(struct readahead_control *ractl);
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extern int nfs_netfs_read_folio(struct file *file, struct folio *folio);
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static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
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{
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if (folio_test_private_2(folio)) { /* [DEPRECATED] */
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if (current_is_kswapd() || !(gfp & __GFP_FS))
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return false;
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folio_wait_private_2(folio);
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}
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fscache_note_page_release(netfs_i_cookie(netfs_inode(folio->mapping->host)));
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return true;
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}
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static inline void nfs_fscache_update_auxdata(struct nfs_fscache_inode_auxdata *auxdata,
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struct inode *inode)
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{
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memset(auxdata, 0, sizeof(*auxdata));
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auxdata->mtime_sec = inode_get_mtime(inode).tv_sec;
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auxdata->mtime_nsec = inode_get_mtime(inode).tv_nsec;
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auxdata->ctime_sec = inode_get_ctime(inode).tv_sec;
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auxdata->ctime_nsec = inode_get_ctime(inode).tv_nsec;
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if (NFS_SERVER(inode)->nfs_client->rpc_ops->version == 4)
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auxdata->change_attr = inode_peek_iversion_raw(inode);
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}
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/*
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* Invalidate the contents of fscache for this inode. This will not sleep.
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*/
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static inline void nfs_fscache_invalidate(struct inode *inode, int flags)
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{
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struct nfs_fscache_inode_auxdata auxdata;
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struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
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nfs_fscache_update_auxdata(&auxdata, inode);
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fscache_invalidate(cookie, &auxdata, i_size_read(inode), flags);
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}
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/*
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* indicate the client caching state as readable text
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*/
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static inline const char *nfs_server_fscache_state(struct nfs_server *server)
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{
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if (server->fscache)
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return "yes";
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return "no ";
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}
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static inline void nfs_netfs_set_pgio_header(struct nfs_pgio_header *hdr,
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struct nfs_pageio_descriptor *desc)
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{
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hdr->netfs = desc->pg_netfs;
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}
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static inline void nfs_netfs_set_pageio_descriptor(struct nfs_pageio_descriptor *desc,
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struct nfs_pgio_header *hdr)
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{
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desc->pg_netfs = hdr->netfs;
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}
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static inline void nfs_netfs_reset_pageio_descriptor(struct nfs_pageio_descriptor *desc)
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{
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desc->pg_netfs = NULL;
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}
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#else /* CONFIG_NFS_FSCACHE */
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static inline void nfs_netfs_inode_init(struct nfs_inode *nfsi) {}
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static inline void nfs_netfs_initiate_read(struct nfs_pgio_header *hdr) {}
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static inline void nfs_netfs_read_completion(struct nfs_pgio_header *hdr) {}
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static inline int nfs_netfs_folio_unlock(struct folio *folio)
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{
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return 1;
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}
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static inline void nfs_fscache_release_super_cookie(struct super_block *sb) {}
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static inline void nfs_fscache_init_inode(struct inode *inode) {}
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static inline void nfs_fscache_clear_inode(struct inode *inode) {}
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static inline void nfs_fscache_open_file(struct inode *inode,
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struct file *filp) {}
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static inline void nfs_fscache_release_file(struct inode *inode, struct file *file) {}
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static inline int nfs_netfs_readahead(struct readahead_control *ractl)
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{
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return -ENOBUFS;
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}
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static inline int nfs_netfs_read_folio(struct file *file, struct folio *folio)
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{
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return -ENOBUFS;
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}
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static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
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{
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return true; /* may release folio */
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}
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static inline void nfs_fscache_invalidate(struct inode *inode, int flags) {}
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static inline const char *nfs_server_fscache_state(struct nfs_server *server)
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{
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return "no ";
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}
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static inline void nfs_netfs_set_pgio_header(struct nfs_pgio_header *hdr,
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struct nfs_pageio_descriptor *desc) {}
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static inline void nfs_netfs_set_pageio_descriptor(struct nfs_pageio_descriptor *desc,
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struct nfs_pgio_header *hdr) {}
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static inline void nfs_netfs_reset_pageio_descriptor(struct nfs_pageio_descriptor *desc) {}
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#endif /* CONFIG_NFS_FSCACHE */
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#endif /* _NFS_FSCACHE_H */
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