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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>
378 lines
10 KiB
C
378 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* NFS filesystem cache interface
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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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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/nfs_fs.h>
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#include <linux/nfs_fs_sb.h>
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#include <linux/in6.h>
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#include <linux/seq_file.h>
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#include <linux/slab.h>
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#include <linux/iversion.h>
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#include <linux/xarray.h>
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#include <linux/fscache.h>
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#include <linux/netfs.h>
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#include "internal.h"
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#include "iostat.h"
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#include "fscache.h"
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#include "nfstrace.h"
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#define NFS_MAX_KEY_LEN 1000
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static bool nfs_append_int(char *key, int *_len, unsigned long long x)
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{
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if (*_len > NFS_MAX_KEY_LEN)
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return false;
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if (x == 0)
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key[(*_len)++] = ',';
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else
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*_len += sprintf(key + *_len, ",%llx", x);
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return true;
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}
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/*
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* Get the per-client index cookie for an NFS client if the appropriate mount
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* flag was set
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* - We always try and get an index cookie for the client, but get filehandle
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* cookies on a per-superblock basis, depending on the mount flags
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*/
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static bool nfs_fscache_get_client_key(struct nfs_client *clp,
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char *key, int *_len)
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{
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const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) &clp->cl_addr;
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const struct sockaddr_in *sin = (struct sockaddr_in *) &clp->cl_addr;
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*_len += snprintf(key + *_len, NFS_MAX_KEY_LEN - *_len,
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",%u.%u,%x",
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clp->rpc_ops->version,
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clp->cl_minorversion,
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clp->cl_addr.ss_family);
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switch (clp->cl_addr.ss_family) {
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case AF_INET:
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if (!nfs_append_int(key, _len, sin->sin_port) ||
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!nfs_append_int(key, _len, sin->sin_addr.s_addr))
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return false;
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return true;
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case AF_INET6:
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if (!nfs_append_int(key, _len, sin6->sin6_port) ||
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!nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[0]) ||
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!nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[1]) ||
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!nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[2]) ||
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!nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[3]))
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return false;
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return true;
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default:
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printk(KERN_WARNING "NFS: Unknown network family '%d'\n",
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clp->cl_addr.ss_family);
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return false;
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}
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}
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/*
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* Get the cache cookie for an NFS superblock.
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*
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* The default uniquifier is just an empty string, but it may be overridden
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* either by the 'fsc=xxx' option to mount, or by inheriting it from the parent
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* superblock across an automount point of some nature.
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*/
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int nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq, int ulen)
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{
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struct fscache_volume *vcookie;
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struct nfs_server *nfss = NFS_SB(sb);
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unsigned int len = 3;
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char *key;
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if (uniq) {
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nfss->fscache_uniq = kmemdup_nul(uniq, ulen, GFP_KERNEL);
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if (!nfss->fscache_uniq)
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return -ENOMEM;
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}
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key = kmalloc(NFS_MAX_KEY_LEN + 24, GFP_KERNEL);
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if (!key)
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return -ENOMEM;
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memcpy(key, "nfs", 3);
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if (!nfs_fscache_get_client_key(nfss->nfs_client, key, &len) ||
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!nfs_append_int(key, &len, nfss->fsid.major) ||
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!nfs_append_int(key, &len, nfss->fsid.minor) ||
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!nfs_append_int(key, &len, sb->s_flags & NFS_SB_MASK) ||
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!nfs_append_int(key, &len, nfss->flags) ||
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!nfs_append_int(key, &len, nfss->rsize) ||
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!nfs_append_int(key, &len, nfss->wsize) ||
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!nfs_append_int(key, &len, nfss->acregmin) ||
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!nfs_append_int(key, &len, nfss->acregmax) ||
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!nfs_append_int(key, &len, nfss->acdirmin) ||
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!nfs_append_int(key, &len, nfss->acdirmax) ||
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!nfs_append_int(key, &len, nfss->client->cl_auth->au_flavor))
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goto out;
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if (ulen > 0) {
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if (ulen > NFS_MAX_KEY_LEN - len)
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goto out;
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key[len++] = ',';
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memcpy(key + len, uniq, ulen);
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len += ulen;
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}
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key[len] = 0;
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/* create a cache index for looking up filehandles */
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vcookie = fscache_acquire_volume(key,
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NULL, /* preferred_cache */
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NULL, 0 /* coherency_data */);
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if (IS_ERR(vcookie)) {
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if (vcookie != ERR_PTR(-EBUSY)) {
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kfree(key);
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return PTR_ERR(vcookie);
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}
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pr_err("NFS: Cache volume key already in use (%s)\n", key);
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vcookie = NULL;
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}
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nfss->fscache = vcookie;
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out:
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kfree(key);
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return 0;
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}
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/*
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* release a per-superblock cookie
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*/
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void nfs_fscache_release_super_cookie(struct super_block *sb)
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{
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struct nfs_server *nfss = NFS_SB(sb);
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fscache_relinquish_volume(nfss->fscache, NULL, false);
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nfss->fscache = NULL;
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kfree(nfss->fscache_uniq);
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}
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/*
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* Initialise the per-inode cache cookie pointer for an NFS inode.
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*/
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void nfs_fscache_init_inode(struct inode *inode)
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{
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struct nfs_fscache_inode_auxdata auxdata;
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struct nfs_server *nfss = NFS_SERVER(inode);
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struct nfs_inode *nfsi = NFS_I(inode);
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netfs_inode(inode)->cache = NULL;
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if (!(nfss->fscache && S_ISREG(inode->i_mode)))
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return;
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nfs_fscache_update_auxdata(&auxdata, inode);
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netfs_inode(inode)->cache = fscache_acquire_cookie(
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nfss->fscache,
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0,
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nfsi->fh.data, /* index_key */
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nfsi->fh.size,
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&auxdata, /* aux_data */
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sizeof(auxdata),
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i_size_read(inode));
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if (netfs_inode(inode)->cache)
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mapping_set_release_always(inode->i_mapping);
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}
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/*
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* Release a per-inode cookie.
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*/
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void nfs_fscache_clear_inode(struct inode *inode)
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{
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fscache_relinquish_cookie(netfs_i_cookie(netfs_inode(inode)), false);
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netfs_inode(inode)->cache = NULL;
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}
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/*
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* Enable or disable caching for a file that is being opened as appropriate.
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* The cookie is allocated when the inode is initialised, but is not enabled at
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* that time. Enablement is deferred to file-open time to avoid stat() and
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* access() thrashing the cache.
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*
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* For now, with NFS, only regular files that are open read-only will be able
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* to use the cache.
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*
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* We enable the cache for an inode if we open it read-only and it isn't
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* currently open for writing. We disable the cache if the inode is open
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* write-only.
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*
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* The caller uses the file struct to pin i_writecount on the inode before
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* calling us when a file is opened for writing, so we can make use of that.
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*
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* Note that this may be invoked multiple times in parallel by parallel
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* nfs_open() functions.
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*/
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void nfs_fscache_open_file(struct inode *inode, struct file *filp)
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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(netfs_inode(inode));
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bool open_for_write = inode_is_open_for_write(inode);
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if (!fscache_cookie_valid(cookie))
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return;
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fscache_use_cookie(cookie, open_for_write);
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if (open_for_write) {
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nfs_fscache_update_auxdata(&auxdata, inode);
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fscache_invalidate(cookie, &auxdata, i_size_read(inode),
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FSCACHE_INVAL_DIO_WRITE);
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}
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}
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EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
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void nfs_fscache_release_file(struct inode *inode, struct file *filp)
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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(netfs_inode(inode));
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loff_t i_size = i_size_read(inode);
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nfs_fscache_update_auxdata(&auxdata, inode);
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fscache_unuse_cookie(cookie, &auxdata, &i_size);
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}
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int nfs_netfs_read_folio(struct file *file, struct folio *folio)
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{
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if (!netfs_inode(folio_inode(folio))->cache)
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return -ENOBUFS;
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return netfs_read_folio(file, folio);
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}
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int nfs_netfs_readahead(struct readahead_control *ractl)
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{
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struct inode *inode = ractl->mapping->host;
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if (!netfs_inode(inode)->cache)
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return -ENOBUFS;
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netfs_readahead(ractl);
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return 0;
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}
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static atomic_t nfs_netfs_debug_id;
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static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *file)
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{
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rreq->netfs_priv = get_nfs_open_context(nfs_file_open_context(file));
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rreq->debug_id = atomic_inc_return(&nfs_netfs_debug_id);
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/* [DEPRECATED] Use PG_private_2 to mark folio being written to the cache. */
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__set_bit(NETFS_RREQ_USE_PGPRIV2, &rreq->flags);
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rreq->io_streams[0].sreq_max_len = NFS_SB(rreq->inode->i_sb)->rsize;
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return 0;
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}
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static void nfs_netfs_free_request(struct netfs_io_request *rreq)
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{
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put_nfs_open_context(rreq->netfs_priv);
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}
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static struct nfs_netfs_io_data *nfs_netfs_alloc(struct netfs_io_subrequest *sreq)
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{
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struct nfs_netfs_io_data *netfs;
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netfs = kzalloc(sizeof(*netfs), GFP_KERNEL_ACCOUNT);
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if (!netfs)
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return NULL;
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netfs->sreq = sreq;
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refcount_set(&netfs->refcount, 1);
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return netfs;
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}
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static void nfs_netfs_issue_read(struct netfs_io_subrequest *sreq)
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{
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struct nfs_netfs_io_data *netfs;
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struct nfs_pageio_descriptor pgio;
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struct inode *inode = sreq->rreq->inode;
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struct nfs_open_context *ctx = sreq->rreq->netfs_priv;
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struct page *page;
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unsigned long idx;
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pgoff_t start, last;
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int err;
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start = (sreq->start + sreq->transferred) >> PAGE_SHIFT;
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last = ((sreq->start + sreq->len - sreq->transferred - 1) >> PAGE_SHIFT);
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nfs_pageio_init_read(&pgio, inode, false,
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&nfs_async_read_completion_ops);
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netfs = nfs_netfs_alloc(sreq);
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if (!netfs)
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return netfs_read_subreq_terminated(sreq, -ENOMEM, false);
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pgio.pg_netfs = netfs; /* used in completion */
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xa_for_each_range(&sreq->rreq->mapping->i_pages, idx, page, start, last) {
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/* nfs_read_add_folio() may schedule() due to pNFS layout and other RPCs */
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err = nfs_read_add_folio(&pgio, ctx, page_folio(page));
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if (err < 0) {
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netfs->error = err;
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goto out;
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}
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}
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out:
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nfs_pageio_complete_read(&pgio);
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nfs_netfs_put(netfs);
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}
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void nfs_netfs_initiate_read(struct nfs_pgio_header *hdr)
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{
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struct nfs_netfs_io_data *netfs = hdr->netfs;
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if (!netfs)
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return;
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nfs_netfs_get(netfs);
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}
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int nfs_netfs_folio_unlock(struct folio *folio)
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{
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struct inode *inode = folio->mapping->host;
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/*
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* If fscache is enabled, netfs will unlock pages.
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*/
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if (netfs_inode(inode)->cache)
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return 0;
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return 1;
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}
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void nfs_netfs_read_completion(struct nfs_pgio_header *hdr)
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{
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struct nfs_netfs_io_data *netfs = hdr->netfs;
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struct netfs_io_subrequest *sreq;
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if (!netfs)
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return;
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sreq = netfs->sreq;
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if (test_bit(NFS_IOHDR_EOF, &hdr->flags) &&
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sreq->rreq->origin != NETFS_DIO_READ)
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__set_bit(NETFS_SREQ_CLEAR_TAIL, &sreq->flags);
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if (hdr->error)
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netfs->error = hdr->error;
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else
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atomic64_add(hdr->res.count, &netfs->transferred);
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nfs_netfs_put(netfs);
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hdr->netfs = NULL;
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}
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const struct netfs_request_ops nfs_netfs_ops = {
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.init_request = nfs_netfs_init_request,
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.free_request = nfs_netfs_free_request,
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.issue_read = nfs_netfs_issue_read,
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};
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