swh:1:snp:c3bf2749e3476071fa748f67b0ffa2fdc5fe49d9
Tip revision: 3d7cb6b04c3f3115719235cc6866b10326de34cd authored by Linus Torvalds on 31 July 2022, 21:03:01 UTC
Linux 5.19
Linux 5.19
Tip revision: 3d7cb6b
fscache.c
// SPDX-License-Identifier: GPL-2.0-or-later
/* NFS filesystem cache interface
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/in6.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/iversion.h>
#include "internal.h"
#include "iostat.h"
#include "fscache.h"
#include "nfstrace.h"
#define NFS_MAX_KEY_LEN 1000
static bool nfs_append_int(char *key, int *_len, unsigned long long x)
{
if (*_len > NFS_MAX_KEY_LEN)
return false;
if (x == 0)
key[(*_len)++] = ',';
else
*_len += sprintf(key + *_len, ",%llx", x);
return true;
}
/*
* Get the per-client index cookie for an NFS client if the appropriate mount
* flag was set
* - We always try and get an index cookie for the client, but get filehandle
* cookies on a per-superblock basis, depending on the mount flags
*/
static bool nfs_fscache_get_client_key(struct nfs_client *clp,
char *key, int *_len)
{
const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) &clp->cl_addr;
const struct sockaddr_in *sin = (struct sockaddr_in *) &clp->cl_addr;
*_len += snprintf(key + *_len, NFS_MAX_KEY_LEN - *_len,
",%u.%u,%x",
clp->rpc_ops->version,
clp->cl_minorversion,
clp->cl_addr.ss_family);
switch (clp->cl_addr.ss_family) {
case AF_INET:
if (!nfs_append_int(key, _len, sin->sin_port) ||
!nfs_append_int(key, _len, sin->sin_addr.s_addr))
return false;
return true;
case AF_INET6:
if (!nfs_append_int(key, _len, sin6->sin6_port) ||
!nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[0]) ||
!nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[1]) ||
!nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[2]) ||
!nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[3]))
return false;
return true;
default:
printk(KERN_WARNING "NFS: Unknown network family '%d'\n",
clp->cl_addr.ss_family);
return false;
}
}
/*
* Get the cache cookie for an NFS superblock.
*
* The default uniquifier is just an empty string, but it may be overridden
* either by the 'fsc=xxx' option to mount, or by inheriting it from the parent
* superblock across an automount point of some nature.
*/
int nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq, int ulen)
{
struct fscache_volume *vcookie;
struct nfs_server *nfss = NFS_SB(sb);
unsigned int len = 3;
char *key;
if (uniq) {
nfss->fscache_uniq = kmemdup_nul(uniq, ulen, GFP_KERNEL);
if (!nfss->fscache_uniq)
return -ENOMEM;
}
key = kmalloc(NFS_MAX_KEY_LEN + 24, GFP_KERNEL);
if (!key)
return -ENOMEM;
memcpy(key, "nfs", 3);
if (!nfs_fscache_get_client_key(nfss->nfs_client, key, &len) ||
!nfs_append_int(key, &len, nfss->fsid.major) ||
!nfs_append_int(key, &len, nfss->fsid.minor) ||
!nfs_append_int(key, &len, sb->s_flags & NFS_SB_MASK) ||
!nfs_append_int(key, &len, nfss->flags) ||
!nfs_append_int(key, &len, nfss->rsize) ||
!nfs_append_int(key, &len, nfss->wsize) ||
!nfs_append_int(key, &len, nfss->acregmin) ||
!nfs_append_int(key, &len, nfss->acregmax) ||
!nfs_append_int(key, &len, nfss->acdirmin) ||
!nfs_append_int(key, &len, nfss->acdirmax) ||
!nfs_append_int(key, &len, nfss->client->cl_auth->au_flavor))
goto out;
if (ulen > 0) {
if (ulen > NFS_MAX_KEY_LEN - len)
goto out;
key[len++] = ',';
memcpy(key + len, uniq, ulen);
len += ulen;
}
key[len] = 0;
/* create a cache index for looking up filehandles */
vcookie = fscache_acquire_volume(key,
NULL, /* preferred_cache */
NULL, 0 /* coherency_data */);
if (IS_ERR(vcookie)) {
if (vcookie != ERR_PTR(-EBUSY)) {
kfree(key);
return PTR_ERR(vcookie);
}
pr_err("NFS: Cache volume key already in use (%s)\n", key);
vcookie = NULL;
}
nfss->fscache = vcookie;
out:
kfree(key);
return 0;
}
/*
* release a per-superblock cookie
*/
void nfs_fscache_release_super_cookie(struct super_block *sb)
{
struct nfs_server *nfss = NFS_SB(sb);
fscache_relinquish_volume(nfss->fscache, NULL, false);
nfss->fscache = NULL;
kfree(nfss->fscache_uniq);
}
/*
* Initialise the per-inode cache cookie pointer for an NFS inode.
*/
void nfs_fscache_init_inode(struct inode *inode)
{
struct nfs_fscache_inode_auxdata auxdata;
struct nfs_server *nfss = NFS_SERVER(inode);
struct nfs_inode *nfsi = NFS_I(inode);
nfsi->fscache = NULL;
if (!(nfss->fscache && S_ISREG(inode->i_mode)))
return;
nfs_fscache_update_auxdata(&auxdata, inode);
nfsi->fscache = fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache,
0,
nfsi->fh.data, /* index_key */
nfsi->fh.size,
&auxdata, /* aux_data */
sizeof(auxdata),
i_size_read(inode));
}
/*
* Release a per-inode cookie.
*/
void nfs_fscache_clear_inode(struct inode *inode)
{
struct nfs_inode *nfsi = NFS_I(inode);
struct fscache_cookie *cookie = nfs_i_fscache(inode);
fscache_relinquish_cookie(cookie, false);
nfsi->fscache = NULL;
}
/*
* Enable or disable caching for a file that is being opened as appropriate.
* The cookie is allocated when the inode is initialised, but is not enabled at
* that time. Enablement is deferred to file-open time to avoid stat() and
* access() thrashing the cache.
*
* For now, with NFS, only regular files that are open read-only will be able
* to use the cache.
*
* We enable the cache for an inode if we open it read-only and it isn't
* currently open for writing. We disable the cache if the inode is open
* write-only.
*
* The caller uses the file struct to pin i_writecount on the inode before
* calling us when a file is opened for writing, so we can make use of that.
*
* Note that this may be invoked multiple times in parallel by parallel
* nfs_open() functions.
*/
void nfs_fscache_open_file(struct inode *inode, struct file *filp)
{
struct nfs_fscache_inode_auxdata auxdata;
struct fscache_cookie *cookie = nfs_i_fscache(inode);
bool open_for_write = inode_is_open_for_write(inode);
if (!fscache_cookie_valid(cookie))
return;
fscache_use_cookie(cookie, open_for_write);
if (open_for_write) {
nfs_fscache_update_auxdata(&auxdata, inode);
fscache_invalidate(cookie, &auxdata, i_size_read(inode),
FSCACHE_INVAL_DIO_WRITE);
}
}
EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
void nfs_fscache_release_file(struct inode *inode, struct file *filp)
{
struct nfs_fscache_inode_auxdata auxdata;
struct fscache_cookie *cookie = nfs_i_fscache(inode);
loff_t i_size = i_size_read(inode);
nfs_fscache_update_auxdata(&auxdata, inode);
fscache_unuse_cookie(cookie, &auxdata, &i_size);
}
/*
* Fallback page reading interface.
*/
static int fscache_fallback_read_page(struct inode *inode, struct page *page)
{
struct netfs_cache_resources cres;
struct fscache_cookie *cookie = nfs_i_fscache(inode);
struct iov_iter iter;
struct bio_vec bvec[1];
int ret;
memset(&cres, 0, sizeof(cres));
bvec[0].bv_page = page;
bvec[0].bv_offset = 0;
bvec[0].bv_len = PAGE_SIZE;
iov_iter_bvec(&iter, READ, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
ret = fscache_begin_read_operation(&cres, cookie);
if (ret < 0)
return ret;
ret = fscache_read(&cres, page_offset(page), &iter, NETFS_READ_HOLE_FAIL,
NULL, NULL);
fscache_end_operation(&cres);
return ret;
}
/*
* Fallback page writing interface.
*/
static int fscache_fallback_write_page(struct inode *inode, struct page *page,
bool no_space_allocated_yet)
{
struct netfs_cache_resources cres;
struct fscache_cookie *cookie = nfs_i_fscache(inode);
struct iov_iter iter;
struct bio_vec bvec[1];
loff_t start = page_offset(page);
size_t len = PAGE_SIZE;
int ret;
memset(&cres, 0, sizeof(cres));
bvec[0].bv_page = page;
bvec[0].bv_offset = 0;
bvec[0].bv_len = PAGE_SIZE;
iov_iter_bvec(&iter, WRITE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
ret = fscache_begin_write_operation(&cres, cookie);
if (ret < 0)
return ret;
ret = cres.ops->prepare_write(&cres, &start, &len, i_size_read(inode),
no_space_allocated_yet);
if (ret == 0)
ret = fscache_write(&cres, page_offset(page), &iter, NULL, NULL);
fscache_end_operation(&cres);
return ret;
}
/*
* Retrieve a page from fscache
*/
int __nfs_fscache_read_page(struct inode *inode, struct page *page)
{
int ret;
trace_nfs_fscache_read_page(inode, page);
if (PageChecked(page)) {
ClearPageChecked(page);
ret = 1;
goto out;
}
ret = fscache_fallback_read_page(inode, page);
if (ret < 0) {
nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
SetPageChecked(page);
goto out;
}
/* Read completed synchronously */
nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
SetPageUptodate(page);
ret = 0;
out:
trace_nfs_fscache_read_page_exit(inode, page, ret);
return ret;
}
/*
* Store a newly fetched page in fscache. We can be certain there's no page
* stored in the cache as yet otherwise we would've read it from there.
*/
void __nfs_fscache_write_page(struct inode *inode, struct page *page)
{
int ret;
trace_nfs_fscache_write_page(inode, page);
ret = fscache_fallback_write_page(inode, page, true);
if (ret != 0) {
nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
} else {
nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
}
trace_nfs_fscache_write_page_exit(inode, page, ret);
}