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linux-next/fs/9p/cache.c
Sasha Levin 8f5fed1e91 fs/9p: use fscache mutex rather than spinlock
We may sleep inside a the lock, so use a mutex rather than spinlock.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-01-09 02:57:21 -05:00

415 lines
10 KiB
C

/*
* V9FS cache definitions.
*
* Copyright (C) 2009 by Abhishek Kulkarni <adkulkar@umail.iu.edu>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to:
* Free Software Foundation
* 51 Franklin Street, Fifth Floor
* Boston, MA 02111-1301 USA
*
*/
#include <linux/jiffies.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <net/9p/9p.h>
#include "v9fs.h"
#include "cache.h"
#define CACHETAG_LEN 11
struct fscache_netfs v9fs_cache_netfs = {
.name = "9p",
.version = 0,
};
/**
* v9fs_random_cachetag - Generate a random tag to be associated
* with a new cache session.
*
* The value of jiffies is used for a fairly randomly cache tag.
*/
static
int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
{
v9ses->cachetag = kmalloc(CACHETAG_LEN, GFP_KERNEL);
if (!v9ses->cachetag)
return -ENOMEM;
return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
}
static uint16_t v9fs_cache_session_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
struct v9fs_session_info *v9ses;
uint16_t klen = 0;
v9ses = (struct v9fs_session_info *)cookie_netfs_data;
p9_debug(P9_DEBUG_FSC, "session %p buf %p size %u\n",
v9ses, buffer, bufmax);
if (v9ses->cachetag)
klen = strlen(v9ses->cachetag);
if (klen > bufmax)
return 0;
memcpy(buffer, v9ses->cachetag, klen);
p9_debug(P9_DEBUG_FSC, "cache session tag %s\n", v9ses->cachetag);
return klen;
}
const struct fscache_cookie_def v9fs_cache_session_index_def = {
.name = "9P.session",
.type = FSCACHE_COOKIE_TYPE_INDEX,
.get_key = v9fs_cache_session_get_key,
};
void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
{
/* If no cache session tag was specified, we generate a random one. */
if (!v9ses->cachetag)
v9fs_random_cachetag(v9ses);
v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
&v9fs_cache_session_index_def,
v9ses, true);
p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
v9ses, v9ses->fscache);
}
void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
{
p9_debug(P9_DEBUG_FSC, "session %p put cookie %p\n",
v9ses, v9ses->fscache);
fscache_relinquish_cookie(v9ses->fscache, 0);
v9ses->fscache = NULL;
}
static uint16_t v9fs_cache_inode_get_key(const void *cookie_netfs_data,
void *buffer, uint16_t bufmax)
{
const struct v9fs_inode *v9inode = cookie_netfs_data;
memcpy(buffer, &v9inode->qid.path, sizeof(v9inode->qid.path));
p9_debug(P9_DEBUG_FSC, "inode %p get key %llu\n",
&v9inode->vfs_inode, v9inode->qid.path);
return sizeof(v9inode->qid.path);
}
static void v9fs_cache_inode_get_attr(const void *cookie_netfs_data,
uint64_t *size)
{
const struct v9fs_inode *v9inode = cookie_netfs_data;
*size = i_size_read(&v9inode->vfs_inode);
p9_debug(P9_DEBUG_FSC, "inode %p get attr %llu\n",
&v9inode->vfs_inode, *size);
}
static uint16_t v9fs_cache_inode_get_aux(const void *cookie_netfs_data,
void *buffer, uint16_t buflen)
{
const struct v9fs_inode *v9inode = cookie_netfs_data;
memcpy(buffer, &v9inode->qid.version, sizeof(v9inode->qid.version));
p9_debug(P9_DEBUG_FSC, "inode %p get aux %u\n",
&v9inode->vfs_inode, v9inode->qid.version);
return sizeof(v9inode->qid.version);
}
static enum
fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
const void *buffer,
uint16_t buflen)
{
const struct v9fs_inode *v9inode = cookie_netfs_data;
if (buflen != sizeof(v9inode->qid.version))
return FSCACHE_CHECKAUX_OBSOLETE;
if (memcmp(buffer, &v9inode->qid.version,
sizeof(v9inode->qid.version)))
return FSCACHE_CHECKAUX_OBSOLETE;
return FSCACHE_CHECKAUX_OKAY;
}
static void v9fs_cache_inode_now_uncached(void *cookie_netfs_data)
{
struct v9fs_inode *v9inode = cookie_netfs_data;
struct pagevec pvec;
pgoff_t first;
int loop, nr_pages;
pagevec_init(&pvec, 0);
first = 0;
for (;;) {
nr_pages = pagevec_lookup(&pvec, v9inode->vfs_inode.i_mapping,
first,
PAGEVEC_SIZE - pagevec_count(&pvec));
if (!nr_pages)
break;
for (loop = 0; loop < nr_pages; loop++)
ClearPageFsCache(pvec.pages[loop]);
first = pvec.pages[nr_pages - 1]->index + 1;
pvec.nr = nr_pages;
pagevec_release(&pvec);
cond_resched();
}
}
const struct fscache_cookie_def v9fs_cache_inode_index_def = {
.name = "9p.inode",
.type = FSCACHE_COOKIE_TYPE_DATAFILE,
.get_key = v9fs_cache_inode_get_key,
.get_attr = v9fs_cache_inode_get_attr,
.get_aux = v9fs_cache_inode_get_aux,
.check_aux = v9fs_cache_inode_check_aux,
.now_uncached = v9fs_cache_inode_now_uncached,
};
void v9fs_cache_inode_get_cookie(struct inode *inode)
{
struct v9fs_inode *v9inode;
struct v9fs_session_info *v9ses;
if (!S_ISREG(inode->i_mode))
return;
v9inode = V9FS_I(inode);
if (v9inode->fscache)
return;
v9ses = v9fs_inode2v9ses(inode);
v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
&v9fs_cache_inode_index_def,
v9inode, true);
p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
inode, v9inode->fscache);
}
void v9fs_cache_inode_put_cookie(struct inode *inode)
{
struct v9fs_inode *v9inode = V9FS_I(inode);
if (!v9inode->fscache)
return;
p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",
inode, v9inode->fscache);
fscache_relinquish_cookie(v9inode->fscache, 0);
v9inode->fscache = NULL;
}
void v9fs_cache_inode_flush_cookie(struct inode *inode)
{
struct v9fs_inode *v9inode = V9FS_I(inode);
if (!v9inode->fscache)
return;
p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",
inode, v9inode->fscache);
fscache_relinquish_cookie(v9inode->fscache, 1);
v9inode->fscache = NULL;
}
void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
{
struct v9fs_inode *v9inode = V9FS_I(inode);
if (!v9inode->fscache)
return;
mutex_lock(&v9inode->fscache_lock);
if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
v9fs_cache_inode_flush_cookie(inode);
else
v9fs_cache_inode_get_cookie(inode);
mutex_unlock(&v9inode->fscache_lock);
}
void v9fs_cache_inode_reset_cookie(struct inode *inode)
{
struct v9fs_inode *v9inode = V9FS_I(inode);
struct v9fs_session_info *v9ses;
struct fscache_cookie *old;
if (!v9inode->fscache)
return;
old = v9inode->fscache;
mutex_lock(&v9inode->fscache_lock);
fscache_relinquish_cookie(v9inode->fscache, 1);
v9ses = v9fs_inode2v9ses(inode);
v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
&v9fs_cache_inode_index_def,
v9inode, true);
p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
inode, old, v9inode->fscache);
mutex_unlock(&v9inode->fscache_lock);
}
int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
{
struct inode *inode = page->mapping->host;
struct v9fs_inode *v9inode = V9FS_I(inode);
BUG_ON(!v9inode->fscache);
return fscache_maybe_release_page(v9inode->fscache, page, gfp);
}
void __v9fs_fscache_invalidate_page(struct page *page)
{
struct inode *inode = page->mapping->host;
struct v9fs_inode *v9inode = V9FS_I(inode);
BUG_ON(!v9inode->fscache);
if (PageFsCache(page)) {
fscache_wait_on_page_write(v9inode->fscache, page);
BUG_ON(!PageLocked(page));
fscache_uncache_page(v9inode->fscache, page);
}
}
static void v9fs_vfs_readpage_complete(struct page *page, void *data,
int error)
{
if (!error)
SetPageUptodate(page);
unlock_page(page);
}
/**
* __v9fs_readpage_from_fscache - read a page from cache
*
* Returns 0 if the pages are in cache and a BIO is submitted,
* 1 if the pages are not in cache and -error otherwise.
*/
int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
{
int ret;
const struct v9fs_inode *v9inode = V9FS_I(inode);
p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
if (!v9inode->fscache)
return -ENOBUFS;
ret = fscache_read_or_alloc_page(v9inode->fscache,
page,
v9fs_vfs_readpage_complete,
NULL,
GFP_KERNEL);
switch (ret) {
case -ENOBUFS:
case -ENODATA:
p9_debug(P9_DEBUG_FSC, "page/inode not in cache %d\n", ret);
return 1;
case 0:
p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
return ret;
default:
p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
return ret;
}
}
/**
* __v9fs_readpages_from_fscache - read multiple pages from cache
*
* Returns 0 if the pages are in cache and a BIO is submitted,
* 1 if the pages are not in cache and -error otherwise.
*/
int __v9fs_readpages_from_fscache(struct inode *inode,
struct address_space *mapping,
struct list_head *pages,
unsigned *nr_pages)
{
int ret;
const struct v9fs_inode *v9inode = V9FS_I(inode);
p9_debug(P9_DEBUG_FSC, "inode %p pages %u\n", inode, *nr_pages);
if (!v9inode->fscache)
return -ENOBUFS;
ret = fscache_read_or_alloc_pages(v9inode->fscache,
mapping, pages, nr_pages,
v9fs_vfs_readpage_complete,
NULL,
mapping_gfp_mask(mapping));
switch (ret) {
case -ENOBUFS:
case -ENODATA:
p9_debug(P9_DEBUG_FSC, "pages/inodes not in cache %d\n", ret);
return 1;
case 0:
BUG_ON(!list_empty(pages));
BUG_ON(*nr_pages != 0);
p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
return ret;
default:
p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
return ret;
}
}
/**
* __v9fs_readpage_to_fscache - write a page to the cache
*
*/
void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
{
int ret;
const struct v9fs_inode *v9inode = V9FS_I(inode);
p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
ret = fscache_write_page(v9inode->fscache, page, GFP_KERNEL);
p9_debug(P9_DEBUG_FSC, "ret = %d\n", ret);
if (ret != 0)
v9fs_uncache_page(inode, page);
}
/*
* wait for a page to complete writing to the cache
*/
void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
{
const struct v9fs_inode *v9inode = V9FS_I(inode);
p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
if (PageFsCache(page))
fscache_wait_on_page_write(v9inode->fscache, page);
}