9p: Add fscache support to 9p
This patch adds a persistent, read-only caching facility for 9p clients using the FS-Cache caching backend. When the fscache facility is enabled, each inode is associated with a corresponding vcookie which is an index into the FS-Cache indexing tree. The FS-Cache indexing tree is indexed at 3 levels: - session object associated with each mount. - inode/vcookie - actual data (pages) A cache tag is chosen randomly for each session. These tags can be read off /sys/fs/9p/caches and can be passed as a mount-time parameter to re-attach to the specified caching session. Signed-off-by: Abhishek Kulkarni <adkulkar@umail.iu.edu> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
This commit is contained in:
Abhishek Kulkarni
committed by
Eric Van Hensbergen
Eric Van Hensbergen
parent
637d020a02
commit
60e78d2c99
474
fs/9p/cache.c
Normal file
474
fs/9p/cache.c
Normal file
@@ -0,0 +1,474 @@
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/*
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* V9FS cache definitions.
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*
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* Copyright (C) 2009 by Abhishek Kulkarni <adkulkar@umail.iu.edu>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to:
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* Free Software Foundation
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* 51 Franklin Street, Fifth Floor
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* Boston, MA 02111-1301 USA
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*
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*/
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#include <linux/jiffies.h>
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#include <linux/file.h>
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#include <linux/stat.h>
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#include <linux/sched.h>
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#include <linux/fs.h>
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#include <net/9p/9p.h>
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#include "v9fs.h"
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#include "cache.h"
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#define CACHETAG_LEN 11
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struct kmem_cache *vcookie_cache;
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struct fscache_netfs v9fs_cache_netfs = {
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.name = "9p",
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.version = 0,
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};
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static void init_once(void *foo)
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{
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struct v9fs_cookie *vcookie = (struct v9fs_cookie *) foo;
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vcookie->fscache = NULL;
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vcookie->qid = NULL;
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inode_init_once(&vcookie->inode);
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}
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/**
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* v9fs_init_vcookiecache - initialize a cache for vcookies to maintain
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* vcookie to inode mapping
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*
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* Returns 0 on success.
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*/
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static int v9fs_init_vcookiecache(void)
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{
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vcookie_cache = kmem_cache_create("vcookie_cache",
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sizeof(struct v9fs_cookie),
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0, (SLAB_RECLAIM_ACCOUNT|
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SLAB_MEM_SPREAD),
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init_once);
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if (!vcookie_cache)
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return -ENOMEM;
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return 0;
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}
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/**
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* v9fs_destroy_vcookiecache - destroy the cache of vcookies
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*
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*/
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static void v9fs_destroy_vcookiecache(void)
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{
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kmem_cache_destroy(vcookie_cache);
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}
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int __v9fs_cache_register(void)
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{
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int ret;
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ret = v9fs_init_vcookiecache();
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if (ret < 0)
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return ret;
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return fscache_register_netfs(&v9fs_cache_netfs);
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}
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void __v9fs_cache_unregister(void)
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{
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v9fs_destroy_vcookiecache();
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fscache_unregister_netfs(&v9fs_cache_netfs);
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}
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/**
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* v9fs_random_cachetag - Generate a random tag to be associated
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* with a new cache session.
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*
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* The value of jiffies is used for a fairly randomly cache tag.
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*/
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static
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int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
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{
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v9ses->cachetag = kmalloc(CACHETAG_LEN, GFP_KERNEL);
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if (!v9ses->cachetag)
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return -ENOMEM;
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return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
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}
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static uint16_t v9fs_cache_session_get_key(const void *cookie_netfs_data,
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void *buffer, uint16_t bufmax)
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{
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struct v9fs_session_info *v9ses;
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uint16_t klen = 0;
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v9ses = (struct v9fs_session_info *)cookie_netfs_data;
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P9_DPRINTK(P9_DEBUG_FSC, "session %p buf %p size %u", v9ses,
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buffer, bufmax);
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if (v9ses->cachetag)
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klen = strlen(v9ses->cachetag);
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if (klen > bufmax)
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return 0;
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memcpy(buffer, v9ses->cachetag, klen);
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P9_DPRINTK(P9_DEBUG_FSC, "cache session tag %s", v9ses->cachetag);
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return klen;
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}
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const struct fscache_cookie_def v9fs_cache_session_index_def = {
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.name = "9P.session",
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.type = FSCACHE_COOKIE_TYPE_INDEX,
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.get_key = v9fs_cache_session_get_key,
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};
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void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
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{
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/* If no cache session tag was specified, we generate a random one. */
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if (!v9ses->cachetag)
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v9fs_random_cachetag(v9ses);
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v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
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&v9fs_cache_session_index_def,
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v9ses);
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P9_DPRINTK(P9_DEBUG_FSC, "session %p get cookie %p", v9ses,
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v9ses->fscache);
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}
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void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
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{
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P9_DPRINTK(P9_DEBUG_FSC, "session %p put cookie %p", v9ses,
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v9ses->fscache);
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fscache_relinquish_cookie(v9ses->fscache, 0);
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v9ses->fscache = NULL;
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}
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static uint16_t v9fs_cache_inode_get_key(const void *cookie_netfs_data,
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void *buffer, uint16_t bufmax)
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{
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const struct v9fs_cookie *vcookie = cookie_netfs_data;
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memcpy(buffer, &vcookie->qid->path, sizeof(vcookie->qid->path));
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P9_DPRINTK(P9_DEBUG_FSC, "inode %p get key %llu", &vcookie->inode,
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vcookie->qid->path);
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return sizeof(vcookie->qid->path);
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}
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static void v9fs_cache_inode_get_attr(const void *cookie_netfs_data,
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uint64_t *size)
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{
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const struct v9fs_cookie *vcookie = cookie_netfs_data;
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*size = i_size_read(&vcookie->inode);
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P9_DPRINTK(P9_DEBUG_FSC, "inode %p get attr %llu", &vcookie->inode,
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*size);
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}
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static uint16_t v9fs_cache_inode_get_aux(const void *cookie_netfs_data,
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void *buffer, uint16_t buflen)
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{
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const struct v9fs_cookie *vcookie = cookie_netfs_data;
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memcpy(buffer, &vcookie->qid->version, sizeof(vcookie->qid->version));
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P9_DPRINTK(P9_DEBUG_FSC, "inode %p get aux %u", &vcookie->inode,
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vcookie->qid->version);
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return sizeof(vcookie->qid->version);
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}
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static enum
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fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
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const void *buffer,
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uint16_t buflen)
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{
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const struct v9fs_cookie *vcookie = cookie_netfs_data;
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if (buflen != sizeof(vcookie->qid->version))
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return FSCACHE_CHECKAUX_OBSOLETE;
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if (memcmp(buffer, &vcookie->qid->version,
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sizeof(vcookie->qid->version)))
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return FSCACHE_CHECKAUX_OBSOLETE;
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return FSCACHE_CHECKAUX_OKAY;
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}
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static void v9fs_cache_inode_now_uncached(void *cookie_netfs_data)
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{
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struct v9fs_cookie *vcookie = cookie_netfs_data;
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struct pagevec pvec;
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pgoff_t first;
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int loop, nr_pages;
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pagevec_init(&pvec, 0);
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first = 0;
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for (;;) {
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nr_pages = pagevec_lookup(&pvec, vcookie->inode.i_mapping,
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first,
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PAGEVEC_SIZE - pagevec_count(&pvec));
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if (!nr_pages)
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break;
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for (loop = 0; loop < nr_pages; loop++)
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ClearPageFsCache(pvec.pages[loop]);
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first = pvec.pages[nr_pages - 1]->index + 1;
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pvec.nr = nr_pages;
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pagevec_release(&pvec);
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cond_resched();
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}
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}
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const struct fscache_cookie_def v9fs_cache_inode_index_def = {
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.name = "9p.inode",
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.type = FSCACHE_COOKIE_TYPE_DATAFILE,
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.get_key = v9fs_cache_inode_get_key,
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.get_attr = v9fs_cache_inode_get_attr,
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.get_aux = v9fs_cache_inode_get_aux,
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.check_aux = v9fs_cache_inode_check_aux,
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.now_uncached = v9fs_cache_inode_now_uncached,
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};
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void v9fs_cache_inode_get_cookie(struct inode *inode)
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{
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struct v9fs_cookie *vcookie;
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struct v9fs_session_info *v9ses;
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if (!S_ISREG(inode->i_mode))
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return;
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vcookie = v9fs_inode2cookie(inode);
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if (vcookie->fscache)
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return;
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v9ses = v9fs_inode2v9ses(inode);
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vcookie->fscache = fscache_acquire_cookie(v9ses->fscache,
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&v9fs_cache_inode_index_def,
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vcookie);
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P9_DPRINTK(P9_DEBUG_FSC, "inode %p get cookie %p", inode,
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vcookie->fscache);
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}
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void v9fs_cache_inode_put_cookie(struct inode *inode)
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{
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struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
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if (!vcookie->fscache)
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return;
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P9_DPRINTK(P9_DEBUG_FSC, "inode %p put cookie %p", inode,
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vcookie->fscache);
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fscache_relinquish_cookie(vcookie->fscache, 0);
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vcookie->fscache = NULL;
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}
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void v9fs_cache_inode_flush_cookie(struct inode *inode)
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{
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struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
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if (!vcookie->fscache)
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return;
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P9_DPRINTK(P9_DEBUG_FSC, "inode %p flush cookie %p", inode,
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vcookie->fscache);
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fscache_relinquish_cookie(vcookie->fscache, 1);
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vcookie->fscache = NULL;
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}
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void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
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{
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struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
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struct p9_fid *fid;
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if (!vcookie->fscache)
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return;
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spin_lock(&vcookie->lock);
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fid = filp->private_data;
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if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
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v9fs_cache_inode_flush_cookie(inode);
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else
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v9fs_cache_inode_get_cookie(inode);
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spin_unlock(&vcookie->lock);
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}
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void v9fs_cache_inode_reset_cookie(struct inode *inode)
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{
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struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
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struct v9fs_session_info *v9ses;
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struct fscache_cookie *old;
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if (!vcookie->fscache)
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return;
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old = vcookie->fscache;
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spin_lock(&vcookie->lock);
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fscache_relinquish_cookie(vcookie->fscache, 1);
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v9ses = v9fs_inode2v9ses(inode);
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vcookie->fscache = fscache_acquire_cookie(v9ses->fscache,
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&v9fs_cache_inode_index_def,
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vcookie);
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P9_DPRINTK(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p",
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inode, old, vcookie->fscache);
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spin_unlock(&vcookie->lock);
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}
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int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
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{
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struct inode *inode = page->mapping->host;
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struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
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BUG_ON(!vcookie->fscache);
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if (PageFsCache(page)) {
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if (fscache_check_page_write(vcookie->fscache, page)) {
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if (!(gfp & __GFP_WAIT))
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return 0;
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fscache_wait_on_page_write(vcookie->fscache, page);
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}
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fscache_uncache_page(vcookie->fscache, page);
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ClearPageFsCache(page);
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}
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return 1;
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}
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void __v9fs_fscache_invalidate_page(struct page *page)
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{
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struct inode *inode = page->mapping->host;
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struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
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BUG_ON(!vcookie->fscache);
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if (PageFsCache(page)) {
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fscache_wait_on_page_write(vcookie->fscache, page);
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BUG_ON(!PageLocked(page));
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fscache_uncache_page(vcookie->fscache, page);
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ClearPageFsCache(page);
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}
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}
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static void v9fs_vfs_readpage_complete(struct page *page, void *data,
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int error)
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{
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if (!error)
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SetPageUptodate(page);
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unlock_page(page);
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}
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/**
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* __v9fs_readpage_from_fscache - read a page from cache
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*
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* Returns 0 if the pages are in cache and a BIO is submitted,
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* 1 if the pages are not in cache and -error otherwise.
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*/
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int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
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{
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int ret;
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const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
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P9_DPRINTK(P9_DEBUG_FSC, "inode %p page %p", inode, page);
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if (!vcookie->fscache)
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return -ENOBUFS;
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ret = fscache_read_or_alloc_page(vcookie->fscache,
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page,
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v9fs_vfs_readpage_complete,
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NULL,
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GFP_KERNEL);
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switch (ret) {
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case -ENOBUFS:
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case -ENODATA:
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P9_DPRINTK(P9_DEBUG_FSC, "page/inode not in cache %d", ret);
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return 1;
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case 0:
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P9_DPRINTK(P9_DEBUG_FSC, "BIO submitted");
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return ret;
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default:
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P9_DPRINTK(P9_DEBUG_FSC, "ret %d", ret);
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return ret;
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}
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}
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/**
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* __v9fs_readpages_from_fscache - read multiple pages from cache
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*
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* Returns 0 if the pages are in cache and a BIO is submitted,
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* 1 if the pages are not in cache and -error otherwise.
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*/
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int __v9fs_readpages_from_fscache(struct inode *inode,
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struct address_space *mapping,
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struct list_head *pages,
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unsigned *nr_pages)
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{
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int ret;
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const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
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P9_DPRINTK(P9_DEBUG_FSC, "inode %p pages %u", inode, *nr_pages);
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if (!vcookie->fscache)
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return -ENOBUFS;
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ret = fscache_read_or_alloc_pages(vcookie->fscache,
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mapping, pages, nr_pages,
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v9fs_vfs_readpage_complete,
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NULL,
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mapping_gfp_mask(mapping));
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switch (ret) {
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case -ENOBUFS:
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case -ENODATA:
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P9_DPRINTK(P9_DEBUG_FSC, "pages/inodes not in cache %d", ret);
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return 1;
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case 0:
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BUG_ON(!list_empty(pages));
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BUG_ON(*nr_pages != 0);
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P9_DPRINTK(P9_DEBUG_FSC, "BIO submitted");
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return ret;
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default:
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P9_DPRINTK(P9_DEBUG_FSC, "ret %d", ret);
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return ret;
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}
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}
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/**
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* __v9fs_readpage_to_fscache - write a page to the cache
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*
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*/
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void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
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{
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int ret;
|
||||
const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
|
||||
|
||||
P9_DPRINTK(P9_DEBUG_FSC, "inode %p page %p", inode, page);
|
||||
ret = fscache_write_page(vcookie->fscache, page, GFP_KERNEL);
|
||||
P9_DPRINTK(P9_DEBUG_FSC, "ret = %d", ret);
|
||||
if (ret != 0)
|
||||
v9fs_uncache_page(inode, page);
|
||||
}
|
||||
Reference in New Issue
Block a user