Commit d1065b0a authored by David Howells's avatar David Howells

cachefiles: Implement cache registration and withdrawal

Do the following:

 (1) Fill out cachefiles_daemon_add_cache() so that it sets up the cache
     directories and registers the cache with cachefiles.

 (2) Add a function to do the top-level part of cache withdrawal and
     unregistration.

 (3) Add a function to sync a cache.
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819633175.215744.10857127598041268340.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906935445.143852.15545194974036410029.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967142904.1823006.244055483596047072.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021543872.640689.14370017789605073222.stgit@warthog.procyon.org.uk/ # v4
parent 32759f7d
......@@ -6,6 +6,7 @@
cachefiles-y := \
cache.o \
daemon.o \
interface.o \
main.o \
namei.o \
security.o
......
......@@ -10,6 +10,166 @@
#include <linux/namei.h>
#include "internal.h"
/*
* Bring a cache online.
*/
int cachefiles_add_cache(struct cachefiles_cache *cache)
{
struct fscache_cache *cache_cookie;
struct path path;
struct kstatfs stats;
struct dentry *graveyard, *cachedir, *root;
const struct cred *saved_cred;
int ret;
_enter("");
cache_cookie = fscache_acquire_cache(cache->tag);
if (IS_ERR(cache_cookie))
return PTR_ERR(cache_cookie);
/* we want to work under the module's security ID */
ret = cachefiles_get_security_ID(cache);
if (ret < 0)
goto error_getsec;
cachefiles_begin_secure(cache, &saved_cred);
/* look up the directory at the root of the cache */
ret = kern_path(cache->rootdirname, LOOKUP_DIRECTORY, &path);
if (ret < 0)
goto error_open_root;
cache->mnt = path.mnt;
root = path.dentry;
ret = -EINVAL;
if (mnt_user_ns(path.mnt) != &init_user_ns) {
pr_warn("File cache on idmapped mounts not supported");
goto error_unsupported;
}
/* check parameters */
ret = -EOPNOTSUPP;
if (d_is_negative(root) ||
!d_backing_inode(root)->i_op->lookup ||
!d_backing_inode(root)->i_op->mkdir ||
!(d_backing_inode(root)->i_opflags & IOP_XATTR) ||
!root->d_sb->s_op->statfs ||
!root->d_sb->s_op->sync_fs ||
root->d_sb->s_blocksize > PAGE_SIZE)
goto error_unsupported;
ret = -EROFS;
if (sb_rdonly(root->d_sb))
goto error_unsupported;
/* determine the security of the on-disk cache as this governs
* security ID of files we create */
ret = cachefiles_determine_cache_security(cache, root, &saved_cred);
if (ret < 0)
goto error_unsupported;
/* get the cache size and blocksize */
ret = vfs_statfs(&path, &stats);
if (ret < 0)
goto error_unsupported;
ret = -ERANGE;
if (stats.f_bsize <= 0)
goto error_unsupported;
ret = -EOPNOTSUPP;
if (stats.f_bsize > PAGE_SIZE)
goto error_unsupported;
cache->bsize = stats.f_bsize;
cache->bshift = 0;
if (stats.f_bsize < PAGE_SIZE)
cache->bshift = PAGE_SHIFT - ilog2(stats.f_bsize);
_debug("blksize %u (shift %u)",
cache->bsize, cache->bshift);
_debug("size %llu, avail %llu",
(unsigned long long) stats.f_blocks,
(unsigned long long) stats.f_bavail);
/* set up caching limits */
do_div(stats.f_files, 100);
cache->fstop = stats.f_files * cache->fstop_percent;
cache->fcull = stats.f_files * cache->fcull_percent;
cache->frun = stats.f_files * cache->frun_percent;
_debug("limits {%llu,%llu,%llu} files",
(unsigned long long) cache->frun,
(unsigned long long) cache->fcull,
(unsigned long long) cache->fstop);
stats.f_blocks >>= cache->bshift;
do_div(stats.f_blocks, 100);
cache->bstop = stats.f_blocks * cache->bstop_percent;
cache->bcull = stats.f_blocks * cache->bcull_percent;
cache->brun = stats.f_blocks * cache->brun_percent;
_debug("limits {%llu,%llu,%llu} blocks",
(unsigned long long) cache->brun,
(unsigned long long) cache->bcull,
(unsigned long long) cache->bstop);
/* get the cache directory and check its type */
cachedir = cachefiles_get_directory(cache, root, "cache", NULL);
if (IS_ERR(cachedir)) {
ret = PTR_ERR(cachedir);
goto error_unsupported;
}
cache->store = cachedir;
/* get the graveyard directory */
graveyard = cachefiles_get_directory(cache, root, "graveyard", NULL);
if (IS_ERR(graveyard)) {
ret = PTR_ERR(graveyard);
goto error_unsupported;
}
cache->graveyard = graveyard;
cache->cache = cache_cookie;
ret = fscache_add_cache(cache_cookie, &cachefiles_cache_ops, cache);
if (ret < 0)
goto error_add_cache;
/* done */
set_bit(CACHEFILES_READY, &cache->flags);
dput(root);
pr_info("File cache on %s registered\n", cache_cookie->name);
/* check how much space the cache has */
cachefiles_has_space(cache, 0, 0);
cachefiles_end_secure(cache, saved_cred);
_leave(" = 0 [%px]", cache->cache);
return 0;
error_add_cache:
cachefiles_put_directory(cache->graveyard);
cache->graveyard = NULL;
error_unsupported:
cachefiles_put_directory(cache->store);
cache->store = NULL;
mntput(cache->mnt);
cache->mnt = NULL;
dput(root);
error_open_root:
cachefiles_end_secure(cache, saved_cred);
error_getsec:
fscache_relinquish_cache(cache_cookie);
cache->cache = NULL;
pr_err("Failed to register: %d\n", ret);
return ret;
}
/*
* See if we have space for a number of pages and/or a number of files in the
* cache
......@@ -101,3 +261,50 @@ int cachefiles_has_space(struct cachefiles_cache *cache,
_leave(" = %d", ret);
return ret;
}
/*
* Sync a cache to backing disk.
*/
static void cachefiles_sync_cache(struct cachefiles_cache *cache)
{
const struct cred *saved_cred;
int ret;
_enter("%s", cache->cache->name);
/* make sure all pages pinned by operations on behalf of the netfs are
* written to disc */
cachefiles_begin_secure(cache, &saved_cred);
down_read(&cache->mnt->mnt_sb->s_umount);
ret = sync_filesystem(cache->mnt->mnt_sb);
up_read(&cache->mnt->mnt_sb->s_umount);
cachefiles_end_secure(cache, saved_cred);
if (ret == -EIO)
cachefiles_io_error(cache,
"Attempt to sync backing fs superblock returned error %d",
ret);
}
/*
* Withdraw cache objects.
*/
void cachefiles_withdraw_cache(struct cachefiles_cache *cache)
{
struct fscache_cache *fscache = cache->cache;
pr_info("File cache on %s unregistering\n", fscache->name);
fscache_withdraw_cache(fscache);
/* we now have to destroy all the active objects pertaining to this
* cache - which we do by passing them off to thread pool to be
* disposed of */
// PLACEHOLDER: Withdraw objects
fscache_wait_for_objects(fscache);
// PLACEHOLDER: Withdraw volume
cachefiles_sync_cache(cache);
cache->cache = NULL;
fscache_relinquish_cache(fscache);
}
......@@ -702,6 +702,7 @@ static int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
pr_warn("Cache is disabled for development\n");
return -ENOANO; // Don't allow the cache to operate yet
//return cachefiles_add_cache(cache);
}
/*
......@@ -711,10 +712,11 @@ static void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
{
_enter("");
if (test_bit(CACHEFILES_READY, &cache->flags)) {
// PLACEHOLDER: Withdraw cache
}
if (test_bit(CACHEFILES_READY, &cache->flags))
cachefiles_withdraw_cache(cache);
cachefiles_put_directory(cache->graveyard);
cachefiles_put_directory(cache->store);
mntput(cache->mnt);
kfree(cache->rootdirname);
......
// SPDX-License-Identifier: GPL-2.0-or-later
/* FS-Cache interface to CacheFiles
*
* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/slab.h>
#include <linux/mount.h>
#include <linux/xattr.h>
#include <linux/file.h>
#include <linux/falloc.h>
#include <trace/events/fscache.h>
#include "internal.h"
const struct fscache_cache_ops cachefiles_cache_ops = {
.name = "cachefiles",
};
......@@ -32,6 +32,8 @@ struct cachefiles_object {
struct cachefiles_cache {
struct fscache_cache *cache; /* Cache cookie */
struct vfsmount *mnt; /* mountpoint holding the cache */
struct dentry *store; /* Directory into which live objects go */
struct dentry *graveyard; /* directory into which dead objects go */
struct file *cachefilesd; /* manager daemon handle */
const struct cred *cache_cred; /* security override for accessing cache */
struct mutex daemon_mutex; /* command serialisation mutex */
......@@ -78,8 +80,10 @@ static inline void cachefiles_state_changed(struct cachefiles_cache *cache)
/*
* cache.c
*/
extern int cachefiles_add_cache(struct cachefiles_cache *cache);
extern int cachefiles_has_space(struct cachefiles_cache *cache,
unsigned fnr, unsigned bnr);
extern void cachefiles_withdraw_cache(struct cachefiles_cache *cache);
/*
* daemon.c
......@@ -125,6 +129,11 @@ static inline int cachefiles_inject_remove_error(void)
return cachefiles_error_injection_state & 2 ? -EIO : 0;
}
/*
* interface.c
*/
extern const struct fscache_cache_ops cachefiles_cache_ops;
/*
* namei.c
*/
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment