Implement support for creating the directory layout for a volume on disk and setting up and withdrawing volume caching.
Each volume has a directory named for the volume key under the root of the cache (prefixed with an 'I' to indicate to cachefilesd that it's an index) and then creates a bunch of hash bucket subdirectories under that (named as '@' plus a hex number) in which cookie files will be created. Signed-off-by: David Howells <dhowe...@redhat.com> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/163819635314.215744.13081522301564537723.st...@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906936397.143852.17788457778396467161.st...@warthog.procyon.org.uk/ # v2 --- fs/cachefiles/Makefile | 3 + fs/cachefiles/cache.c | 28 ++++++++++- fs/cachefiles/daemon.c | 2 + fs/cachefiles/interface.c | 2 + fs/cachefiles/internal.h | 20 ++++++++ fs/cachefiles/volume.c | 118 +++++++++++++++++++++++++++++++++++++++++++++ 6 files changed, 171 insertions(+), 2 deletions(-) create mode 100644 fs/cachefiles/volume.c diff --git a/fs/cachefiles/Makefile b/fs/cachefiles/Makefile index 92af5daee8ce..d67210ece9cd 100644 --- a/fs/cachefiles/Makefile +++ b/fs/cachefiles/Makefile @@ -9,7 +9,8 @@ cachefiles-y := \ interface.o \ main.o \ namei.o \ - security.o + security.o \ + volume.o cachefiles-$(CONFIG_CACHEFILES_ERROR_INJECTION) += error_inject.o diff --git a/fs/cachefiles/cache.c b/fs/cachefiles/cache.c index 0462e7af87fb..c4b9280ca0cd 100644 --- a/fs/cachefiles/cache.c +++ b/fs/cachefiles/cache.c @@ -262,6 +262,32 @@ int cachefiles_has_space(struct cachefiles_cache *cache, return ret; } +/* + * Withdraw volumes. + */ +static void cachefiles_withdraw_volumes(struct cachefiles_cache *cache) +{ + _enter(""); + + for (;;) { + struct cachefiles_volume *volume = NULL; + + spin_lock(&cache->object_list_lock); + if (!list_empty(&cache->volumes)) { + volume = list_first_entry(&cache->volumes, + struct cachefiles_volume, cache_link); + list_del_init(&volume->cache_link); + } + spin_unlock(&cache->object_list_lock); + if (!volume) + break; + + cachefiles_withdraw_volume(volume); + } + + _leave(""); +} + /* * Sync a cache to backing disk. */ @@ -303,7 +329,7 @@ void cachefiles_withdraw_cache(struct cachefiles_cache *cache) // PLACEHOLDER: Withdraw objects fscache_wait_for_objects(fscache); - // PLACEHOLDER: Withdraw volume + cachefiles_withdraw_volumes(cache); cachefiles_sync_cache(cache); cache->cache = NULL; fscache_relinquish_cache(fscache); diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c index a449ee661987..337597a4e30c 100644 --- a/fs/cachefiles/daemon.c +++ b/fs/cachefiles/daemon.c @@ -105,6 +105,8 @@ static int cachefiles_daemon_open(struct inode *inode, struct file *file) mutex_init(&cache->daemon_mutex); init_waitqueue_head(&cache->daemon_pollwq); + INIT_LIST_HEAD(&cache->volumes); + spin_lock_init(&cache->object_list_lock); /* set default caching limits * - limit at 1% free space and/or free files diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c index 564ea8fa6641..1793e46bd3e7 100644 --- a/fs/cachefiles/interface.c +++ b/fs/cachefiles/interface.c @@ -15,4 +15,6 @@ const struct fscache_cache_ops cachefiles_cache_ops = { .name = "cachefiles", + .acquire_volume = cachefiles_acquire_volume, + .free_volume = cachefiles_free_volume, }; diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h index 77e874c2bbe7..ab0e9307be7b 100644 --- a/fs/cachefiles/internal.h +++ b/fs/cachefiles/internal.h @@ -19,6 +19,17 @@ struct cachefiles_cache; struct cachefiles_object; +/* + * Cached volume representation. + */ +struct cachefiles_volume { + struct cachefiles_cache *cache; + struct list_head cache_link; /* Link in cache->volumes */ + struct fscache_volume *vcookie; /* The netfs's representation */ + struct dentry *dentry; /* The volume dentry */ + struct dentry *fanout[256]; /* Fanout subdirs */ +}; + /* * Data file records. */ @@ -35,6 +46,8 @@ struct cachefiles_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 */ + struct list_head volumes; /* List of volume objects */ + spinlock_t object_list_lock; /* Lock for volumes and object_list */ const struct cred *cache_cred; /* security override for accessing cache */ struct mutex daemon_mutex; /* command serialisation mutex */ wait_queue_head_t daemon_pollwq; /* poll waitqueue for daemon */ @@ -163,6 +176,13 @@ static inline void cachefiles_end_secure(struct cachefiles_cache *cache, revert_creds(saved_cred); } +/* + * volume.c + */ +void cachefiles_acquire_volume(struct fscache_volume *volume); +void cachefiles_free_volume(struct fscache_volume *volume); +void cachefiles_withdraw_volume(struct cachefiles_volume *volume); + /* * Error handling */ diff --git a/fs/cachefiles/volume.c b/fs/cachefiles/volume.c new file mode 100644 index 000000000000..4a14f5e72764 --- /dev/null +++ b/fs/cachefiles/volume.c @@ -0,0 +1,118 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* Volume handling. + * + * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowe...@redhat.com) + */ + +#include <linux/fs.h> +#include <linux/slab.h> +#include "internal.h" +#include <trace/events/fscache.h> + +/* + * Allocate and set up a volume representation. We make sure all the fanout + * directories are created and pinned. + */ +void cachefiles_acquire_volume(struct fscache_volume *vcookie) +{ + struct cachefiles_volume *volume; + struct cachefiles_cache *cache = vcookie->cache->cache_priv; + const struct cred *saved_cred; + struct dentry *vdentry, *fan; + size_t len; + char *name; + int n_accesses, i; + + _enter(""); + + volume = kzalloc(sizeof(struct cachefiles_volume), GFP_KERNEL); + if (!volume) + return; + volume->vcookie = vcookie; + volume->cache = cache; + INIT_LIST_HEAD(&volume->cache_link); + + cachefiles_begin_secure(cache, &saved_cred); + + len = vcookie->key[0]; + name = kmalloc(len + 3, GFP_NOFS); + if (!name) + goto error_vol; + name[0] = 'I'; + memcpy(name + 1, vcookie->key + 1, len); + name[len + 1] = 0; + + vdentry = cachefiles_get_directory(cache, cache->store, name, NULL); + if (IS_ERR(vdentry)) + goto error_name; + volume->dentry = vdentry; + + for (i = 0; i < 256; i++) { + sprintf(name, "@%02x", i); + fan = cachefiles_get_directory(cache, vdentry, name, NULL); + if (IS_ERR(fan)) + goto error_fan; + volume->fanout[i] = fan; + } + + cachefiles_end_secure(cache, saved_cred); + + vcookie->cache_priv = volume; + n_accesses = atomic_inc_return(&vcookie->n_accesses); /* Stop wakeups on dec-to-0 */ + trace_fscache_access_volume(vcookie->debug_id, 0, + refcount_read(&vcookie->ref), + n_accesses, fscache_access_cache_pin); + + spin_lock(&cache->object_list_lock); + list_add(&volume->cache_link, &volume->cache->volumes); + spin_unlock(&cache->object_list_lock); + + kfree(name); + return; + +error_fan: + for (i = 0; i < 256; i++) + cachefiles_put_directory(volume->fanout[i]); + cachefiles_put_directory(volume->dentry); +error_name: + kfree(name); +error_vol: + kfree(volume); + cachefiles_end_secure(cache, saved_cred); +} + +/* + * Release a volume representation. + */ +static void __cachefiles_free_volume(struct cachefiles_volume *volume) +{ + int i; + + _enter(""); + + volume->vcookie->cache_priv = NULL; + + for (i = 0; i < 256; i++) + cachefiles_put_directory(volume->fanout[i]); + cachefiles_put_directory(volume->dentry); + kfree(volume); +} + +void cachefiles_free_volume(struct fscache_volume *vcookie) +{ + struct cachefiles_volume *volume = vcookie->cache_priv; + + if (volume) { + spin_lock(&volume->cache->object_list_lock); + list_del_init(&volume->cache_link); + spin_unlock(&volume->cache->object_list_lock); + __cachefiles_free_volume(volume); + } +} + +void cachefiles_withdraw_volume(struct cachefiles_volume *volume) +{ + fscache_withdraw_volume(volume->vcookie); + __cachefiles_free_volume(volume); +} -- Linux-cachefs mailing list Linux-cachefs@redhat.com https://listman.redhat.com/mailman/listinfo/linux-cachefs
