[PATCH v2 41/67] cachefiles: Implement volume support
David Howells
dhowells at redhat.com
Thu Dec 9 09:02:43 PST 2021
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 <dhowells at redhat.com>
cc: linux-cachefs at redhat.com
Link: https://lore.kernel.org/r/163819635314.215744.13081522301564537723.stgit@warthog.procyon.org.uk/ # v1
---
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 4c4121105750..d87db9b6e4c8 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 0ccea2373b40..3b1a6d67cf96 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 */
@@ -162,6 +175,13 @@ 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..2d3635f1aea1
--- /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 (dhowells at 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);
+ 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);
+ 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);
+}
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