Implement the FS-Cache interface to check the consistency of a cache object in
CacheFiles.
Original-author: Hongyi Jia <jiayis...@gmail.com>
Signed-off-by: David Howells <dhowe...@redhat.com>
cc: Hongyi Jia <jiayis...@gmail.com>
cc: Milosz Tanski <mil...@adfin.com>
---
fs/cachefiles/interface.c | 26 ++++++++++++++++++++++++++
fs/cachefiles/internal.h | 1 +
fs/cachefiles/xattr.c | 36 ++++++++++++++++++++++++++++++++++++
3 files changed, 63 insertions(+)
diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
index d4c1206..43eb559 100644
--- a/fs/cachefiles/interface.c
+++ b/fs/cachefiles/interface.c
@@ -378,6 +378,31 @@ static void cachefiles_sync_cache(struct fscache_cache
*_cache)
}
/*
+ * check if the backing cache is updated to FS-Cache
+ * - called by FS-Cache when evaluates if need to invalidate the cache
+ */
+static bool cachefiles_check_consistency(struct fscache_operation *op)
+{
+ struct cachefiles_object *object;
+ struct cachefiles_cache *cache;
+ const struct cred *saved_cred;
+ int ret;
+
+ _enter("{OBJ%x}", op->object->debug_id);
+
+ object = container_of(op->object, struct cachefiles_object, fscache);
+ cache = container_of(object->fscache.cache,
+ struct cachefiles_cache, cache);
+
+ cachefiles_begin_secure(cache, &saved_cred);
+ ret = cachefiles_check_auxdata(object);
+ cachefiles_end_secure(cache, saved_cred);
+
+ _leave(" = %d", ret);
+ return ret;
+}
+
+/*
* notification the attributes on an object have changed
* - called with reads/writes excluded by FS-Cache
*/
@@ -522,4 +547,5 @@ const struct fscache_cache_ops cachefiles_cache_ops = {
.write_page = cachefiles_write_page,
.uncache_page = cachefiles_uncache_page,
.dissociate_pages = cachefiles_dissociate_pages,
+ .check_consistency = cachefiles_check_consistency,
};
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index 4938251..5349473 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -235,6 +235,7 @@ extern int cachefiles_set_object_xattr(struct
cachefiles_object *object,
struct cachefiles_xattr *auxdata);
extern int cachefiles_update_object_xattr(struct cachefiles_object *object,
struct cachefiles_xattr *auxdata);
+extern int cachefiles_check_auxdata(struct cachefiles_object *object);
extern int cachefiles_check_object_xattr(struct cachefiles_object *object,
struct cachefiles_xattr *auxdata);
extern int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
diff --git a/fs/cachefiles/xattr.c b/fs/cachefiles/xattr.c
index 2476e51..34c88b8 100644
--- a/fs/cachefiles/xattr.c
+++ b/fs/cachefiles/xattr.c
@@ -157,6 +157,42 @@ int cachefiles_update_object_xattr(struct
cachefiles_object *object,
}
/*
+ * check the consistency between the backing cache and the FS-Cache cookie
+ */
+int cachefiles_check_auxdata(struct cachefiles_object *object)
+{
+ struct cachefiles_xattr *auxbuf;
+ struct dentry *dentry = object->dentry;
+ unsigned int dlen;
+ int ret;
+
+ ASSERT(dentry);
+ ASSERT(dentry->d_inode);
+ ASSERT(object->fscache.cookie->def->check_aux);
+
+ auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, GFP_KERNEL);
+ if (!auxbuf)
+ return -ENOMEM;
+
+ auxbuf->len = vfs_getxattr(dentry, cachefiles_xattr_cache,
+ &auxbuf->type, 512 + 1);
+ if (auxbuf->len < 1)
+ return -ESTALE;
+
+ if (auxbuf->type != object->fscache.cookie->def->type)
+ return -ESTALE;
+
+ dlen = auxbuf->len - 1;
+ ret = fscache_check_aux(&object->fscache, &auxbuf->data, dlen);
+
+ kfree(auxbuf);
+ if (ret != FSCACHE_CHECKAUX_OKAY)
+ return -ESTALE;
+
+ return 0;
+}
+
+/*
* check the state xattr on a cache file
* - return -ESTALE if the object should be deleted
*/
--
1.7.9.5
--
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