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authorDavid Howells <dhowells@redhat.com>2013-08-21 17:29:38 -0400
committerDavid Howells <dhowells@redhat.com>2013-09-06 09:17:30 +0100
commitda9803bc8812f5bd3b26baaa90e515b843c65ff7 (patch)
tree889b39ec88863fb46606cf345eeb4fdf8a90a67e /fs
parent6e4664525b1db28f8c4e1130957f70a94c19213e (diff)
FS-Cache: Add interface to check consistency of a cached object
Extend the fscache netfs API so that the netfs can ask as to whether a cache object is up to date with respect to its corresponding netfs object: int fscache_check_consistency(struct fscache_cookie *cookie) This will call back to the netfs to check whether the auxiliary data associated with a cookie is correct. It returns 0 if it is and -ESTALE if it isn't; it may also return -ENOMEM and -ERESTARTSYS. The backends now have to implement a mandatory operation pointer: int (*check_consistency)(struct fscache_object *object) that corresponds to the above API call. FS-Cache takes care of pinning the object and the cookie in memory and managing this call with respect to the object state. Original-author: Hongyi Jia <jiayisuse@gmail.com> Signed-off-by: David Howells <dhowells@redhat.com> cc: Hongyi Jia <jiayisuse@gmail.com> cc: Milosz Tanski <milosz@adfin.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/fscache/cookie.c71
-rw-r--r--fs/fscache/internal.h6
-rw-r--r--fs/fscache/page.c55
3 files changed, 108 insertions, 24 deletions
diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
index 0e91a3c9fdb2..318e8433527c 100644
--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -558,3 +558,74 @@ void __fscache_cookie_put(struct fscache_cookie *cookie)
_leave("");
}
+
+/*
+ * check the consistency between the netfs inode and the backing cache
+ *
+ * NOTE: it only serves no-index type
+ */
+int __fscache_check_consistency(struct fscache_cookie *cookie)
+{
+ struct fscache_operation *op;
+ struct fscache_object *object;
+ int ret;
+
+ _enter("%p,", cookie);
+
+ ASSERTCMP(cookie->def->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE);
+
+ if (fscache_wait_for_deferred_lookup(cookie) < 0)
+ return -ERESTARTSYS;
+
+ if (hlist_empty(&cookie->backing_objects))
+ return 0;
+
+ op = kzalloc(sizeof(*op), GFP_NOIO | __GFP_NOMEMALLOC | __GFP_NORETRY);
+ if (!op)
+ return -ENOMEM;
+
+ fscache_operation_init(op, NULL, NULL);
+ op->flags = FSCACHE_OP_MYTHREAD |
+ (1 << FSCACHE_OP_WAITING);
+
+ spin_lock(&cookie->lock);
+
+ if (hlist_empty(&cookie->backing_objects))
+ goto inconsistent;
+ object = hlist_entry(cookie->backing_objects.first,
+ struct fscache_object, cookie_link);
+ if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
+ goto inconsistent;
+
+ op->debug_id = atomic_inc_return(&fscache_op_debug_id);
+
+ atomic_inc(&cookie->n_active);
+ if (fscache_submit_op(object, op) < 0)
+ goto submit_failed;
+
+ /* the work queue now carries its own ref on the object */
+ spin_unlock(&cookie->lock);
+
+ ret = fscache_wait_for_operation_activation(object, op,
+ NULL, NULL, NULL);
+ if (ret == 0) {
+ /* ask the cache to honour the operation */
+ ret = object->cache->ops->check_consistency(op);
+ fscache_op_complete(op, false);
+ } else if (ret == -ENOBUFS) {
+ ret = 0;
+ }
+
+ fscache_put_operation(op);
+ _leave(" = %d", ret);
+ return ret;
+
+submit_failed:
+ atomic_dec(&cookie->n_active);
+inconsistent:
+ spin_unlock(&cookie->lock);
+ kfree(op);
+ _leave(" = -ESTALE");
+ return -ESTALE;
+}
+EXPORT_SYMBOL(__fscache_check_consistency);
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
index 12d505bedb5c..4226f6680b06 100644
--- a/fs/fscache/internal.h
+++ b/fs/fscache/internal.h
@@ -130,6 +130,12 @@ extern void fscache_operation_gc(struct work_struct *);
/*
* page.c
*/
+extern int fscache_wait_for_deferred_lookup(struct fscache_cookie *);
+extern int fscache_wait_for_operation_activation(struct fscache_object *,
+ struct fscache_operation *,
+ atomic_t *,
+ atomic_t *,
+ void (*)(struct fscache_operation *));
extern void fscache_invalidate_writes(struct fscache_cookie *);
/*
diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index d479ab3c63e4..793e3d5ca4b5 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -278,7 +278,7 @@ static struct fscache_retrieval *fscache_alloc_retrieval(
/*
* wait for a deferred lookup to complete
*/
-static int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie)
+int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie)
{
unsigned long jif;
@@ -322,42 +322,46 @@ static void fscache_do_cancel_retrieval(struct fscache_operation *_op)
/*
* wait for an object to become active (or dead)
*/
-static int fscache_wait_for_retrieval_activation(struct fscache_object *object,
- struct fscache_retrieval *op,
- atomic_t *stat_op_waits,
- atomic_t *stat_object_dead)
+int fscache_wait_for_operation_activation(struct fscache_object *object,
+ struct fscache_operation *op,
+ atomic_t *stat_op_waits,
+ atomic_t *stat_object_dead,
+ void (*do_cancel)(struct fscache_operation *))
{
int ret;
- if (!test_bit(FSCACHE_OP_WAITING, &op->op.flags))
+ if (!test_bit(FSCACHE_OP_WAITING, &op->flags))
goto check_if_dead;
_debug(">>> WT");
- fscache_stat(stat_op_waits);
- if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
+ if (stat_op_waits)
+ fscache_stat(stat_op_waits);
+ if (wait_on_bit(&op->flags, FSCACHE_OP_WAITING,
fscache_wait_bit_interruptible,
TASK_INTERRUPTIBLE) != 0) {
- ret = fscache_cancel_op(&op->op, fscache_do_cancel_retrieval);
+ ret = fscache_cancel_op(op, do_cancel);
if (ret == 0)
return -ERESTARTSYS;
/* it's been removed from the pending queue by another party,
* so we should get to run shortly */
- wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
+ wait_on_bit(&op->flags, FSCACHE_OP_WAITING,
fscache_wait_bit, TASK_UNINTERRUPTIBLE);
}
_debug("<<< GO");
check_if_dead:
- if (op->op.state == FSCACHE_OP_ST_CANCELLED) {
- fscache_stat(stat_object_dead);
+ if (op->state == FSCACHE_OP_ST_CANCELLED) {
+ if (stat_object_dead)
+ fscache_stat(stat_object_dead);
_leave(" = -ENOBUFS [cancelled]");
return -ENOBUFS;
}
if (unlikely(fscache_object_is_dead(object))) {
- pr_err("%s() = -ENOBUFS [obj dead %d]\n", __func__, op->op.state);
- fscache_cancel_op(&op->op, fscache_do_cancel_retrieval);
- fscache_stat(stat_object_dead);
+ pr_err("%s() = -ENOBUFS [obj dead %d]\n", __func__, op->state);
+ fscache_cancel_op(op, do_cancel);
+ if (stat_object_dead)
+ fscache_stat(stat_object_dead);
return -ENOBUFS;
}
return 0;
@@ -432,10 +436,11 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
/* we wait for the operation to become active, and then process it
* *here*, in this thread, and not in the thread pool */
- ret = fscache_wait_for_retrieval_activation(
- object, op,
+ ret = fscache_wait_for_operation_activation(
+ object, &op->op,
__fscache_stat(&fscache_n_retrieval_op_waits),
- __fscache_stat(&fscache_n_retrievals_object_dead));
+ __fscache_stat(&fscache_n_retrievals_object_dead),
+ fscache_do_cancel_retrieval);
if (ret < 0)
goto error;
@@ -557,10 +562,11 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
/* we wait for the operation to become active, and then process it
* *here*, in this thread, and not in the thread pool */
- ret = fscache_wait_for_retrieval_activation(
- object, op,
+ ret = fscache_wait_for_operation_activation(
+ object, &op->op,
__fscache_stat(&fscache_n_retrieval_op_waits),
- __fscache_stat(&fscache_n_retrievals_object_dead));
+ __fscache_stat(&fscache_n_retrievals_object_dead),
+ fscache_do_cancel_retrieval);
if (ret < 0)
goto error;
@@ -658,10 +664,11 @@ int __fscache_alloc_page(struct fscache_cookie *cookie,
fscache_stat(&fscache_n_alloc_ops);
- ret = fscache_wait_for_retrieval_activation(
- object, op,
+ ret = fscache_wait_for_operation_activation(
+ object, &op->op,
__fscache_stat(&fscache_n_alloc_op_waits),
- __fscache_stat(&fscache_n_allocs_object_dead));
+ __fscache_stat(&fscache_n_allocs_object_dead),
+ fscache_do_cancel_retrieval);
if (ret < 0)
goto error;