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>
diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index d479ab3..793e3d5 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -278,7 +278,7 @@
/*
* 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 @@
/*
* 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 @@
/* 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 @@
/* 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 @@
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;