From da9803bc8812f5bd3b26baaa90e515b843c65ff7 Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 21 Aug 2013 17:29:38 -0400 Subject: 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 Signed-off-by: David Howells cc: Hongyi Jia cc: Milosz Tanski --- fs/fscache/page.c | 55 +++++++++++++++++++++++++++++++------------------------ 1 file changed, 31 insertions(+), 24 deletions(-) (limited to 'fs/fscache/page.c') 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; -- cgit v1.2.3