From 8fb883f3e30065529e4f35d4b4f355193dcdb7a2 Mon Sep 17 00:00:00 2001 From: David Howells Date: Sat, 21 Sep 2013 00:09:31 +0100 Subject: FS-Cache: Add use/unuse/wake cookie wrappers Add wrapper functions for dealing with cookie->n_active: (*) __fscache_use_cookie() to increment it. (*) __fscache_unuse_cookie() to decrement and test against zero. (*) __fscache_wake_unused_cookie() to wake up anyone waiting for it to reach zero. The second and third are split so that the third can be done after cookie->lock has been released in case the waiter wakes up whilst we're still holding it and tries to get it. We will need to wake-on-zero once the cookie disablement patch is applied because it will then be possible to see n_active become zero without the cookie being relinquished. Also move the cookie usement out of fscache_attr_changed_op() and into fscache_attr_changed() and the operation struct so that cookie disablement will be able to track it. Whilst we're at it, only increment n_active if we're about to do fscache_submit_op() so that we don't have to deal with undoing it if anything earlier fails. Possibly this should be moved into fscache_submit_op() which could look at FSCACHE_OP_UNUSE_COOKIE. Signed-off-by: David Howells --- fs/fscache/cookie.c | 7 +++++-- fs/fscache/page.c | 42 +++++++++++++++++++++++++++++++----------- 2 files changed, 36 insertions(+), 13 deletions(-) (limited to 'fs/fscache') diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c index b2a86e324aac..d851aa555d28 100644 --- a/fs/fscache/cookie.c +++ b/fs/fscache/cookie.c @@ -568,6 +568,7 @@ int __fscache_check_consistency(struct fscache_cookie *cookie) { struct fscache_operation *op; struct fscache_object *object; + bool wake_cookie = false; int ret; _enter("%p,", cookie); @@ -600,7 +601,7 @@ int __fscache_check_consistency(struct fscache_cookie *cookie) op->debug_id = atomic_inc_return(&fscache_op_debug_id); - atomic_inc(&cookie->n_active); + __fscache_use_cookie(cookie); if (fscache_submit_op(object, op) < 0) goto submit_failed; @@ -622,9 +623,11 @@ int __fscache_check_consistency(struct fscache_cookie *cookie) return ret; submit_failed: - atomic_dec(&cookie->n_active); + wake_cookie = __fscache_unuse_cookie(cookie); inconsistent: spin_unlock(&cookie->lock); + if (wake_cookie) + __fscache_wake_unused_cookie(cookie); kfree(op); _leave(" = -ESTALE"); return -ESTALE; diff --git a/fs/fscache/page.c b/fs/fscache/page.c index 73899c1c3449..0fe42a6d0e9c 100644 --- a/fs/fscache/page.c +++ b/fs/fscache/page.c @@ -163,12 +163,10 @@ static void fscache_attr_changed_op(struct fscache_operation *op) fscache_stat(&fscache_n_attr_changed_calls); - if (fscache_object_is_active(object) && - fscache_use_cookie(object)) { + if (fscache_object_is_active(object)) { fscache_stat(&fscache_n_cop_attr_changed); ret = object->cache->ops->attr_changed(object); fscache_stat_d(&fscache_n_cop_attr_changed); - fscache_unuse_cookie(object); if (ret < 0) fscache_abort_object(object); } @@ -184,6 +182,7 @@ int __fscache_attr_changed(struct fscache_cookie *cookie) { struct fscache_operation *op; struct fscache_object *object; + bool wake_cookie; _enter("%p", cookie); @@ -199,7 +198,9 @@ int __fscache_attr_changed(struct fscache_cookie *cookie) } fscache_operation_init(op, fscache_attr_changed_op, NULL); - op->flags = FSCACHE_OP_ASYNC | (1 << FSCACHE_OP_EXCLUSIVE); + op->flags = FSCACHE_OP_ASYNC | + (1 << FSCACHE_OP_EXCLUSIVE) | + (1 << FSCACHE_OP_UNUSE_COOKIE); spin_lock(&cookie->lock); @@ -208,6 +209,7 @@ int __fscache_attr_changed(struct fscache_cookie *cookie) object = hlist_entry(cookie->backing_objects.first, struct fscache_object, cookie_link); + __fscache_use_cookie(cookie); if (fscache_submit_exclusive_op(object, op) < 0) goto nobufs; spin_unlock(&cookie->lock); @@ -217,8 +219,11 @@ int __fscache_attr_changed(struct fscache_cookie *cookie) return 0; nobufs: + wake_cookie = __fscache_unuse_cookie(cookie); spin_unlock(&cookie->lock); kfree(op); + if (wake_cookie) + __fscache_wake_unused_cookie(cookie); fscache_stat(&fscache_n_attr_changed_nobufs); _leave(" = %d", -ENOBUFS); return -ENOBUFS; @@ -263,7 +268,6 @@ static struct fscache_retrieval *fscache_alloc_retrieval( } fscache_operation_init(&op->op, NULL, fscache_release_retrieval_op); - atomic_inc(&cookie->n_active); op->op.flags = FSCACHE_OP_MYTHREAD | (1UL << FSCACHE_OP_WAITING) | (1UL << FSCACHE_OP_UNUSE_COOKIE); @@ -384,6 +388,7 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie, { struct fscache_retrieval *op; struct fscache_object *object; + bool wake_cookie = false; int ret; _enter("%p,%p,,,", cookie, page); @@ -421,6 +426,7 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie, ASSERT(test_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)); + __fscache_use_cookie(cookie); atomic_inc(&object->n_reads); __set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags); @@ -475,9 +481,11 @@ error: nobufs_unlock_dec: atomic_dec(&object->n_reads); + wake_cookie = __fscache_unuse_cookie(cookie); nobufs_unlock: spin_unlock(&cookie->lock); - atomic_dec(&cookie->n_active); + if (wake_cookie) + __fscache_wake_unused_cookie(cookie); kfree(op); nobufs: fscache_stat(&fscache_n_retrievals_nobufs); @@ -514,6 +522,7 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie, { struct fscache_retrieval *op; struct fscache_object *object; + bool wake_cookie = false; int ret; _enter("%p,,%d,,,", cookie, *nr_pages); @@ -547,6 +556,7 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie, object = hlist_entry(cookie->backing_objects.first, struct fscache_object, cookie_link); + __fscache_use_cookie(cookie); atomic_inc(&object->n_reads); __set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags); @@ -601,10 +611,12 @@ error: nobufs_unlock_dec: atomic_dec(&object->n_reads); + wake_cookie = __fscache_unuse_cookie(cookie); nobufs_unlock: spin_unlock(&cookie->lock); - atomic_dec(&cookie->n_active); kfree(op); + if (wake_cookie) + __fscache_wake_unused_cookie(cookie); nobufs: fscache_stat(&fscache_n_retrievals_nobufs); _leave(" = -ENOBUFS"); @@ -626,6 +638,7 @@ int __fscache_alloc_page(struct fscache_cookie *cookie, { struct fscache_retrieval *op; struct fscache_object *object; + bool wake_cookie = false; int ret; _enter("%p,%p,,,", cookie, page); @@ -658,8 +671,9 @@ int __fscache_alloc_page(struct fscache_cookie *cookie, object = hlist_entry(cookie->backing_objects.first, struct fscache_object, cookie_link); + __fscache_use_cookie(cookie); if (fscache_submit_op(object, &op->op) < 0) - goto nobufs_unlock; + goto nobufs_unlock_dec; spin_unlock(&cookie->lock); fscache_stat(&fscache_n_alloc_ops); @@ -689,10 +703,13 @@ error: _leave(" = %d", ret); return ret; +nobufs_unlock_dec: + wake_cookie = __fscache_unuse_cookie(cookie); nobufs_unlock: spin_unlock(&cookie->lock); - atomic_dec(&cookie->n_active); kfree(op); + if (wake_cookie) + __fscache_wake_unused_cookie(cookie); nobufs: fscache_stat(&fscache_n_allocs_nobufs); _leave(" = -ENOBUFS"); @@ -889,6 +906,7 @@ int __fscache_write_page(struct fscache_cookie *cookie, { struct fscache_storage *op; struct fscache_object *object; + bool wake_cookie = false; int ret; _enter("%p,%x,", cookie, (u32) page->flags); @@ -957,7 +975,7 @@ int __fscache_write_page(struct fscache_cookie *cookie, op->op.debug_id = atomic_inc_return(&fscache_op_debug_id); op->store_limit = object->store_limit; - atomic_inc(&cookie->n_active); + __fscache_use_cookie(cookie); if (fscache_submit_op(object, &op->op) < 0) goto submit_failed; @@ -984,10 +1002,10 @@ already_pending: return 0; submit_failed: - atomic_dec(&cookie->n_active); spin_lock(&cookie->stores_lock); radix_tree_delete(&cookie->stores, page->index); spin_unlock(&cookie->stores_lock); + wake_cookie = __fscache_unuse_cookie(cookie); page_cache_release(page); ret = -ENOBUFS; goto nobufs; @@ -999,6 +1017,8 @@ nobufs: spin_unlock(&cookie->lock); radix_tree_preload_end(); kfree(op); + if (wake_cookie) + __fscache_wake_unused_cookie(cookie); fscache_stat(&fscache_n_stores_nobufs); _leave(" = -ENOBUFS"); return -ENOBUFS; -- cgit v1.2.3