diff options
author | James Morris <jmorris@macbook.(none)> | 2009-12-03 12:03:40 +0530 |
---|---|---|
committer | James Morris <jmorris@macbook.(none)> | 2009-12-03 12:03:40 +0530 |
commit | c84d6efd363a3948eb32ec40d46bab6338580454 (patch) | |
tree | 3ba7ac46e6626fe8ac843834588609eb6ccee5c6 /fs/fscache/page.c | |
parent | 7539cf4b92be4aecc573ea962135f246a7a33401 (diff) | |
parent | 22763c5cf3690a681551162c15d34d935308c8d7 (diff) |
Merge branch 'master' into next
Diffstat (limited to 'fs/fscache/page.c')
-rw-r--r-- | fs/fscache/page.c | 273 |
1 files changed, 224 insertions, 49 deletions
diff --git a/fs/fscache/page.c b/fs/fscache/page.c index 2568e0eb644..c598ea4c4e7 100644 --- a/fs/fscache/page.c +++ b/fs/fscache/page.c @@ -43,18 +43,102 @@ void __fscache_wait_on_page_write(struct fscache_cookie *cookie, struct page *pa EXPORT_SYMBOL(__fscache_wait_on_page_write); /* - * note that a page has finished being written to the cache + * decide whether a page can be released, possibly by cancelling a store to it + * - we're allowed to sleep if __GFP_WAIT is flagged */ -static void fscache_end_page_write(struct fscache_cookie *cookie, struct page *page) +bool __fscache_maybe_release_page(struct fscache_cookie *cookie, + struct page *page, + gfp_t gfp) { struct page *xpage; + void *val; + + _enter("%p,%p,%x", cookie, page, gfp); + + rcu_read_lock(); + val = radix_tree_lookup(&cookie->stores, page->index); + if (!val) { + rcu_read_unlock(); + fscache_stat(&fscache_n_store_vmscan_not_storing); + __fscache_uncache_page(cookie, page); + return true; + } + + /* see if the page is actually undergoing storage - if so we can't get + * rid of it till the cache has finished with it */ + if (radix_tree_tag_get(&cookie->stores, page->index, + FSCACHE_COOKIE_STORING_TAG)) { + rcu_read_unlock(); + goto page_busy; + } + + /* the page is pending storage, so we attempt to cancel the store and + * discard the store request so that the page can be reclaimed */ + spin_lock(&cookie->stores_lock); + rcu_read_unlock(); + + if (radix_tree_tag_get(&cookie->stores, page->index, + FSCACHE_COOKIE_STORING_TAG)) { + /* the page started to undergo storage whilst we were looking, + * so now we can only wait or return */ + spin_unlock(&cookie->stores_lock); + goto page_busy; + } - spin_lock(&cookie->lock); xpage = radix_tree_delete(&cookie->stores, page->index); - spin_unlock(&cookie->lock); - ASSERT(xpage != NULL); + spin_unlock(&cookie->stores_lock); + + if (xpage) { + fscache_stat(&fscache_n_store_vmscan_cancelled); + fscache_stat(&fscache_n_store_radix_deletes); + ASSERTCMP(xpage, ==, page); + } else { + fscache_stat(&fscache_n_store_vmscan_gone); + } wake_up_bit(&cookie->flags, 0); + if (xpage) + page_cache_release(xpage); + __fscache_uncache_page(cookie, page); + return true; + +page_busy: + /* we might want to wait here, but that could deadlock the allocator as + * the slow-work threads writing to the cache may all end up sleeping + * on memory allocation */ + fscache_stat(&fscache_n_store_vmscan_busy); + return false; +} +EXPORT_SYMBOL(__fscache_maybe_release_page); + +/* + * note that a page has finished being written to the cache + */ +static void fscache_end_page_write(struct fscache_object *object, + struct page *page) +{ + struct fscache_cookie *cookie; + struct page *xpage = NULL; + + spin_lock(&object->lock); + cookie = object->cookie; + if (cookie) { + /* delete the page from the tree if it is now no longer + * pending */ + spin_lock(&cookie->stores_lock); + radix_tree_tag_clear(&cookie->stores, page->index, + FSCACHE_COOKIE_STORING_TAG); + if (!radix_tree_tag_get(&cookie->stores, page->index, + FSCACHE_COOKIE_PENDING_TAG)) { + fscache_stat(&fscache_n_store_radix_deletes); + xpage = radix_tree_delete(&cookie->stores, page->index); + } + spin_unlock(&cookie->stores_lock); + wake_up_bit(&cookie->flags, 0); + } + spin_unlock(&object->lock); + if (xpage) + page_cache_release(xpage); } /* @@ -63,14 +147,21 @@ static void fscache_end_page_write(struct fscache_cookie *cookie, struct page *p static void fscache_attr_changed_op(struct fscache_operation *op) { struct fscache_object *object = op->object; + int ret; _enter("{OBJ%x OP%x}", object->debug_id, op->debug_id); fscache_stat(&fscache_n_attr_changed_calls); - if (fscache_object_is_active(object) && - object->cache->ops->attr_changed(object) < 0) - fscache_abort_object(object); + if (fscache_object_is_active(object)) { + fscache_set_op_state(op, "CallFS"); + fscache_stat(&fscache_n_cop_attr_changed); + ret = object->cache->ops->attr_changed(object); + fscache_stat_d(&fscache_n_cop_attr_changed); + fscache_set_op_state(op, "Done"); + if (ret < 0) + fscache_abort_object(object); + } _leave(""); } @@ -99,6 +190,7 @@ int __fscache_attr_changed(struct fscache_cookie *cookie) fscache_operation_init(op, NULL); fscache_operation_init_slow(op, fscache_attr_changed_op); op->flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_EXCLUSIVE); + fscache_set_op_name(op, "Attr"); spin_lock(&cookie->lock); @@ -184,6 +276,7 @@ static struct fscache_retrieval *fscache_alloc_retrieval( op->start_time = jiffies; INIT_WORK(&op->op.fast_work, fscache_retrieval_work); INIT_LIST_HEAD(&op->to_do); + fscache_set_op_name(&op->op, "Retr"); return op; } @@ -221,6 +314,43 @@ static int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie) } /* + * 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 ret; + + if (!test_bit(FSCACHE_OP_WAITING, &op->op.flags)) + goto check_if_dead; + + _debug(">>> WT"); + fscache_stat(stat_op_waits); + if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, + fscache_wait_bit_interruptible, + TASK_INTERRUPTIBLE) < 0) { + ret = fscache_cancel_op(&op->op); + 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, + fscache_wait_bit, TASK_UNINTERRUPTIBLE); + } + _debug("<<< GO"); + +check_if_dead: + if (unlikely(fscache_object_is_dead(object))) { + fscache_stat(stat_object_dead); + return -ENOBUFS; + } + return 0; +} + +/* * read a page from the cache or allocate a block in which to store it * - we return: * -ENOMEM - out of memory, nothing done @@ -257,6 +387,7 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie, _leave(" = -ENOMEM"); return -ENOMEM; } + fscache_set_op_name(&op->op, "RetrRA1"); spin_lock(&cookie->lock); @@ -267,6 +398,9 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie, ASSERTCMP(object->state, >, FSCACHE_OBJECT_LOOKING_UP); + atomic_inc(&object->n_reads); + set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags); + if (fscache_submit_op(object, &op->op) < 0) goto nobufs_unlock; spin_unlock(&cookie->lock); @@ -279,23 +413,27 @@ 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 */ - if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) { - _debug(">>> WT"); - fscache_stat(&fscache_n_retrieval_op_waits); - wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, - fscache_wait_bit, TASK_UNINTERRUPTIBLE); - _debug("<<< GO"); - } + ret = fscache_wait_for_retrieval_activation( + object, op, + __fscache_stat(&fscache_n_retrieval_op_waits), + __fscache_stat(&fscache_n_retrievals_object_dead)); + if (ret < 0) + goto error; /* ask the cache to honour the operation */ if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) { + fscache_stat(&fscache_n_cop_allocate_page); ret = object->cache->ops->allocate_page(op, page, gfp); + fscache_stat_d(&fscache_n_cop_allocate_page); if (ret == 0) ret = -ENODATA; } else { + fscache_stat(&fscache_n_cop_read_or_alloc_page); ret = object->cache->ops->read_or_alloc_page(op, page, gfp); + fscache_stat_d(&fscache_n_cop_read_or_alloc_page); } +error: if (ret == -ENOMEM) fscache_stat(&fscache_n_retrievals_nomem); else if (ret == -ERESTARTSYS) @@ -347,7 +485,6 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie, void *context, gfp_t gfp) { - fscache_pages_retrieval_func_t func; struct fscache_retrieval *op; struct fscache_object *object; int ret; @@ -369,6 +506,7 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie, op = fscache_alloc_retrieval(mapping, end_io_func, context); if (!op) return -ENOMEM; + fscache_set_op_name(&op->op, "RetrRAN"); spin_lock(&cookie->lock); @@ -377,6 +515,9 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie, object = hlist_entry(cookie->backing_objects.first, struct fscache_object, cookie_link); + atomic_inc(&object->n_reads); + set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags); + if (fscache_submit_op(object, &op->op) < 0) goto nobufs_unlock; spin_unlock(&cookie->lock); @@ -389,21 +530,27 @@ 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 */ - if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) { - _debug(">>> WT"); - fscache_stat(&fscache_n_retrieval_op_waits); - wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, - fscache_wait_bit, TASK_UNINTERRUPTIBLE); - _debug("<<< GO"); - } + ret = fscache_wait_for_retrieval_activation( + object, op, + __fscache_stat(&fscache_n_retrieval_op_waits), + __fscache_stat(&fscache_n_retrievals_object_dead)); + if (ret < 0) + goto error; /* ask the cache to honour the operation */ - if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) - func = object->cache->ops->allocate_pages; - else - func = object->cache->ops->read_or_alloc_pages; - ret = func(op, pages, nr_pages, gfp); + if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) { + fscache_stat(&fscache_n_cop_allocate_pages); + ret = object->cache->ops->allocate_pages( + op, pages, nr_pages, gfp); + fscache_stat_d(&fscache_n_cop_allocate_pages); + } else { + fscache_stat(&fscache_n_cop_read_or_alloc_pages); + ret = object->cache->ops->read_or_alloc_pages( + op, pages, nr_pages, gfp); + fscache_stat_d(&fscache_n_cop_read_or_alloc_pages); + } +error: if (ret == -ENOMEM) fscache_stat(&fscache_n_retrievals_nomem); else if (ret == -ERESTARTSYS) @@ -461,6 +608,7 @@ int __fscache_alloc_page(struct fscache_cookie *cookie, op = fscache_alloc_retrieval(page->mapping, NULL, NULL); if (!op) return -ENOMEM; + fscache_set_op_name(&op->op, "RetrAL1"); spin_lock(&cookie->lock); @@ -475,18 +623,22 @@ int __fscache_alloc_page(struct fscache_cookie *cookie, fscache_stat(&fscache_n_alloc_ops); - if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) { - _debug(">>> WT"); - fscache_stat(&fscache_n_alloc_op_waits); - wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, - fscache_wait_bit, TASK_UNINTERRUPTIBLE); - _debug("<<< GO"); - } + ret = fscache_wait_for_retrieval_activation( + object, op, + __fscache_stat(&fscache_n_alloc_op_waits), + __fscache_stat(&fscache_n_allocs_object_dead)); + if (ret < 0) + goto error; /* ask the cache to honour the operation */ + fscache_stat(&fscache_n_cop_allocate_page); ret = object->cache->ops->allocate_page(op, page, gfp); + fscache_stat_d(&fscache_n_cop_allocate_page); - if (ret < 0) +error: + if (ret == -ERESTARTSYS) + fscache_stat(&fscache_n_allocs_intr); + else if (ret < 0) fscache_stat(&fscache_n_allocs_nobufs); else fscache_stat(&fscache_n_allocs_ok); @@ -521,7 +673,7 @@ static void fscache_write_op(struct fscache_operation *_op) struct fscache_storage *op = container_of(_op, struct fscache_storage, op); struct fscache_object *object = op->op.object; - struct fscache_cookie *cookie = object->cookie; + struct fscache_cookie *cookie; struct page *page; unsigned n; void *results[1]; @@ -529,16 +681,19 @@ static void fscache_write_op(struct fscache_operation *_op) _enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage)); - spin_lock(&cookie->lock); + fscache_set_op_state(&op->op, "GetPage"); + spin_lock(&object->lock); + cookie = object->cookie; - if (!fscache_object_is_active(object)) { + if (!fscache_object_is_active(object) || !cookie) { spin_unlock(&object->lock); - spin_unlock(&cookie->lock); _leave(""); return; } + spin_lock(&cookie->stores_lock); + fscache_stat(&fscache_n_store_calls); /* find a page to store */ @@ -549,23 +704,35 @@ static void fscache_write_op(struct fscache_operation *_op) goto superseded; page = results[0]; _debug("gang %d [%lx]", n, page->index); - if (page->index > op->store_limit) + if (page->index > op->store_limit) { + fscache_stat(&fscache_n_store_pages_over_limit); goto superseded; + } - radix_tree_tag_clear(&cookie->stores, page->index, - FSCACHE_COOKIE_PENDING_TAG); + if (page) { + radix_tree_tag_set(&cookie->stores, page->index, + FSCACHE_COOKIE_STORING_TAG); + radix_tree_tag_clear(&cookie->stores, page->index, + FSCACHE_COOKIE_PENDING_TAG); + } + spin_unlock(&cookie->stores_lock); spin_unlock(&object->lock); - spin_unlock(&cookie->lock); if (page) { + fscache_set_op_state(&op->op, "Store"); + fscache_stat(&fscache_n_store_pages); + fscache_stat(&fscache_n_cop_write_page); ret = object->cache->ops->write_page(op, page); - fscache_end_page_write(cookie, page); - page_cache_release(page); - if (ret < 0) + fscache_stat_d(&fscache_n_cop_write_page); + fscache_set_op_state(&op->op, "EndWrite"); + fscache_end_page_write(object, page); + if (ret < 0) { + fscache_set_op_state(&op->op, "Abort"); fscache_abort_object(object); - else + } else { fscache_enqueue_operation(&op->op); + } } _leave(""); @@ -575,9 +742,9 @@ superseded: /* this writer is going away and there aren't any more things to * write */ _debug("cease"); + spin_unlock(&cookie->stores_lock); clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); spin_unlock(&object->lock); - spin_unlock(&cookie->lock); _leave(""); } @@ -634,6 +801,7 @@ int __fscache_write_page(struct fscache_cookie *cookie, fscache_operation_init(&op->op, fscache_release_write_op); fscache_operation_init_slow(&op->op, fscache_write_op); op->op.flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_WAITING); + fscache_set_op_name(&op->op, "Write1"); ret = radix_tree_preload(gfp & ~__GFP_HIGHMEM); if (ret < 0) @@ -652,6 +820,7 @@ int __fscache_write_page(struct fscache_cookie *cookie, /* add the page to the pending-storage radix tree on the backing * object */ spin_lock(&object->lock); + spin_lock(&cookie->stores_lock); _debug("store limit %llx", (unsigned long long) object->store_limit); @@ -672,6 +841,7 @@ int __fscache_write_page(struct fscache_cookie *cookie, if (test_and_set_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags)) goto already_pending; + spin_unlock(&cookie->stores_lock); spin_unlock(&object->lock); op->op.debug_id = atomic_inc_return(&fscache_op_debug_id); @@ -693,6 +863,7 @@ int __fscache_write_page(struct fscache_cookie *cookie, already_queued: fscache_stat(&fscache_n_stores_again); already_pending: + spin_unlock(&cookie->stores_lock); spin_unlock(&object->lock); spin_unlock(&cookie->lock); radix_tree_preload_end(); @@ -702,7 +873,9 @@ already_pending: return 0; submit_failed: + spin_lock(&cookie->stores_lock); radix_tree_delete(&cookie->stores, page->index); + spin_unlock(&cookie->stores_lock); page_cache_release(page); ret = -ENOBUFS; goto nobufs; @@ -763,7 +936,9 @@ void __fscache_uncache_page(struct fscache_cookie *cookie, struct page *page) if (TestClearPageFsCache(page) && object->cache->ops->uncache_page) { /* the cache backend releases the cookie lock */ + fscache_stat(&fscache_n_cop_uncache_page); object->cache->ops->uncache_page(object, page); + fscache_stat_d(&fscache_n_cop_uncache_page); goto done; } |