diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-03 10:07:43 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-03 10:07:43 -0700 |
commit | 3cc50ac0dbda5100684e570247782330155d35e0 (patch) | |
tree | f4b8f22d1725ebe65d2fe658d292dabacd7ed564 /fs/fscache/page.c | |
parent | d9b9be024a6628a01d8730d1fd0b5f25658a2794 (diff) | |
parent | b797cac7487dee6bfddeb161631c1bbc54fa3cdb (diff) | |
download | op-kernel-dev-3cc50ac0dbda5100684e570247782330155d35e0.zip op-kernel-dev-3cc50ac0dbda5100684e570247782330155d35e0.tar.gz |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-fscache
* git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-fscache: (41 commits)
NFS: Add mount options to enable local caching on NFS
NFS: Display local caching state
NFS: Store pages from an NFS inode into a local cache
NFS: Read pages from FS-Cache into an NFS inode
NFS: nfs_readpage_async() needs to be accessible as a fallback for local caching
NFS: Add read context retention for FS-Cache to call back with
NFS: FS-Cache page management
NFS: Add some new I/O counters for FS-Cache doing things for NFS
NFS: Invalidate FsCache page flags when cache removed
NFS: Use local disk inode cache
NFS: Define and create inode-level cache objects
NFS: Define and create superblock-level objects
NFS: Define and create server-level objects
NFS: Register NFS for caching and retrieve the top-level index
NFS: Permit local filesystem caching to be enabled for NFS
NFS: Add FS-Cache option bit and debug bit
NFS: Add comment banners to some NFS functions
FS-Cache: Make kAFS use FS-Cache
CacheFiles: A cache that backs onto a mounted filesystem
CacheFiles: Export things for CacheFiles
...
Diffstat (limited to 'fs/fscache/page.c')
-rw-r--r-- | fs/fscache/page.c | 816 |
1 files changed, 816 insertions, 0 deletions
diff --git a/fs/fscache/page.c b/fs/fscache/page.c new file mode 100644 index 0000000..2568e0e --- /dev/null +++ b/fs/fscache/page.c @@ -0,0 +1,816 @@ +/* Cache page management and data I/O routines + * + * Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#define FSCACHE_DEBUG_LEVEL PAGE +#include <linux/module.h> +#include <linux/fscache-cache.h> +#include <linux/buffer_head.h> +#include <linux/pagevec.h> +#include "internal.h" + +/* + * check to see if a page is being written to the cache + */ +bool __fscache_check_page_write(struct fscache_cookie *cookie, struct page *page) +{ + void *val; + + rcu_read_lock(); + val = radix_tree_lookup(&cookie->stores, page->index); + rcu_read_unlock(); + + return val != NULL; +} +EXPORT_SYMBOL(__fscache_check_page_write); + +/* + * wait for a page to finish being written to the cache + */ +void __fscache_wait_on_page_write(struct fscache_cookie *cookie, struct page *page) +{ + wait_queue_head_t *wq = bit_waitqueue(&cookie->flags, 0); + + wait_event(*wq, !__fscache_check_page_write(cookie, page)); +} +EXPORT_SYMBOL(__fscache_wait_on_page_write); + +/* + * note that a page has finished being written to the cache + */ +static void fscache_end_page_write(struct fscache_cookie *cookie, struct page *page) +{ + struct page *xpage; + + spin_lock(&cookie->lock); + xpage = radix_tree_delete(&cookie->stores, page->index); + spin_unlock(&cookie->lock); + ASSERT(xpage != NULL); + + wake_up_bit(&cookie->flags, 0); +} + +/* + * actually apply the changed attributes to a cache object + */ +static void fscache_attr_changed_op(struct fscache_operation *op) +{ + struct fscache_object *object = op->object; + + _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); + + _leave(""); +} + +/* + * notification that the attributes on an object have changed + */ +int __fscache_attr_changed(struct fscache_cookie *cookie) +{ + struct fscache_operation *op; + struct fscache_object *object; + + _enter("%p", cookie); + + ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); + + fscache_stat(&fscache_n_attr_changed); + + op = kzalloc(sizeof(*op), GFP_KERNEL); + if (!op) { + fscache_stat(&fscache_n_attr_changed_nomem); + _leave(" = -ENOMEM"); + return -ENOMEM; + } + + fscache_operation_init(op, NULL); + fscache_operation_init_slow(op, fscache_attr_changed_op); + op->flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_EXCLUSIVE); + + spin_lock(&cookie->lock); + + if (hlist_empty(&cookie->backing_objects)) + goto nobufs; + object = hlist_entry(cookie->backing_objects.first, + struct fscache_object, cookie_link); + + if (fscache_submit_exclusive_op(object, op) < 0) + goto nobufs; + spin_unlock(&cookie->lock); + fscache_stat(&fscache_n_attr_changed_ok); + fscache_put_operation(op); + _leave(" = 0"); + return 0; + +nobufs: + spin_unlock(&cookie->lock); + kfree(op); + fscache_stat(&fscache_n_attr_changed_nobufs); + _leave(" = %d", -ENOBUFS); + return -ENOBUFS; +} +EXPORT_SYMBOL(__fscache_attr_changed); + +/* + * handle secondary execution given to a retrieval op on behalf of the + * cache + */ +static void fscache_retrieval_work(struct work_struct *work) +{ + struct fscache_retrieval *op = + container_of(work, struct fscache_retrieval, op.fast_work); + unsigned long start; + + _enter("{OP%x}", op->op.debug_id); + + start = jiffies; + op->op.processor(&op->op); + fscache_hist(fscache_ops_histogram, start); + fscache_put_operation(&op->op); +} + +/* + * release a retrieval op reference + */ +static void fscache_release_retrieval_op(struct fscache_operation *_op) +{ + struct fscache_retrieval *op = + container_of(_op, struct fscache_retrieval, op); + + _enter("{OP%x}", op->op.debug_id); + + fscache_hist(fscache_retrieval_histogram, op->start_time); + if (op->context) + fscache_put_context(op->op.object->cookie, op->context); + + _leave(""); +} + +/* + * allocate a retrieval op + */ +static struct fscache_retrieval *fscache_alloc_retrieval( + struct address_space *mapping, + fscache_rw_complete_t end_io_func, + void *context) +{ + struct fscache_retrieval *op; + + /* allocate a retrieval operation and attempt to submit it */ + op = kzalloc(sizeof(*op), GFP_NOIO); + if (!op) { + fscache_stat(&fscache_n_retrievals_nomem); + return NULL; + } + + fscache_operation_init(&op->op, fscache_release_retrieval_op); + op->op.flags = FSCACHE_OP_MYTHREAD | (1 << FSCACHE_OP_WAITING); + op->mapping = mapping; + op->end_io_func = end_io_func; + op->context = context; + op->start_time = jiffies; + INIT_WORK(&op->op.fast_work, fscache_retrieval_work); + INIT_LIST_HEAD(&op->to_do); + return op; +} + +/* + * wait for a deferred lookup to complete + */ +static int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie) +{ + unsigned long jif; + + _enter(""); + + if (!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) { + _leave(" = 0 [imm]"); + return 0; + } + + fscache_stat(&fscache_n_retrievals_wait); + + jif = jiffies; + if (wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP, + fscache_wait_bit_interruptible, + TASK_INTERRUPTIBLE) != 0) { + fscache_stat(&fscache_n_retrievals_intr); + _leave(" = -ERESTARTSYS"); + return -ERESTARTSYS; + } + + ASSERT(!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)); + + smp_rmb(); + fscache_hist(fscache_retrieval_delay_histogram, jif); + _leave(" = 0 [dly]"); + 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 + * -ERESTARTSYS - interrupted + * -ENOBUFS - no backing object available in which to cache the block + * -ENODATA - no data available in the backing object for this block + * 0 - dispatched a read - it'll call end_io_func() when finished + */ +int __fscache_read_or_alloc_page(struct fscache_cookie *cookie, + struct page *page, + fscache_rw_complete_t end_io_func, + void *context, + gfp_t gfp) +{ + struct fscache_retrieval *op; + struct fscache_object *object; + int ret; + + _enter("%p,%p,,,", cookie, page); + + fscache_stat(&fscache_n_retrievals); + + if (hlist_empty(&cookie->backing_objects)) + goto nobufs; + + ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); + ASSERTCMP(page, !=, NULL); + + if (fscache_wait_for_deferred_lookup(cookie) < 0) + return -ERESTARTSYS; + + op = fscache_alloc_retrieval(page->mapping, end_io_func, context); + if (!op) { + _leave(" = -ENOMEM"); + return -ENOMEM; + } + + spin_lock(&cookie->lock); + + if (hlist_empty(&cookie->backing_objects)) + goto nobufs_unlock; + object = hlist_entry(cookie->backing_objects.first, + struct fscache_object, cookie_link); + + ASSERTCMP(object->state, >, FSCACHE_OBJECT_LOOKING_UP); + + if (fscache_submit_op(object, &op->op) < 0) + goto nobufs_unlock; + spin_unlock(&cookie->lock); + + fscache_stat(&fscache_n_retrieval_ops); + + /* pin the netfs read context in case we need to do the actual netfs + * read because we've encountered a cache read failure */ + fscache_get_context(object->cookie, op->context); + + /* 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"); + } + + /* ask the cache to honour the operation */ + if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) { + ret = object->cache->ops->allocate_page(op, page, gfp); + if (ret == 0) + ret = -ENODATA; + } else { + ret = object->cache->ops->read_or_alloc_page(op, page, gfp); + } + + if (ret == -ENOMEM) + fscache_stat(&fscache_n_retrievals_nomem); + else if (ret == -ERESTARTSYS) + fscache_stat(&fscache_n_retrievals_intr); + else if (ret == -ENODATA) + fscache_stat(&fscache_n_retrievals_nodata); + else if (ret < 0) + fscache_stat(&fscache_n_retrievals_nobufs); + else + fscache_stat(&fscache_n_retrievals_ok); + + fscache_put_retrieval(op); + _leave(" = %d", ret); + return ret; + +nobufs_unlock: + spin_unlock(&cookie->lock); + kfree(op); +nobufs: + fscache_stat(&fscache_n_retrievals_nobufs); + _leave(" = -ENOBUFS"); + return -ENOBUFS; +} +EXPORT_SYMBOL(__fscache_read_or_alloc_page); + +/* + * read a list of page from the cache or allocate a block in which to store + * them + * - we return: + * -ENOMEM - out of memory, some pages may be being read + * -ERESTARTSYS - interrupted, some pages may be being read + * -ENOBUFS - no backing object or space available in which to cache any + * pages not being read + * -ENODATA - no data available in the backing object for some or all of + * the pages + * 0 - dispatched a read on all pages + * + * end_io_func() will be called for each page read from the cache as it is + * finishes being read + * + * any pages for which a read is dispatched will be removed from pages and + * nr_pages + */ +int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie, + struct address_space *mapping, + struct list_head *pages, + unsigned *nr_pages, + fscache_rw_complete_t end_io_func, + void *context, + gfp_t gfp) +{ + fscache_pages_retrieval_func_t func; + struct fscache_retrieval *op; + struct fscache_object *object; + int ret; + + _enter("%p,,%d,,,", cookie, *nr_pages); + + fscache_stat(&fscache_n_retrievals); + + if (hlist_empty(&cookie->backing_objects)) + goto nobufs; + + ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); + ASSERTCMP(*nr_pages, >, 0); + ASSERT(!list_empty(pages)); + + if (fscache_wait_for_deferred_lookup(cookie) < 0) + return -ERESTARTSYS; + + op = fscache_alloc_retrieval(mapping, end_io_func, context); + if (!op) + return -ENOMEM; + + spin_lock(&cookie->lock); + + if (hlist_empty(&cookie->backing_objects)) + goto nobufs_unlock; + object = hlist_entry(cookie->backing_objects.first, + struct fscache_object, cookie_link); + + if (fscache_submit_op(object, &op->op) < 0) + goto nobufs_unlock; + spin_unlock(&cookie->lock); + + fscache_stat(&fscache_n_retrieval_ops); + + /* pin the netfs read context in case we need to do the actual netfs + * read because we've encountered a cache read failure */ + fscache_get_context(object->cookie, op->context); + + /* 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"); + } + + /* 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 (ret == -ENOMEM) + fscache_stat(&fscache_n_retrievals_nomem); + else if (ret == -ERESTARTSYS) + fscache_stat(&fscache_n_retrievals_intr); + else if (ret == -ENODATA) + fscache_stat(&fscache_n_retrievals_nodata); + else if (ret < 0) + fscache_stat(&fscache_n_retrievals_nobufs); + else + fscache_stat(&fscache_n_retrievals_ok); + + fscache_put_retrieval(op); + _leave(" = %d", ret); + return ret; + +nobufs_unlock: + spin_unlock(&cookie->lock); + kfree(op); +nobufs: + fscache_stat(&fscache_n_retrievals_nobufs); + _leave(" = -ENOBUFS"); + return -ENOBUFS; +} +EXPORT_SYMBOL(__fscache_read_or_alloc_pages); + +/* + * allocate a block in the cache on which to store a page + * - we return: + * -ENOMEM - out of memory, nothing done + * -ERESTARTSYS - interrupted + * -ENOBUFS - no backing object available in which to cache the block + * 0 - block allocated + */ +int __fscache_alloc_page(struct fscache_cookie *cookie, + struct page *page, + gfp_t gfp) +{ + struct fscache_retrieval *op; + struct fscache_object *object; + int ret; + + _enter("%p,%p,,,", cookie, page); + + fscache_stat(&fscache_n_allocs); + + if (hlist_empty(&cookie->backing_objects)) + goto nobufs; + + ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); + ASSERTCMP(page, !=, NULL); + + if (fscache_wait_for_deferred_lookup(cookie) < 0) + return -ERESTARTSYS; + + op = fscache_alloc_retrieval(page->mapping, NULL, NULL); + if (!op) + return -ENOMEM; + + spin_lock(&cookie->lock); + + if (hlist_empty(&cookie->backing_objects)) + goto nobufs_unlock; + object = hlist_entry(cookie->backing_objects.first, + struct fscache_object, cookie_link); + + if (fscache_submit_op(object, &op->op) < 0) + goto nobufs_unlock; + spin_unlock(&cookie->lock); + + 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"); + } + + /* ask the cache to honour the operation */ + ret = object->cache->ops->allocate_page(op, page, gfp); + + if (ret < 0) + fscache_stat(&fscache_n_allocs_nobufs); + else + fscache_stat(&fscache_n_allocs_ok); + + fscache_put_retrieval(op); + _leave(" = %d", ret); + return ret; + +nobufs_unlock: + spin_unlock(&cookie->lock); + kfree(op); +nobufs: + fscache_stat(&fscache_n_allocs_nobufs); + _leave(" = -ENOBUFS"); + return -ENOBUFS; +} +EXPORT_SYMBOL(__fscache_alloc_page); + +/* + * release a write op reference + */ +static void fscache_release_write_op(struct fscache_operation *_op) +{ + _enter("{OP%x}", _op->debug_id); +} + +/* + * perform the background storage of a page into the cache + */ +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 page *page; + unsigned n; + void *results[1]; + int ret; + + _enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage)); + + spin_lock(&cookie->lock); + spin_lock(&object->lock); + + if (!fscache_object_is_active(object)) { + spin_unlock(&object->lock); + spin_unlock(&cookie->lock); + _leave(""); + return; + } + + fscache_stat(&fscache_n_store_calls); + + /* find a page to store */ + page = NULL; + n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, 1, + FSCACHE_COOKIE_PENDING_TAG); + if (n != 1) + goto superseded; + page = results[0]; + _debug("gang %d [%lx]", n, page->index); + if (page->index > op->store_limit) + goto superseded; + + radix_tree_tag_clear(&cookie->stores, page->index, + FSCACHE_COOKIE_PENDING_TAG); + + spin_unlock(&object->lock); + spin_unlock(&cookie->lock); + + if (page) { + ret = object->cache->ops->write_page(op, page); + fscache_end_page_write(cookie, page); + page_cache_release(page); + if (ret < 0) + fscache_abort_object(object); + else + fscache_enqueue_operation(&op->op); + } + + _leave(""); + return; + +superseded: + /* this writer is going away and there aren't any more things to + * write */ + _debug("cease"); + clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); + spin_unlock(&object->lock); + spin_unlock(&cookie->lock); + _leave(""); +} + +/* + * request a page be stored in the cache + * - returns: + * -ENOMEM - out of memory, nothing done + * -ENOBUFS - no backing object available in which to cache the page + * 0 - dispatched a write - it'll call end_io_func() when finished + * + * if the cookie still has a backing object at this point, that object can be + * in one of a few states with respect to storage processing: + * + * (1) negative lookup, object not yet created (FSCACHE_COOKIE_CREATING is + * set) + * + * (a) no writes yet (set FSCACHE_COOKIE_PENDING_FILL and queue deferred + * fill op) + * + * (b) writes deferred till post-creation (mark page for writing and + * return immediately) + * + * (2) negative lookup, object created, initial fill being made from netfs + * (FSCACHE_COOKIE_INITIAL_FILL is set) + * + * (a) fill point not yet reached this page (mark page for writing and + * return) + * + * (b) fill point passed this page (queue op to store this page) + * + * (3) object extant (queue op to store this page) + * + * any other state is invalid + */ +int __fscache_write_page(struct fscache_cookie *cookie, + struct page *page, + gfp_t gfp) +{ + struct fscache_storage *op; + struct fscache_object *object; + int ret; + + _enter("%p,%x,", cookie, (u32) page->flags); + + ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); + ASSERT(PageFsCache(page)); + + fscache_stat(&fscache_n_stores); + + op = kzalloc(sizeof(*op), GFP_NOIO); + if (!op) + goto nomem; + + 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); + + ret = radix_tree_preload(gfp & ~__GFP_HIGHMEM); + if (ret < 0) + goto nomem_free; + + ret = -ENOBUFS; + spin_lock(&cookie->lock); + + if (hlist_empty(&cookie->backing_objects)) + goto nobufs; + object = hlist_entry(cookie->backing_objects.first, + struct fscache_object, cookie_link); + if (test_bit(FSCACHE_IOERROR, &object->cache->flags)) + goto nobufs; + + /* add the page to the pending-storage radix tree on the backing + * object */ + spin_lock(&object->lock); + + _debug("store limit %llx", (unsigned long long) object->store_limit); + + ret = radix_tree_insert(&cookie->stores, page->index, page); + if (ret < 0) { + if (ret == -EEXIST) + goto already_queued; + _debug("insert failed %d", ret); + goto nobufs_unlock_obj; + } + + radix_tree_tag_set(&cookie->stores, page->index, + FSCACHE_COOKIE_PENDING_TAG); + page_cache_get(page); + + /* we only want one writer at a time, but we do need to queue new + * writers after exclusive ops */ + if (test_and_set_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags)) + goto already_pending; + + spin_unlock(&object->lock); + + op->op.debug_id = atomic_inc_return(&fscache_op_debug_id); + op->store_limit = object->store_limit; + + if (fscache_submit_op(object, &op->op) < 0) + goto submit_failed; + + spin_unlock(&cookie->lock); + radix_tree_preload_end(); + fscache_stat(&fscache_n_store_ops); + fscache_stat(&fscache_n_stores_ok); + + /* the slow work queue now carries its own ref on the object */ + fscache_put_operation(&op->op); + _leave(" = 0"); + return 0; + +already_queued: + fscache_stat(&fscache_n_stores_again); +already_pending: + spin_unlock(&object->lock); + spin_unlock(&cookie->lock); + radix_tree_preload_end(); + kfree(op); + fscache_stat(&fscache_n_stores_ok); + _leave(" = 0"); + return 0; + +submit_failed: + radix_tree_delete(&cookie->stores, page->index); + page_cache_release(page); + ret = -ENOBUFS; + goto nobufs; + +nobufs_unlock_obj: + spin_unlock(&object->lock); +nobufs: + spin_unlock(&cookie->lock); + radix_tree_preload_end(); + kfree(op); + fscache_stat(&fscache_n_stores_nobufs); + _leave(" = -ENOBUFS"); + return -ENOBUFS; + +nomem_free: + kfree(op); +nomem: + fscache_stat(&fscache_n_stores_oom); + _leave(" = -ENOMEM"); + return -ENOMEM; +} +EXPORT_SYMBOL(__fscache_write_page); + +/* + * remove a page from the cache + */ +void __fscache_uncache_page(struct fscache_cookie *cookie, struct page *page) +{ + struct fscache_object *object; + + _enter(",%p", page); + + ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); + ASSERTCMP(page, !=, NULL); + + fscache_stat(&fscache_n_uncaches); + + /* cache withdrawal may beat us to it */ + if (!PageFsCache(page)) + goto done; + + /* get the object */ + spin_lock(&cookie->lock); + + if (hlist_empty(&cookie->backing_objects)) { + ClearPageFsCache(page); + goto done_unlock; + } + + object = hlist_entry(cookie->backing_objects.first, + struct fscache_object, cookie_link); + + /* there might now be stuff on disk we could read */ + clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); + + /* only invoke the cache backend if we managed to mark the page + * uncached here; this deals with synchronisation vs withdrawal */ + if (TestClearPageFsCache(page) && + object->cache->ops->uncache_page) { + /* the cache backend releases the cookie lock */ + object->cache->ops->uncache_page(object, page); + goto done; + } + +done_unlock: + spin_unlock(&cookie->lock); +done: + _leave(""); +} +EXPORT_SYMBOL(__fscache_uncache_page); + +/** + * fscache_mark_pages_cached - Mark pages as being cached + * @op: The retrieval op pages are being marked for + * @pagevec: The pages to be marked + * + * Mark a bunch of netfs pages as being cached. After this is called, + * the netfs must call fscache_uncache_page() to remove the mark. + */ +void fscache_mark_pages_cached(struct fscache_retrieval *op, + struct pagevec *pagevec) +{ + struct fscache_cookie *cookie = op->op.object->cookie; + unsigned long loop; + +#ifdef CONFIG_FSCACHE_STATS + atomic_add(pagevec->nr, &fscache_n_marks); +#endif + + for (loop = 0; loop < pagevec->nr; loop++) { + struct page *page = pagevec->pages[loop]; + + _debug("- mark %p{%lx}", page, page->index); + if (TestSetPageFsCache(page)) { + static bool once_only; + if (!once_only) { + once_only = true; + printk(KERN_WARNING "FS-Cache:" + " Cookie type %s marked page %lx" + " multiple times\n", + cookie->def->name, page->index); + } + } + } + + if (cookie->def->mark_pages_cached) + cookie->def->mark_pages_cached(cookie->netfs_data, + op->mapping, pagevec); + pagevec_reinit(pagevec); +} +EXPORT_SYMBOL(fscache_mark_pages_cached); |