--- /dev/null
+/* 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);
projects / openwrt / staging / blogic.git / commitdiff