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);
}
/*
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("");
}
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);
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;
}
return 0;
}
+/*
+ * 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:
_leave(" = -ENOMEM");
return -ENOMEM;
}
+ fscache_set_op_name(&op->op, "RetrRA1");
spin_lock(&cookie->lock);
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);
/* 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)
void *context,
gfp_t gfp)
{
- fscache_pages_retrieval_func_t func;
struct fscache_retrieval *op;
struct fscache_object *object;
int ret;
op = fscache_alloc_retrieval(mapping, end_io_func, context);
if (!op)
return -ENOMEM;
+ fscache_set_op_name(&op->op, "RetrRAN");
spin_lock(&cookie->lock);
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);
/* 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)
op = fscache_alloc_retrieval(page->mapping, NULL, NULL);
if (!op)
return -ENOMEM;
+ fscache_set_op_name(&op->op, "RetrAL1");
spin_lock(&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");
- }
+ 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);
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];
_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 */
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("");
/* 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("");
}
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)
/* 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);
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);
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();
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;
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;
}
git.openpandora.org / pandora-kernel.git / blobdiff