![David Howells](/assets/img/avatar_default.png)
struct fscache_retrieval contains a count of the number of pages that still need some processing (n_pages). This is decremented as the pages are processed. However, this needs to be atomic as fscache_retrieval_complete() (I think) just occasionally may be called from cachefiles_read_backing_file() and cachefiles_read_copier() simultaneously. This happens when an fscache_read_or_alloc_pages() request containing a lot of pages (say a couple of hundred) is being processed. The read on each backing page is dispatched individually because we need to insert a monitor into the waitqueue to catch when the read completes. However, under low-memory conditions, we might be forced to wait in the allocator - and this gives the I/O on the backing page a chance to complete first. When the I/O completes, fscache_enqueue_retrieval() chucks the retrieval onto the workqueue without waiting for the operation to finish the initial I/O dispatch (we want to release any pages we can as soon as we can), thus both can end up running simultaneously and potentially attempting to partially complete the retrieval simultaneously (ENOMEM may occur, backing pages may already be in the page cache). This was demonstrated by parallelling the non-atomic counter with an atomic counter and printing both of them when the assertion fails. At this point, the atomic counter has reached zero, but the non-atomic counter has not. To fix this, make the counter an atomic_t. This results in the following bug appearing FS-Cache: Assertion failed 3 == 5 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:421! or FS-Cache: Assertion failed 3 == 5 is false ------------[ cut here ]------------ kernel BUG at fs/fscache/operation.c:414! With a backtrace like the following: RIP: 0010:[<ffffffffa0211b1d>] fscache_put_operation+0x1ad/0x240 [fscache] Call Trace: [<ffffffffa0213185>] fscache_retrieval_work+0x55/0x270 [fscache] [<ffffffffa0213130>] ? fscache_retrieval_work+0x0/0x270 [fscache] [<ffffffff81090b10>] worker_thread+0x170/0x2a0 [<ffffffff81096d10>] ? autoremove_wake_function+0x0/0x40 [<ffffffff810909a0>] ? worker_thread+0x0/0x2a0 [<ffffffff81096966>] kthread+0x96/0xa0 [<ffffffff8100c0ca>] child_rip+0xa/0x20 [<ffffffff810968d0>] ? kthread+0x0/0xa0 [<ffffffff8100c0c0>] ? child_rip+0x0/0x20 Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-and-tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
1135 lines
29 KiB
C
1135 lines
29 KiB
C
/* Cache page management and data I/O routines
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*
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* Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#define FSCACHE_DEBUG_LEVEL PAGE
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#include <linux/module.h>
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#include <linux/fscache-cache.h>
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#include <linux/buffer_head.h>
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#include <linux/pagevec.h>
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#include <linux/slab.h>
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#include "internal.h"
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/*
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* check to see if a page is being written to the cache
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*/
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bool __fscache_check_page_write(struct fscache_cookie *cookie, struct page *page)
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{
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void *val;
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rcu_read_lock();
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val = radix_tree_lookup(&cookie->stores, page->index);
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rcu_read_unlock();
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return val != NULL;
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}
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EXPORT_SYMBOL(__fscache_check_page_write);
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/*
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* wait for a page to finish being written to the cache
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*/
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void __fscache_wait_on_page_write(struct fscache_cookie *cookie, struct page *page)
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{
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wait_queue_head_t *wq = bit_waitqueue(&cookie->flags, 0);
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wait_event(*wq, !__fscache_check_page_write(cookie, page));
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}
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EXPORT_SYMBOL(__fscache_wait_on_page_write);
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/*
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* decide whether a page can be released, possibly by cancelling a store to it
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* - we're allowed to sleep if __GFP_WAIT is flagged
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*/
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bool __fscache_maybe_release_page(struct fscache_cookie *cookie,
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struct page *page,
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gfp_t gfp)
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{
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struct page *xpage;
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void *val;
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_enter("%p,%p,%x", cookie, page, gfp);
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try_again:
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rcu_read_lock();
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val = radix_tree_lookup(&cookie->stores, page->index);
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if (!val) {
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rcu_read_unlock();
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fscache_stat(&fscache_n_store_vmscan_not_storing);
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__fscache_uncache_page(cookie, page);
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return true;
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}
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/* see if the page is actually undergoing storage - if so we can't get
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* rid of it till the cache has finished with it */
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if (radix_tree_tag_get(&cookie->stores, page->index,
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FSCACHE_COOKIE_STORING_TAG)) {
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rcu_read_unlock();
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goto page_busy;
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}
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/* the page is pending storage, so we attempt to cancel the store and
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* discard the store request so that the page can be reclaimed */
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spin_lock(&cookie->stores_lock);
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rcu_read_unlock();
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if (radix_tree_tag_get(&cookie->stores, page->index,
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FSCACHE_COOKIE_STORING_TAG)) {
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/* the page started to undergo storage whilst we were looking,
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* so now we can only wait or return */
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spin_unlock(&cookie->stores_lock);
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goto page_busy;
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}
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xpage = radix_tree_delete(&cookie->stores, page->index);
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spin_unlock(&cookie->stores_lock);
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if (xpage) {
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fscache_stat(&fscache_n_store_vmscan_cancelled);
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fscache_stat(&fscache_n_store_radix_deletes);
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ASSERTCMP(xpage, ==, page);
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} else {
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fscache_stat(&fscache_n_store_vmscan_gone);
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}
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wake_up_bit(&cookie->flags, 0);
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if (xpage)
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page_cache_release(xpage);
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__fscache_uncache_page(cookie, page);
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return true;
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page_busy:
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/* We will wait here if we're allowed to, but that could deadlock the
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* allocator as the work threads writing to the cache may all end up
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* sleeping on memory allocation, so we may need to impose a timeout
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* too. */
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if (!(gfp & __GFP_WAIT) || !(gfp & __GFP_FS)) {
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fscache_stat(&fscache_n_store_vmscan_busy);
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return false;
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}
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fscache_stat(&fscache_n_store_vmscan_wait);
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__fscache_wait_on_page_write(cookie, page);
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gfp &= ~__GFP_WAIT;
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goto try_again;
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}
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EXPORT_SYMBOL(__fscache_maybe_release_page);
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/*
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* note that a page has finished being written to the cache
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*/
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static void fscache_end_page_write(struct fscache_object *object,
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struct page *page)
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{
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struct fscache_cookie *cookie;
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struct page *xpage = NULL;
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spin_lock(&object->lock);
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cookie = object->cookie;
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if (cookie) {
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/* delete the page from the tree if it is now no longer
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* pending */
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spin_lock(&cookie->stores_lock);
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radix_tree_tag_clear(&cookie->stores, page->index,
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FSCACHE_COOKIE_STORING_TAG);
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if (!radix_tree_tag_get(&cookie->stores, page->index,
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FSCACHE_COOKIE_PENDING_TAG)) {
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fscache_stat(&fscache_n_store_radix_deletes);
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xpage = radix_tree_delete(&cookie->stores, page->index);
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}
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spin_unlock(&cookie->stores_lock);
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wake_up_bit(&cookie->flags, 0);
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}
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spin_unlock(&object->lock);
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if (xpage)
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page_cache_release(xpage);
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}
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/*
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* actually apply the changed attributes to a cache object
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*/
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static void fscache_attr_changed_op(struct fscache_operation *op)
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{
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struct fscache_object *object = op->object;
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int ret;
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_enter("{OBJ%x OP%x}", object->debug_id, op->debug_id);
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fscache_stat(&fscache_n_attr_changed_calls);
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if (fscache_object_is_active(object) &&
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fscache_use_cookie(object)) {
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fscache_stat(&fscache_n_cop_attr_changed);
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ret = object->cache->ops->attr_changed(object);
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fscache_stat_d(&fscache_n_cop_attr_changed);
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fscache_unuse_cookie(object);
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if (ret < 0)
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fscache_abort_object(object);
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}
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fscache_op_complete(op, true);
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_leave("");
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}
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/*
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* notification that the attributes on an object have changed
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*/
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int __fscache_attr_changed(struct fscache_cookie *cookie)
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{
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struct fscache_operation *op;
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struct fscache_object *object;
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_enter("%p", cookie);
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ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
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fscache_stat(&fscache_n_attr_changed);
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op = kzalloc(sizeof(*op), GFP_KERNEL);
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if (!op) {
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fscache_stat(&fscache_n_attr_changed_nomem);
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_leave(" = -ENOMEM");
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return -ENOMEM;
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}
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fscache_operation_init(op, fscache_attr_changed_op, NULL);
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op->flags = FSCACHE_OP_ASYNC | (1 << FSCACHE_OP_EXCLUSIVE);
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spin_lock(&cookie->lock);
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if (hlist_empty(&cookie->backing_objects))
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goto nobufs;
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object = hlist_entry(cookie->backing_objects.first,
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struct fscache_object, cookie_link);
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if (fscache_submit_exclusive_op(object, op) < 0)
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goto nobufs;
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spin_unlock(&cookie->lock);
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fscache_stat(&fscache_n_attr_changed_ok);
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fscache_put_operation(op);
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_leave(" = 0");
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return 0;
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nobufs:
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spin_unlock(&cookie->lock);
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kfree(op);
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fscache_stat(&fscache_n_attr_changed_nobufs);
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_leave(" = %d", -ENOBUFS);
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return -ENOBUFS;
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}
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EXPORT_SYMBOL(__fscache_attr_changed);
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/*
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* release a retrieval op reference
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*/
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static void fscache_release_retrieval_op(struct fscache_operation *_op)
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{
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struct fscache_retrieval *op =
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container_of(_op, struct fscache_retrieval, op);
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_enter("{OP%x}", op->op.debug_id);
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ASSERTCMP(atomic_read(&op->n_pages), ==, 0);
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fscache_hist(fscache_retrieval_histogram, op->start_time);
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if (op->context)
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fscache_put_context(op->op.object->cookie, op->context);
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_leave("");
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}
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/*
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* allocate a retrieval op
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*/
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static struct fscache_retrieval *fscache_alloc_retrieval(
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struct fscache_cookie *cookie,
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struct address_space *mapping,
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fscache_rw_complete_t end_io_func,
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void *context)
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{
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struct fscache_retrieval *op;
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/* allocate a retrieval operation and attempt to submit it */
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op = kzalloc(sizeof(*op), GFP_NOIO);
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if (!op) {
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fscache_stat(&fscache_n_retrievals_nomem);
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return NULL;
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}
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fscache_operation_init(&op->op, NULL, fscache_release_retrieval_op);
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atomic_inc(&cookie->n_active);
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op->op.flags = FSCACHE_OP_MYTHREAD |
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(1UL << FSCACHE_OP_WAITING) |
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(1UL << FSCACHE_OP_UNUSE_COOKIE);
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op->mapping = mapping;
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op->end_io_func = end_io_func;
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op->context = context;
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op->start_time = jiffies;
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INIT_LIST_HEAD(&op->to_do);
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return op;
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}
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/*
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* wait for a deferred lookup to complete
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*/
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static int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie)
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{
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unsigned long jif;
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_enter("");
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if (!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) {
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_leave(" = 0 [imm]");
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return 0;
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}
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fscache_stat(&fscache_n_retrievals_wait);
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jif = jiffies;
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if (wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP,
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fscache_wait_bit_interruptible,
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TASK_INTERRUPTIBLE) != 0) {
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fscache_stat(&fscache_n_retrievals_intr);
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_leave(" = -ERESTARTSYS");
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return -ERESTARTSYS;
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}
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ASSERT(!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags));
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smp_rmb();
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fscache_hist(fscache_retrieval_delay_histogram, jif);
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_leave(" = 0 [dly]");
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return 0;
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}
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/*
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* Handle cancellation of a pending retrieval op
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*/
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static void fscache_do_cancel_retrieval(struct fscache_operation *_op)
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{
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struct fscache_retrieval *op =
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container_of(_op, struct fscache_retrieval, op);
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atomic_set(&op->n_pages, 0);
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}
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/*
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* wait for an object to become active (or dead)
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*/
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static int fscache_wait_for_retrieval_activation(struct fscache_object *object,
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struct fscache_retrieval *op,
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atomic_t *stat_op_waits,
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atomic_t *stat_object_dead)
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{
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int ret;
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if (!test_bit(FSCACHE_OP_WAITING, &op->op.flags))
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goto check_if_dead;
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_debug(">>> WT");
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fscache_stat(stat_op_waits);
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if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
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fscache_wait_bit_interruptible,
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TASK_INTERRUPTIBLE) != 0) {
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ret = fscache_cancel_op(&op->op, fscache_do_cancel_retrieval);
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if (ret == 0)
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return -ERESTARTSYS;
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/* it's been removed from the pending queue by another party,
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* so we should get to run shortly */
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wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
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fscache_wait_bit, TASK_UNINTERRUPTIBLE);
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}
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_debug("<<< GO");
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check_if_dead:
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if (op->op.state == FSCACHE_OP_ST_CANCELLED) {
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fscache_stat(stat_object_dead);
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_leave(" = -ENOBUFS [cancelled]");
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return -ENOBUFS;
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}
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if (unlikely(fscache_object_is_dead(object))) {
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pr_err("%s() = -ENOBUFS [obj dead %d]\n", __func__, op->op.state);
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fscache_cancel_op(&op->op, fscache_do_cancel_retrieval);
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fscache_stat(stat_object_dead);
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return -ENOBUFS;
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}
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return 0;
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}
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/*
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* read a page from the cache or allocate a block in which to store it
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* - we return:
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* -ENOMEM - out of memory, nothing done
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* -ERESTARTSYS - interrupted
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* -ENOBUFS - no backing object available in which to cache the block
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* -ENODATA - no data available in the backing object for this block
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* 0 - dispatched a read - it'll call end_io_func() when finished
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*/
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int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
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struct page *page,
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fscache_rw_complete_t end_io_func,
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void *context,
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gfp_t gfp)
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{
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struct fscache_retrieval *op;
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struct fscache_object *object;
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int ret;
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_enter("%p,%p,,,", cookie, page);
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fscache_stat(&fscache_n_retrievals);
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if (hlist_empty(&cookie->backing_objects))
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goto nobufs;
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if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
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_leave(" = -ENOBUFS [invalidating]");
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return -ENOBUFS;
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}
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ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
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ASSERTCMP(page, !=, NULL);
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if (fscache_wait_for_deferred_lookup(cookie) < 0)
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return -ERESTARTSYS;
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op = fscache_alloc_retrieval(cookie, page->mapping,
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end_io_func,context);
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if (!op) {
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_leave(" = -ENOMEM");
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return -ENOMEM;
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}
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atomic_set(&op->n_pages, 1);
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spin_lock(&cookie->lock);
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if (hlist_empty(&cookie->backing_objects))
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goto nobufs_unlock;
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object = hlist_entry(cookie->backing_objects.first,
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struct fscache_object, cookie_link);
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ASSERT(test_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags));
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atomic_inc(&object->n_reads);
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__set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
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if (fscache_submit_op(object, &op->op) < 0)
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goto nobufs_unlock_dec;
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spin_unlock(&cookie->lock);
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fscache_stat(&fscache_n_retrieval_ops);
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/* pin the netfs read context in case we need to do the actual netfs
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* read because we've encountered a cache read failure */
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fscache_get_context(object->cookie, op->context);
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|
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/* we wait for the operation to become active, and then process it
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* *here*, in this thread, and not in the thread pool */
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ret = fscache_wait_for_retrieval_activation(
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object, op,
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__fscache_stat(&fscache_n_retrieval_op_waits),
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__fscache_stat(&fscache_n_retrievals_object_dead));
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if (ret < 0)
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goto error;
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|
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/* ask the cache to honour the operation */
|
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if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
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fscache_stat(&fscache_n_cop_allocate_page);
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ret = object->cache->ops->allocate_page(op, page, gfp);
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fscache_stat_d(&fscache_n_cop_allocate_page);
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if (ret == 0)
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ret = -ENODATA;
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} else {
|
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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)
|
|
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_dec:
|
|
atomic_dec(&object->n_reads);
|
|
nobufs_unlock:
|
|
spin_unlock(&cookie->lock);
|
|
atomic_dec(&cookie->n_active);
|
|
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)
|
|
{
|
|
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;
|
|
|
|
if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
|
|
_leave(" = -ENOBUFS [invalidating]");
|
|
return -ENOBUFS;
|
|
}
|
|
|
|
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(cookie, mapping, end_io_func, context);
|
|
if (!op)
|
|
return -ENOMEM;
|
|
atomic_set(&op->n_pages, *nr_pages);
|
|
|
|
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);
|
|
|
|
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_dec;
|
|
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 */
|
|
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_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)
|
|
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_dec:
|
|
atomic_dec(&object->n_reads);
|
|
nobufs_unlock:
|
|
spin_unlock(&cookie->lock);
|
|
atomic_dec(&cookie->n_active);
|
|
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 (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
|
|
_leave(" = -ENOBUFS [invalidating]");
|
|
return -ENOBUFS;
|
|
}
|
|
|
|
if (fscache_wait_for_deferred_lookup(cookie) < 0)
|
|
return -ERESTARTSYS;
|
|
|
|
op = fscache_alloc_retrieval(cookie, page->mapping, NULL, NULL);
|
|
if (!op)
|
|
return -ENOMEM;
|
|
atomic_set(&op->n_pages, 1);
|
|
|
|
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);
|
|
|
|
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);
|
|
|
|
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);
|
|
|
|
fscache_put_retrieval(op);
|
|
_leave(" = %d", ret);
|
|
return ret;
|
|
|
|
nobufs_unlock:
|
|
spin_unlock(&cookie->lock);
|
|
atomic_dec(&cookie->n_active);
|
|
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;
|
|
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(&object->lock);
|
|
cookie = object->cookie;
|
|
|
|
if (!fscache_object_is_active(object)) {
|
|
/* If we get here, then the on-disk cache object likely longer
|
|
* exists, so we should just cancel this write operation.
|
|
*/
|
|
spin_unlock(&object->lock);
|
|
fscache_op_complete(&op->op, false);
|
|
_leave(" [inactive]");
|
|
return;
|
|
}
|
|
|
|
if (!cookie) {
|
|
/* If we get here, then the cookie belonging to the object was
|
|
* detached, probably by the cookie being withdrawn due to
|
|
* memory pressure, which means that the pages we might write
|
|
* to the cache from no longer exist - therefore, we can just
|
|
* cancel this write operation.
|
|
*/
|
|
spin_unlock(&object->lock);
|
|
fscache_op_complete(&op->op, false);
|
|
_leave(" [cancel] op{f=%lx s=%u} obj{s=%s f=%lx}",
|
|
_op->flags, _op->state, object->state->short_name,
|
|
object->flags);
|
|
return;
|
|
}
|
|
|
|
spin_lock(&cookie->stores_lock);
|
|
|
|
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) {
|
|
fscache_stat(&fscache_n_store_pages_over_limit);
|
|
goto superseded;
|
|
}
|
|
|
|
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);
|
|
|
|
fscache_stat(&fscache_n_store_pages);
|
|
fscache_stat(&fscache_n_cop_write_page);
|
|
ret = object->cache->ops->write_page(op, page);
|
|
fscache_stat_d(&fscache_n_cop_write_page);
|
|
fscache_end_page_write(object, page);
|
|
if (ret < 0) {
|
|
fscache_abort_object(object);
|
|
fscache_op_complete(&op->op, true);
|
|
} 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");
|
|
spin_unlock(&cookie->stores_lock);
|
|
clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
|
|
spin_unlock(&object->lock);
|
|
fscache_op_complete(&op->op, true);
|
|
_leave("");
|
|
}
|
|
|
|
/*
|
|
* Clear the pages pending writing for invalidation
|
|
*/
|
|
void fscache_invalidate_writes(struct fscache_cookie *cookie)
|
|
{
|
|
struct page *page;
|
|
void *results[16];
|
|
int n, i;
|
|
|
|
_enter("");
|
|
|
|
for (;;) {
|
|
spin_lock(&cookie->stores_lock);
|
|
n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0,
|
|
ARRAY_SIZE(results),
|
|
FSCACHE_COOKIE_PENDING_TAG);
|
|
if (n == 0) {
|
|
spin_unlock(&cookie->stores_lock);
|
|
break;
|
|
}
|
|
|
|
for (i = n - 1; i >= 0; i--) {
|
|
page = results[i];
|
|
radix_tree_delete(&cookie->stores, page->index);
|
|
}
|
|
|
|
spin_unlock(&cookie->stores_lock);
|
|
|
|
for (i = n - 1; i >= 0; i--)
|
|
page_cache_release(results[i]);
|
|
}
|
|
|
|
_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
|
|
*
|
|
* (b) writes deferred till post-creation (mark page for writing and
|
|
* return immediately)
|
|
*
|
|
* (2) negative lookup, object created, initial fill being made from netfs
|
|
*
|
|
* (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);
|
|
|
|
if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
|
|
_leave(" = -ENOBUFS [invalidating]");
|
|
return -ENOBUFS;
|
|
}
|
|
|
|
op = kzalloc(sizeof(*op), GFP_NOIO | __GFP_NOMEMALLOC | __GFP_NORETRY);
|
|
if (!op)
|
|
goto nomem;
|
|
|
|
fscache_operation_init(&op->op, fscache_write_op,
|
|
fscache_release_write_op);
|
|
op->op.flags = FSCACHE_OP_ASYNC |
|
|
(1 << FSCACHE_OP_WAITING) |
|
|
(1 << FSCACHE_OP_UNUSE_COOKIE);
|
|
|
|
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);
|
|
spin_lock(&cookie->stores_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(&cookie->stores_lock);
|
|
spin_unlock(&object->lock);
|
|
|
|
op->op.debug_id = atomic_inc_return(&fscache_op_debug_id);
|
|
op->store_limit = object->store_limit;
|
|
|
|
atomic_inc(&cookie->n_active);
|
|
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 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(&cookie->stores_lock);
|
|
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:
|
|
atomic_dec(&cookie->n_active);
|
|
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;
|
|
|
|
nobufs_unlock_obj:
|
|
spin_unlock(&cookie->stores_lock);
|
|
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 */
|
|
fscache_stat(&fscache_n_cop_uncache_page);
|
|
object->cache->ops->uncache_page(object, page);
|
|
fscache_stat_d(&fscache_n_cop_uncache_page);
|
|
goto done;
|
|
}
|
|
|
|
done_unlock:
|
|
spin_unlock(&cookie->lock);
|
|
done:
|
|
_leave("");
|
|
}
|
|
EXPORT_SYMBOL(__fscache_uncache_page);
|
|
|
|
/**
|
|
* fscache_mark_page_cached - Mark a page as being cached
|
|
* @op: The retrieval op pages are being marked for
|
|
* @page: The page to be marked
|
|
*
|
|
* Mark a netfs page as being cached. After this is called, the netfs
|
|
* must call fscache_uncache_page() to remove the mark.
|
|
*/
|
|
void fscache_mark_page_cached(struct fscache_retrieval *op, struct page *page)
|
|
{
|
|
struct fscache_cookie *cookie = op->op.object->cookie;
|
|
|
|
#ifdef CONFIG_FSCACHE_STATS
|
|
atomic_inc(&fscache_n_marks);
|
|
#endif
|
|
|
|
_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_page_cached)
|
|
cookie->def->mark_page_cached(cookie->netfs_data,
|
|
op->mapping, page);
|
|
}
|
|
EXPORT_SYMBOL(fscache_mark_page_cached);
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
unsigned long loop;
|
|
|
|
for (loop = 0; loop < pagevec->nr; loop++)
|
|
fscache_mark_page_cached(op, pagevec->pages[loop]);
|
|
|
|
pagevec_reinit(pagevec);
|
|
}
|
|
EXPORT_SYMBOL(fscache_mark_pages_cached);
|
|
|
|
/*
|
|
* Uncache all the pages in an inode that are marked PG_fscache, assuming them
|
|
* to be associated with the given cookie.
|
|
*/
|
|
void __fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,
|
|
struct inode *inode)
|
|
{
|
|
struct address_space *mapping = inode->i_mapping;
|
|
struct pagevec pvec;
|
|
pgoff_t next;
|
|
int i;
|
|
|
|
_enter("%p,%p", cookie, inode);
|
|
|
|
if (!mapping || mapping->nrpages == 0) {
|
|
_leave(" [no pages]");
|
|
return;
|
|
}
|
|
|
|
pagevec_init(&pvec, 0);
|
|
next = 0;
|
|
do {
|
|
if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE))
|
|
break;
|
|
for (i = 0; i < pagevec_count(&pvec); i++) {
|
|
struct page *page = pvec.pages[i];
|
|
next = page->index;
|
|
if (PageFsCache(page)) {
|
|
__fscache_wait_on_page_write(cookie, page);
|
|
__fscache_uncache_page(cookie, page);
|
|
}
|
|
}
|
|
pagevec_release(&pvec);
|
|
cond_resched();
|
|
} while (++next);
|
|
|
|
_leave("");
|
|
}
|
|
EXPORT_SYMBOL(__fscache_uncache_all_inode_pages);
|