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ae9d8f1711
While the inode cache caching kthread is calling btrfs_unpin_free_ino(),
we could have a concurrent call to btrfs_return_ino() that adds a new
entry to the root's free space cache of pinned inodes. This concurrent
call does not acquire the fs_info->commit_root_sem before adding a new
entry if the caching state is BTRFS_CACHE_FINISHED, which is a problem
because the caching kthread calls btrfs_unpin_free_ino() after setting
the caching state to BTRFS_CACHE_FINISHED and therefore races with
the task calling btrfs_return_ino(), which is adding a new entry, while
the former (caching kthread) is navigating the cache's rbtree, removing
and freeing nodes from the cache's rbtree without acquiring the spinlock
that protects the rbtree.
This race resulted in memory corruption due to double free of struct
btrfs_free_space objects because both tasks can end up doing freeing the
same objects. Note that adding a new entry can result in merging it with
other entries in the cache, in which case those entries are freed.
This is particularly important as btrfs_free_space structures are also
used for the block group free space caches.
This memory corruption can be detected by a debugging kernel, which
reports it with the following trace:
[132408.501148] slab error in verify_redzone_free(): cache `btrfs_free_space': double free detected
[132408.505075] CPU: 15 PID: 12248 Comm: btrfs-ino-cache Tainted: G W 4.1.0-rc5-btrfs-next-10+ #1
[132408.505075] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.1-0-g4adadbd-20150316_085822-nilsson.home.kraxel.org 04/01/2014
[132408.505075] ffff880023e7d320 ffff880163d73cd8 ffffffff8145eec7 ffffffff81095dce
[132408.505075] ffff880009735d40 ffff880163d73ce8 ffffffff81154e1e ffff880163d73d68
[132408.505075] ffffffff81155733 ffffffffa054a95a ffff8801b6099f00 ffffffffa0505b5f
[132408.505075] Call Trace:
[132408.505075] [<ffffffff8145eec7>] dump_stack+0x4f/0x7b
[132408.505075] [<ffffffff81095dce>] ? console_unlock+0x356/0x3a2
[132408.505075] [<ffffffff81154e1e>] __slab_error.isra.28+0x25/0x36
[132408.505075] [<ffffffff81155733>] __cache_free+0xe2/0x4b6
[132408.505075] [<ffffffffa054a95a>] ? __btrfs_add_free_space+0x2f0/0x343 [btrfs]
[132408.505075] [<ffffffffa0505b5f>] ? btrfs_unpin_free_ino+0x8e/0x99 [btrfs]
[132408.505075] [<ffffffff810f3b30>] ? time_hardirqs_off+0x15/0x28
[132408.505075] [<ffffffff81084d42>] ? trace_hardirqs_off+0xd/0xf
[132408.505075] [<ffffffff811563a1>] ? kfree+0xb6/0x14e
[132408.505075] [<ffffffff811563d0>] kfree+0xe5/0x14e
[132408.505075] [<ffffffffa0505b5f>] btrfs_unpin_free_ino+0x8e/0x99 [btrfs]
[132408.505075] [<ffffffffa0505e08>] caching_kthread+0x29e/0x2d9 [btrfs]
[132408.505075] [<ffffffffa0505b6a>] ? btrfs_unpin_free_ino+0x99/0x99 [btrfs]
[132408.505075] [<ffffffff8106698f>] kthread+0xef/0xf7
[132408.505075] [<ffffffff810f3b08>] ? time_hardirqs_on+0x15/0x28
[132408.505075] [<ffffffff810668a0>] ? __kthread_parkme+0xad/0xad
[132408.505075] [<ffffffff814653d2>] ret_from_fork+0x42/0x70
[132408.505075] [<ffffffff810668a0>] ? __kthread_parkme+0xad/0xad
[132408.505075] ffff880023e7d320: redzone 1:0x9f911029d74e35b, redzone 2:0x9f911029d74e35b.
[132409.501654] slab: double free detected in cache 'btrfs_free_space', objp ffff880023e7d320
[132409.503355] ------------[ cut here ]------------
[132409.504241] kernel BUG at mm/slab.c:2571!
Therefore fix this by having btrfs_unpin_free_ino() acquire the lock
that protects the rbtree while doing the searches and removing entries.
Fixes: 1c70d8fb4d
("Btrfs: fix inode caching vs tree log")
Cc: stable@vger.kernel.org
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
575 lines
14 KiB
C
575 lines
14 KiB
C
/*
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* Copyright (C) 2007 Oracle. All rights reserved.
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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
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#include <linux/delay.h>
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#include <linux/kthread.h>
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#include <linux/pagemap.h>
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#include "ctree.h"
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#include "disk-io.h"
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#include "free-space-cache.h"
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#include "inode-map.h"
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#include "transaction.h"
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static int caching_kthread(void *data)
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{
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struct btrfs_root *root = data;
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struct btrfs_fs_info *fs_info = root->fs_info;
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struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
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struct btrfs_key key;
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struct btrfs_path *path;
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struct extent_buffer *leaf;
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u64 last = (u64)-1;
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int slot;
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int ret;
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if (!btrfs_test_opt(root, INODE_MAP_CACHE))
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return 0;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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/* Since the commit root is read-only, we can safely skip locking. */
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path->skip_locking = 1;
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path->search_commit_root = 1;
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path->reada = 2;
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key.objectid = BTRFS_FIRST_FREE_OBJECTID;
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key.offset = 0;
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key.type = BTRFS_INODE_ITEM_KEY;
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again:
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/* need to make sure the commit_root doesn't disappear */
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down_read(&fs_info->commit_root_sem);
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ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
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if (ret < 0)
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goto out;
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while (1) {
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if (btrfs_fs_closing(fs_info))
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goto out;
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leaf = path->nodes[0];
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slot = path->slots[0];
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if (slot >= btrfs_header_nritems(leaf)) {
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ret = btrfs_next_leaf(root, path);
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if (ret < 0)
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goto out;
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else if (ret > 0)
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break;
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if (need_resched() ||
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btrfs_transaction_in_commit(fs_info)) {
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leaf = path->nodes[0];
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if (WARN_ON(btrfs_header_nritems(leaf) == 0))
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break;
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/*
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* Save the key so we can advances forward
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* in the next search.
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*/
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btrfs_item_key_to_cpu(leaf, &key, 0);
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btrfs_release_path(path);
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root->ino_cache_progress = last;
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up_read(&fs_info->commit_root_sem);
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schedule_timeout(1);
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goto again;
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} else
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continue;
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}
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btrfs_item_key_to_cpu(leaf, &key, slot);
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if (key.type != BTRFS_INODE_ITEM_KEY)
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goto next;
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if (key.objectid >= root->highest_objectid)
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break;
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if (last != (u64)-1 && last + 1 != key.objectid) {
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__btrfs_add_free_space(ctl, last + 1,
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key.objectid - last - 1);
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wake_up(&root->ino_cache_wait);
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}
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last = key.objectid;
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next:
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path->slots[0]++;
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}
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if (last < root->highest_objectid - 1) {
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__btrfs_add_free_space(ctl, last + 1,
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root->highest_objectid - last - 1);
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}
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spin_lock(&root->ino_cache_lock);
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root->ino_cache_state = BTRFS_CACHE_FINISHED;
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spin_unlock(&root->ino_cache_lock);
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root->ino_cache_progress = (u64)-1;
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btrfs_unpin_free_ino(root);
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out:
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wake_up(&root->ino_cache_wait);
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up_read(&fs_info->commit_root_sem);
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btrfs_free_path(path);
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return ret;
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}
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static void start_caching(struct btrfs_root *root)
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{
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struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
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struct task_struct *tsk;
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int ret;
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u64 objectid;
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if (!btrfs_test_opt(root, INODE_MAP_CACHE))
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return;
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spin_lock(&root->ino_cache_lock);
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if (root->ino_cache_state != BTRFS_CACHE_NO) {
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spin_unlock(&root->ino_cache_lock);
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return;
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}
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root->ino_cache_state = BTRFS_CACHE_STARTED;
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spin_unlock(&root->ino_cache_lock);
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ret = load_free_ino_cache(root->fs_info, root);
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if (ret == 1) {
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spin_lock(&root->ino_cache_lock);
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root->ino_cache_state = BTRFS_CACHE_FINISHED;
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spin_unlock(&root->ino_cache_lock);
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return;
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}
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/*
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* It can be quite time-consuming to fill the cache by searching
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* through the extent tree, and this can keep ino allocation path
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* waiting. Therefore at start we quickly find out the highest
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* inode number and we know we can use inode numbers which fall in
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* [highest_ino + 1, BTRFS_LAST_FREE_OBJECTID].
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*/
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ret = btrfs_find_free_objectid(root, &objectid);
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if (!ret && objectid <= BTRFS_LAST_FREE_OBJECTID) {
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__btrfs_add_free_space(ctl, objectid,
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BTRFS_LAST_FREE_OBJECTID - objectid + 1);
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}
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tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu",
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root->root_key.objectid);
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if (IS_ERR(tsk)) {
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btrfs_warn(root->fs_info, "failed to start inode caching task");
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btrfs_clear_pending_and_info(root->fs_info, INODE_MAP_CACHE,
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"disabling inode map caching");
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}
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}
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int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid)
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{
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if (!btrfs_test_opt(root, INODE_MAP_CACHE))
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return btrfs_find_free_objectid(root, objectid);
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again:
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*objectid = btrfs_find_ino_for_alloc(root);
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if (*objectid != 0)
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return 0;
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start_caching(root);
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wait_event(root->ino_cache_wait,
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root->ino_cache_state == BTRFS_CACHE_FINISHED ||
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root->free_ino_ctl->free_space > 0);
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if (root->ino_cache_state == BTRFS_CACHE_FINISHED &&
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root->free_ino_ctl->free_space == 0)
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return -ENOSPC;
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else
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goto again;
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}
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void btrfs_return_ino(struct btrfs_root *root, u64 objectid)
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{
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struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
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if (!btrfs_test_opt(root, INODE_MAP_CACHE))
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return;
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again:
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if (root->ino_cache_state == BTRFS_CACHE_FINISHED) {
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__btrfs_add_free_space(pinned, objectid, 1);
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} else {
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down_write(&root->fs_info->commit_root_sem);
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spin_lock(&root->ino_cache_lock);
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if (root->ino_cache_state == BTRFS_CACHE_FINISHED) {
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spin_unlock(&root->ino_cache_lock);
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up_write(&root->fs_info->commit_root_sem);
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goto again;
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}
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spin_unlock(&root->ino_cache_lock);
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start_caching(root);
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__btrfs_add_free_space(pinned, objectid, 1);
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up_write(&root->fs_info->commit_root_sem);
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}
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}
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/*
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* When a transaction is committed, we'll move those inode numbers which are
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* smaller than root->ino_cache_progress from pinned tree to free_ino tree, and
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* others will just be dropped, because the commit root we were searching has
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* changed.
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*
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* Must be called with root->fs_info->commit_root_sem held
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*/
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void btrfs_unpin_free_ino(struct btrfs_root *root)
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{
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struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
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struct rb_root *rbroot = &root->free_ino_pinned->free_space_offset;
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spinlock_t *rbroot_lock = &root->free_ino_pinned->tree_lock;
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struct btrfs_free_space *info;
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struct rb_node *n;
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u64 count;
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if (!btrfs_test_opt(root, INODE_MAP_CACHE))
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return;
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while (1) {
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bool add_to_ctl = true;
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spin_lock(rbroot_lock);
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n = rb_first(rbroot);
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if (!n) {
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spin_unlock(rbroot_lock);
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break;
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}
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info = rb_entry(n, struct btrfs_free_space, offset_index);
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BUG_ON(info->bitmap); /* Logic error */
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if (info->offset > root->ino_cache_progress)
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add_to_ctl = false;
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else if (info->offset + info->bytes > root->ino_cache_progress)
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count = root->ino_cache_progress - info->offset + 1;
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else
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count = info->bytes;
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rb_erase(&info->offset_index, rbroot);
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spin_unlock(rbroot_lock);
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if (add_to_ctl)
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__btrfs_add_free_space(ctl, info->offset, count);
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kmem_cache_free(btrfs_free_space_cachep, info);
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}
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}
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#define INIT_THRESHOLD (((1024 * 32) / 2) / sizeof(struct btrfs_free_space))
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#define INODES_PER_BITMAP (PAGE_CACHE_SIZE * 8)
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/*
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* The goal is to keep the memory used by the free_ino tree won't
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* exceed the memory if we use bitmaps only.
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*/
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static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
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{
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struct btrfs_free_space *info;
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struct rb_node *n;
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int max_ino;
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int max_bitmaps;
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n = rb_last(&ctl->free_space_offset);
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if (!n) {
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ctl->extents_thresh = INIT_THRESHOLD;
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return;
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}
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info = rb_entry(n, struct btrfs_free_space, offset_index);
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/*
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* Find the maximum inode number in the filesystem. Note we
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* ignore the fact that this can be a bitmap, because we are
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* not doing precise calculation.
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*/
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max_ino = info->bytes - 1;
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max_bitmaps = ALIGN(max_ino, INODES_PER_BITMAP) / INODES_PER_BITMAP;
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if (max_bitmaps <= ctl->total_bitmaps) {
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ctl->extents_thresh = 0;
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return;
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}
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ctl->extents_thresh = (max_bitmaps - ctl->total_bitmaps) *
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PAGE_CACHE_SIZE / sizeof(*info);
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}
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/*
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* We don't fall back to bitmap, if we are below the extents threshold
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* or this chunk of inode numbers is a big one.
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*/
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static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
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struct btrfs_free_space *info)
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{
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if (ctl->free_extents < ctl->extents_thresh ||
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info->bytes > INODES_PER_BITMAP / 10)
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return false;
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return true;
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}
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static struct btrfs_free_space_op free_ino_op = {
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.recalc_thresholds = recalculate_thresholds,
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.use_bitmap = use_bitmap,
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};
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static void pinned_recalc_thresholds(struct btrfs_free_space_ctl *ctl)
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{
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}
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static bool pinned_use_bitmap(struct btrfs_free_space_ctl *ctl,
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struct btrfs_free_space *info)
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{
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/*
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* We always use extents for two reasons:
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*
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* - The pinned tree is only used during the process of caching
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* work.
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* - Make code simpler. See btrfs_unpin_free_ino().
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*/
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return false;
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}
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static struct btrfs_free_space_op pinned_free_ino_op = {
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.recalc_thresholds = pinned_recalc_thresholds,
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.use_bitmap = pinned_use_bitmap,
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};
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void btrfs_init_free_ino_ctl(struct btrfs_root *root)
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{
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struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
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struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
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spin_lock_init(&ctl->tree_lock);
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ctl->unit = 1;
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ctl->start = 0;
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ctl->private = NULL;
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ctl->op = &free_ino_op;
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INIT_LIST_HEAD(&ctl->trimming_ranges);
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mutex_init(&ctl->cache_writeout_mutex);
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/*
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* Initially we allow to use 16K of ram to cache chunks of
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* inode numbers before we resort to bitmaps. This is somewhat
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* arbitrary, but it will be adjusted in runtime.
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*/
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ctl->extents_thresh = INIT_THRESHOLD;
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spin_lock_init(&pinned->tree_lock);
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pinned->unit = 1;
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pinned->start = 0;
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pinned->private = NULL;
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pinned->extents_thresh = 0;
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pinned->op = &pinned_free_ino_op;
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}
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int btrfs_save_ino_cache(struct btrfs_root *root,
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struct btrfs_trans_handle *trans)
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{
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struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
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struct btrfs_path *path;
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struct inode *inode;
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struct btrfs_block_rsv *rsv;
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u64 num_bytes;
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u64 alloc_hint = 0;
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int ret;
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int prealloc;
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bool retry = false;
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/* only fs tree and subvol/snap needs ino cache */
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if (root->root_key.objectid != BTRFS_FS_TREE_OBJECTID &&
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(root->root_key.objectid < BTRFS_FIRST_FREE_OBJECTID ||
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root->root_key.objectid > BTRFS_LAST_FREE_OBJECTID))
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return 0;
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/* Don't save inode cache if we are deleting this root */
|
|
if (btrfs_root_refs(&root->root_item) == 0)
|
|
return 0;
|
|
|
|
if (!btrfs_test_opt(root, INODE_MAP_CACHE))
|
|
return 0;
|
|
|
|
path = btrfs_alloc_path();
|
|
if (!path)
|
|
return -ENOMEM;
|
|
|
|
rsv = trans->block_rsv;
|
|
trans->block_rsv = &root->fs_info->trans_block_rsv;
|
|
|
|
num_bytes = trans->bytes_reserved;
|
|
/*
|
|
* 1 item for inode item insertion if need
|
|
* 4 items for inode item update (in the worst case)
|
|
* 1 items for slack space if we need do truncation
|
|
* 1 item for free space object
|
|
* 3 items for pre-allocation
|
|
*/
|
|
trans->bytes_reserved = btrfs_calc_trans_metadata_size(root, 10);
|
|
ret = btrfs_block_rsv_add(root, trans->block_rsv,
|
|
trans->bytes_reserved,
|
|
BTRFS_RESERVE_NO_FLUSH);
|
|
if (ret)
|
|
goto out;
|
|
trace_btrfs_space_reservation(root->fs_info, "ino_cache",
|
|
trans->transid, trans->bytes_reserved, 1);
|
|
again:
|
|
inode = lookup_free_ino_inode(root, path);
|
|
if (IS_ERR(inode) && (PTR_ERR(inode) != -ENOENT || retry)) {
|
|
ret = PTR_ERR(inode);
|
|
goto out_release;
|
|
}
|
|
|
|
if (IS_ERR(inode)) {
|
|
BUG_ON(retry); /* Logic error */
|
|
retry = true;
|
|
|
|
ret = create_free_ino_inode(root, trans, path);
|
|
if (ret)
|
|
goto out_release;
|
|
goto again;
|
|
}
|
|
|
|
BTRFS_I(inode)->generation = 0;
|
|
ret = btrfs_update_inode(trans, root, inode);
|
|
if (ret) {
|
|
btrfs_abort_transaction(trans, root, ret);
|
|
goto out_put;
|
|
}
|
|
|
|
if (i_size_read(inode) > 0) {
|
|
ret = btrfs_truncate_free_space_cache(root, trans, NULL, inode);
|
|
if (ret) {
|
|
if (ret != -ENOSPC)
|
|
btrfs_abort_transaction(trans, root, ret);
|
|
goto out_put;
|
|
}
|
|
}
|
|
|
|
spin_lock(&root->ino_cache_lock);
|
|
if (root->ino_cache_state != BTRFS_CACHE_FINISHED) {
|
|
ret = -1;
|
|
spin_unlock(&root->ino_cache_lock);
|
|
goto out_put;
|
|
}
|
|
spin_unlock(&root->ino_cache_lock);
|
|
|
|
spin_lock(&ctl->tree_lock);
|
|
prealloc = sizeof(struct btrfs_free_space) * ctl->free_extents;
|
|
prealloc = ALIGN(prealloc, PAGE_CACHE_SIZE);
|
|
prealloc += ctl->total_bitmaps * PAGE_CACHE_SIZE;
|
|
spin_unlock(&ctl->tree_lock);
|
|
|
|
/* Just to make sure we have enough space */
|
|
prealloc += 8 * PAGE_CACHE_SIZE;
|
|
|
|
ret = btrfs_delalloc_reserve_space(inode, prealloc);
|
|
if (ret)
|
|
goto out_put;
|
|
|
|
ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, prealloc,
|
|
prealloc, prealloc, &alloc_hint);
|
|
if (ret) {
|
|
btrfs_delalloc_release_space(inode, prealloc);
|
|
goto out_put;
|
|
}
|
|
btrfs_free_reserved_data_space(inode, prealloc);
|
|
|
|
ret = btrfs_write_out_ino_cache(root, trans, path, inode);
|
|
out_put:
|
|
iput(inode);
|
|
out_release:
|
|
trace_btrfs_space_reservation(root->fs_info, "ino_cache",
|
|
trans->transid, trans->bytes_reserved, 0);
|
|
btrfs_block_rsv_release(root, trans->block_rsv, trans->bytes_reserved);
|
|
out:
|
|
trans->block_rsv = rsv;
|
|
trans->bytes_reserved = num_bytes;
|
|
|
|
btrfs_free_path(path);
|
|
return ret;
|
|
}
|
|
|
|
static int btrfs_find_highest_objectid(struct btrfs_root *root, u64 *objectid)
|
|
{
|
|
struct btrfs_path *path;
|
|
int ret;
|
|
struct extent_buffer *l;
|
|
struct btrfs_key search_key;
|
|
struct btrfs_key found_key;
|
|
int slot;
|
|
|
|
path = btrfs_alloc_path();
|
|
if (!path)
|
|
return -ENOMEM;
|
|
|
|
search_key.objectid = BTRFS_LAST_FREE_OBJECTID;
|
|
search_key.type = -1;
|
|
search_key.offset = (u64)-1;
|
|
ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
|
|
if (ret < 0)
|
|
goto error;
|
|
BUG_ON(ret == 0); /* Corruption */
|
|
if (path->slots[0] > 0) {
|
|
slot = path->slots[0] - 1;
|
|
l = path->nodes[0];
|
|
btrfs_item_key_to_cpu(l, &found_key, slot);
|
|
*objectid = max_t(u64, found_key.objectid,
|
|
BTRFS_FIRST_FREE_OBJECTID - 1);
|
|
} else {
|
|
*objectid = BTRFS_FIRST_FREE_OBJECTID - 1;
|
|
}
|
|
ret = 0;
|
|
error:
|
|
btrfs_free_path(path);
|
|
return ret;
|
|
}
|
|
|
|
int btrfs_find_free_objectid(struct btrfs_root *root, u64 *objectid)
|
|
{
|
|
int ret;
|
|
mutex_lock(&root->objectid_mutex);
|
|
|
|
if (unlikely(root->highest_objectid < BTRFS_FIRST_FREE_OBJECTID)) {
|
|
ret = btrfs_find_highest_objectid(root,
|
|
&root->highest_objectid);
|
|
if (ret)
|
|
goto out;
|
|
}
|
|
|
|
if (unlikely(root->highest_objectid >= BTRFS_LAST_FREE_OBJECTID)) {
|
|
ret = -ENOSPC;
|
|
goto out;
|
|
}
|
|
|
|
*objectid = ++root->highest_objectid;
|
|
ret = 0;
|
|
out:
|
|
mutex_unlock(&root->objectid_mutex);
|
|
return ret;
|
|
}
|