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btrfs: fix crash in remount(thread_pool=) case

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Reproducer:
    mount /dev/ubda /mnt
    mount -oremount,thread_pool=42 /mnt

Gives a crash:
    ? btrfs_workqueue_set_max+0x0/0x70
    btrfs_resize_thread_pool+0xe3/0xf0
    ? sync_filesystem+0x0/0xc0
    ? btrfs_resize_thread_pool+0x0/0xf0
    btrfs_remount+0x1d2/0x570
    ? kern_path+0x0/0x80
    do_remount_sb+0xd9/0x1c0
    do_mount+0x26a/0xbf0
    ? kfree+0x0/0x1b0
    SyS_mount+0xc4/0x110

It's a call
    btrfs_workqueue_set_max(fs_info->scrub_wr_completion_workers, new_pool_size);
with
    fs_info->scrub_wr_completion_workers = NULL;

as scrub wqs get created only on user's demand.

Patch skips not-created-yet workqueues.

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
CC: Qu Wenruo <quwenruo@cn.fujitsu.com>
CC: Chris Mason <clm@fb.com>
CC: Josef Bacik <jbacik@fb.com>
CC: linux-btrfs@vger.kernel.org
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Sergei Trofimovich 2014-04-07 10:55:46 +03:00 committed by Chris Mason
parent c4a050bbbb
commit 800ee2247f
1 changed files with 2 additions and 0 deletions
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2
fs/btrfs/async-thread.c
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@ -323,6 +323,8 @@ void btrfs_destroy_workqueue(struct btrfs_workqueue *wq)
void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int max)
{
if (!wq)
return;
wq->normal->max_active = max;
if (wq->high)
wq->high->max_active = max;