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authorAnand Jain <anand.jain@oracle.com>2018-05-17 10:16:51 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-05-22 19:54:01 +0300
commit1d16f615bb7d1742e1616dcbdcc4c7d5d1e5a5a5 (patch)
tree33fdc3aa4662fbef3eae9f00512e12c7409e3560 /fs
parentf9b02febeabf687bae3861d0af80fb61cfa94683 (diff)
downloadlinux-1d16f615bb7d1742e1616dcbdcc4c7d5d1e5a5a5.tar.xz
btrfs: fix crash when trying to resume balance without the resume flag
commit 02ee654d3a04563c67bfe658a05384548b9bb105 upstream. We set the BTRFS_BALANCE_RESUME flag in the btrfs_recover_balance() only, which isn't called during the remount. So when resuming from the paused balance we hit the bug: kernel: kernel BUG at fs/btrfs/volumes.c:3890! :: kernel: balance_kthread+0x51/0x60 [btrfs] kernel: kthread+0x111/0x130 :: kernel: RIP: btrfs_balance+0x12e1/0x1570 [btrfs] RSP: ffffba7d0090bde8 Reproducer: On a mounted filesystem: btrfs balance start --full-balance /btrfs btrfs balance pause /btrfs mount -o remount,ro /dev/sdb /btrfs mount -o remount,rw /dev/sdb /btrfs To fix this set the BTRFS_BALANCE_RESUME flag in btrfs_resume_balance_async(). CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/volumes.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b983e7fb200b..08afafb6ecf7 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3964,6 +3964,15 @@ int btrfs_resume_balance_async(struct btrfs_fs_info *fs_info)
return 0;
}
+ /*
+ * A ro->rw remount sequence should continue with the paused balance
+ * regardless of who pauses it, system or the user as of now, so set
+ * the resume flag.
+ */
+ spin_lock(&fs_info->balance_lock);
+ fs_info->balance_ctl->flags |= BTRFS_BALANCE_RESUME;
+ spin_unlock(&fs_info->balance_lock);
+
tsk = kthread_run(balance_kthread, fs_info, "btrfs-balance");
return PTR_ERR_OR_ZERO(tsk);
}