3.16.51-rc1 review patch. If anyone has any objections, please let me know.
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From: Aleksa Sarai asarai@suse.de
commit 6c6b5a39c4bf3dbd8cf629c9f5450e983c19dbb9 upstream.
Several distributions mount the "proper root" as ro during initrd and then remount it as rw before pivot_root(2). Thus, if a rescan had been aborted by a previous shutdown, the rescan would never be resumed.
This issue would manifest itself as several btrfs ioctl(2)s causing the entire machine to hang when btrfs_qgroup_wait_for_completion was hit (due to the fs_info->qgroup_rescan_running flag being set but the rescan itself not being resumed). Notably, Docker's btrfs storage driver makes regular use of BTRFS_QUOTA_CTL_DISABLE and BTRFS_IOC_QUOTA_RESCAN_WAIT (causing this problem to be manifested on boot for some machines).
Cc: Jeff Mahoney jeffm@suse.com Fixes: b382a324b60f ("Btrfs: fix qgroup rescan resume on mount") Signed-off-by: Aleksa Sarai asarai@suse.de Reviewed-by: Nikolay Borisov nborisov@suse.com Tested-by: Nikolay Borisov nborisov@suse.com Signed-off-by: David Sterba dsterba@suse.com [bwh: Backported to 3.16: add #include "qgroup.h"] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -59,6 +59,7 @@ #include "free-space-cache.h" #include "backref.h" #include "tests/btrfs-tests.h" +#include "qgroup.h"
#define CREATE_TRACE_POINTS #include <trace/events/btrfs.h> @@ -1495,6 +1496,8 @@ static int btrfs_remount(struct super_bl goto restore; }
+ btrfs_qgroup_rescan_resume(fs_info); + if (!fs_info->uuid_root) { btrfs_info(fs_info, "creating UUID tree"); ret = btrfs_create_uuid_tree(fs_info);