This is a note to let you know that I've just added the patch titled Btrfs: adjust outstanding_extents counter properly when dio write is split to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: btrfs-adjust-outstanding_extents-counter-properly-when-dio-write-is-split.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Fri Aug 4 15:15:51 PDT 2017 From: Liu Bo <bo.li.liu@xxxxxxxxxx> Date: Thu, 22 Dec 2016 17:13:54 -0800 Subject: Btrfs: adjust outstanding_extents counter properly when dio write is split From: Liu Bo <bo.li.liu@xxxxxxxxxx> [ Upstream commit c2931667c83ded6504b3857e99cc45b21fa496fb ] Currently how btrfs dio deals with split dio write is not good enough if dio write is split into several segments due to the lack of contiguous space, a large dio write like 'dd bs=1G count=1' can end up with incorrect outstanding_extents counter and endio would complain loudly with an assertion. This fixes the problem by compensating the outstanding_extents counter in inode if a large dio write gets split. Reported-by: Anand Jain <anand.jain@xxxxxxxxxx> Tested-by: Anand Jain <anand.jain@xxxxxxxxxx> Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx> Signed-off-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/btrfs/inode.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -7521,11 +7521,18 @@ static void adjust_dio_outstanding_exten * within our reservation, otherwise we need to adjust our inode * counter appropriately. */ - if (dio_data->outstanding_extents) { + if (dio_data->outstanding_extents >= num_extents) { dio_data->outstanding_extents -= num_extents; } else { + /* + * If dio write length has been split due to no large enough + * contiguous space, we need to compensate our inode counter + * appropriately. + */ + u64 num_needed = num_extents - dio_data->outstanding_extents; + spin_lock(&BTRFS_I(inode)->lock); - BTRFS_I(inode)->outstanding_extents += num_extents; + BTRFS_I(inode)->outstanding_extents += num_needed; spin_unlock(&BTRFS_I(inode)->lock); } } Patches currently in stable-queue which might be from bo.li.liu@xxxxxxxxxx are queue-4.4/btrfs-adjust-outstanding_extents-counter-properly-when-dio-write-is-split.patch queue-4.4/btrfs-use-down_read_nested-to-make-lockdep-silent.patch