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Btrfs: adjust outstanding_extents counter properly when dio write is split

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[ 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@oracle.com>
Tested-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Liu Bo 2016-12-22 17:13:54 -08:00 committed by Greg Kroah-Hartman
parent 7ea3cc440e
commit 786fd31f60
1 changed files with 9 additions and 2 deletions
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11
fs/btrfs/inode.c
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@ -7521,11 +7521,18 @@ static void adjust_dio_outstanding_extents(struct inode *inode,
* 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);
}
}