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>
Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
---
fs/btrfs/inode.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index a4c8796..4175987 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7641,11 +7641,18 @@ 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);
}
}
--
2.5.5
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