I found following ext4 error occurs on a certain storage since v4.10-rc1:
EXT4-fs (sdc1): Delayed block allocation failed for inode 12 at logical
offset 100 with max blocks 2 with error 121
EXT4-fs (sdc1): This should not happen!! Data will be lost
Error 121 (EREMOTEIO) was returned from blkdev_issue_zeroout().
That came from sd driver because WRITE SAME was sent to the device
which didn't support it.
The problem was introduced by commit e73c23ff736e ("block: add async
variant of blkdev_issue_zeroout"). Before the commit, blkdev_issue_zeroout
fell back to normal zero writing when WRITE SAME failed and it seems
sd driver's heuristics depends on that behaviour.
Below is a band-aid fix to restore the fallback behaviour for sd. Although
there should be better fix as retrying blindly is not a good idea...
v4.10-rc6:
# cat /sys/block/sdc/queue/write_same_max_bytes
33553920
# fallocate -v -z -l 512 /dev/sdc1
fallocate: fallocate failed: Remote I/O error
# cat /sys/block/sdc/queue/write_same_max_bytes
0
# fallocate -v -z -l 512 /dev/sdc1
# echo $?
0
v4.9 or v4.10-rc6 + this patch:
# grep . /sys/block/sdc/queue/write_same_max_bytes
33553920
# fallocate -v -z -l 512 /dev/sdc1
# echo $?
0
# grep . /sys/block/sdc/queue/write_same_max_bytes
0
diff --git a/block/blk-lib.c b/block/blk-lib.c
index f8c82a9..8e53474 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -360,6 +360,7 @@ int blkdev_issue_zeroout(struct block_device *bdev,
sector_t sector,
sector_t nr_sects, gfp_t gfp_mask, bool discard)
{
int ret;
+ int pass = 0;
struct bio *bio = NULL;
struct blk_plug plug;
@@ -369,6 +370,7 @@ int blkdev_issue_zeroout(struct block_device *bdev,
sector_t sector,
return 0;
}
+ retry_other_method:
blk_start_plug(&plug);
ret = __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask,
&bio, discard);
@@ -378,6 +380,11 @@ int blkdev_issue_zeroout(struct block_device *bdev,
sector_t sector,
}
blk_finish_plug(&plug);
+ if (ret && pass++ == 0) {
+ bio = NULL;
+ goto retry_other_method;
+ }
+
return ret;
}
EXPORT_SYMBOL(blkdev_issue_zeroout);
--
Jun'ichi Nomura, NEC Corporation / NEC Solution Innovators, Ltd.
