Commit d5ce4c31 authored by Ilya Dryomov's avatar Ilya Dryomov Committed by Jens Axboe

block: cope with WRITE ZEROES failing in blkdev_issue_zeroout()

sd_config_write_same() ignores ->max_ws_blocks == 0 and resets it to
permit trying WRITE SAME on older SCSI devices, unless ->no_write_same
is set.  Because REQ_OP_WRITE_ZEROES is implemented in terms of WRITE
SAME, blkdev_issue_zeroout() may fail with -EREMOTEIO:

  $ fallocate -zn -l 1k /dev/sdg
  fallocate: fallocate failed: Remote I/O error
  $ fallocate -zn -l 1k /dev/sdg  # OK
  $ fallocate -zn -l 1k /dev/sdg  # OK

The following calls succeed because sd_done() sets ->no_write_same in
response to a sense that would become BLK_STS_TARGET/-EREMOTEIO, causing
__blkdev_issue_zeroout() to fall back to generating ZERO_PAGE bios.

This means blkdev_issue_zeroout() must cope with WRITE ZEROES failing
and fall back to manually zeroing, unless BLKDEV_ZERO_NOFALLBACK is
specified.  For BLKDEV_ZERO_NOFALLBACK case, return -EOPNOTSUPP if
sd_done() has just set ->no_write_same thus indicating lack of offload

Fixes: c20cfc27 ("block: stop using blkdev_issue_write_same for zeroing")
Cc: Hannes Reinecke <>
Reviewed-by: default avatarChristoph Hellwig <>
Reviewed-by: default avatarMartin K. Petersen <>
Signed-off-by: default avatarIlya Dryomov <>
Signed-off-by: default avatarJens Axboe <>
parent 425a4dba
......@@ -321,12 +321,6 @@ static int __blkdev_issue_zero_pages(struct block_device *bdev,
* Zero-fill a block range, either using hardware offload or by explicitly
* writing zeroes to the device.
* Note that this function may fail with -EOPNOTSUPP if the driver signals
* zeroing offload support, but the device fails to process the command (for
* some devices there is no non-destructive way to verify whether this
* operation is actually supported). In this case the caller should call
* retry the call to blkdev_issue_zeroout() and the fallback path will be used.
* If a device is using logical block provisioning, the underlying space will
* not be released if %flags contains BLKDEV_ZERO_NOUNMAP.
......@@ -370,18 +364,49 @@ EXPORT_SYMBOL(__blkdev_issue_zeroout);
int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
sector_t nr_sects, gfp_t gfp_mask, unsigned flags)
int ret;
struct bio *bio = NULL;
int ret = 0;
sector_t bs_mask;
struct bio *bio;
struct blk_plug plug;
bool try_write_zeroes = !!bdev_write_zeroes_sectors(bdev);
bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
if ((sector | nr_sects) & bs_mask)
return -EINVAL;
bio = NULL;
ret = __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask,
&bio, flags);
if (try_write_zeroes) {
ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects,
gfp_mask, &bio, flags);
} else if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
ret = __blkdev_issue_zero_pages(bdev, sector, nr_sects,
gfp_mask, &bio);
} else {
/* No zeroing offload support */
if (ret == 0 && bio) {
ret = submit_bio_wait(bio);
if (ret && try_write_zeroes) {
if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
try_write_zeroes = false;
goto retry;
if (!bdev_write_zeroes_sectors(bdev)) {
* Zeroing offload support was indicated, but the
* device reported ILLEGAL REQUEST (for some devices
* there is no non-destructive way to verify whether
* WRITE ZEROES is actually supported).
return ret;
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