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. This means blkdev_issue_zeroout() must cope with WRITE SAME
failing with BLK_STS_TARGET/-EREMOTEIO and explicitly write zeroes,
unless BLKDEV_ZERO_NOFALLBACK is specified.
Commit 71027e97d796 ("block: stop using discards for zeroing") added
the following to __blkdev_issue_zeroout() comment:
"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."
But __blkdev_issue_zeroout() doesn't fail in this case: if WRITE SAME
support is indicated, a REQ_OP_WRITE_ZEROES bio is built and returned
to blkdev_issue_zeroout(). -EREMOTEIO is then propagated up:
$ fallocate -zn -l 1k /dev/sdg
fallocate: fallocate failed: Remote I/O error
$ fallocate -zn -l 1k /dev/sdg # OK
(The second fallocate(1) succeeds because sd_done() sets ->no_write_same
in response to a sense that would become BLK_STS_TARGET.)
Retry __blkdev_issue_zeroout() if the I/O fails with -EREMOTEIO. This
is roughly what we did until 4.12, sans BLKDEV_ZERO_NOFALLBACK knob.
Fixes: c20cfc27a473 ("block: stop using blkdev_issue_write_same for zeroing")
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # 4.12+
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
---
block/blk-lib.c | 49 +++++++++++++++++++++++++++++++++----------------
1 file changed, 33 insertions(+), 16 deletions(-)
diff --git a/block/blk-lib.c b/block/blk-lib.c
index 3fe0aec90597..876b5478c1a2 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -287,12 +287,6 @@ static unsigned int __blkdev_sectors_to_bio_pages(sector_t nr_sects)
* 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.
*
@@ -343,6 +337,34 @@ int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
}
EXPORT_SYMBOL(__blkdev_issue_zeroout);
+/*
+ * This function may fail with -EREMOTEIO 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
+ * retry and the fallback path in __blkdev_issue_zeroout() will be used
+ * unless %flags contains BLKDEV_ZERO_NOFALLBACK.
+ */
+static int __blkdev_issue_zeroout_wait(struct block_device *bdev,
+ sector_t sector, sector_t nr_sects,
+ gfp_t gfp_mask, unsigned flags)
+{
+ int ret;
+ struct bio *bio = NULL;
+ struct blk_plug plug;
+
+ blk_start_plug(&plug);
+ ret = __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask,
+ &bio, flags);
+ if (ret == 0 && bio) {
+ ret = submit_bio_wait(bio);
+ bio_put(bio);
+ }
+ blk_finish_plug(&plug);
+
+ return ret;
+}
+
/**
* blkdev_issue_zeroout - zero-fill a block range
* @bdev: blockdev to write
@@ -360,17 +382,12 @@ 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;
- struct blk_plug plug;
- blk_start_plug(&plug);
- ret = __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask,
- &bio, flags);
- if (ret == 0 && bio) {
- ret = submit_bio_wait(bio);
- bio_put(bio);
- }
- blk_finish_plug(&plug);
+ ret = __blkdev_issue_zeroout_wait(bdev, sector, nr_sects,
+ gfp_mask, flags);
+ if (ret == -EREMOTEIO)
+ ret = __blkdev_issue_zeroout_wait(bdev, sector, nr_sects,
+ gfp_mask, flags);
return ret;
}
--
2.4.3
