[PATCH v2 2/2] block: cope with WRITE ZEROES failing in blkdev_issue_zeroout()
From: Ilya Dryomov <idryomov@gmail.com>
Date: 2017-10-04 15:03:30
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
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
support.
Fixes: c20cfc27a473 ("block: stop using blkdev_issue_write_same for zeroing")
Cc: Christoph Hellwig <hch@lst.de>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
---
block/blk-lib.c | 41 +++++++++++++++++++++++++++++++----------
1 file changed, 31 insertions(+), 10 deletions(-)
diff --git a/block/blk-lib.c b/block/blk-lib.c
index 9d2ab8bba52a..17494275673e 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c@@ -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 +364,45 @@ 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; +retry: + bio = NULL; blk_start_plug(&plug); - 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 if (!bdev_write_zeroes_sectors(bdev)) { + /* + * Manual zeroout is not allowed and either: + * - no zeroing offload support + * - 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) + */ + ret = -EOPNOTSUPP; + } if (ret == 0 && bio) { ret = submit_bio_wait(bio); bio_put(bio); } blk_finish_plug(&plug); + if (ret && try_write_zeroes) { + try_write_zeroes = false; + goto retry; + } return ret; }
--
2.4.3