4.14-stable review patch. If anyone has any objections, please let me know.
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From: Ilya Dryomov idryomov@gmail.com
commit d5ce4c31d6df518dd8f63bbae20d7423c5018a6c upstream.
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: Hannes Reinecke hare@suse.com Reviewed-by: Christoph Hellwig hch@lst.de Reviewed-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Ilya Dryomov idryomov@gmail.com Signed-off-by: Jens Axboe axboe@kernel.dk Cc: Janne Huttunen janne.huttunen@nokia.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- block/blk-lib.c | 45 +++++++++++++++++++++++++++++++++++---------- 1 file changed, 35 insertions(+), 10 deletions(-)
--- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -322,12 +322,6 @@ static int __blkdev_issue_zero_pages(str * 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. * @@ -371,18 +365,49 @@ 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; + +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 { + /* No zeroing offload support */ + ret = -EOPNOTSUPP; + } if (ret == 0 && bio) { ret = submit_bio_wait(bio); bio_put(bio); } blk_finish_plug(&plug); + 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). + */ + ret = -EOPNOTSUPP; + } + }
return ret; }