blkdev_issue_zeroout try discard/writesame first, if they fail, zeroout fallback to regular write. The problem is discard/writesame doesn't return error for -EOPNOTSUPP, then zeroout can't do fallback and leave disk data not changed. zeroout should have guaranteed zero-fill behavior.
https://bugzilla.kernel.org/show_bug.cgi?id=118581 V2: move the return value policy to blkdev_issue_discard and delete the policy for blkdev_issue_write_same (Martin) Cc: Sitsofe Wheeler <sits...@yahoo.com> Cc: Mike Snitzer <snit...@redhat.com> Cc: Jens Axboe <ax...@fb.com> Cc: Martin K. Petersen <martin.peter...@oracle.com> Signed-off-by: Shaohua Li <s...@fb.com> --- block/blk-lib.c | 49 +++++++++++++++++++++++++++++++------------------ 1 file changed, 31 insertions(+), 18 deletions(-) diff --git a/block/blk-lib.c b/block/blk-lib.c index 23d7f30..a3a26c8 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -84,6 +84,28 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, } EXPORT_SYMBOL(__blkdev_issue_discard); +static int do_blkdev_issue_discard(struct block_device *bdev, sector_t sector, + sector_t nr_sects, gfp_t gfp_mask, unsigned long flags, + int *io_err) +{ + int type = REQ_WRITE | REQ_DISCARD; + struct bio *bio = NULL; + struct blk_plug plug; + int ret; + + if (flags & BLKDEV_DISCARD_SECURE) + type |= REQ_SECURE; + + blk_start_plug(&plug); + ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, type, + &bio); + if (!ret && bio) + *io_err = submit_bio_wait(type, bio); + blk_finish_plug(&plug); + + return ret; +} + /** * blkdev_issue_discard - queue a discard * @bdev: blockdev to issue discard for @@ -98,23 +120,12 @@ EXPORT_SYMBOL(__blkdev_issue_discard); int blkdev_issue_discard(struct block_device *bdev, sector_t sector, sector_t nr_sects, gfp_t gfp_mask, unsigned long flags) { - int type = REQ_WRITE | REQ_DISCARD; - struct bio *bio = NULL; - struct blk_plug plug; - int ret; + int ret, io_err; - if (flags & BLKDEV_DISCARD_SECURE) - type |= REQ_SECURE; - - blk_start_plug(&plug); - ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, type, - &bio); - if (!ret && bio) { - ret = submit_bio_wait(type, bio); - if (ret == -EOPNOTSUPP) - ret = 0; - } - blk_finish_plug(&plug); + ret = do_blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, + flags, &io_err); + if (!ret && io_err != -EOPNOTSUPP) + ret = io_err; return ret; } @@ -167,7 +178,7 @@ int blkdev_issue_write_same(struct block_device *bdev, sector_t sector, if (bio) ret = submit_bio_wait(REQ_WRITE | REQ_WRITE_SAME, bio); - return ret != -EOPNOTSUPP ? ret : 0; + return ret; } EXPORT_SYMBOL(blkdev_issue_write_same); @@ -236,9 +247,11 @@ int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector, sector_t nr_sects, gfp_t gfp_mask, bool discard) { struct request_queue *q = bdev_get_queue(bdev); + int io_err = 0; if (discard && blk_queue_discard(q) && q->limits.discard_zeroes_data && - blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, 0) == 0) + (do_blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, 0, + &io_err) == 0 && io_err == 0)) return 0; if (bdev_write_same(bdev) && -- 2.8.0.rc2
