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block: Read max write zeroes once for __blkdev_issue_write_zeroes()

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As reported in [0], we may get a hang when formatting a XFS FS on a RAID0
drive.

Commit 73a768d5f9 ("block: factor out a blk_write_zeroes_limit helper")
changed __blkdev_issue_write_zeroes() to read the max write zeroes
value in the loop. This is not safe as max write zeroes may change in
value. Specifically for the case of [0], the value goes to 0, and we get
an infinite loop.

Lift the limit reading out of the loop.

[0] https://lore.kernel.org/linux-xfs/4d31268f-310b-4220-88a2-e191c3932a82@oracle.com/T/#t

Fixes: 73a768d5f9 ("block: factor out a blk_write_zeroes_limit helper")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240815163228.216051-2-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
John Garry 2024-08-15 16:32:27 +00:00 committed by Jens Axboe
parent b313a8c835
commit 64b582ca88
1 changed files with 18 additions and 7 deletions
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25
block/blk-lib.c
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@ -111,13 +111,20 @@ static sector_t bio_write_zeroes_limit(struct block_device *bdev)
(UINT_MAX >> SECTOR_SHIFT) & ~bs_mask);
}
/*
* There is no reliable way for the SCSI subsystem to determine whether a
* device supports a WRITE SAME operation without actually performing a write
* to media. As a result, write_zeroes is enabled by default and will be
* disabled if a zeroing operation subsequently fails. This means that this
* queue limit is likely to change at runtime.
*/
static void __blkdev_issue_write_zeroes(struct block_device *bdev,
sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
struct bio **biop, unsigned flags)
struct bio **biop, unsigned flags, sector_t limit)
{
while (nr_sects) {
unsigned int len = min_t(sector_t, nr_sects,
bio_write_zeroes_limit(bdev));
unsigned int len = min(nr_sects, limit);
struct bio *bio;
if ((flags & BLKDEV_ZERO_KILLABLE) &&
@ -141,12 +148,14 @@ static void __blkdev_issue_write_zeroes(struct block_device *bdev,
static int blkdev_issue_write_zeroes(struct block_device *bdev, sector_t sector,
sector_t nr_sects, gfp_t gfp, unsigned flags)
{
sector_t limit = bio_write_zeroes_limit(bdev);
struct bio *bio = NULL;
struct blk_plug plug;
int ret = 0;
blk_start_plug(&plug);
__blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp, &bio, flags);
__blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp, &bio,
flags, limit);
if (bio) {
if ((flags & BLKDEV_ZERO_KILLABLE) &&
fatal_signal_pending(current)) {
@ -165,7 +174,7 @@ static int blkdev_issue_write_zeroes(struct block_device *bdev, sector_t sector,
* on an I/O error, in which case we'll turn any error into
* "not supported" here.
*/
if (ret && !bdev_write_zeroes_sectors(bdev))
if (ret && !limit)
return -EOPNOTSUPP;
return ret;
}
@ -265,12 +274,14 @@ int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
unsigned flags)
{
sector_t limit = bio_write_zeroes_limit(bdev);
if (bdev_read_only(bdev))
return -EPERM;
if (bdev_write_zeroes_sectors(bdev)) {
if (limit) {
__blkdev_issue_write_zeroes(bdev, sector, nr_sects,
gfp_mask, biop, flags);
gfp_mask, biop, flags, limit);
} else {
if (flags & BLKDEV_ZERO_NOFALLBACK)
return -EOPNOTSUPP;