As reported in [0], we may get a hang when formatting a XFS FS on a RAID0
drive.
Commit 73a768d5f955 ("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@xxxxxxxxxx/T/#t
Fixes: 73a768d5f955 ("block: factor out a blk_write_zeroes_limit helper")
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
---
block/blk-lib.c | 25 ++++++++++++++++++-------
1 file changed, 18 insertions(+), 7 deletions(-)
diff --git a/block/blk-lib.c b/block/blk-lib.c
index 9f735efa6c94..83eb7761c2bf 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -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;
--
2.31.1
