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://urldefense.com/v3/__https://lore.kernel.org/linux-
xfs/4d31268f-310b-4220-88a2-e191c3932a82@xxxxxxxxxx/T/*t__;Iw!!
ACWV5N9M2RV99hQ! KNrgu0c216k_Y_2RLxTasjxizyhbN8eKD61JwIwDxT5OJJDamER6hw1nvf5biNMqQLaLl9PqC2qRUDdHlrGF7g$
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);
