If backing file's filesystem has implemented ->fallocate(), we think the
loop device can support discard, then pass sb->s_blocksize as
discard_granularity. However, some underlying FS, such as overlayfs,
doesn't set sb->s_blocksize, and causes discard_granularity to be set as
zero, then the warning in __blkdev_issue_discard() is triggered.
Fix the issue by setting discard_granularity as PAGE_SIZE in this case
since PAGE_SIZE is the most common data unit for FS.
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Reported-by: Pei Zhang <pezhang@xxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
drivers/block/loop.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index b1b05c45c07c..8c15bfab7e1a 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -776,6 +776,10 @@ static void loop_config_discard(struct loop_device *lo)
} else {
max_discard_sectors = UINT_MAX >> 9;
granularity = inode->i_sb->s_blocksize;
+
+ /* Take PAGE_SIZE if the FS doesn't provide us one hint */
+ if (!granularity)
+ granularity = PAGE_SIZE;
}
if (max_discard_sectors) {
--
2.31.1
