[07/26] loop: also use the default block size from an underlying block device

Commit Message

Christoph Hellwig June 17, 2024, 6:04 a.m. UTC

Fix the code in loop_reconfigure_limits to pick a default block size for
O_DIRECT file descriptors to also work when the loop device sits on top
of a block device and not just on a regular file on a block device based
file system.

Signed-off-by: Christoph Hellwig <[e-mail]>
Reviewed-by: Hannes Reinecke <[e-mail]>
Reviewed-by: Bart Van Assche <[e-mail]>
---
 drivers/block/loop.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Comments

Damien Le Moal June 17, 2024, 6:14 a.m. UTC | #1

On 6/17/24 15:04, Christoph Hellwig wrote:
> Fix the code in loop_reconfigure_limits to pick a default block size for
> O_DIRECT file descriptors to also work when the loop device sits on top
> of a block device and not just on a regular file on a block device based
> file system.
> 
> Signed-off-by: Christoph Hellwig <[e-mail]>
> Reviewed-by: Hannes Reinecke <[e-mail]>
> Reviewed-by: Bart Van Assche <[e-mail]>

Reviewed-by: Damien Le Moal <[e-mail]>

Patch

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index eea3e4919e356e..6a4826708a3acf 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -988,10 +988,16 @@  static int loop_reconfigure_limits(struct loop_device *lo, unsigned short bsize)
 {
 	struct file *file = lo->lo_backing_file;
 	struct inode *inode = file->f_mapping->host;
+	struct block_device *backing_bdev = NULL;
 	struct queue_limits lim;
 
+	if (S_ISBLK(inode->i_mode))
+		backing_bdev = I_BDEV(inode);
+	else if (inode->i_sb->s_bdev)
+		backing_bdev = inode->i_sb->s_bdev;
+
 	if (!bsize)
-		bsize = loop_default_blocksize(lo, inode->i_sb->s_bdev);
+		bsize = loop_default_blocksize(lo, backing_bdev);
 
 	lim = queue_limits_start_update(lo->lo_queue);
 	lim.logical_block_size = bsize;