[PATCH 06/26] loop: also use the default block size from an underlying block device

Christoph Hellwig <[email protected]>
Newsgroups dev.linux.lists.drbd-dev,dev.linux.lists.dm-devel,dev.linux.lists.nvdimm,dev.linux.lists.virtualization,org.infradead.lists.linux-mtd,org.infradead.lists.linux-nvme,org.infradead.lists.linux-um,org.kernel.vger.ceph-devel,org.kernel.vger.linux-bcache,org.kernel.vger.linux-block,org.kernel.vger.linux-m68k,org.kernel.vger.linux-mmc,org.kernel.vger.linux-raid,org.kernel.vger.linux-s390,org.kernel.vger.linux-scsi,org.ozlabs.lists.linuxppc-dev,org.xenproject.lists.xen-devel
Message-ID <[email protected]>
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 <[email protected]>
---
 drivers/block/loop.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 4f6d8514d19bd6..d7cf6bbbfb1b86 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;
-- 
2.43.0
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