[PATCH 06/26] loop: regularize upgrading the block size for direct I/O

[Christoph Hellwig]

The LOOP_CONFIGURE path automatically upgrades the block size to that
of the underlying file for O_DIRECT file descriptors, but the
LOOP_SET_BLOCK_SIZE path does not.  Fix this by lifting the code to
pick the block size into common code.

Signed-off-by: Christoph Hellwig <h...@lst.de>
Reviewed-by: Hannes Reinecke <h...@suse.de>
Reviewed-by: Bart Van Assche <bvanass...@acm.org>
---
 drivers/block/loop.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index ce197cbea5f434..eea3e4919e356e 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -975,10 +975,24 @@ loop_set_status_from_info(struct loop_device *lo,
        return 0;
 }
 
+static unsigned short loop_default_blocksize(struct loop_device *lo,
+               struct block_device *backing_bdev)
+{
+       /* In case of direct I/O, match underlying block size */
+       if ((lo->lo_backing_file->f_flags & O_DIRECT) && backing_bdev)
+               return bdev_logical_block_size(backing_bdev);
+       return SECTOR_SIZE;
+}
+
 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 queue_limits lim;
 
+       if (!bsize)
+               bsize = loop_default_blocksize(lo, inode->i_sb->s_bdev);
+
        lim = queue_limits_start_update(lo->lo_queue);
        lim.logical_block_size = bsize;
        lim.physical_block_size = bsize;
@@ -997,7 +1011,6 @@ static int loop_configure(struct loop_device *lo, 
blk_mode_t mode,
        int error;
        loff_t size;
        bool partscan;
-       unsigned short bsize;
        bool is_loop;
 
        if (!file)
@@ -1076,15 +1089,7 @@ static int loop_configure(struct loop_device *lo, 
blk_mode_t mode,
        if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
                blk_queue_write_cache(lo->lo_queue, true, false);
 
-       if (config->block_size)
-               bsize = config->block_size;
-       else if ((lo->lo_backing_file->f_flags & O_DIRECT) && 
inode->i_sb->s_bdev)
-               /* In case of direct I/O, match underlying block size */
-               bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
-       else
-               bsize = 512;
-
-       error = loop_reconfigure_limits(lo, bsize);
+       error = loop_reconfigure_limits(lo, config->block_size);
        if (WARN_ON_ONCE(error))
                goto out_unlock;
 
-- 
2.43.0