blob: 764cfaef639aafe93b5084cd31288c8c93b25b37 [file] [log] [blame]
From 262bb64d60b9e8d1b1a30cfff61eb4ebe1d65f4f Mon Sep 17 00:00:00 2001
From: Martijn Coenen <>
Date: Wed, 4 Sep 2019 21:49:01 +0200
Subject: [PATCH] loop: change queue block size to match when using DIO
commit 85560117d00f5d528e928918b8f61cadcefff98b upstream.
The loop driver assumes that if the passed in fd is opened with
O_DIRECT, the caller wants to use direct I/O on the loop device.
However, if the underlying block device has a different block size than
the loop block queue, direct I/O can't be enabled. Instead of requiring
userspace to manually change the blocksize and re-enable direct I/O,
just change the queue block sizes to match, as well as the io_min size.
Reviewed-by: Christoph Hellwig <>
Signed-off-by: Martijn Coenen <>
Signed-off-by: Jens Axboe <>
Signed-off-by: Paul Gortmaker <>
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 8e32930f65a1..2f191194d719 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1002,6 +1002,16 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
blk_queue_write_cache(lo->lo_queue, true, false);
+ if (io_is_direct(lo->lo_backing_file) && inode->i_sb->s_bdev) {
+ /* In case of direct I/O, match underlying block size */
+ unsigned short bsize = bdev_logical_block_size(
+ inode->i_sb->s_bdev);
+ blk_queue_logical_block_size(lo->lo_queue, bsize);
+ blk_queue_physical_block_size(lo->lo_queue, bsize);
+ blk_queue_io_min(lo->lo_queue, bsize);
+ }
set_capacity(lo->lo_disk, size);