[PATCH 2/4] loop: Enable correct physical blocksize

[Hannes Reinecke <hare@suse.de>]

When running on files the physical blocksize is actually 4k,
so we should be announcing it as such. This is enabled with
a new LO_FLAGS_BLOCKSIZE flag value to the existing ioctl.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/block/loop.c      | 9 ++++++++-
 include/uapi/linux/loop.h | 1 +
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index b9e12a0..fce13bd 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -177,6 +177,8 @@ figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
 		lo->lo_offset = offset;
 	if (lo->lo_sizelimit != sizelimit)
 		lo->lo_sizelimit = sizelimit;
+	if (lo->lo_flags & LO_FLAGS_BLOCKSIZE)
+		blk_queue_physical_block_size(lo->lo_queue, lo->lo_blocksize);
 	set_capacity(lo->lo_disk, x);
 	bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
 	/* let user-space know about the new size */
@@ -758,7 +760,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
 
 	lo->lo_blocksize = lo_blocksize;
 	lo->lo_device = bdev;
-	lo->lo_flags = lo_flags;
+	lo->lo_flags |= lo_flags;
 	lo->lo_backing_file = file;
 	lo->transfer = NULL;
 	lo->ioctl = NULL;
@@ -769,6 +771,8 @@ 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_flush(lo->lo_queue, REQ_FLUSH);
 
+	if (lo->lo_flags & LO_FLAGS_BLOCKSIZE)
+		blk_queue_physical_block_size(lo->lo_queue, lo->lo_blocksize);
 	set_capacity(lo->lo_disk, size);
 	bd_set_size(bdev, size << 9);
 	loop_sysfs_init(lo);
@@ -951,6 +955,9 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
 	if (err)
 		return err;
 
+	if (info->lo_flags & LO_FLAGS_BLOCKSIZE)
+		lo->lo_flags |= LO_FLAGS_BLOCKSIZE;
+
 	if (lo->lo_offset != info->lo_offset ||
 	    lo->lo_sizelimit != info->lo_sizelimit)
 		if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
diff --git a/include/uapi/linux/loop.h b/include/uapi/linux/loop.h
index e0cecd2..caec9d3 100644
--- a/include/uapi/linux/loop.h
+++ b/include/uapi/linux/loop.h
@@ -21,6 +21,7 @@ enum {
 	LO_FLAGS_READ_ONLY	= 1,
 	LO_FLAGS_AUTOCLEAR	= 4,
 	LO_FLAGS_PARTSCAN	= 8,
+	LO_FLAGS_BLOCKSIZE	= 16,
 };
 
 #include <asm/posix_types.h>	/* for __kernel_old_dev_t */
-- 
1.8.4.5