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

From: Hannes Reinecke
Date: Mon Oct 31 2016 - 15:38:33 EST


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
loop_set_status ioctl.

Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
---
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 3008dec..ff5c874 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -233,6 +233,8 @@ 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 */
@@ -1087,6 +1089,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
int err;
struct loop_func_table *xfer;
kuid_t uid = current_uid();
+ int lo_flags = lo->lo_flags;

if (lo->lo_encrypt_key_size &&
!uid_eq(lo->lo_key_owner, uid) &&
@@ -1116,8 +1119,12 @@ 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)
+ lo->lo_sizelimit != info->lo_sizelimit ||
+ lo->lo_flags != lo_flags)
if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
return -EFBIG;

diff --git a/include/uapi/linux/loop.h b/include/uapi/linux/loop.h
index c8125ec..2691c1c 100644
--- a/include/uapi/linux/loop.h
+++ b/include/uapi/linux/loop.h
@@ -22,6 +22,7 @@ enum {
LO_FLAGS_AUTOCLEAR = 4,
LO_FLAGS_PARTSCAN = 8,
LO_FLAGS_DIRECT_IO = 16,
+ LO_FLAGS_BLOCKSIZE = 32,
};

#include <asm/posix_types.h> /* for __kernel_old_dev_t */
--
2.6.6