loop: Set correct device size when using LOOP_CONFIGURE

commit 79e5dc59e2974a48764269fa9ff544ae8ffe3338 upstream.

The device size calculation was done before processing the loop
configuration, which meant that the we set the size on the underlying
block device incorrectly in case lo_offset/lo_sizelimit were set in the
configuration. Delay computing the size until we've setup the device
parameters correctly.

Fixes: 3448914e8cc5("loop: Add LOOP_CONFIGURE ioctl")
Reported-by: Lennart Poettering <mzxreary@0pointer.de>
Tested-by: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
Signed-off-by: Martijn Coenen <maco@android.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 84433922aed162b38a9fe02e7ea00bf13edd9b31..dfc66038bef9fda7860c156cbf0e0f535bfa9700 100644 (file)
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1114,8 +1114,6 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
        mapping = file->f_mapping;
        inode = mapping->host;
 
-       size = get_loop_size(lo, file);
-
        if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) {
                error = -EINVAL;
                goto out_unlock;
@@ -1165,6 +1163,8 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
        loop_update_rotational(lo);
        loop_update_dio(lo);
        loop_sysfs_init(lo);
+
+       size = get_loop_size(lo, file);
        loop_set_size(lo, size);
 
        set_blocksize(bdev, S_ISBLK(inode->i_mode) ?