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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Lennart Poettering <mzxreary@0pointer.de>,
        Yang Xu <xuyang2018.jy@cn.fujitsu.com>,
        Martijn Coenen <maco@android.com>, Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 5.8 007/118] loop: Set correct device size when using LOOP_CONFIGURE
Date:   Mon, 21 Sep 2020 18:26:59 +0200
Message-Id: <20200921162036.684858019@linuxfoundation.org>
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From: Martijn Coenen <maco@android.com>

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>

---
 drivers/block/loop.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1114,8 +1114,6 @@ static int loop_configure(struct loop_de
 	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_de
 	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) ?