UPSTREAM: loop: drop caches if offset or block_size are changed
If we don't drop caches used in old offset or block_size, we can get old data
from new offset/block_size, which gives unexpected data to user.
For example, Martijn found a loopback bug in the below scenario.
1) LOOP_SET_FD loads first two pages on loop file
2) LOOP_SET_STATUS64 changes the offset on the loop file
3) mount is failed due to the cached pages having wrong superblock
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Reported-by: Martijn Coenen <maco@google.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit 490b8c65b9db45896769e1095e78725775f47b3e)
Change-Id: Iffb7e1f04ab587e1a8785bc862a425efb654be24
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 6d61633a..01312c4 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1097,6 +1097,12 @@
if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
return -EINVAL;
+ if (lo->lo_offset != info->lo_offset ||
+ lo->lo_sizelimit != info->lo_sizelimit) {
+ sync_blockdev(lo->lo_device);
+ kill_bdev(lo->lo_device);
+ }
+
/* I/O need to be drained during transfer transition */
blk_mq_freeze_queue(lo->lo_queue);
@@ -1125,6 +1131,14 @@
if (lo->lo_offset != info->lo_offset ||
lo->lo_sizelimit != info->lo_sizelimit) {
+ /* kill_bdev should have truncated all the pages */
+ if (lo->lo_device->bd_inode->i_mapping->nrpages) {
+ err = -EAGAIN;
+ pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n",
+ __func__, lo->lo_number, lo->lo_file_name,
+ lo->lo_device->bd_inode->i_mapping->nrpages);
+ goto exit;
+ }
if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit)) {
err = -EFBIG;
goto exit;
@@ -1346,22 +1360,39 @@
static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
{
+ int err = 0;
+
if (lo->lo_state != Lo_bound)
return -ENXIO;
if (arg < 512 || arg > PAGE_SIZE || !is_power_of_2(arg))
return -EINVAL;
+ if (lo->lo_queue->limits.logical_block_size != arg) {
+ sync_blockdev(lo->lo_device);
+ kill_bdev(lo->lo_device);
+ }
+
blk_mq_freeze_queue(lo->lo_queue);
+ /* kill_bdev should have truncated all the pages */
+ if (lo->lo_queue->limits.logical_block_size != arg &&
+ lo->lo_device->bd_inode->i_mapping->nrpages) {
+ err = -EAGAIN;
+ pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n",
+ __func__, lo->lo_number, lo->lo_file_name,
+ lo->lo_device->bd_inode->i_mapping->nrpages);
+ goto out_unfreeze;
+ }
+
blk_queue_logical_block_size(lo->lo_queue, arg);
blk_queue_physical_block_size(lo->lo_queue, arg);
blk_queue_io_min(lo->lo_queue, arg);
loop_update_dio(lo);
-
+out_unfreeze:
blk_mq_unfreeze_queue(lo->lo_queue);
- return 0;
+ return err;
}
static int lo_ioctl(struct block_device *bdev, fmode_t mode,
