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UPSTREAM: loop: fix queue freeze vs limits lock order

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Match the locking order used by the core block code by only freezing
the queue after taking the limits lock using the
queue_limits_commit_update_frozen helper and document the callers that
do not freeze the queue at all.

Change-Id: Ia906c96b35abd306a35a43a7e81ef581f21792ef
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250110054726.1499538-12-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit b03732a9c0db91522914185739505d92d3b0d816)
Signed-off-by: Bart Van Assche <bvanassche@google.com>
This commit is contained in:
Christoph Hellwig
2025-01-10 06:47:19 +01:00
committed by Bart Van Assche
parent d2eefa734f
commit 4a77dbe5c5
1 changed files with 16 additions and 2 deletions
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18
drivers/block/loop.c
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@@ -311,6 +311,13 @@ static void loop_clear_limits(struct loop_device *lo, int mode)
lim.discard_granularity = 0;
}
/*
* XXX: this updates the queue limits without freezing the queue, which
* is against the locking protocol and dangerous. But we can't just
* freeze the queue as we're inside the ->queue_rq method here. So this
* should move out into a workqueue unless we get the file operations to
* advertise if they support specific fallocate operations.
*/
queue_limits_commit_update(lo->lo_queue, &lim);
}
@@ -1091,6 +1098,7 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode,
lim = queue_limits_start_update(lo->lo_queue);
loop_update_limits(lo, &lim, config->block_size);
/* No need to freeze the queue as the device isn't bound yet. */
error = queue_limits_commit_update(lo->lo_queue, &lim);
if (error)
goto out_unlock;
@@ -1151,7 +1159,12 @@ static void __loop_clr_fd(struct loop_device *lo)
lo->lo_sizelimit = 0;
memset(lo->lo_file_name, 0, LO_NAME_SIZE);
/* reset the block size to the default */
/*
* Reset the block size to the default.
*
* No queue freezing needed because this is called from the final
* ->release call only, so there can't be any outstanding I/O.
*/
lim = queue_limits_start_update(lo->lo_queue);
lim.logical_block_size = SECTOR_SIZE;
lim.physical_block_size = SECTOR_SIZE;
@@ -1471,9 +1484,10 @@ static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
sync_blockdev(lo->lo_device);
invalidate_bdev(lo->lo_device);
blk_mq_freeze_queue(lo->lo_queue);
lim = queue_limits_start_update(lo->lo_queue);
loop_update_limits(lo, &lim, arg);
blk_mq_freeze_queue(lo->lo_queue);
err = queue_limits_commit_update(lo->lo_queue, &lim);
loop_update_dio(lo);
blk_mq_unfreeze_queue(lo->lo_queue);