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dm thin: stop no_space_timeout worker when switching to write-mode 

Now both check_for_space() and do_no_space_timeout() will read & write
pool->pf.error_if_no_space.  If these functions run concurrently, as
shown in the following case, the default setting of "queue_if_no_space"
can get lost.

precondition:
    * error_if_no_space = false (aka "queue_if_no_space")
    * pool is in Out-of-Data-Space (OODS) mode
    * no_space_timeout worker has been queued

CPU 0:                          CPU 1:
// delete a thin device
process_delete_mesg()
// check_for_space() invoked by commit()
set_pool_mode(pool, PM_WRITE)
    pool->pf.error_if_no_space = \
     pt->requested_pf.error_if_no_space

				// timeout, pool is still in OODS mode
				do_no_space_timeout
				    // "queue_if_no_space" config is lost
				    pool->pf.error_if_no_space = true
    pool->pf.mode = new_mode

Fix it by stopping no_space_timeout worker when switching to write mode.

Fixes: bcc696fac1 ("dm thin: stay in out-of-data-space mode once no_space_timeout expires")
Cc: stable@vger.kernel.org
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Hou Tao 2018-08-02 16:18:24 +08:00 committed by Mike Snitzer
parent 7209049d40
commit 75294442d8
1 changed files with 2 additions and 0 deletions
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2
drivers/md/dm-thin.c
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@ -2503,6 +2503,8 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
case PM_WRITE:
if (old_mode != new_mode)
notify_of_pool_mode_change(pool, "write");
if (old_mode == PM_OUT_OF_DATA_SPACE)
cancel_delayed_work_sync(&pool->no_space_timeout);
pool->out_of_data_space = false;
pool->pf.error_if_no_space = pt->requested_pf.error_if_no_space;
dm_pool_metadata_read_write(pool->pmd);