From ba1cbad93dd47223b1f3b8edd50dd9ef2abcb2ed Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Wed, 26 Sep 2012 23:45:42 +0100 Subject: [PATCH] dm: handle requests beyond end of device instead of using BUG_ON The access beyond the end of device BUG_ON that was introduced to dm_request_fn via commit 29e4013de7ad950280e4b2208 ("dm: implement REQ_FLUSH/FUA support for request-based dm") was an overly drastic (but simple) response to this situation. I have received a report that this BUG_ON was hit and now think it would be better to use dm_kill_unmapped_request() to fail the clone and original request with -EIO. map_request() will assign the valid target returned by dm_table_find_target to tio->ti. But when the target isn't valid tio->ti is never assigned (because map_request isn't called); so add a check for tio->ti != NULL to dm_done(). Reported-by: Mike Christie Signed-off-by: Mike Snitzer Signed-off-by: Jun'ichi Nomura Cc: stable@vger.kernel.org # v2.6.37+ Signed-off-by: Alasdair G Kergon --- drivers/md/dm.c | 56 +++++++++++++++++++++++++++++++++---------------- 1 file changed, 38 insertions(+), 18 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 4e09b6ff5b49..6748e0c4df1f 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -865,10 +865,14 @@ static void dm_done(struct request *clone, int error, bool mapped) { int r = error; struct dm_rq_target_io *tio = clone->end_io_data; - dm_request_endio_fn rq_end_io = tio->ti->type->rq_end_io; + dm_request_endio_fn rq_end_io = NULL; - if (mapped && rq_end_io) - r = rq_end_io(tio->ti, clone, error, &tio->info); + if (tio->ti) { + rq_end_io = tio->ti->type->rq_end_io; + + if (mapped && rq_end_io) + r = rq_end_io(tio->ti, clone, error, &tio->info); + } if (r <= 0) /* The target wants to complete the I/O */ @@ -1588,15 +1592,6 @@ static int map_request(struct dm_target *ti, struct request *clone, int r, requeued = 0; struct dm_rq_target_io *tio = clone->end_io_data; - /* - * Hold the md reference here for the in-flight I/O. - * We can't rely on the reference count by device opener, - * because the device may be closed during the request completion - * when all bios are completed. - * See the comment in rq_completed() too. - */ - dm_get(md); - tio->ti = ti; r = ti->type->map_rq(ti, clone, &tio->info); switch (r) { @@ -1628,6 +1623,26 @@ static int map_request(struct dm_target *ti, struct request *clone, return requeued; } +static struct request *dm_start_request(struct mapped_device *md, struct request *orig) +{ + struct request *clone; + + blk_start_request(orig); + clone = orig->special; + atomic_inc(&md->pending[rq_data_dir(clone)]); + + /* + * Hold the md reference here for the in-flight I/O. + * We can't rely on the reference count by device opener, + * because the device may be closed during the request completion + * when all bios are completed. + * See the comment in rq_completed() too. + */ + dm_get(md); + + return clone; +} + /* * q->request_fn for request-based dm. * Called with the queue lock held. @@ -1657,14 +1672,21 @@ static void dm_request_fn(struct request_queue *q) pos = blk_rq_pos(rq); ti = dm_table_find_target(map, pos); - BUG_ON(!dm_target_is_valid(ti)); + if (!dm_target_is_valid(ti)) { + /* + * Must perform setup, that dm_done() requires, + * before calling dm_kill_unmapped_request + */ + DMERR_LIMIT("request attempted access beyond the end of device"); + clone = dm_start_request(md, rq); + dm_kill_unmapped_request(clone, -EIO); + continue; + } if (ti->type->busy && ti->type->busy(ti)) goto delay_and_out; - blk_start_request(rq); - clone = rq->special; - atomic_inc(&md->pending[rq_data_dir(clone)]); + clone = dm_start_request(md, rq); spin_unlock(q->queue_lock); if (map_request(ti, clone, md)) @@ -1684,8 +1706,6 @@ static void dm_request_fn(struct request_queue *q) blk_delay_queue(q, HZ / 10); out: dm_table_put(map); - - return; } int dm_underlying_device_busy(struct request_queue *q) -- GitLab