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authorMike Snitzer <snitzer@redhat.com>2012-09-26 23:45:42 +0100
committerAlasdair G Kergon <agk@redhat.com>2012-09-26 23:45:42 +0100
commitba1cbad93dd47223b1f3b8edd50dd9ef2abcb2ed (patch)
tree3cf301491e0c9ce60a8b90f8e9313ce95d75d695 /drivers/md
parent7ba10aa6fbac7158a50bec142132b04bc480bb29 (diff)
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 <michaelc@cs.wisc.edu> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Cc: stable@vger.kernel.org # v2.6.37+ Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/dm.c56
1 files changed, 38 insertions, 18 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 4e09b6ff5b4..6748e0c4df1 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 @@ delay_and_out:
blk_delay_queue(q, HZ / 10);
out:
dm_table_put(map);
-
- return;
}
int dm_underlying_device_busy(struct request_queue *q)