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authorJun'ichi Nomura <j-nomura@ce.jp.nec.com>2007-12-13 14:15:25 +0000
committerAlasdair G Kergon <agk@redhat.com>2007-12-20 17:32:08 +0000
commit512875bd9661368da6f993205a61213b79ba1df0 (patch)
tree7a2e010060b6233cd02e2e36b62f5dcaa96c2c36 /drivers/md/dm.h
parentfbdcf18df73758b2e187ab94678b30cd5f6ff9f9 (diff)
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dm: table detect io beyond device
This patch fixes a panic on shrinking a DM device if there is outstanding I/O to the part of the device that is being removed. (Normally this doesn't happen - a filesystem would be resized first, for example.) The bug is that __clone_and_map() assumes dm_table_find_target() always returns a valid pointer. It may fail if a bio arrives from the block layer but its target sector is no longer included in the DM btree. This patch appends an empty entry to table->targets[] which will be returned by a lookup beyond the end of the device. After calling dm_table_find_target(), __clone_and_map() and target_message() check for this condition using dm_target_is_valid(). Sample test script to trigger oops:
Diffstat (limited to 'drivers/md/dm.h')
-rw-r--r--drivers/md/dm.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 4b3faa45277e..177297a88ebd 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -112,6 +112,11 @@ int dm_table_resume_targets(struct dm_table *t);
int dm_table_any_congested(struct dm_table *t, int bdi_bits);
void dm_table_unplug_all(struct dm_table *t);
+/*
+ * To check the return value from dm_table_find_target().
+ */
+#define dm_target_is_valid(t) ((t)->table)
+
/*-----------------------------------------------------------------
* A registry of target types.
*---------------------------------------------------------------*/