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| author | Jun'ichi Nomura <j-nomura@ce.jp.nec.com> | 2007-12-13 14:15:25 +0000 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2007-12-20 17:32:08 +0000 |
| commit | 512875bd9661368da6f993205a61213b79ba1df0 (patch) | |
| tree | 7a2e010060b6233cd02e2e36b62f5dcaa96c2c36 /drivers/md/dm.h | |
| parent | fbdcf18df73758b2e187ab94678b30cd5f6ff9f9 (diff) | |
| download | linux-512875bd9661368da6f993205a61213b79ba1df0.tar.bz2 | |
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.h | 5 |
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. *---------------------------------------------------------------*/ |