diff options
| author | Milan Broz <mbroz@redhat.com> | 2012-09-26 23:45:43 +0100 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2012-10-10 03:31:06 +0100 |
| commit | e3dd7a09f14902688ae99eb8f3a49e3651147283 (patch) | |
| tree | 0a6c787ed39c487afbeb7321cfe3a19d8e4deb68 /drivers/md | |
| parent | 1bd6669684e5b889713164a76d42250afefdd1aa (diff) | |
dm table: clear add_random unless all devices have it set
commit c3c4555edd10dbc0b388a0125b9c50de5e79af05 upstream.
Always clear QUEUE_FLAG_ADD_RANDOM if any underlying device does not
have it set. Otherwise devices with predictable characteristics may
contribute entropy.
QUEUE_FLAG_ADD_RANDOM specifies whether or not queue IO timings
contribute to the random pool.
For bio-based targets this flag is always 0 because such devices have no
real queue.
For request-based devices this flag was always set to 1 by default.
Now set it according to the flags on underlying devices. If there is at
least one device which should not contribute, set the flag to zero: If a
device, such as fast SSD storage, is not suitable for supplying entropy,
a request-based queue stacked over it will not be either.
Because the checking logic is exactly same as for the rotational flag,
share the iteration function with device_is_nonrot().
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/dm-table.c | 26 |
1 files changed, 22 insertions, 4 deletions
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 8e9132130142..52848ab56c95 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -1350,17 +1350,25 @@ static int device_is_nonrot(struct dm_target *ti, struct dm_dev *dev, return q && blk_queue_nonrot(q); } -static bool dm_table_is_nonrot(struct dm_table *t) +static int device_is_not_random(struct dm_target *ti, struct dm_dev *dev, + sector_t start, sector_t len, void *data) +{ + struct request_queue *q = bdev_get_queue(dev->bdev); + + return q && !blk_queue_add_random(q); +} + +static bool dm_table_all_devices_attribute(struct dm_table *t, + iterate_devices_callout_fn func) { struct dm_target *ti; unsigned i = 0; - /* Ensure that all underlying device are non-rotational. */ while (i < dm_table_get_num_targets(t)) { ti = dm_table_get_target(t, i++); if (!ti->type->iterate_devices || - !ti->type->iterate_devices(ti, device_is_nonrot, NULL)) + !ti->type->iterate_devices(ti, func, NULL)) return 0; } @@ -1392,7 +1400,8 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, if (!dm_table_discard_zeroes_data(t)) q->limits.discard_zeroes_data = 0; - if (dm_table_is_nonrot(t)) + /* Ensure that all underlying devices are non-rotational. */ + if (dm_table_all_devices_attribute(t, device_is_nonrot)) queue_flag_set_unlocked(QUEUE_FLAG_NONROT, q); else queue_flag_clear_unlocked(QUEUE_FLAG_NONROT, q); @@ -1400,6 +1409,15 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, dm_table_set_integrity(t); /* + * Determine whether or not this queue's I/O timings contribute + * to the entropy pool, Only request-based targets use this. + * Clear QUEUE_FLAG_ADD_RANDOM if any underlying device does not + * have it set. + */ + if (blk_queue_add_random(q) && dm_table_all_devices_attribute(t, device_is_not_random)) + queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, q); + + /* * QUEUE_FLAG_STACKABLE must be set after all queue settings are * visible to other CPUs because, once the flag is set, incoming bios * are processed by request-based dm, which refers to the queue |