[ 77/98] MD RAID5: Avoid accessing gendisk or queue structs when not available

Greg Kroah-Hartman
2013-03-26T22:47:45Z

From: Jonathan Brassow <jbrassow@redhat.com>

commit e3620a3ad52609f64a2402e4b59300afb4b83b77 upstream.

MD RAID5: Fix kernel oops when RAID4/5/6 is used via device-mapper

Commit a9add5d (v3.8-rc1) added blktrace calls to the RAID4/5/6 driver.
However, when device-mapper is used to create RAID4/5/6 arrays, the
mddev->gendisk and mddev->queue fields are not setup. Therefore, calling
things like trace_block_bio_remap will cause a kernel oops. This patch
conditionalizes those calls on whether the proper fields exist to make
the calls. (Device-mapper will call trace_block_bio_remap on its own.)

This patch is suitable for the 3.8.y stable kernel.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/md/raid5.c | 33 ++++++++++++++++++++-------------
1 file changed, 20 insertions(+), 13 deletions(-)

--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -674,9 +674,11 @@ static void ops_run_io(struct stripe_hea
bi->bi_next = NULL;
if (rrdev)
set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
- trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
- bi, disk_devt(conf->mddev->gendisk),
- sh->dev[i].sector);
+
+ if (conf->mddev->gendisk)
+ trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
+ bi, disk_devt(conf->mddev->gendisk),
+ sh->dev[i].sector);
generic_make_request(bi);
}
if (rrdev) {
@@ -704,9 +706,10 @@ static void ops_run_io(struct stripe_hea
rbi->bi_io_vec[0].bv_offset = 0;
rbi->bi_size = STRIPE_SIZE;
rbi->bi_next = NULL;
- trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
- rbi, disk_devt(conf->mddev->gendisk),
- sh->dev[i].sector);
+ if (conf->mddev->gendisk)
+ trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
+ rbi, disk_devt(conf->mddev->gendisk),
+ sh->dev[i].sector);
generic_make_request(rbi);
}
if (!rdev && !rrdev) {
@@ -2871,8 +2874,10 @@ static void handle_stripe_dirtying(struc
set_bit(STRIPE_HANDLE, &sh->state);
if (rmw < rcw && rmw > 0) {
/* prefer read-modify-write, but need to get some data */
- blk_add_trace_msg(conf->mddev->queue, "raid5 rmw %llu %d",
- (unsigned long long)sh->sector, rmw);
+ if (conf->mddev->queue)
+ blk_add_trace_msg(conf->mddev->queue,
+ "raid5 rmw %llu %d",
+ (unsigned long long)sh->sector, rmw);
for (i = disks; i--; ) {
struct r5dev *dev = &sh->dev[i];
if ((dev->towrite || i == sh->pd_idx) &&
@@ -2922,7 +2927,7 @@ static void handle_stripe_dirtying(struc
}
}
}
- if (rcw)
+ if (rcw && conf->mddev->queue)
blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
(unsigned long long)sh->sector,
rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
@@ -4029,9 +4034,10 @@ static int chunk_aligned_read(struct mdd
atomic_inc(&conf->active_aligned_reads);
spin_unlock_irq(&conf->device_lock);

- trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
- align_bi, disk_devt(mddev->gendisk),
- raid_bio->bi_sector);
+ if (mddev->gendisk)
+ trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
+ align_bi, disk_devt(mddev->gendisk),
+ raid_bio->bi_sector);
generic_make_request(align_bi);
return 1;
} else {
@@ -4125,7 +4131,8 @@ static void raid5_unplug(struct blk_plug
}
spin_unlock_irq(&conf->device_lock);
}
- trace_block_unplug(mddev->queue, cnt, !from_schedule);
+ if (mddev->queue)
+ trace_block_unplug(mddev->queue, cnt, !from_schedule);
kfree(cb);
}