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authorNeilBrown <neilb@suse.de>2013-08-27 15:52:13 +1000
committerNeilBrown <neilb@suse.de>2013-08-28 16:58:36 +1000
commitc46501b2deaa06efcaaf82917281941f02c6b307 (patch)
treebafe1a096cda8f657074d59cec815b7ae717cd96 /drivers/md
parentb721420e8719131896b009b11edbbd27d9b85e98 (diff)
md/raid5: use seqcount to protect access to shape in make_request.
make_request() access various shape parameters (raid_disks, chunk_size etc) which might be changed by raid5_start_reshape(). If the later is called at and awkward time during the form, the wrong stripe_head might be used. So introduce a 'seqcount' and after finding a stripe_head make sure there is no reason to expect that we got the wrong one. Signed-off-by: NeilBrown <neilb@suse.de>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/raid5.c14
-rw-r--r--drivers/md/raid5.h1
2 files changed, 14 insertions, 1 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index d79ecd903269..4263df11d597 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4408,8 +4408,10 @@ static void make_request(struct mddev *mddev, struct bio * bi)
for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
DEFINE_WAIT(w);
int previous;
+ int seq;
retry:
+ seq = read_seqcount_begin(&conf->gen_lock);
previous = 0;
prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
if (unlikely(conf->reshape_progress != MaxSector)) {
@@ -4442,7 +4444,7 @@ static void make_request(struct mddev *mddev, struct bio * bi)
previous,
&dd_idx, NULL);
pr_debug("raid456: make_request, sector %llu logical %llu\n",
- (unsigned long long)new_sector,
+ (unsigned long long)new_sector,
(unsigned long long)logical_sector);
sh = get_active_stripe(conf, new_sector, previous,
@@ -4471,6 +4473,13 @@ static void make_request(struct mddev *mddev, struct bio * bi)
goto retry;
}
}
+ if (read_seqcount_retry(&conf->gen_lock, seq)) {
+ /* Might have got the wrong stripe_head
+ * by accident
+ */
+ release_stripe(sh);
+ goto retry;
+ }
if (rw == WRITE &&
logical_sector >= mddev->suspend_lo &&
@@ -5437,6 +5446,7 @@ static struct r5conf *setup_conf(struct mddev *mddev)
if (alloc_thread_groups(conf, 0))
goto abort;
spin_lock_init(&conf->device_lock);
+ seqcount_init(&conf->gen_lock);
init_waitqueue_head(&conf->wait_for_stripe);
init_waitqueue_head(&conf->wait_for_overlap);
INIT_LIST_HEAD(&conf->handle_list);
@@ -6249,6 +6259,7 @@ static int raid5_start_reshape(struct mddev *mddev)
atomic_set(&conf->reshape_stripes, 0);
spin_lock_irq(&conf->device_lock);
+ write_seqcount_begin(&conf->gen_lock);
conf->previous_raid_disks = conf->raid_disks;
conf->raid_disks += mddev->delta_disks;
conf->prev_chunk_sectors = conf->chunk_sectors;
@@ -6265,6 +6276,7 @@ static int raid5_start_reshape(struct mddev *mddev)
else
conf->reshape_progress = 0;
conf->reshape_safe = conf->reshape_progress;
+ write_seqcount_end(&conf->gen_lock);
spin_unlock_irq(&conf->device_lock);
/* Add some new drives, as many as will fit.
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 105366371fbf..435b12d58165 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -400,6 +400,7 @@ struct r5conf {
int prev_chunk_sectors;
int prev_algo;
short generation; /* increments with every reshape */
+ seqcount_t gen_lock; /* lock against generation changes */
unsigned long reshape_checkpoint; /* Time we last updated
* metadata */
long long min_offset_diff; /* minimum difference between