diff options
| author | NeilBrown <neilb@suse.de> | 2013-08-27 15:52:13 +1000 |
|---|---|---|
| committer | NeilBrown <neilb@suse.de> | 2013-08-28 16:58:36 +1000 |
| commit | c46501b2deaa06efcaaf82917281941f02c6b307 (patch) | |
| tree | bafe1a096cda8f657074d59cec815b7ae717cd96 | |
| parent | b721420e8719131896b009b11edbbd27d9b85e98 (diff) | |
| download | linux-c46501b2deaa06efcaaf82917281941f02c6b307.tar.bz2 | |
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>
| -rw-r--r-- | drivers/md/raid5.c | 14 | ||||
| -rw-r--r-- | drivers/md/raid5.h | 1 |
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 |