The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From cc27b0c78c79680d128dbac79de0d40556d041bb Mon Sep 17 00:00:00 2001 From: NeilBrown <neilb@xxxxxxxx> Date: Mon, 5 Jun 2017 16:49:39 +1000 Subject: [PATCH] md: fix deadlock between mddev_suspend() and md_write_start() If mddev_suspend() races with md_write_start() we can deadlock with mddev_suspend() waiting for the request that is currently in md_write_start() to complete the ->make_request() call, and md_write_start() waiting for the metadata to be updated to mark the array as 'dirty'. As metadata updates done by md_check_recovery() only happen then the mddev_lock() can be claimed, and as mddev_suspend() is often called with the lock held, these threads wait indefinitely for each other. We fix this by having md_write_start() abort if mddev_suspend() is happening, and ->make_request() aborts if md_write_start() aborted. md_make_request() can detect this abort, decrease the ->active_io count, and wait for mddev_suspend(). Reported-by: Nix <nix@xxxxxxxxxxxxx> Fix: 68866e425be2(MD: no sync IO while suspended) Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: NeilBrown <neilb@xxxxxxxx> Signed-off-by: Shaohua Li <shli@xxxxxx> diff --git a/drivers/md/faulty.c b/drivers/md/faulty.c index b0536cfd8e17..06a64d5d8c6c 100644 --- a/drivers/md/faulty.c +++ b/drivers/md/faulty.c @@ -170,7 +170,7 @@ static void add_sector(struct faulty_conf *conf, sector_t start, int mode) conf->nfaults = n+1; } -static void faulty_make_request(struct mddev *mddev, struct bio *bio) +static bool faulty_make_request(struct mddev *mddev, struct bio *bio) { struct faulty_conf *conf = mddev->private; int failit = 0; @@ -182,7 +182,7 @@ static void faulty_make_request(struct mddev *mddev, struct bio *bio) * just fail immediately */ bio_io_error(bio); - return; + return true; } if (check_sector(conf, bio->bi_iter.bi_sector, @@ -224,6 +224,7 @@ static void faulty_make_request(struct mddev *mddev, struct bio *bio) bio->bi_bdev = conf->rdev->bdev; generic_make_request(bio); + return true; } static void faulty_status(struct seq_file *seq, struct mddev *mddev) diff --git a/drivers/md/linear.c b/drivers/md/linear.c index df6f2c98eca7..5f1eb9189542 100644 --- a/drivers/md/linear.c +++ b/drivers/md/linear.c @@ -245,7 +245,7 @@ static void linear_free(struct mddev *mddev, void *priv) kfree(conf); } -static void linear_make_request(struct mddev *mddev, struct bio *bio) +static bool linear_make_request(struct mddev *mddev, struct bio *bio) { char b[BDEVNAME_SIZE]; struct dev_info *tmp_dev; @@ -254,7 +254,7 @@ static void linear_make_request(struct mddev *mddev, struct bio *bio) if (unlikely(bio->bi_opf & REQ_PREFLUSH)) { md_flush_request(mddev, bio); - return; + return true; } tmp_dev = which_dev(mddev, bio_sector); @@ -292,7 +292,7 @@ static void linear_make_request(struct mddev *mddev, struct bio *bio) mddev_check_write_zeroes(mddev, bio); generic_make_request(bio); } - return; + return true; out_of_bounds: pr_err("md/linear:%s: make_request: Sector %llu out of bounds on dev %s: %llu sectors, offset %llu\n", @@ -302,6 +302,7 @@ static void linear_make_request(struct mddev *mddev, struct bio *bio) (unsigned long long)tmp_dev->rdev->sectors, (unsigned long long)start_sector); bio_io_error(bio); + return true; } static void linear_status (struct seq_file *seq, struct mddev *mddev) diff --git a/drivers/md/md.c b/drivers/md/md.c index 87edc342ccb3..d7847014821a 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -277,7 +277,7 @@ static blk_qc_t md_make_request(struct request_queue *q, struct bio *bio) bio_endio(bio); return BLK_QC_T_NONE; } - smp_rmb(); /* Ensure implications of 'active' are visible */ +check_suspended: rcu_read_lock(); if (mddev->suspended) { DEFINE_WAIT(__wait); @@ -302,7 +302,11 @@ static blk_qc_t md_make_request(struct request_queue *q, struct bio *bio) sectors = bio_sectors(bio); /* bio could be mergeable after passing to underlayer */ bio->bi_opf &= ~REQ_NOMERGE; - mddev->pers->make_request(mddev, bio); + if (!mddev->pers->make_request(mddev, bio)) { + atomic_dec(&mddev->active_io); + wake_up(&mddev->sb_wait); + goto check_suspended; + } cpu = part_stat_lock(); part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]); @@ -327,6 +331,7 @@ void mddev_suspend(struct mddev *mddev) if (mddev->suspended++) return; synchronize_rcu(); + wake_up(&mddev->sb_wait); wait_event(mddev->sb_wait, atomic_read(&mddev->active_io) == 0); mddev->pers->quiesce(mddev, 1); @@ -7950,12 +7955,14 @@ EXPORT_SYMBOL(md_done_sync); * If we need to update some array metadata (e.g. 'active' flag * in superblock) before writing, schedule a superblock update * and wait for it to complete. + * A return value of 'false' means that the write wasn't recorded + * and cannot proceed as the array is being suspend. */ -void md_write_start(struct mddev *mddev, struct bio *bi) +bool md_write_start(struct mddev *mddev, struct bio *bi) { int did_change = 0; if (bio_data_dir(bi) != WRITE) - return; + return true; BUG_ON(mddev->ro == 1); if (mddev->ro == 2) { @@ -7987,7 +7994,12 @@ void md_write_start(struct mddev *mddev, struct bio *bi) if (did_change) sysfs_notify_dirent_safe(mddev->sysfs_state); wait_event(mddev->sb_wait, - !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)); + !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) && !mddev->suspended); + if (test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) { + percpu_ref_put(&mddev->writes_pending); + return false; + } + return true; } EXPORT_SYMBOL(md_write_start); diff --git a/drivers/md/md.h b/drivers/md/md.h index 0fa1de42c42b..63d342d560b8 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -510,7 +510,7 @@ struct md_personality int level; struct list_head list; struct module *owner; - void (*make_request)(struct mddev *mddev, struct bio *bio); + bool (*make_request)(struct mddev *mddev, struct bio *bio); int (*run)(struct mddev *mddev); void (*free)(struct mddev *mddev, void *priv); void (*status)(struct seq_file *seq, struct mddev *mddev); @@ -649,7 +649,7 @@ extern void md_wakeup_thread(struct md_thread *thread); extern void md_check_recovery(struct mddev *mddev); extern void md_reap_sync_thread(struct mddev *mddev); extern int mddev_init_writes_pending(struct mddev *mddev); -extern void md_write_start(struct mddev *mddev, struct bio *bi); +extern bool md_write_start(struct mddev *mddev, struct bio *bi); extern void md_write_inc(struct mddev *mddev, struct bio *bi); extern void md_write_end(struct mddev *mddev); extern void md_done_sync(struct mddev *mddev, int blocks, int ok); diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c index e95d521d93e9..c8d985ba008d 100644 --- a/drivers/md/multipath.c +++ b/drivers/md/multipath.c @@ -106,7 +106,7 @@ static void multipath_end_request(struct bio *bio) rdev_dec_pending(rdev, conf->mddev); } -static void multipath_make_request(struct mddev *mddev, struct bio * bio) +static bool multipath_make_request(struct mddev *mddev, struct bio * bio) { struct mpconf *conf = mddev->private; struct multipath_bh * mp_bh; @@ -114,7 +114,7 @@ static void multipath_make_request(struct mddev *mddev, struct bio * bio) if (unlikely(bio->bi_opf & REQ_PREFLUSH)) { md_flush_request(mddev, bio); - return; + return true; } mp_bh = mempool_alloc(conf->pool, GFP_NOIO); @@ -126,7 +126,7 @@ static void multipath_make_request(struct mddev *mddev, struct bio * bio) if (mp_bh->path < 0) { bio_io_error(bio); mempool_free(mp_bh, conf->pool); - return; + return true; } multipath = conf->multipaths + mp_bh->path; @@ -141,7 +141,7 @@ static void multipath_make_request(struct mddev *mddev, struct bio * bio) mddev_check_writesame(mddev, &mp_bh->bio); mddev_check_write_zeroes(mddev, &mp_bh->bio); generic_make_request(&mp_bh->bio); - return; + return true; } static void multipath_status(struct seq_file *seq, struct mddev *mddev) diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c index d6c0bc76e837..94d9ae9b0fd0 100644 --- a/drivers/md/raid0.c +++ b/drivers/md/raid0.c @@ -548,7 +548,7 @@ static void raid0_handle_discard(struct mddev *mddev, struct bio *bio) bio_endio(bio); } -static void raid0_make_request(struct mddev *mddev, struct bio *bio) +static bool raid0_make_request(struct mddev *mddev, struct bio *bio) { struct strip_zone *zone; struct md_rdev *tmp_dev; @@ -559,12 +559,12 @@ static void raid0_make_request(struct mddev *mddev, struct bio *bio) if (unlikely(bio->bi_opf & REQ_PREFLUSH)) { md_flush_request(mddev, bio); - return; + return true; } if (unlikely((bio_op(bio) == REQ_OP_DISCARD))) { raid0_handle_discard(mddev, bio); - return; + return true; } bio_sector = bio->bi_iter.bi_sector; @@ -599,6 +599,7 @@ static void raid0_make_request(struct mddev *mddev, struct bio *bio) mddev_check_writesame(mddev, bio); mddev_check_write_zeroes(mddev, bio); generic_make_request(bio); + return true; } static void raid0_status(struct seq_file *seq, struct mddev *mddev) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index e1a7e3d4c5e4..c71739b87ab7 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -1321,7 +1321,6 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, * Continue immediately if no resync is active currently. */ - md_write_start(mddev, bio); /* wait on superblock update early */ if ((bio_end_sector(bio) > mddev->suspend_lo && bio->bi_iter.bi_sector < mddev->suspend_hi) || @@ -1550,13 +1549,13 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, wake_up(&conf->wait_barrier); } -static void raid1_make_request(struct mddev *mddev, struct bio *bio) +static bool raid1_make_request(struct mddev *mddev, struct bio *bio) { sector_t sectors; if (unlikely(bio->bi_opf & REQ_PREFLUSH)) { md_flush_request(mddev, bio); - return; + return true; } /* @@ -1571,8 +1570,12 @@ static void raid1_make_request(struct mddev *mddev, struct bio *bio) if (bio_data_dir(bio) == READ) raid1_read_request(mddev, bio, sectors, NULL); - else + else { + if (!md_write_start(mddev,bio)) + return false; raid1_write_request(mddev, bio, sectors); + } + return true; } static void raid1_status(struct seq_file *seq, struct mddev *mddev) diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 797ed60abd5e..52acffa7a06a 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -1303,8 +1303,6 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio, sector_t sectors; int max_sectors; - md_write_start(mddev, bio); - /* * Register the new request and wait if the reconstruction * thread has put up a bar for new requests. @@ -1525,7 +1523,7 @@ static void __make_request(struct mddev *mddev, struct bio *bio, int sectors) raid10_write_request(mddev, bio, r10_bio); } -static void raid10_make_request(struct mddev *mddev, struct bio *bio) +static bool raid10_make_request(struct mddev *mddev, struct bio *bio) { struct r10conf *conf = mddev->private; sector_t chunk_mask = (conf->geo.chunk_mask & conf->prev.chunk_mask); @@ -1534,9 +1532,12 @@ static void raid10_make_request(struct mddev *mddev, struct bio *bio) if (unlikely(bio->bi_opf & REQ_PREFLUSH)) { md_flush_request(mddev, bio); - return; + return true; } + if (!md_write_start(mddev, bio)) + return false; + /* * If this request crosses a chunk boundary, we need to split * it. @@ -1553,6 +1554,7 @@ static void raid10_make_request(struct mddev *mddev, struct bio *bio) /* In case raid10d snuck in to freeze_array */ wake_up(&conf->wait_barrier); + return true; } static void raid10_status(struct seq_file *seq, struct mddev *mddev) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index ec0f951ae19f..b218a42fd702 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -5479,7 +5479,6 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi) last_sector = bi->bi_iter.bi_sector + (bi->bi_iter.bi_size>>9); bi->bi_next = NULL; - md_write_start(mddev, bi); stripe_sectors = conf->chunk_sectors * (conf->raid_disks - conf->max_degraded); @@ -5549,11 +5548,10 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi) release_stripe_plug(mddev, sh); } - md_write_end(mddev); bio_endio(bi); } -static void raid5_make_request(struct mddev *mddev, struct bio * bi) +static bool raid5_make_request(struct mddev *mddev, struct bio * bi) { struct r5conf *conf = mddev->private; int dd_idx; @@ -5569,10 +5567,10 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi) int ret = r5l_handle_flush_request(conf->log, bi); if (ret == 0) - return; + return true; if (ret == -ENODEV) { md_flush_request(mddev, bi); - return; + return true; } /* ret == -EAGAIN, fallback */ /* @@ -5582,6 +5580,8 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi) do_flush = bi->bi_opf & REQ_PREFLUSH; } + if (!md_write_start(mddev, bi)) + return false; /* * If array is degraded, better not do chunk aligned read because * later we might have to read it again in order to reconstruct @@ -5591,18 +5591,18 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi) mddev->reshape_position == MaxSector) { bi = chunk_aligned_read(mddev, bi); if (!bi) - return; + return true; } if (unlikely(bio_op(bi) == REQ_OP_DISCARD)) { make_discard_request(mddev, bi); - return; + md_write_end(mddev); + return true; } logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1); last_sector = bio_end_sector(bi); bi->bi_next = NULL; - md_write_start(mddev, bi); prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE); for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) { @@ -5740,6 +5740,7 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi) if (rw == WRITE) md_write_end(mddev); bio_endio(bi); + return true; } static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);