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authorNeilBrown <neilb@suse.com>2017-06-05 09:49:39 +0300
committerShaohua Li <shli@fb.com>2017-06-13 20:18:01 +0300
commitcc27b0c78c79680d128dbac79de0d40556d041bb (patch)
tree1f32d4acd29d825eecc1aef90d423cdacea8121c /drivers/md/md.h
parent63f700aab4c11d46626de3cd051dae56cf7e9056 (diff)
downloadlinux-cc27b0c78c79680d128dbac79de0d40556d041bb.tar.xz
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@esperi.org.uk> Fix: 68866e425be2(MD: no sync IO while suspended) Cc: stable@vger.kernel.org Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Shaohua Li <shli@fb.com>
Diffstat (limited to 'drivers/md/md.h')
-rw-r--r--drivers/md/md.h4
1 files changed, 2 insertions, 2 deletions
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);