diff options
| author | Boris Protopopov <[email protected]> | 2017-08-09 14:10:47 -0400 |
|---|---|---|
| committer | Brian Behlendorf <[email protected]> | 2017-08-09 11:10:47 -0700 |
| commit | 5146d802b4e371cab1d6db79bea482c056be7bf2 (patch) | |
| tree | 028280638f8fa27f3708553dba5d06e43a747c7e /module | |
| parent | 520faf5ddcb1a9536f53438963d1c96678040466 (diff) | |
zv_suspend_lock in zvol_open()/zvol_release()
Acquire zv_suspend_lock on first open and last close only.
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Boris Protopopov <[email protected]>
Closes #6342
Diffstat (limited to 'module')
| -rw-r--r-- | module/zfs/zvol.c | 64 |
1 files changed, 41 insertions, 23 deletions
diff --git a/module/zfs/zvol.c b/module/zfs/zvol.c index 254760220..40fdf0777 100644 --- a/module/zfs/zvol.c +++ b/module/zfs/zvol.c @@ -1304,9 +1304,9 @@ zvol_open(struct block_device *bdev, fmode_t flag) { zvol_state_t *zv; int error = 0; - boolean_t drop_suspend = B_FALSE; + boolean_t drop_suspend = B_TRUE; - ASSERT(!mutex_owned(&zvol_state_lock)); + ASSERT(!MUTEX_HELD(&zvol_state_lock)); mutex_enter(&zvol_state_lock); /* @@ -1321,23 +1321,31 @@ zvol_open(struct block_device *bdev, fmode_t flag) return (SET_ERROR(-ENXIO)); } - /* take zv_suspend_lock before zv_state_lock */ - rw_enter(&zv->zv_suspend_lock, RW_READER); - mutex_enter(&zv->zv_state_lock); - /* * make sure zvol is not suspended during first open - * (hold zv_suspend_lock), otherwise, drop the lock + * (hold zv_suspend_lock) and respect proper lock acquisition + * ordering - zv_suspend_lock before zv_state_lock */ if (zv->zv_open_count == 0) { - drop_suspend = B_TRUE; + if (!rw_tryenter(&zv->zv_suspend_lock, RW_READER)) { + mutex_exit(&zv->zv_state_lock); + rw_enter(&zv->zv_suspend_lock, RW_READER); + mutex_enter(&zv->zv_state_lock); + /* check to see if zv_suspend_lock is needed */ + if (zv->zv_open_count != 0) { + rw_exit(&zv->zv_suspend_lock); + drop_suspend = B_FALSE; + } + } } else { - rw_exit(&zv->zv_suspend_lock); + drop_suspend = B_FALSE; } - mutex_exit(&zvol_state_lock); + ASSERT(MUTEX_HELD(&zv->zv_state_lock)); + ASSERT(zv->zv_open_count != 0 || RW_READ_HELD(&zv->zv_suspend_lock)); + if (zv->zv_open_count == 0) { error = zvol_first_open(zv); if (error) @@ -1374,28 +1382,38 @@ static int zvol_release(struct gendisk *disk, fmode_t mode) { zvol_state_t *zv; - boolean_t drop_suspend = B_FALSE; + boolean_t drop_suspend = B_TRUE; - ASSERT(!mutex_owned(&zvol_state_lock)); + ASSERT(!MUTEX_HELD(&zvol_state_lock)); mutex_enter(&zvol_state_lock); zv = disk->private_data; - ASSERT(zv && zv->zv_open_count > 0); - - /* take zv_suspend_lock before zv_state_lock */ - rw_enter(&zv->zv_suspend_lock, RW_READER); mutex_enter(&zv->zv_state_lock); - mutex_exit(&zvol_state_lock); - + ASSERT(zv->zv_open_count > 0); /* * make sure zvol is not suspended during last close - * (hold zv_suspend_lock), otherwise, drop the lock + * (hold zv_suspend_lock) and respect proper lock acquisition + * ordering - zv_suspend_lock before zv_state_lock */ - if (zv->zv_open_count == 1) - drop_suspend = B_TRUE; - else - rw_exit(&zv->zv_suspend_lock); + if (zv->zv_open_count == 1) { + if (!rw_tryenter(&zv->zv_suspend_lock, RW_READER)) { + mutex_exit(&zv->zv_state_lock); + rw_enter(&zv->zv_suspend_lock, RW_READER); + mutex_enter(&zv->zv_state_lock); + /* check to see if zv_suspend_lock is needed */ + if (zv->zv_open_count != 1) { + rw_exit(&zv->zv_suspend_lock); + drop_suspend = B_FALSE; + } + } + } else { + drop_suspend = B_FALSE; + } + mutex_exit(&zvol_state_lock); + + ASSERT(MUTEX_HELD(&zv->zv_state_lock)); + ASSERT(zv->zv_open_count != 1 || RW_READ_HELD(&zv->zv_suspend_lock)); zv->zv_open_count--; if (zv->zv_open_count == 0) |