| Message ID | 20170404104144.9414-1-anand.jain@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Apr 04, 2017 at 06:41:44PM +0800, Anand Jain wrote: > blkdev_issue_flush() or the empty buffer with the flag REQ_PREFLUSH > will never return BIO_EOPNOTSUPP as of now, however it should rather > or it may in future. So for now the BTRFS to have least affected by > this change at the blk layer, we can check if the device is flush > capable. > > In this process, I rename the unused nobarrier member as flushable, > which the below patch made it redundant. > > Per commit b25de9d6da49b1a8760a89672283128aa8c78345 > block: remove BIO_EOPNOTSUPP > > Signed-off-by: Anand Jain <anand.jain@oracle.com> So up to now, dev->nobarriers was always 0 and thus write_dev_flush always sent down the empty bio with PREFLUSH. Depending on the actual device flush capabilities, it either kept the flush bit or removed it in the generic_make_request_checks, and then proceeded to generic_make_request. In short, we always sent the flush bio. What your patch changes is that this will happen only for devices that have the flush capability, determined by the queue bit. This change does not seem to contradict the commit 387125fc722a8ed432066b85a552917343bdafca that brought the dev->nobarriers, so regarding metadata ordering and superblock flushes, all seem ok. But this could use some doublechecking. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 3c476b118440..6c15f5685d25 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3517,7 +3517,7 @@ static void btrfs_dev_issue_flush(struct work_struct *work) */ static int write_dev_flush(struct btrfs_device *device, int wait) { - if (device->nobarriers) + if (!device->flushable) return 0; if (wait) { diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 4de5b2d549bd..3c5142d66260 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1010,6 +1010,8 @@ static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices, device->can_discard = 1; if (!blk_queue_nonrot(q)) fs_devices->rotating = 1; + if (test_bit(QUEUE_FLAG_WC, &q->queue_flags)) + device->flushable = true; device->bdev = bdev; device->in_fs_metadata = 0; @@ -2377,6 +2379,8 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path q = bdev_get_queue(bdev); if (blk_queue_discard(q)) device->can_discard = 1; + if (test_bit(QUEUE_FLAG_WC, &q->queue_flags)) + device->flushable = true; device->writeable = 1; device->generation = trans->transid; device->io_width = fs_info->sectorsize; @@ -2580,6 +2584,8 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info, q = bdev_get_queue(bdev); if (blk_queue_discard(q)) device->can_discard = 1; + if (test_bit(QUEUE_FLAG_WC, &q->queue_flags)) + device->flushable = true; mutex_lock(&fs_info->fs_devices->device_list_mutex); device->writeable = 1; device->generation = 0; diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index 0df50bc65578..bbaf5238b6ca 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -123,7 +123,7 @@ struct btrfs_device { struct list_head resized_list; /* for sending down flush barriers */ - int nobarriers; + bool flushable; struct completion flush_wait; struct work_struct flush_work; int last_flush_error;
blkdev_issue_flush() or the empty buffer with the flag REQ_PREFLUSH will never return BIO_EOPNOTSUPP as of now, however it should rather or it may in future. So for now the BTRFS to have least affected by this change at the blk layer, we can check if the device is flush capable. In this process, I rename the unused nobarrier member as flushable, which the below patch made it redundant. Per commit b25de9d6da49b1a8760a89672283128aa8c78345 block: remove BIO_EOPNOTSUPP Signed-off-by: Anand Jain <anand.jain@oracle.com> --- v1: This patch will replace [PATCH] btrfs: delete unused member nobarriers fs/btrfs/disk-io.c | 2 +- fs/btrfs/volumes.c | 6 ++++++ fs/btrfs/volumes.h | 2 +- 3 files changed, 8 insertions(+), 2 deletions(-)