Re: [PATCH 4/5] btrfs: Allow barrier_all_devices to do per-chunk device check

[Anand Jain <anand.jain@oracle.com>]

Qu,

  We shouldn't mark FS readonly when chunks are degradable.
  As below.

Thanks, Anand


diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 39a2d57..dbb2483 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3530,7 +3530,7 @@ static int write_all_supers(struct btrfs_root 
*root, int max_mirrors)

         if (do_barriers) {
                 ret = barrier_all_devices(root->fs_info);
-               if (ret) {
+               if (ret < 0) {
                         mutex_unlock(
 
&root->fs_info->fs_devices->device_list_mutex);
                         btrfs_std_error(root->fs_info, ret,




On 09/21/2015 10:10 AM, Qu Wenruo wrote:
> The last user of num_tolerated_disk_barrier_failures is
> barrier_all_devices().
> But it's can be easily changed to new per-chunk degradable check
> framework.
>
> Now btrfs_device will have two extra members, representing send/wait
> error, set at write_dev_flush() time.
> And then check it in a similar but more accurate behavior than old code.
>
> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
> ---
>   fs/btrfs/disk-io.c | 13 +++++--------
>   fs/btrfs/volumes.c |  6 +++++-
>   fs/btrfs/volumes.h |  4 ++++
>   3 files changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index d64299f..7cd94e7 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -3400,8 +3400,6 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
>   {
>   	struct list_head *head;
>   	struct btrfs_device *dev;
> -	int errors_send = 0;
> -	int errors_wait = 0;
>   	int ret;
>
>   	/* send down all the barriers */
> @@ -3410,7 +3408,7 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
>   		if (dev->missing)
>   			continue;
>   		if (!dev->bdev) {
> -			errors_send++;
> +			dev->err_send = 1;
>   			continue;
>   		}
>   		if (!dev->in_fs_metadata || !dev->writeable)
> @@ -3418,7 +3416,7 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
>
>   		ret = write_dev_flush(dev, 0);
>   		if (ret)
> -			errors_send++;
> +			dev->err_send = 1;
>   	}
>
>   	/* wait for all the barriers */
> @@ -3426,7 +3424,7 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
>   		if (dev->missing)
>   			continue;
>   		if (!dev->bdev) {
> -			errors_wait++;
> +			dev->err_wait = 1;
>   			continue;
>   		}
>   		if (!dev->in_fs_metadata || !dev->writeable)
> @@ -3434,10 +3432,9 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
>
>   		ret = write_dev_flush(dev, 1);
>   		if (ret)
> -			errors_wait++;
> +			dev->err_wait = 1;
>   	}
> -	if (errors_send > info->num_tolerated_disk_barrier_failures ||
> -	    errors_wait > info->num_tolerated_disk_barrier_failures)
> +	if (btrfs_check_degradable(info, info->sb->s_flags) < 0)
>   		return -EIO;
>   	return 0;
>   }
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index f1ef215..88266fa 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -6945,8 +6945,12 @@ int btrfs_check_degradable(struct btrfs_fs_info *fs_info, unsigned flags)
>   			btrfs_get_num_tolerated_disk_barrier_failures(
>   					map->type);
>   		for (i = 0; i < map->num_stripes; i++) {
> -			if (map->stripes[i].dev->missing)
> +			if (map->stripes[i].dev->missing ||
> +			    map->stripes[i].dev->err_wait ||
> +			    map->stripes[i].dev->err_send)
>   				missing++;
> +			map->stripes[i].dev->err_wait = 0;
> +			map->stripes[i].dev->err_send = 0;
>   		}
>   		if (missing > max_tolerated) {
>   			ret = -EIO;
> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
> index fe758df..cd02556 100644
> --- a/fs/btrfs/volumes.h
> +++ b/fs/btrfs/volumes.h
> @@ -76,6 +76,10 @@ struct btrfs_device {
>   	int can_discard;
>   	int is_tgtdev_for_dev_replace;
>
> +	/* for barrier_all_devices() check */
> +	int err_send;
> +	int err_wait;
> +
>   #ifdef __BTRFS_NEED_DEVICE_DATA_ORDERED
>   	seqcount_t data_seqcount;
>   #endif
>