btrfs: Add raid56 support for updating

 num_tolerated_disk_barrier_failures in btrfs_balance

Code for updating fs_info->num_tolerated_disk_barrier_failures in
btrfs_balance() lacks raid56 support.

Reason:
 Above code was wroten in 2012-08-01, together with
 btrfs_calc_num_tolerated_disk_barrier_failures()'s first version.

 Then, btrfs_calc_num_tolerated_disk_barrier_failures() got updated
 later to support raid56, but code in btrfs_balance() was not
 updated together.

Fix:
 Merge above similar code to a common function:
 btrfs_get_num_tolerated_disk_barrier_failures()
 and make it support both case.

 It can fix this bug with a bonus of cleanup, and make these code
 never in above no-sync state from now on.

Suggested-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 25 insertions, 22 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 51192d94c90c..0b658d0230f0 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3440,6 +3440,26 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
 	return 0;
 }
 
+int btrfs_get_num_tolerated_disk_barrier_failures(u64 flags)
+{
+	if ((flags & (BTRFS_BLOCK_GROUP_DUP |
+		      BTRFS_BLOCK_GROUP_RAID0 |
+		      BTRFS_AVAIL_ALLOC_BIT_SINGLE)) ||
+	    ((flags & BTRFS_BLOCK_GROUP_PROFILE_MASK) == 0))
+		return 0;
+
+	if (flags & (BTRFS_BLOCK_GROUP_RAID1 |
+		     BTRFS_BLOCK_GROUP_RAID5 |
+		     BTRFS_BLOCK_GROUP_RAID10))
+		return 1;
+
+	if (flags & BTRFS_BLOCK_GROUP_RAID6)
+		return 2;
+
+	pr_warn("BTRFS: unknown raid type: %llu\n", flags);
+	return 0;
+}
+
 int btrfs_calc_num_tolerated_disk_barrier_failures(
 	struct btrfs_fs_info *fs_info)
 {
@@ -3482,28 +3502,11 @@ int btrfs_calc_num_tolerated_disk_barrier_failures(
 			if (space.total_bytes == 0 || space.used_bytes == 0)
 				continue;
 			flags = space.flags;
-			/*
-			 * return
-			 * 0: if dup, single or RAID0 is configured for
-			 *    any of metadata, system or data, else
-			 * 1: if RAID5 is configured, or if RAID1 or
-			 *    RAID10 is configured and only two mirrors
-			 *    are used, else
-			 * 2: if RAID6 is configured
-			 */
-			if (num_tolerated_disk_barrier_failures > 0 &&
-			    ((flags & (BTRFS_BLOCK_GROUP_DUP |
-				       BTRFS_BLOCK_GROUP_RAID0)) ||
-			     ((flags & BTRFS_BLOCK_GROUP_PROFILE_MASK) == 0)))
-				num_tolerated_disk_barrier_failures = 0;
-			else if (num_tolerated_disk_barrier_failures > 1 &&
-				 (flags & (BTRFS_BLOCK_GROUP_RAID1 |
-					   BTRFS_BLOCK_GROUP_RAID5 |
-					   BTRFS_BLOCK_GROUP_RAID10)))
-				num_tolerated_disk_barrier_failures = 1;
-			else if (num_tolerated_disk_barrier_failures > 2 &&
-				 (flags & BTRFS_BLOCK_GROUP_RAID6))
-				num_tolerated_disk_barrier_failures = 2;
+
+			num_tolerated_disk_barrier_failures = min(
+				num_tolerated_disk_barrier_failures,
+				btrfs_get_num_tolerated_disk_barrier_failures(
+					flags));
 		}
 		up_read(&sinfo->groups_sem);
 	}