Re: [PATCH] Btrfs: make filesystem read-only when submitting barrier fails

On Sat, 11 Aug 2012 10:36:17 +0800, Liu Bo wrote:

On 08/10/2012 09:38 PM, Stefan Behrens wrote:

[...]

quoted

+				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, else
+				 * num_mirrors - 1: if RAID1 or RAID10 is
+				 *                  configured and more than
+				 *                  2 mirrors are used.
+				 */
+				if (num_tolerated_disk_barrier_failures > 0 &&
+				    ((flags & (BTRFS_BLOCK_GROUP_DUP |
+					       BTRFS_BLOCK_GROUP_RAID0)) ||
+				     ((flags & BTRFS_BLOCK_GROUP_PROFILE_MASK)
+				      == 0)))

Good work.

We already have __get_block_group_index(), for dup, single, raid0 we can do the same thing like
this:
__get_block_group_index(flags) > 1

the only problem is to make the function public :)

Thanks for your comments Liu Bo. And good luck with Oracle (please
correct me if I misinterpreted your updated email address).

That's correct that "__get_block_group_index() > 1" would be a little
bit shorter way to evaluate the RAID flags. But the rest of the btrfs
code (except for btrfs_can_relocate()) also explicitly evaluates the
flags instead of using the array index that __get_block_group_index()
returns. It is just following the convention.

quoted

+					num_tolerated_disk_barrier_failures = 0;
+				else if (num_tolerated_disk_barrier_failures > 1
+					 &&
+					 (flags & (BTRFS_BLOCK_GROUP_RAID1 |
+						   BTRFS_BLOCK_GROUP_RAID10)))
+					num_tolerated_disk_barrier_failures = 1;
+			}

[...]

quoted

@@ -2807,6 +2812,26 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
 		}
 	}
 
+	if (bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT) {
+		int num_tolerated_disk_barrier_failures;
+		u64 target = bctl->sys.target;
+
+		num_tolerated_disk_barrier_failures =
+			btrfs_calc_num_tolerated_disk_barrier_failures(fs_info);
+		if (num_tolerated_disk_barrier_failures > 0 &&
+		    (target &
+		     (BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID0 |
+		      BTRFS_AVAIL_ALLOC_BIT_SINGLE)))

ditto.

Same as before + this time the code is working on the balance conversion
parameters where SINGLE is encoded in a different way.