btrfs: Cleanup for btrfs_calc_num_tolerated_disk_barrier_failures

1: Use ARRAY_SIZE(types) to replace a static-value variant:
   int num_types = 4;

2: Use 'continue' on condition to reduce one level tab
   if (!XXX) {
       code;
       ...
   }
   ->
   if (XXX)
       continue;
   code;
   ...

3: Put setting 'num_tolerated_disk_barrier_failures = 2' to
   (num_tolerated_disk_barrier_failures > 2) condition to make
   make logic neat.
   if (num_tolerated_disk_barrier_failures > 0 && XXX)
       num_tolerated_disk_barrier_failures = 0;
   else if (num_tolerated_disk_barrier_failures > 1) {
       if (XXX)
           num_tolerated_disk_barrier_failures = 1;
       else if (XXX)
           num_tolerated_disk_barrier_failures = 2;
   ->
   if (num_tolerated_disk_barrier_failures > 0 && XXX)
       num_tolerated_disk_barrier_failures = 0;
   if (num_tolerated_disk_barrier_failures > 1 && XXX)
       num_tolerated_disk_barrier_failures = ;
   if (num_tolerated_disk_barrier_failures > 2 && XXX)
       num_tolerated_disk_barrier_failures = 2;

4: Remove comment of:
   num_mirrors - 1: if RAID1 or RAID10 is configured and more
   than 2 mirrors are used.
   which is not fit with code.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 33 insertions, 40 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index cc15514b4a76..51192d94c90c 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3449,13 +3449,12 @@ int btrfs_calc_num_tolerated_disk_barrier_failures(
                        BTRFS_BLOCK_GROUP_SYSTEM,
                        BTRFS_BLOCK_GROUP_METADATA,
                        BTRFS_BLOCK_GROUP_DATA | BTRFS_BLOCK_GROUP_METADATA};
-        int num_types = 4;
         int i;
         int c;
         int num_tolerated_disk_barrier_failures =
                 (int)fs_info->fs_devices->num_devices;
 
-        for (i = 0; i < num_types; i++) {
+        for (i = 0; i < ARRAY_SIZE(types); i++) {
                 struct btrfs_space_info *tmp;
 
                 sinfo = NULL;
@@ -3473,44 +3472,38 @@ int btrfs_calc_num_tolerated_disk_barrier_failures(
 
                 down_read(&sinfo->groups_sem);
                 for (c = 0; c < BTRFS_NR_RAID_TYPES; c++) {
-                        if (!list_empty(&sinfo->block_groups[c])) {
-                                u64 flags;
-
-                                btrfs_get_block_group_info(
-                                        &sinfo->block_groups[c], &space);
-                                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, 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)))
-                                        num_tolerated_disk_barrier_failures = 0;
-                                else if (num_tolerated_disk_barrier_failures > 1) {
-                                        if (flags & (BTRFS_BLOCK_GROUP_RAID1 |
-                                            BTRFS_BLOCK_GROUP_RAID5 |
-                                            BTRFS_BLOCK_GROUP_RAID10)) {
-                                                num_tolerated_disk_barrier_failures = 1;
-                                        } else if (flags &
-                                                   BTRFS_BLOCK_GROUP_RAID6) {
-                                                num_tolerated_disk_barrier_failures = 2;
-                                        }
-                                }
-                        }
+                        u64 flags;
+
+                        if (list_empty(&sinfo->block_groups[c]))
+                                continue;
+
+                        btrfs_get_block_group_info(&sinfo->block_groups[c],
+                                                   &space);
+                        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;
                 }
                 up_read(&sinfo->groups_sem);
         }