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>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index cc15514..51192d9 100644 (file)
--- 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);
        }