ext4: replace CR_FAST macro with inline function for readability

Replace CR_FAST with ext4_mb_cr_expensive() inline function for better
readability. This function returns true if the criteria is one of the
expensive/slower ones where lots of disk IO/prefetching is acceptable.

No functional changes are intended in this patch.

Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230630085927.140137-1-ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 89d76d5..532b70f 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -176,9 +176,6 @@ enum criteria {
        EXT4_MB_NUM_CRS
 };
 
-/* criteria below which we use fast block scanning and avoid unnecessary IO */
-#define CR_FAST CR_GOAL_LEN_SLOW
-
 /*
  * Flags used in mballoc's allocation_context flags field.
  *
@@ -2924,6 +2921,10 @@ extern int ext4_trim_fs(struct super_block *, struct fstrim_range *);
 extern void ext4_process_freed_data(struct super_block *sb, tid_t commit_tid);
 extern void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block,
                       int len, int state);
+static inline bool ext4_mb_cr_expensive(enum criteria cr)
+{
+       return cr >= CR_GOAL_LEN_SLOW;
+}
 
 /* inode.c */
 void ext4_inode_csum_set(struct inode *inode, struct ext4_inode *raw,

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 1dc63e3..a2d7919 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2450,7 +2450,7 @@ void ext4_mb_complex_scan_group(struct ext4_allocation_context *ac,
                        break;
                }
 
-               if (ac->ac_criteria < CR_FAST) {
+               if (!ext4_mb_cr_expensive(ac->ac_criteria)) {
                        /*
                         * In CR_GOAL_LEN_FAST and CR_BEST_AVAIL_LEN, we are
                         * sure that this group will have a large enough
@@ -2634,7 +2634,12 @@ static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
        free = grp->bb_free;
        if (free == 0)
                goto out;
-       if (cr <= CR_FAST && free < ac->ac_g_ex.fe_len)
+       /*
+        * In all criterias except CR_ANY_FREE we try to avoid groups that
+        * can't possibly satisfy the full goal request due to insufficient
+        * free blocks.
+        */
+       if (cr < CR_ANY_FREE && free < ac->ac_g_ex.fe_len)
                goto out;
        if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(grp)))
                goto out;
@@ -2658,7 +2663,7 @@ static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
                 * sure we locate metadata blocks in the first block group in
                 * the flex_bg if possible.
                 */
-               if (cr < CR_FAST &&
+               if (!ext4_mb_cr_expensive(cr) &&
                    (!sbi->s_log_groups_per_flex ||
                     ((group & ((1 << sbi->s_log_groups_per_flex) - 1)) != 0)) &&
                    !(ext4_has_group_desc_csum(sb) &&
@@ -2852,7 +2857,7 @@ repeat:
                         * spend a lot of time loading imperfect groups
                         */
                        if ((prefetch_grp == group) &&
-                           (cr >= CR_FAST ||
+                           (ext4_mb_cr_expensive(cr) ||
                             prefetch_ios < sbi->s_mb_prefetch_limit)) {
                                nr = sbi->s_mb_prefetch;
                                if (ext4_has_feature_flex_bg(sb)) {