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| author | brookxu <brookxu.cn@gmail.com> | 2020-08-07 17:01:39 +0300 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2020-08-18 21:18:36 +0300 |
| commit | dddcd2f9ebdeca9fbd36526e950bbcd0f7c1765f (patch) | |
| tree | e6b9c9d5f175906fcf8510e3aa8c09d917e4f2f5 /fs | |
| parent | 051e2ce8cb90592c8acdc7056ffed966310d91b4 (diff) | |
| download | linux-dddcd2f9ebdeca9fbd36526e950bbcd0f7c1765f.tar.xz | |
ext4: optimize the implementation of ext4_mb_good_group()
It might be better to adjust the code in two places:
1. Determine whether grp is currupt or not should be placed first.
2. (cr<=2 && free <ac->ac_g_ex.fe_len)should may belong to the crx
strategy, and it may be more appropriate to put it in the
subsequent switch statement block. For cr1, cr2, the conditions
in switch potentially realize the above judgment. For cr0, we
should add (free <ac->ac_g_ex.fe_len) judgment, and then delete
(free / fragments) >= ac->ac_g_ex.fe_len), because cr0 returns
true by default.
Signed-off-by: Chunguang Xu <brookxu@tencent.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/e20b2d8f-1154-adb7-3831-a9e11ba842e9@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ext4/mballoc.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 63ffd0057471..f68730eec205 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2112,13 +2112,11 @@ static bool ext4_mb_good_group(struct ext4_allocation_context *ac, BUG_ON(cr < 0 || cr >= 4); - free = grp->bb_free; - if (free == 0) - return false; - if (cr <= 2 && free < ac->ac_g_ex.fe_len) + if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(grp))) return false; - if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(grp))) + free = grp->bb_free; + if (free == 0) return false; fragments = grp->bb_fragments; @@ -2135,8 +2133,10 @@ static bool ext4_mb_good_group(struct ext4_allocation_context *ac, ((group % flex_size) == 0)) return false; - if ((ac->ac_2order > ac->ac_sb->s_blocksize_bits+1) || - (free / fragments) >= ac->ac_g_ex.fe_len) + if (free < ac->ac_g_ex.fe_len) + return false; + + if (ac->ac_2order > ac->ac_sb->s_blocksize_bits+1) return true; if (grp->bb_largest_free_order < ac->ac_2order) |