From dddcd2f9ebdeca9fbd36526e950bbcd0f7c1765f Mon Sep 17 00:00:00 2001 From: brookxu Date: Fri, 7 Aug 2020 22:01:39 +0800 Subject: [PATCH] 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_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_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 Reviewed-by: Andreas Dilger Reviewed-by: Ritesh Harjani Link: https://lore.kernel.org/r/e20b2d8f-1154-adb7-3831-a9e11ba842e9@gmail.com Signed-off-by: Theodore Ts'o --- fs/ext4/mballoc.c | 14 +++++++------- 1 file 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)