On Aug 7, 2020, at 8:01 AM, brookxu <brookxu.cn@xxxxxxxxx> wrote: > > 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@xxxxxxxxxxx> This looks correct. Not quite as simple as moving a few lines around, but I think the logic is equivalent. Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx> > --- > 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 28a139f..4304113 100644 > --- a/fs/ext4/mballoc.c > +++ b/fs/ext4/mballoc.c > @@ -2119,13 +2119,11 @@ static bool ext4_mb_good_group(struct ext4_allocation_context *ac, > > BUG_ON(cr < 0 || cr >= 4); This could also potentially be removed and keep only "BUG()" in the default: case, though it would be good to print the value of "cr". > > - 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; > @@ -2142,8 +2140,10 @@ 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) > -- > 1.8.3.1 > Cheers, Andreas
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