Viewing: ext4-mballoc-skip-uninit-groups-cr0.patch
commit ecb68b84807e5165dd8c513023b3d2a6ddadf5ad
Author: Alex Zhuravlev <bzzz@whamcloud.com>
AuthorDate: Mon Feb 24 06:57:24 2020 +0300
LU-13291 ldiskfs: mballoc don't skip uninit-on-disk groups
as those need no IO to initialize buddy structures and the best
candidates for new blocks.
Fixes: 6a7a700a1490 ("LU-12988 ldiskfs: skip non-loaded groups at cr=0/1")
Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Wang Shilong <wshilong@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Change-Id: Ic3c5a238d8825024d7a0fec6a25e842b7ba1f100
Reviewed-on: https://review.whamcloud.com/37687
Index: kernel-4.18.0-423.el8/fs/ext4/mballoc.c
===================================================================
--- kernel-4.18.0-423.el8.orig/fs/ext4/mballoc.c
+++ kernel-4.18.0-423.el8/fs/ext4/mballoc.c
@@ -1958,6 +1958,21 @@ int ext4_mb_find_by_goal(struct ext4_all
return 0;
}
+static inline int ext4_mb_uninit_on_disk(struct super_block *sb,
+ ext4_group_t group)
+{
+ struct ext4_group_desc *desc;
+
+ if (!ext4_has_group_desc_csum(sb))
+ return 0;
+
+ desc = ext4_get_group_desc(sb, group, NULL);
+ if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))
+ return 1;
+
+ return 0;
+}
+
/*
* The routine scans buddy structures (not bitmap!) from given order
* to max order and tries to find big enough chunk to satisfy the req
@@ -2196,6 +2211,12 @@ static int ext4_mb_good_group_nolock(str
/* We only do this if the grp has never been initialized */
if (unlikely(EXT4_MB_GRP_NEED_INIT(grp))) {
+ /* cr=0/1 is a very optimistic search to find large
+ * good chunks almost for free. if buddy data is
+ * not ready, then this optimization makes no sense */
+
+ if (cr < 2 && !ext4_mb_uninit_on_disk(ac->ac_sb, group))
+ return 0;
ret = ext4_mb_init_group(ac->ac_sb, group, GFP_NOFS);
if (ret)
return ret;
