linux-kernel - [PATCH v2 04/13] ext4: remove gdb backup copy for meta bg in setup_new_flex_group

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Message-Id: <20230826173735.4023594-5-shikemeng@huaweicloud.com>
Date:   Sun, 27 Aug 2023 01:37:26 +0800
From:   Kemeng Shi <shikemeng@...weicloud.com>
To:     tytso@....edu, adilger.kernel@...ger.ca,
        linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 04/13] ext4: remove gdb backup copy for meta bg in setup_new_flex_group_blocks

Wrong check of gdb backup in meta bg as following:
first_group is the first group of meta_bg which contains target group, so
target group is always >= first_group. We check if target group has gdb
backup by comparing first_group with [group + 1] and [group +
EXT4_DESC_PER_BLOCK(sb) - 1]. As group >= first_group, then [group + N] is
> first_group. So no copy of gdb backup in meta bg is done in
setup_new_flex_group_blocks.

No need to do gdb backup copy in meta bg from setup_new_flex_group_blocks
as we always copy updated gdb block to backups at end of
ext4_flex_group_add as following:

ext4_flex_group_add
  /* no gdb backup copy for meta bg any more */
  setup_new_flex_group_blocks

  /* update current group number */
  ext4_update_super
    sbi->s_groups_count += flex_gd->count;

  /*
   * if group in meta bg contains backup is added, the primary gdb block
   * of the meta bg will be copy to backup in new added group here.
   */
  for (; gdb_num <= gdb_num_end; gdb_num++)
    update_backups(...)

In summary, we can remove wrong gdb backup copy code in
setup_new_flex_group_blocks.

Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
Reviewed-by: Theodore Ts'o <tytso@....edu>
---
 fs/ext4/resize.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 9cb9ed968599..667381180b26 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -560,13 +560,8 @@ static int setup_new_flex_group_blocks(struct super_block *sb,
 		if (meta_bg == 0 && !ext4_bg_has_super(sb, group))
 			goto handle_itb;
 
-		if (meta_bg == 1) {
-			ext4_group_t first_group;
-			first_group = ext4_meta_bg_first_group(sb, group);
-			if (first_group != group + 1 &&
-			    first_group != group + EXT4_DESC_PER_BLOCK(sb) - 1)
-				goto handle_itb;
-		}
+		if (meta_bg == 1)
+			goto handle_itb;
 
 		block = start + ext4_bg_has_super(sb, group);
 		/* Copy all of the GDT blocks into the backup in this group */
-- 
2.30.0