linux-ext4 - [PATCH] ext4: Enable meta_bg only when new desc blocks are needed

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Date: Tue, 27 Feb 2024 13:13:29 +0000
From: Srivathsa Dara <srivathsa.d.dara@...cle.com>
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu, adilger.kernel@...ger.ca,
        rajesh.sivaramasubramaniom@...cle.com, junxiao.bi@...cle.com
Subject: [PATCH] ext4: Enable meta_bg only when new desc blocks are needed

This patch addresses an issue observed when resize_inode is disabled
and an online extension of a filesysyem is performed. When a filesystem
is expanded to a size that does not require a addition of a new
descriptor block, the meta_bg feature is being enabled even though no
part of the filesystem uses this layout.

This patch ensures that the meta_bg feature is only enabled if
any of the added block groups utilize meta_bg layout.

Signed-off-by: Srivathsa Dara <srivathsa.d.dara@...cle.com>
---
 fs/ext4/resize.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 928700d57eb6..99b52f26e818 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -1996,7 +1996,7 @@ int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
 		}
 	}

-	if ((!resize_inode && !meta_bg) || n_blocks_count == o_blocks_count) {
+	if ((!resize_inode && !meta_bg && n_desc_blocks > o_desc_blocks) || n_blocks_count == o_blocks_count) {
 		err = ext4_convert_meta_bg(sb, resize_inode);
 		if (err)
 			goto out;
-- 
2.39.3