linux-ext4 - [RFC PATCH 01/16] ext4: correct the start block of counting reserved clusters

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Date:   Thu, 24 Aug 2023 17:26:04 +0800
From:   Zhang Yi <yi.zhang@...weicloud.com>
To:     linux-ext4@...r.kernel.org
Cc:     tytso@....edu, adilger.kernel@...ger.ca, jack@...e.cz,
        yi.zhang@...wei.com, yi.zhang@...weicloud.com,
        chengzhihao1@...wei.com, yukuai3@...wei.com
Subject: [RFC PATCH 01/16] ext4: correct the start block of counting reserved clusters

From: Zhang Yi <yi.zhang@...wei.com>

When big allocate feature is enabled, we need to count and update
reserved clusters before removing a delayed only extent_status entry.
{init|count|get}_rsvd() have already done this, but the start block
number of this counting isn's correct in the following case.

  lblk            end
   |               |
   v               v
          -------------------------
          |                       | orig_es
          -------------------------
                   ^              ^
      len1 is 0    |     len2     |

If the start block of the orig_es entry founded is bigger than lblk, we
passed lblk as start block to count_rsvd(), but the length is correct,
finally, the range to be counted is offset. This patch fix this by
passing the start blocks to 'orig_es->lblk + len1'.

Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
---
 fs/ext4/extents_status.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index 6f7de14c0fa8..5e625ea4545d 100644
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -1405,8 +1405,8 @@ static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
 			}
 		}
 		if (count_reserved)
-			count_rsvd(inode, lblk, orig_es.es_len - len1 - len2,
-				   &orig_es, &rc);
+			count_rsvd(inode, orig_es.es_lblk + len1,
+				   orig_es.es_len - len1 - len2, &orig_es, &rc);
 		goto out_get_reserved;
 	}
 
-- 
2.39.2