linux-kernel - [PATCH -next 6/7] ext4: simply the mapping query logic in ext4_iomap

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Message-ID: <20251213022008.1766912-7-yi.zhang@huaweicloud.com>
Date: Sat, 13 Dec 2025 10:20:07 +0800
From: Zhang Yi <yi.zhang@...weicloud.com>
To: linux-ext4@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	tytso@....edu,
	adilger.kernel@...ger.ca,
	jack@...e.cz,
	ojaswin@...ux.ibm.com,
	ritesh.list@...il.com,
	yi.zhang@...wei.com,
	yi.zhang@...weicloud.com,
	yizhang089@...il.com,
	libaokun1@...wei.com,
	yangerkun@...wei.com,
	yukuai@...as.com
Subject: [PATCH -next 6/7] ext4: simply the mapping query logic in ext4_iomap_begin()

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

In the write path mapping check of ext4_iomap_begin(), the return value
'ret' should never greater than orig_mlen. If 'ret' equals 'orig_mlen',
it can be returned directly without checking IOMAP_ATOMIC.

Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
---
 fs/ext4/inode.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 88144e2ce3e2..39348ee46e5c 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3815,15 +3815,15 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 		 */
 		if (offset + length <= i_size_read(inode)) {
 			ret = ext4_map_blocks(NULL, inode, &map, 0);
-			/*
-			 * For atomic writes the entire requested length should
-			 * be mapped.
-			 */
 			if ((map.m_flags & EXT4_MAP_MAPPED) ||
 			    (!(flags & IOMAP_DAX) &&
 			     (map.m_flags & EXT4_MAP_UNWRITTEN))) {
-				if ((!(flags & IOMAP_ATOMIC) && ret > 0) ||
-				   (flags & IOMAP_ATOMIC && ret >= orig_mlen))
+				/*
+				 * For atomic writes the entire requested
+				 * length should be mapped.
+				 */
+				if (ret == orig_mlen ||
+				    (!(flags & IOMAP_ATOMIC) && ret > 0))
 					goto out;
 			}
 			map.m_len = orig_mlen;
-- 
2.46.1