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ext4: simplify the mapping query logic in ext4_iomap_begin()

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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@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/20260105014522.1937690-7-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Zhang Yi
2026-01-05 09:45:21 +08:00
committed by Theodore Ts'o
parent 8bd1f257af
commit 5ca28af074
1 changed files with 9 additions and 7 deletions
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16
fs/ext4/inode.c
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@@ -3812,17 +3812,19 @@ 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. For DAX we convert extents to initialized
* ones before copying the data, otherwise we do it
* after I/O so there's no need to call into
* ext4_iomap_alloc().
* For DAX we convert extents to initialized ones before
* copying the data, otherwise we do it after I/O so
* there's no need to call into ext4_iomap_alloc().
*/
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;