Commit 5ca28af0 authored by Zhang Yi's avatar Zhang Yi Committed by Theodore Ts'o
Browse files

ext4: simplify the mapping query logic in ext4_iomap_begin() 



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: default avatarZhang Yi <yi.zhang@huawei.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarBaokun Li <libaokun1@huawei.com>
Reviewed-by: default avatarOjaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/20260105014522.1937690-7-yi.zhang@huaweicloud.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 8bd1f257

fs/ext4/inode.c

+9 −7
Original line number Diff line number Diff line
@@ -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;