ext4: subdivide EXT4_EXT_DATA_VALID1

When splitting an extent, if the EXT4_GET_BLOCKS_CONVERT flag is set and
it is necessary to split the target extent in the middle,
ext4_split_extent() first handles splitting the latter half of the
extent and passes the EXT4_EXT_DATA_VALID1 flag. This flag implies that
all blocks before the split point contain valid data; however, this
assumption is incorrect.

Therefore, subdivid EXT4_EXT_DATA_VALID1 into
EXT4_EXT_DATA_ENTIRE_VALID1 and EXT4_EXT_DATA_PARTIAL_VALID1, which
indicate that the first half of the extent is either entirely valid or
only partially valid, respectively. These two flags cannot be set
simultaneously.

This patch does not use EXT4_EXT_DATA_PARTIAL_VALID1, it only replaces
EXT4_EXT_DATA_VALID1 with EXT4_EXT_DATA_ENTIRE_VALID1 at the location
where it is set, no logical changes.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Cc: stable@kernel.org
Message-ID: <20251129103247.686136-2-yi.zhang@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 2cf5759ba68940c4413343c82062a275f9a644a6..8d5ca450aa5d23b5d27d4d5c496442f8dd2ca5cb 100644 (file)
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -43,8 +43,13 @@
 #define EXT4_EXT_MARK_UNWRIT1  0x2  /* mark first half unwritten */
 #define EXT4_EXT_MARK_UNWRIT2  0x4  /* mark second half unwritten */
 
-#define EXT4_EXT_DATA_VALID1   0x8  /* first half contains valid data */
-#define EXT4_EXT_DATA_VALID2   0x10 /* second half contains valid data */
+/* first half contains valid data */
+#define EXT4_EXT_DATA_ENTIRE_VALID1    0x8   /* has entirely valid data */
+#define EXT4_EXT_DATA_PARTIAL_VALID1   0x10  /* has partially valid data */
+#define EXT4_EXT_DATA_VALID1           (EXT4_EXT_DATA_ENTIRE_VALID1 | \
+                                        EXT4_EXT_DATA_PARTIAL_VALID1)
+
+#define EXT4_EXT_DATA_VALID2   0x20 /* second half contains valid data */
 
 static __le32 ext4_extent_block_csum(struct inode *inode,
                                     struct ext4_extent_header *eh)
@@ -3190,8 +3195,9 @@ static struct ext4_ext_path *ext4_split_extent_at(handle_t *handle,
        unsigned int ee_len, depth;
        int err = 0;
 
-       BUG_ON((split_flag & (EXT4_EXT_DATA_VALID1 | EXT4_EXT_DATA_VALID2)) ==
-              (EXT4_EXT_DATA_VALID1 | EXT4_EXT_DATA_VALID2));
+       BUG_ON((split_flag & EXT4_EXT_DATA_VALID1) == EXT4_EXT_DATA_VALID1);
+       BUG_ON((split_flag & EXT4_EXT_DATA_VALID1) &&
+              (split_flag & EXT4_EXT_DATA_VALID2));
 
        ext_debug(inode, "logical block %llu\n", (unsigned long long)split);
 
@@ -3373,7 +3379,7 @@ static struct ext4_ext_path *ext4_split_extent(handle_t *handle,
                        split_flag1 |= EXT4_EXT_MARK_UNWRIT1 |
                                       EXT4_EXT_MARK_UNWRIT2;
                if (split_flag & EXT4_EXT_DATA_VALID2)
-                       split_flag1 |= EXT4_EXT_DATA_VALID1;
+                       split_flag1 |= EXT4_EXT_DATA_ENTIRE_VALID1;
                path = ext4_split_extent_at(handle, inode, path,
                                map->m_lblk + map->m_len, split_flag1, flags1);
                if (IS_ERR(path))
@@ -3728,7 +3734,7 @@ static struct ext4_ext_path *ext4_split_convert_extents(handle_t *handle,
 
        /* Convert to unwritten */
        if (flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN) {
-               split_flag |= EXT4_EXT_DATA_VALID1;
+               split_flag |= EXT4_EXT_DATA_ENTIRE_VALID1;
        /* Convert to initialized */
        } else if (flags & EXT4_GET_BLOCKS_CONVERT) {
                /*