[PATCH] ext4: return -EINVAL on hole in ext4_convert_unwritten_extents_atomic()

[Ojaswin Mujoo <ojaswin@linux.ibm.com>]

We should ideally never encounter a hole during the endio conversion as
that indicates something is wrong with our extent handling. Still if we do
find a hole at atomic write endio, ext4_map_blocks() returns 0 which would
be returned back to callers by ext4_convert_unwritten_extents_atomic().
This can be wrongly interpreted as a success. Fix this by bailing out with
-EINVAL instead.

Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
---
 fs/ext4/extents.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 7193429a05e1..b54d8227786b 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -5107,6 +5107,14 @@ int ext4_convert_unwritten_extents_atomic(handle_t *handle, struct inode *inode,
 		map.m_lblk += ret;
 		map.m_len = (max_blocks -= ret);
 		ret = ext4_map_blocks(handle, inode, &map, flags);
+		if (ret == 0) {
+			ext4_msg(inode->i_sb, KERN_ERR,
+				 "inode #%llu: block %u: len %u: "
+				 "hole found while converting extents for atomic write",
+				 inode->i_ino, map.m_lblk, map.m_len);
+			ret = -EINVAL;
+			break;
+		}
 		if (ret != max_blocks)
 			ext4_msg(inode->i_sb, KERN_INFO,
 				     "inode #%llu: block %u: len %u: "

---
base-commit: 8c4f6e3376348fc3162eed86a05b933921c8f9ed
change-id: 20261023-ext4-atomic-endio-fix-b4-9e1ead9e1aca

Best regards,
-- 
Ojaswin Mujoo <ojaswin@linux.ibm.com>