[PATCH 2/6] ext4: Check for atomic writes support in write iter

["Ritesh Harjani (IBM)" <ritesh.list@xxxxxxxxx>]

Let's validate using generic_atomic_write_valid() in
ext4_file_write_iter() if the write request has IOCB_ATOMIC set.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
---
 fs/ext4/file.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index f14aed14b9cf..b06c5d34bbd2 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -692,6 +692,20 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (IS_DAX(inode))
 		return ext4_dax_write_iter(iocb, from);
 #endif
+
+	if (iocb->ki_flags & IOCB_ATOMIC) {
+		size_t len = iov_iter_count(from);
+		int ret;
+
+		if (!IS_ALIGNED(len, EXT4_SB(inode->i_sb)->fs_awu_min) ||
+			len > EXT4_SB(inode->i_sb)->fs_awu_max)
+			return -EINVAL;
+
+		ret = generic_atomic_write_valid(iocb, from);
+		if (ret)
+			return ret;
+	}
+
 	if (iocb->ki_flags & IOCB_DIRECT)
 		return ext4_dio_write_iter(iocb, from);
 	else
-- 
2.46.0