[PATCH v2 13/14] fs: xfs: Validate atomic writes

[John Garry <john.g.garry@oracle.com>]

Validate that an atomic write adheres to length/offset rules. Since we
require extent alignment for atomic writes, this effectively also enforces
that the BIO which iomap produces is aligned.

Signed-off-by: John Garry <john.g.garry@oracle.com>
---
 fs/xfs/xfs_file.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index d0bd9d5f596c..cecc5428fd7c 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -709,11 +709,20 @@ xfs_file_dio_write(
 	struct kiocb		*iocb,
 	struct iov_iter		*from)
 {
-	struct xfs_inode	*ip = XFS_I(file_inode(iocb->ki_filp));
+	struct inode		*inode = file_inode(iocb->ki_filp);
+	struct xfs_inode	*ip = XFS_I(inode);
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_buftarg      *target = xfs_inode_buftarg(ip);
 	size_t			count = iov_iter_count(from);
 
+	if (iocb->ki_flags & IOCB_ATOMIC) {
+		if (!generic_atomic_write_valid(iocb->ki_pos, from,
+			i_blocksize(inode),
+			XFS_FSB_TO_B(mp, xfs_get_extsz(ip)))) {
+			return -EINVAL;
+		}
+	}
+
 	/* direct I/O must be aligned to device logical sector size */
 	if ((iocb->ki_pos | count) & target->bt_logical_sectormask)
 		return -EINVAL;
-- 
2.31.1