[PATCH 3/4] xfs: use IOCB_DONTCACHE when falling back to buffered writes

Christoph Hellwig
2025-10-29T07:15:57Z

Doing sub-block direct writes to COW inodes is not supported by XFS,
because new blocks need to be allocated as a whole. Such writes
fall back to buffered I/O, and really should be using the
IOCB_DONTCACHE that didn't exist when the code was added to mimic
direct I/O semantics as closely as possible. Also clear the
IOCB_DIRECT flags so that later code can't get confused by it being
set for something that at this point is not a direct I/O operation
any more.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/xfs/xfs_file.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 5703b6681b1d..e09ae86e118e 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1119,6 +1119,9 @@ xfs_file_write_iter(
ret = xfs_file_dio_write(iocb, from);
if (ret != -ENOTBLK)
return ret;
+
+ iocb->ki_flags &= ~IOCB_DIRECT;
+ iocb->ki_flags |= IOCB_DONTCACHE;
}

if (xfs_is_zoned_inode(ip))
--
2.47.3