Re: [PATCH v2 4/4] ext4: Do not fallback to buffered-io for DIO atomic write

From: John Garry
Date: Tue Oct 29 2024 - 04:58:25 EST


On 27/10/2024 18:17, Ritesh Harjani (IBM) wrote:
iomap can return -ENOTBLK if pagecache invalidation fails.
Let's make sure if -ENOTBLK is ever returned for atomic
writes than we fail the write request (-EIO) instead of
fallback to buffered-io.

Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>

I am not sure if you plan on dropping this patch...

---
fs/ext4/file.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 8116bd78910b..22d31b4fdff3 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -576,8 +576,18 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
iomap_ops = &ext4_iomap_overwrite_ops;
ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops,
dio_flags, NULL, 0);
- if (ret == -ENOTBLK)
+ if (ret == -ENOTBLK) {
ret = 0;
+ /*
+ * iomap can return -ENOTBLK if pagecache invalidation fails.
+ * Let's make sure if -ENOTBLK is ever returned for atomic
+ * writes than we fail the write request instead of fallback
+ * to buffered-io.
+ */
+ if (iocb->ki_flags & IOCB_ATOMIC)
+ ret = -EIO;
+ }
+
if (extend) {
/*
* We always perform extending DIO write synchronously so by
--
2.46.0