atomic writes is currently only supported for single fsblock and only for direct-io. We should not return -ENOTBLK for atomic writes since we want the atomic write request to either complete fully or fail otherwise. We should not fallback to buffered-io in case of DIO atomic write requests. Let's also catch if this ever happens by adding some WARN_ON_ONCE before buffered-io handling for direct-io atomic writes. More details of the discussion [1]. [1]: https://lore.kernel.org/linux-xfs/cover.1729825985.git.ritesh.list@xxxxxxxxx/T/#m9dbecc11bed713ed0d7a486432c56b105b555f04 Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx> --- fs/ext4/file.c | 7 +++++++ fs/ext4/inode.c | 14 +++++++++----- 2 files changed, 16 insertions(+), 5 deletions(-) diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 8116bd78910b..61787a37e9d4 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -599,6 +599,13 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from) ssize_t err; loff_t endbyte; + /* + * There is no support for atomic writes on buffered-io yet, + * we should never fallback to buffered-io for DIO atomic + * writes. + */ + WARN_ON_ONCE(iocb->ki_flags & IOCB_ATOMIC); + offset = iocb->ki_pos; err = ext4_buffered_write_iter(iocb, from); if (err < 0) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index fcdee27b9aa2..26b3c84d7f64 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3449,12 +3449,16 @@ static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length, { /* * Check to see whether an error occurred while writing out the data to - * the allocated blocks. If so, return the magic error code so that we - * fallback to buffered I/O and attempt to complete the remainder of - * the I/O. Any blocks that may have been allocated in preparation for - * the direct I/O will be reused during buffered I/O. + * the allocated blocks. If so, return the magic error code for + * non-atomic write so that we fallback to buffered I/O and attempt to + * complete the remainder of the I/O. + * For atomic writes we will simply fail the I/O request if we coudn't + * write anything. For non-atomic writes, any blocks that may have been + * allocated in preparation for the direct I/O will be reused during + * buffered I/O. */ - if (flags & (IOMAP_WRITE | IOMAP_DIRECT) && written == 0) + if (!(flags & IOMAP_ATOMIC) && (flags & (IOMAP_WRITE | IOMAP_DIRECT)) + && written == 0) return -ENOTBLK; return 0; -- 2.46.0
