On Sat, Aug 17, 2024 at 09:47:59AM +0000, John Garry wrote:
> 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.
>
> For an IOCB with IOCB_ATOMIC set to get as far as xfs_file_dio_write(),
> FMODE_CAN_ATOMIC_WRITE will need to be set for the file; for this,
> FORCEALIGN and also ATOMICWRITES flags would also need to be set for the
> inode.
>
> Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
> ---
> fs/xfs/xfs_file.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 4cdc54dc9686..9b6530a4eb4a 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -684,9 +684,20 @@ 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_buftarg *target = xfs_inode_buftarg(ip);
> size_t count = iov_iter_count(from);
> + struct xfs_mount *mp = ip->i_mount;
> +
> + if (iocb->ki_flags & IOCB_ATOMIC) {
> + if (count < i_blocksize(inode))
> + return -EINVAL;
> + if (count > XFS_FSB_TO_B(mp, ip->i_extsize))
> + return -EINVAL;
Here's also the place to check the dynamic things like dalign/swidth
alignment. Other than that, this looks good.
--D
> + if (!generic_atomic_write_valid(iocb, from))
> + return -EINVAL;
> + }
>
> /* direct I/O must be aligned to device logical sector size */
> if ((iocb->ki_pos | count) & target->bt_logical_sectormask)
> --
> 2.31.1
>
>
