On Wed, May 12, 2021 at 06:02:04PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@xxxxxxxxxx>
>
> Even though reflink and copy-on-write aren't supported on the realtime
> volume, if we ever turn that on, we'd still be constrained to the same
> rt extent alignment requirements because cow involves remapping, and
> we can only allocate and free in rtextsize units on the realtime volume.
>
> At the moment there aren't any filesystems with rt and reflink in the
> wild, so this is should be a zero-risk change.
>
> Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Self NAK; one cannot set a nonzero cowextsize hint on a non-reflink
filesystem, and outside of djwong-dev, reflink on realtime isn't
supported either. I guess I got too enthusiastic when I was
redistributing patches. :(
--D
> ---
> fs/xfs/libxfs/xfs_inode_buf.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
>
> diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
> index 25261dd73290..704faf806e46 100644
> --- a/fs/xfs/libxfs/xfs_inode_buf.c
> +++ b/fs/xfs/libxfs/xfs_inode_buf.c
> @@ -628,14 +628,21 @@ xfs_inode_validate_cowextsize(
> uint16_t flags,
> uint64_t flags2)
> {
> - bool rt_flag;
> + bool rt_flag, rtinherit_flag;
> bool hint_flag;
> uint32_t cowextsize_bytes;
> + uint32_t blocksize_bytes;
>
> rt_flag = (flags & XFS_DIFLAG_REALTIME);
> + rtinherit_flag = (flags & XFS_DIFLAG_RTINHERIT);
> hint_flag = (flags2 & XFS_DIFLAG2_COWEXTSIZE);
> cowextsize_bytes = XFS_FSB_TO_B(mp, cowextsize);
>
> + if (rt_flag || (rtinherit_flag && hint_flag))
> + blocksize_bytes = XFS_FSB_TO_B(mp, mp->m_sb.sb_rextsize);
> + else
> + blocksize_bytes = mp->m_sb.sb_blocksize;
> +
> if (hint_flag && !xfs_sb_version_hasreflink(&mp->m_sb))
> return __this_address;
>
> @@ -652,13 +659,13 @@ xfs_inode_validate_cowextsize(
> if (hint_flag && rt_flag)
> return __this_address;
>
> - if (cowextsize_bytes % mp->m_sb.sb_blocksize)
> + if (cowextsize_bytes % blocksize_bytes)
> return __this_address;
>
> if (cowextsize > MAXEXTLEN)
> return __this_address;
>
> - if (cowextsize > mp->m_sb.sb_agblocks / 2)
> + if (!rt_flag && cowextsize > mp->m_sb.sb_agblocks / 2)
> return __this_address;
>
> return NULL;
>
