On 9/25/17 2:44 PM, Richard Wareing wrote:
> - Reports realtime device free blocks in statfs calls if inheritance
> bit is set on the inode of directory. This is a bit more intuitive,
> especially for use-cases which are using a much larger device for
> the realtime device.
> - Add XFS_IS_REALTIME_MOUNT option to gate based on the existence of a
> realtime device on the mount, similar to the XFS_IS_REALTIME_INODE
> option.
Sorry for chiming in late.
So, this is a major change in behavior of statfs on xfs. How will the
user know this, where is it documented?
Also, if I read this right, does that mean that you get the magical
new statfs results if you stat a /directory/ with XFS_DIFLAG_RTINHERIT
set, but not if you stat a /file/ with XFS_DIFLAG_REALTIME set?
That seems quite confusing, but maybe I'm missing something obvious.
As for which filesystem is getting reported, would it be totally
bonkers to have an xfs-realtime f_type to make it 100% clear what's
being reported?
-Eric
> Signed-off-by: Richard Wareing <rwareing@xxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>
> ---
> Changes since v4:
> * None
>
> Changes since v3:
> * Fixed accounting bug, we are not required to substract m_alloc_set_aside
> as this is a data device only requirement.
> * Added XFS_IS_REALTIME_MOUNT macro based on learnings from CVE-2017-14340,
> now provides similar gating on the mount as XFS_IS_REALTIME_INODE does
> for the inode.
>
> Changes since v2:
> * Style updated per Christoph Hellwig's comment
> * Fixed bug: statp->f_bavail = statp->f_bfree
>
> fs/xfs/xfs_linux.h | 2 ++
> fs/xfs/xfs_super.c | 8 ++++++++
> 2 files changed, 10 insertions(+)
>
> diff --git a/fs/xfs/xfs_linux.h b/fs/xfs/xfs_linux.h
> index 044fb0e..fe46e71 100644
> --- a/fs/xfs/xfs_linux.h
> +++ b/fs/xfs/xfs_linux.h
> @@ -280,8 +280,10 @@ static inline __uint64_t howmany_64(__uint64_t x, __uint32_t y)
>
> #ifdef CONFIG_XFS_RT
> #define XFS_IS_REALTIME_INODE(ip) ((ip)->i_d.di_flags & XFS_DIFLAG_REALTIME)
> +#define XFS_IS_REALTIME_MOUNT(mp) ((mp)->m_rtdev_targp ? 1 : 0)
> #else
> #define XFS_IS_REALTIME_INODE(ip) (0)
> +#define XFS_IS_REALTIME_MOUNT(mp) (0)
> #endif
>
> #endif /* __XFS_LINUX__ */
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 455a575..6d33a5e 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -1136,6 +1136,14 @@ xfs_fs_statfs(
> ((mp->m_qflags & (XFS_PQUOTA_ACCT|XFS_PQUOTA_ENFD))) ==
> (XFS_PQUOTA_ACCT|XFS_PQUOTA_ENFD))
> xfs_qm_statvfs(ip, statp);
> +
> + if (XFS_IS_REALTIME_MOUNT(mp) &&
> + (ip->i_d.di_flags & XFS_DIFLAG_RTINHERIT)) {
> + statp->f_blocks = sbp->sb_rblocks;
> + statp->f_bavail = statp->f_bfree =
> + sbp->sb_frextents * sbp->sb_rextsize;
> + }
> +
> return 0;
> }
>
>
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