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Date: Mon, 13 Apr 2020 09:01:38 -0700
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: ira.weiny@...el.com
Cc: linux-kernel@...r.kernel.org,
Dan Williams <dan.j.williams@...el.com>,
Dave Chinner <david@...morbit.com>,
Christoph Hellwig <hch@....de>,
"Theodore Y. Ts'o" <tytso@....edu>, Jan Kara <jack@...e.cz>,
Jeff Moyer <jmoyer@...hat.com>, linux-ext4@...r.kernel.org,
linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH V7 6/9] fs/xfs: Combine xfs_diflags_to_linux() and
xfs_diflags_to_iflags()
On Sun, Apr 12, 2020 at 10:40:43PM -0700, ira.weiny@...el.com wrote:
> From: Ira Weiny <ira.weiny@...el.com>
>
> The functionality in xfs_diflags_to_linux() and xfs_diflags_to_iflags() are
> nearly identical. The only difference is that *_to_linux() is called after
> inode setup and disallows changing the DAX flag.
>
> Combining them can be done with a flag which indicates if this is the initial
> setup to allow the DAX flag to be properly set only at init time.
>
> So remove xfs_diflags_to_linux() and call the modified xfs_diflags_to_iflags()
> directly.
>
> While we are here simplify xfs_diflags_to_iflags() to take struct xfs_inode and
> use xfs_ip2xflags() to ensure future diflags are included correctly.
>
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>
>
> ---
> Changes from V6:
> Move unrelated hunk to previous patch.
> Change logic for better code generation.
>
> Changes from V5:
> The functions are no longer identical so we can only combine
> them rather than deleting one completely. This is reflected in
> the new init parameter.
> ---
> fs/xfs/xfs_inode.h | 1 +
> fs/xfs/xfs_ioctl.c | 33 +--------------------------------
> fs/xfs/xfs_iops.c | 42 +++++++++++++++++++++++-------------------
> 3 files changed, 25 insertions(+), 51 deletions(-)
>
> diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
> index 492e53992fa9..e76ed9ca17f7 100644
> --- a/fs/xfs/xfs_inode.h
> +++ b/fs/xfs/xfs_inode.h
> @@ -466,6 +466,7 @@ int xfs_break_layouts(struct inode *inode, uint *iolock,
> /* from xfs_iops.c */
> extern void xfs_setup_inode(struct xfs_inode *ip);
> extern void xfs_setup_iops(struct xfs_inode *ip);
> +extern void xfs_diflags_to_iflags(struct xfs_inode *ip, bool init);
>
> /*
> * When setting up a newly allocated inode, we need to call
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index d42de92cb283..c6cd92ef4a05 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -1100,37 +1100,6 @@ xfs_flags2diflags2(
> return di_flags2;
> }
>
> -STATIC void
> -xfs_diflags_to_linux(
> - struct xfs_inode *ip)
> -{
> - struct inode *inode = VFS_I(ip);
> - unsigned int xflags = xfs_ip2xflags(ip);
> -
> - if (xflags & FS_XFLAG_IMMUTABLE)
> - inode->i_flags |= S_IMMUTABLE;
> - else
> - inode->i_flags &= ~S_IMMUTABLE;
> - if (xflags & FS_XFLAG_APPEND)
> - inode->i_flags |= S_APPEND;
> - else
> - inode->i_flags &= ~S_APPEND;
> - if (xflags & FS_XFLAG_SYNC)
> - inode->i_flags |= S_SYNC;
> - else
> - inode->i_flags &= ~S_SYNC;
> - if (xflags & FS_XFLAG_NOATIME)
> - inode->i_flags |= S_NOATIME;
> - else
> - inode->i_flags &= ~S_NOATIME;
> -#if 0 /* disabled until the flag switching races are sorted out */
> - if (xflags & FS_XFLAG_DAX)
> - inode->i_flags |= S_DAX;
> - else
> - inode->i_flags &= ~S_DAX;
> -#endif
> -}
> -
> static int
> xfs_ioctl_setattr_xflags(
> struct xfs_trans *tp,
> @@ -1168,7 +1137,7 @@ xfs_ioctl_setattr_xflags(
> ip->i_d.di_flags = xfs_flags2diflags(ip, fa->fsx_xflags);
> ip->i_d.di_flags2 = di_flags2;
>
> - xfs_diflags_to_linux(ip);
> + xfs_diflags_to_iflags(ip, false);
> xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);
> xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
> XFS_STATS_INC(mp, xs_ig_attrchg);
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index 37bd15b55878..856ad823e754 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -1284,26 +1284,30 @@ xfs_inode_enable_dax(
> #endif /* CONFIG_FS_DAX */
>
>
> -STATIC void
> +void
> xfs_diflags_to_iflags(
> - struct inode *inode,
> - struct xfs_inode *ip)
> + struct xfs_inode *ip,
> + bool init)
> {
> - uint16_t flags = ip->i_d.di_flags;
> -
> - inode->i_flags &= ~(S_IMMUTABLE | S_APPEND | S_SYNC |
> - S_NOATIME | S_DAX);
> -
> - if (flags & XFS_DIFLAG_IMMUTABLE)
> - inode->i_flags |= S_IMMUTABLE;
> - if (flags & XFS_DIFLAG_APPEND)
> - inode->i_flags |= S_APPEND;
> - if (flags & XFS_DIFLAG_SYNC)
> - inode->i_flags |= S_SYNC;
> - if (flags & XFS_DIFLAG_NOATIME)
> - inode->i_flags |= S_NOATIME;
> - if (xfs_inode_enable_dax(ip))
> - inode->i_flags |= S_DAX;
> + struct inode *inode = VFS_I(ip);
> + unsigned int xflags = xfs_ip2xflags(ip);
> + unsigned int flags = 0;
> +
> + ASSERT(!(IS_DAX(inode) && init));
> +
> + if (xflags & FS_XFLAG_IMMUTABLE)
> + flags |= S_IMMUTABLE;
> + if (xflags & FS_XFLAG_APPEND)
> + flags |= S_APPEND;
> + if (xflags & FS_XFLAG_SYNC)
> + flags |= S_SYNC;
> + if (xflags & FS_XFLAG_NOATIME)
> + flags |= S_NOATIME;
> + if (init && xfs_inode_enable_dax(ip))
> + flags |= S_DAX;
> +
> + inode->i_flags &= ~(S_IMMUTABLE | S_APPEND | S_SYNC | S_NOATIME);
I noticed that S_DAX drops out of the mask out operation here, which of
course resulted in an eyebrow-raise because the other four flags are
always set to whatever we just computed. :)
Then I realized that yes, this is intentional since we can't change
S_DAX on the fly, and that S_DAX is never set i_flags on an inode that's
being initialized so we don't need to mask off S_DAX ever.
Could we add a comment here to remind the reader that S_DAX is a bit
special?
/*
* S_DAX can only be set during inode initialization and is never set by
* the VFS, so we cannot mask off S_DAX in i_flags.
*/
With that added,
Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com>
--D
> + inode->i_flags |= flags;
> }
>
> /*
> @@ -1332,7 +1336,7 @@ xfs_setup_inode(
> inode->i_gid = xfs_gid_to_kgid(ip->i_d.di_gid);
>
> i_size_write(inode, ip->i_d.di_size);
> - xfs_diflags_to_iflags(inode, ip);
> + xfs_diflags_to_iflags(ip, true);
>
> if (S_ISDIR(inode->i_mode)) {
> /*
> --
> 2.25.1
>
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