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Re: [PATCH 3/9] xfs: factor out xfs_ioctl_setattr transaciton preamble

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH 3/9] xfs: factor out xfs_ioctl_setattr transaciton preamble
From: Brian Foster <bfoster@xxxxxxxxxx>
Date: Thu, 29 Jan 2015 10:34:36 -0500
Cc: xfs@xxxxxxxxxxx, iustin@xxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1422328486-24661-4-git-send-email-david@xxxxxxxxxxxxx>
References: <1422328486-24661-1-git-send-email-david@xxxxxxxxxxxxx> <1422328486-24661-4-git-send-email-david@xxxxxxxxxxxxx>
User-agent: Mutt/1.5.23 (2014-03-12)
On Tue, Jan 27, 2015 at 02:14:40PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
> 
> The setup of the transaction is done after a random smattering of
> checks and before another bunch of ioperations specific
> validity checks. Pull all the preamble out into a helper function
> that returns a transaction or error.
> 
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> ---
>  fs/xfs/xfs_ioctl.c | 96 
> +++++++++++++++++++++++++++++-------------------------
>  1 file changed, 51 insertions(+), 45 deletions(-)
> 
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index ba98412..d06f596 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -1042,7 +1042,6 @@ xfs_ioctl_setattr_xflags(
>           !capable(CAP_LINUX_IMMUTABLE))
>               return -EPERM;
>  
> -     xfs_trans_ijoin(tp, ip, 0);
>       xfs_set_diflags(ip, fa->fsx_xflags);
>       xfs_diflags_to_linux(ip);
>       xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);
> @@ -1051,6 +1050,54 @@ xfs_ioctl_setattr_xflags(
>       return 0;
>  }
>  
> +/*
> + * Set up the transaction structure for the setattr operation, checking that 
> we
> + * have permission to do so. On success, return a clean transaction and the
> + * inode locked exclusively ready for futher operation specific checks. On

                                        further

> + * failure, return an error without modifying or locking the inode.
> + */
> +static struct xfs_trans *
> +xfs_ioctl_setattr_get_trans(
> +     struct xfs_inode        *ip)
> +{
> +     struct xfs_mount        *mp = ip->i_mount;
> +     struct xfs_trans        *tp;
> +     int                     error;
> +
> +     if (mp->m_flags & XFS_MOUNT_RDONLY)
> +             return ERR_PTR(-EROFS);
> +     if (XFS_FORCED_SHUTDOWN(mp))
> +             return ERR_PTR(-EIO);
> +
> +     tp = xfs_trans_alloc(mp, XFS_TRANS_SETATTR_NOT_SIZE);
> +     error = xfs_trans_reserve(tp, &M_RES(mp)->tr_ichange, 0, 0);
> +     if (error)
> +             goto out_cancel;
> +
> +     xfs_ilock(ip, XFS_ILOCK_EXCL);
> +     xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
> +
> +     /*
> +      * CAP_FOWNER overrides the following restrictions:
> +      *
> +      * The user ID of the calling process must be equal to the file owner
> +      * ID, except in cases where the CAP_FSETID capability is applicable.
> +      */
> +     if (!inode_owner_or_capable(VFS_I(ip))) {
> +             error = -EPERM;
> +             goto out_cancel;
> +     }
> +
> +     if (mp->m_flags & XFS_MOUNT_WSYNC)
> +             xfs_trans_set_sync(tp);
> +
> +     return tp;
> +
> +out_cancel:
> +     xfs_trans_cancel(tp, 0);
> +     return ERR_PTR(error);
> +}
> +
>  #define FSX_PROJID   1
>  #define FSX_EXTSIZE  2
>  #define FSX_XFLAGS   4
> @@ -1063,7 +1110,6 @@ xfs_ioctl_setattr(
>  {
>       struct xfs_mount        *mp = ip->i_mount;
>       struct xfs_trans        *tp;
> -     unsigned int            lock_flags = 0;
>       struct xfs_dquot        *udqp = NULL;
>       struct xfs_dquot        *pdqp = NULL;
>       struct xfs_dquot        *olddquot = NULL;
> @@ -1071,11 +1117,6 @@ xfs_ioctl_setattr(
>  
>       trace_xfs_ioctl_setattr(ip);
>  
> -     if (mp->m_flags & XFS_MOUNT_RDONLY)
> -             return -EROFS;
> -     if (XFS_FORCED_SHUTDOWN(mp))
> -             return -EIO;
> -
>       /*
>        * Disallow 32bit project ids when projid32bit feature is not enabled.
>        */
> @@ -1099,29 +1140,9 @@ xfs_ioctl_setattr(
>                       return code;
>       }
>  
> -     /*
> -      * For the other attributes, we acquire the inode lock and
> -      * first do an error checking pass.
> -      */
> -     tp = xfs_trans_alloc(mp, XFS_TRANS_SETATTR_NOT_SIZE);
> -     code = xfs_trans_reserve(tp, &M_RES(mp)->tr_ichange, 0, 0);
> -     if (code)
> -             goto error_return;
> -
> -     lock_flags = XFS_ILOCK_EXCL;
> -     xfs_ilock(ip, lock_flags);
> -
> -     /*
> -      * CAP_FOWNER overrides the following restrictions:
> -      *
> -      * The user ID of the calling process must be equal
> -      * to the file owner ID, except in cases where the
> -      * CAP_FSETID capability is applicable.
> -      */
> -     if (!inode_owner_or_capable(VFS_I(ip))) {
> -             code = -EPERM;
> -             goto error_return;
> -     }
> +     tp = xfs_ioctl_setattr_get_trans(ip);
> +     if (IS_ERR(tp))
> +             return PTR_ERR(tp);
>   

We need to handle udqp and pdqp in this failure case. The rest looks Ok
to me.

Brian

>       /*
>        * Do a quota reservation only if projid is actually going to change.
> @@ -1244,20 +1265,7 @@ xfs_ioctl_setattr(
>               ip->i_d.di_extsize = extsize;
>       }
>  
> -     /*
> -      * If this is a synchronous mount, make sure that the
> -      * transaction goes to disk before returning to the user.
> -      * This is slightly sub-optimal in that truncates require
> -      * two sync transactions instead of one for wsync filesystems.
> -      * One for the truncate and one for the timestamps since we
> -      * don't want to change the timestamps unless we're sure the
> -      * truncate worked.  Truncates are less than 1% of the laddis
> -      * mix so this probably isn't worth the trouble to optimize.
> -      */
> -     if (mp->m_flags & XFS_MOUNT_WSYNC)
> -             xfs_trans_set_sync(tp);
>       code = xfs_trans_commit(tp, 0);
> -     xfs_iunlock(ip, lock_flags);
>  
>       /*
>        * Release any dquot(s) the inode had kept before chown.
> @@ -1272,8 +1280,6 @@ xfs_ioctl_setattr(
>       xfs_qm_dqrele(udqp);
>       xfs_qm_dqrele(pdqp);
>       xfs_trans_cancel(tp, 0);
> -     if (lock_flags)
> -             xfs_iunlock(ip, lock_flags);
>       return code;
>  }
>  
> -- 
> 2.0.0
> 
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