Re: [PATCH v7 09/17] xfs: add xfs_remount_rw() helper

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Thu, Oct 24, 2019 at 03:51:22PM +0800, Ian Kent wrote:
> Factor the remount read write code into a helper to simplify the
> subsequent change from the super block method .remount_fs to the
> mount-api fs_context_operations method .reconfigure.
> 
> This helper is only used by the mount code, so locate it along with
> that code.
> 
> While we are at it change STATIC -> static for xfs_restore_resvblks().
> 
> Signed-off-by: Ian Kent <raven@themaw.net>
> Reviewed-by: Brian Foster <bfoster@redhat.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/xfs/xfs_super.c |  119 +++++++++++++++++++++++++++++-----------------------
>  1 file changed, 67 insertions(+), 52 deletions(-)
> 
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 297e6c98742e..c07e41489e75 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -47,6 +47,8 @@ static struct kset *xfs_kset;		/* top-level xfs sysfs dir */
>  static struct xfs_kobj xfs_dbg_kobj;	/* global debug sysfs attrs */
>  #endif
>  
> +static void xfs_restore_resvblks(struct xfs_mount *mp);

What's the reason for putting xfs_remount_rw above xfs_restore_resvblks?
I assume that's related to where you want to land later code chunks?

--D

> +
>  /*
>   * Table driven mount option parser.
>   */
> @@ -455,6 +457,68 @@ xfs_mount_free(
>  	kmem_free(mp);
>  }
>  
> +static int
> +xfs_remount_rw(
> +	struct xfs_mount	*mp)
> +{
> +	struct xfs_sb		*sbp = &mp->m_sb;
> +	int			error;
> +
> +	if (mp->m_flags & XFS_MOUNT_NORECOVERY) {
> +		xfs_warn(mp,
> +			"ro->rw transition prohibited on norecovery mount");
> +		return -EINVAL;
> +	}
> +
> +	if (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 &&
> +	    xfs_sb_has_ro_compat_feature(sbp, XFS_SB_FEAT_RO_COMPAT_UNKNOWN)) {
> +		xfs_warn(mp,
> +	"ro->rw transition prohibited on unknown (0x%x) ro-compat filesystem",
> +			(sbp->sb_features_ro_compat &
> +				XFS_SB_FEAT_RO_COMPAT_UNKNOWN));
> +		return -EINVAL;
> +	}
> +
> +	mp->m_flags &= ~XFS_MOUNT_RDONLY;
> +
> +	/*
> +	 * If this is the first remount to writeable state we might have some
> +	 * superblock changes to update.
> +	 */
> +	if (mp->m_update_sb) {
> +		error = xfs_sync_sb(mp, false);
> +		if (error) {
> +			xfs_warn(mp, "failed to write sb changes");
> +			return error;
> +		}
> +		mp->m_update_sb = false;
> +	}
> +
> +	/*
> +	 * Fill out the reserve pool if it is empty. Use the stashed value if
> +	 * it is non-zero, otherwise go with the default.
> +	 */
> +	xfs_restore_resvblks(mp);
> +	xfs_log_work_queue(mp);
> +
> +	/* Recover any CoW blocks that never got remapped. */
> +	error = xfs_reflink_recover_cow(mp);
> +	if (error) {
> +		xfs_err(mp,
> +			"Error %d recovering leftover CoW allocations.", error);
> +			xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
> +		return error;
> +	}
> +	xfs_start_block_reaping(mp);
> +
> +	/* Create the per-AG metadata reservation pool .*/
> +	error = xfs_fs_reserve_ag_blocks(mp);
> +	if (error && error != -ENOSPC)
> +		return error;
> +
> +	return 0;
> +}
> +
>  struct proc_xfs_info {
>  	uint64_t	flag;
>  	char		*str;
> @@ -1169,7 +1233,7 @@ xfs_save_resvblks(struct xfs_mount *mp)
>  	xfs_reserve_blocks(mp, &resblks, NULL);
>  }
>  
> -STATIC void
> +static void
>  xfs_restore_resvblks(struct xfs_mount *mp)
>  {
>  	uint64_t resblks;
> @@ -1307,57 +1371,8 @@ xfs_fs_remount(
>  
>  	/* ro -> rw */
>  	if ((mp->m_flags & XFS_MOUNT_RDONLY) && !(*flags & SB_RDONLY)) {
> -		if (mp->m_flags & XFS_MOUNT_NORECOVERY) {
> -			xfs_warn(mp,
> -		"ro->rw transition prohibited on norecovery mount");
> -			return -EINVAL;
> -		}
> -
> -		if (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 &&
> -		    xfs_sb_has_ro_compat_feature(sbp,
> -					XFS_SB_FEAT_RO_COMPAT_UNKNOWN)) {
> -			xfs_warn(mp,
> -"ro->rw transition prohibited on unknown (0x%x) ro-compat filesystem",
> -				(sbp->sb_features_ro_compat &
> -					XFS_SB_FEAT_RO_COMPAT_UNKNOWN));
> -			return -EINVAL;
> -		}
> -
> -		mp->m_flags &= ~XFS_MOUNT_RDONLY;
> -
> -		/*
> -		 * If this is the first remount to writeable state we
> -		 * might have some superblock changes to update.
> -		 */
> -		if (mp->m_update_sb) {
> -			error = xfs_sync_sb(mp, false);
> -			if (error) {
> -				xfs_warn(mp, "failed to write sb changes");
> -				return error;
> -			}
> -			mp->m_update_sb = false;
> -		}
> -
> -		/*
> -		 * Fill out the reserve pool if it is empty. Use the stashed
> -		 * value if it is non-zero, otherwise go with the default.
> -		 */
> -		xfs_restore_resvblks(mp);
> -		xfs_log_work_queue(mp);
> -
> -		/* Recover any CoW blocks that never got remapped. */
> -		error = xfs_reflink_recover_cow(mp);
> -		if (error) {
> -			xfs_err(mp,
> -	"Error %d recovering leftover CoW allocations.", error);
> -			xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
> -			return error;
> -		}
> -		xfs_start_block_reaping(mp);
> -
> -		/* Create the per-AG metadata reservation pool .*/
> -		error = xfs_fs_reserve_ag_blocks(mp);
> -		if (error && error != -ENOSPC)
> +		error = xfs_remount_rw(mp);
> +		if (error)
>  			return error;
>  	}
>  
>