Re: [PATCH V5 03/12] xfs: Check for extent overflow when punching a hole

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

On Sat, Oct 03, 2020 at 11:26:24AM +0530, Chandan Babu R wrote:
> The extent mapping the file offset at which a hole has to be
> inserted will be split into two extents causing extent count to
> increase by 1.
> 
> Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>

Looks fine,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
>  fs/xfs/libxfs/xfs_inode_fork.h |  7 +++++++
>  fs/xfs/xfs_bmap_item.c         | 15 +++++++++------
>  fs/xfs/xfs_bmap_util.c         | 10 ++++++++++
>  3 files changed, 26 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
> index 7fc2b129a2e7..bcac769a7df6 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.h
> +++ b/fs/xfs/libxfs/xfs_inode_fork.h
> @@ -40,6 +40,13 @@ struct xfs_ifork {
>   */
>  #define XFS_IEXT_ADD_NOSPLIT_CNT	(1)
>  
> +/*
> + * Punching out an extent from the middle of an existing extent can cause the
> + * extent count to increase by 1.
> + * i.e. | Old extent | Hole | Old extent |
> + */
> +#define XFS_IEXT_PUNCH_HOLE_CNT		(1)
> +
>  /*
>   * Fork handling.
>   */
> diff --git a/fs/xfs/xfs_bmap_item.c b/fs/xfs/xfs_bmap_item.c
> index 6a7dcea4ad40..323cee00bd45 100644
> --- a/fs/xfs/xfs_bmap_item.c
> +++ b/fs/xfs/xfs_bmap_item.c
> @@ -440,6 +440,7 @@ xfs_bui_item_recover(
>  	bool				op_ok;
>  	unsigned int			bui_type;
>  	int				whichfork;
> +	int				iext_delta;
>  	int				error = 0;
>  
>  	/* Only one mapping operation per BUI... */
> @@ -519,12 +520,14 @@ xfs_bui_item_recover(
>  	}
>  	xfs_trans_ijoin(tp, ip, 0);
>  
> -	if (bui_type == XFS_BMAP_MAP) {
> -		error = xfs_iext_count_may_overflow(ip, whichfork,
> -				XFS_IEXT_ADD_NOSPLIT_CNT);
> -		if (error)
> -			goto err_inode;
> -	}
> +	if (bui_type == XFS_BMAP_MAP)
> +		iext_delta = XFS_IEXT_ADD_NOSPLIT_CNT;
> +	else
> +		iext_delta = XFS_IEXT_PUNCH_HOLE_CNT;
> +
> +	error = xfs_iext_count_may_overflow(ip, whichfork, iext_delta);
> +	if (error)
> +		goto err_inode;
>  
>  	count = bmap->me_len;
>  	error = xfs_trans_log_finish_bmap_update(tp, budp, type, ip, whichfork,
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
> index dcd6e61df711..0776abd0103c 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -891,6 +891,11 @@ xfs_unmap_extent(
>  
>  	xfs_trans_ijoin(tp, ip, 0);
>  
> +	error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
> +			XFS_IEXT_PUNCH_HOLE_CNT);
> +	if (error)
> +		goto out_trans_cancel;
> +
>  	error = xfs_bunmapi(tp, ip, startoffset_fsb, len_fsb, 0, 2, done);
>  	if (error)
>  		goto out_trans_cancel;
> @@ -1176,6 +1181,11 @@ xfs_insert_file_space(
>  	xfs_ilock(ip, XFS_ILOCK_EXCL);
>  	xfs_trans_ijoin(tp, ip, 0);
>  
> +	error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
> +			XFS_IEXT_PUNCH_HOLE_CNT);
> +	if (error)
> +		goto out_trans_cancel;
> +
>  	/*
>  	 * The extent shifting code works on extent granularity. So, if stop_fsb
>  	 * is not the starting block of extent, we need to split the extent at
> -- 
> 2.28.0
>