Re: [PATCH V14 04/16] xfs: Check for extent overflow when adding dir entries

["Darrick J. Wong" <djwong@kernel.org>]

On Sun, Jan 10, 2021 at 09:37:08PM +0530, Chandan Babu R wrote:
> Directory entry addition can cause the following,
> 1. Data block can be added/removed.
>    A new extent can cause extent count to increase by 1.
> 2. Free disk block can be added/removed.
>    Same behaviour as described above for Data block.
> 3. Dabtree blocks.
>    XFS_DA_NODE_MAXDEPTH blocks can be added. Each of these
>    can be new extents. Hence extent count can increase by
>    XFS_DA_NODE_MAXDEPTH.
> 
> Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>

OK, seems reasonably straight forward,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
>  fs/xfs/libxfs/xfs_inode_fork.h | 13 +++++++++++++
>  fs/xfs/xfs_inode.c             | 10 ++++++++++
>  fs/xfs/xfs_symlink.c           |  5 +++++
>  3 files changed, 28 insertions(+)
> 
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
> index bcac769a7df6..ea1a9dd8a763 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.h
> +++ b/fs/xfs/libxfs/xfs_inode_fork.h
> @@ -47,6 +47,19 @@ struct xfs_ifork {
>   */
>  #define XFS_IEXT_PUNCH_HOLE_CNT		(1)
>  
> +/*
> + * Directory entry addition can cause the following,
> + * 1. Data block can be added/removed.
> + *    A new extent can cause extent count to increase by 1.
> + * 2. Free disk block can be added/removed.
> + *    Same behaviour as described above for Data block.
> + * 3. Dabtree blocks.
> + *    XFS_DA_NODE_MAXDEPTH blocks can be added. Each of these can be new
> + *    extents. Hence extent count can increase by XFS_DA_NODE_MAXDEPTH.
> + */
> +#define XFS_IEXT_DIR_MANIP_CNT(mp) \
> +	((XFS_DA_NODE_MAXDEPTH + 1 + 1) * (mp)->m_dir_geo->fsbcount)
> +
>  /*
>   * Fork handling.
>   */
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index b7352bc4c815..4cc787cc4eee 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -1042,6 +1042,11 @@ xfs_create(
>  	if (error)
>  		goto out_trans_cancel;
>  
> +	error = xfs_iext_count_may_overflow(dp, XFS_DATA_FORK,
> +			XFS_IEXT_DIR_MANIP_CNT(mp));
> +	if (error)
> +		goto out_trans_cancel;
> +
>  	/*
>  	 * A newly created regular or special file just has one directory
>  	 * entry pointing to them, but a directory also the "." entry
> @@ -1258,6 +1263,11 @@ xfs_link(
>  	xfs_trans_ijoin(tp, sip, XFS_ILOCK_EXCL);
>  	xfs_trans_ijoin(tp, tdp, XFS_ILOCK_EXCL);
>  
> +	error = xfs_iext_count_may_overflow(tdp, XFS_DATA_FORK,
> +			XFS_IEXT_DIR_MANIP_CNT(mp));
> +	if (error)
> +		goto error_return;
> +
>  	/*
>  	 * If we are using project inheritance, we only allow hard link
>  	 * creation in our tree when the project IDs are the same; else
> diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c
> index 1f43fd7f3209..0b8136a32484 100644
> --- a/fs/xfs/xfs_symlink.c
> +++ b/fs/xfs/xfs_symlink.c
> @@ -220,6 +220,11 @@ xfs_symlink(
>  	if (error)
>  		goto out_trans_cancel;
>  
> +	error = xfs_iext_count_may_overflow(dp, XFS_DATA_FORK,
> +			XFS_IEXT_DIR_MANIP_CNT(mp));
> +	if (error)
> +		goto out_trans_cancel;
> +
>  	/*
>  	 * Allocate an inode for the symlink.
>  	 */
> -- 
> 2.29.2
>