Re: [PATCH V3 05/10] xfs: Check for extent overflow when adding/removing dir entries

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On Thu, Aug 20, 2020 at 11:13:44AM +0530, Chandan Babu R wrote:
> Directory entry addition/removal 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@xxxxxxxxx>

I wonder how long until someone's going to ask us to make
XFS_IEXT_DIR_MANIP_CNT return a number that's more tightly tied to the
actual directory inode in question, but 4 billion extents would already
be pretty egregious, so maybe we don't care...

Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>

--D

> ---
>  fs/xfs/libxfs/xfs_inode_fork.h | 12 ++++++++++++
>  fs/xfs/xfs_inode.c             | 27 +++++++++++++++++++++++++++
>  fs/xfs/xfs_symlink.c           |  5 +++++
>  3 files changed, 44 insertions(+)
> 
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
> index aae8e6e80b71..f686c7418d2b 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.h
> +++ b/fs/xfs/libxfs/xfs_inode_fork.h
> @@ -54,6 +54,18 @@ struct xfs_ifork {
>   */
>  #define XFS_IEXT_ATTR_MANIP_CNT(rmt_blks) \
>  	(XFS_DA_NODE_MAXDEPTH + max(1, rmt_blks))
> +/*
> + * Directory entry addition/removal 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 407d6299606d..8d195b6ef326 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -1175,6 +1175,11 @@ 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
> @@ -1391,6 +1396,11 @@ 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
> @@ -2861,6 +2871,11 @@ xfs_remove(
>  	xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
>  	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
>  
> +	error = xfs_iext_count_may_overflow(dp, XFS_DATA_FORK,
> +			XFS_IEXT_DIR_MANIP_CNT(mp));
> +	if (error)
> +		goto out_trans_cancel;
> +
>  	/*
>  	 * If we're removing a directory perform some additional validation.
>  	 */
> @@ -3221,6 +3236,18 @@ xfs_rename(
>  	if (wip)
>  		xfs_trans_ijoin(tp, wip, XFS_ILOCK_EXCL);
>  
> +	error = xfs_iext_count_may_overflow(src_dp, XFS_DATA_FORK,
> +			XFS_IEXT_DIR_MANIP_CNT(mp));
> +	if (error)
> +		goto out_trans_cancel;
> +
> +	if (target_ip == NULL) {
> +		error = xfs_iext_count_may_overflow(target_dp, XFS_DATA_FORK,
> +				XFS_IEXT_DIR_MANIP_CNT(mp));
> +		if (error)
> +			goto out_trans_cancel;
> +	}
> +
>  	/*
>  	 * If we are using project inheritance, we only allow renames
>  	 * into our tree when the project IDs are the same; else the
> diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c
> index 8e88a7ca387e..581a4032a817 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.
>  	 */
> -- 
> 2.28.0
> 



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