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

Darrick J. Wong
2020-08-31T16:41:32Z

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@gmail.com>

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@oracle.com>

--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
>