Re: [PATCH V3 02/10] xfs: Check for extent overflow when trivally adding a new extent

Darrick J. Wong
2020-08-31T16:12:34Z

On Thu, Aug 20, 2020 at 11:13:41AM +0530, Chandan Babu R wrote:
> When adding a new data extent (without modifying an inode's existing
> extents) the extent count increases only by 1. This commit checks for
> extent count overflow in such cases.
>
> Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>

Seems fine to me...
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
> fs/xfs/libxfs/xfs_bmap.c | 6 ++++++
> fs/xfs/libxfs/xfs_inode_fork.h | 6 ++++++
> fs/xfs/xfs_bmap_util.c | 5 +++++
> fs/xfs/xfs_dquot.c | 8 +++++++-
> fs/xfs/xfs_iomap.c | 5 +++++
> fs/xfs/xfs_rtalloc.c | 5 +++++
> 6 files changed, 34 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 9c40d5971035..dcc8eeecd571 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -4527,6 +4527,12 @@ xfs_bmapi_convert_delalloc(
> return error;
>
> xfs_ilock(ip, XFS_ILOCK_EXCL);
> +
> + error = xfs_iext_count_may_overflow(ip, whichfork,
> + XFS_IEXT_ADD_NOSPLIT_CNT);
> + if (error)
> + goto out_trans_cancel;
> +
> xfs_trans_ijoin(tp, ip, 0);
>
> if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &bma.icur, &bma.got) ||
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
> index 0beb8e2a00be..7fc2b129a2e7 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.h
> +++ b/fs/xfs/libxfs/xfs_inode_fork.h
> @@ -34,6 +34,12 @@ struct xfs_ifork {
> #define XFS_IFEXTENTS 0x02 /* All extent pointers are read in */
> #define XFS_IFBROOT 0x04 /* i_broot points to the bmap b-tree root */
>
> +/*
> + * Worst-case increase in the fork extent count when we're adding a single
> + * extent to a fork and there's no possibility of splitting an existing mapping.
> + */
> +#define XFS_IEXT_ADD_NOSPLIT_CNT (1)
> +
> /*
> * Fork handling.
> */
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
> index afdc7f8e0e70..7b76a48b0885 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -822,6 +822,11 @@ xfs_alloc_file_space(
> if (error)
> goto error1;
>
> + error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
> + XFS_IEXT_ADD_NOSPLIT_CNT);
> + if (error)
> + goto error0;
> +
> xfs_trans_ijoin(tp, ip, 0);
>
> error = xfs_bmapi_write(tp, ip, startoffset_fsb,
> diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
> index 04dc2be19c3a..59ea9485ebda 100644
> --- a/fs/xfs/xfs_dquot.c
> +++ b/fs/xfs/xfs_dquot.c
> @@ -290,8 +290,14 @@ xfs_dquot_disk_alloc(
> return -ESRCH;
> }
>
> - /* Create the block mapping. */
> xfs_trans_ijoin(tp, quotip, XFS_ILOCK_EXCL);
> +
> + error = xfs_iext_count_may_overflow(quotip, XFS_DATA_FORK,
> + XFS_IEXT_ADD_NOSPLIT_CNT);
> + if (error)
> + return error;
> +
> + /* Create the block mapping. */
> error = xfs_bmapi_write(tp, quotip, dqp->q_fileoffset,
> XFS_DQUOT_CLUSTER_SIZE_FSB, XFS_BMAPI_METADATA, 0, &map,
> &nmaps);
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index 0e3f62cde375..37b0c743c116 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -250,6 +250,11 @@ xfs_iomap_write_direct(
> if (error)
> goto out_trans_cancel;
>
> + error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
> + XFS_IEXT_ADD_NOSPLIT_CNT);
> + if (error)
> + goto out_trans_cancel;
> +
> xfs_trans_ijoin(tp, ip, 0);
>
> /*
> diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
> index 6209e7b6b895..9508ab00a00b 100644
> --- a/fs/xfs/xfs_rtalloc.c
> +++ b/fs/xfs/xfs_rtalloc.c
> @@ -787,6 +787,11 @@ xfs_growfs_rt_alloc(
> xfs_ilock(ip, XFS_ILOCK_EXCL);
> xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
>
> + error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
> + XFS_IEXT_ADD_NOSPLIT_CNT);
> + if (error)
> + goto out_trans_cancel;
> +
> /*
> * Allocate blocks to the bitmap file.
> */
> --
> 2.28.0
>