Commit 8be47263 authored Nov 21, 2022 by Chandan Babu R Committed by Zheng Zengkai Nov 21, 2022

xfs: Check for extent overflow when remapping an extent

mainline inclusion
from mainline-v5.12-rc1
commit ee898d78
category: bugfix
bugzilla: 187510,https://gitee.com/openeuler/kernel/issues/I4KIAO

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ee898d78c3540b44270a5fdffe208d7bbb219d93



--------------------------------

Remapping an extent involves unmapping the existing extent and mapping
in the new extent. When unmapping, an extent containing the entire unmap
range can be split into two extents,
i.e. | Old extent | hole | Old extent |
Hence extent count increases by 1.

Mapping in the new extent into the destination file can increase the
extent count by 1.

Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Guo Xuenan <guoxuenan@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>

parent 7dca67b6

fs/xfs/xfs_reflink.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -997,6 +997,7 @@ xfs_reflink_remap_extent(
		bool quota_reserved = true;
		bool smap_real;
		bool dmap_written = xfs_bmap_is_written_extent(dmap);
		int iext_delta = 0;
		int nimaps;
		int error;

		@@ -1107,6 +1108,16 @@ xfs_reflink_remap_extent(
		goto out_cancel;
		}

		if (smap_real)
		++iext_delta;

		if (dmap_written)
		++iext_delta;

		error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK, iext_delta);
		if (error)
		goto out_cancel;

		if (smap_real) {
		/*
		* If the extent we're unmapping is backed by storage (written