提交 7dca67b6 编写于 作者: C Chandan Babu R 提交者: Zheng Zengkai

xfs: Check for extent overflow when moving extent from cow to data fork

mainline inclusion
from mainline-v5.12-rc1
commit 5f1d5bbf
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=5f1d5bbfb2e674052a9fe542f53678978af20770

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

Moving an extent to data fork can cause a sub-interval of an existing
extent to be unmapped. This will increase extent count by 1. Mapping in
the new extent can increase the extent count by 1 again i.e.
 | Old extent | New extent | Old extent |
Hence number of extents increases by 2.
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NAllison Henderson <allison.henderson@oracle.com>
Signed-off-by: NChandan Babu R <chandanrlinux@gmail.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NYu Kuai <yukuai3@huawei.com>
Signed-off-by: NGuo Xuenan <guoxuenan@huawei.com>
Reviewed-by: NZhang Yi <yi.zhang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
上级 c354ad22
......@@ -79,6 +79,15 @@ struct xfs_ifork {
#define XFS_IEXT_WRITE_UNWRITTEN_CNT (2)
/*
* Moving an extent to data fork can cause a sub-interval of an existing extent
* to be unmapped. This will increase extent count by 1. Mapping in the new
* extent can increase the extent count by 1 again i.e.
* | Old extent | New extent | Old extent |
* Hence number of extents increases by 2.
*/
#define XFS_IEXT_REFLINK_END_COW_CNT (2)
/*
* Fork handling.
*/
......
......@@ -615,6 +615,11 @@ xfs_reflink_end_cow_extent(
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip, 0);
error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
XFS_IEXT_REFLINK_END_COW_CNT);
if (error)
goto out_cancel;
/*
* In case of racing, overlapping AIO writes no COW extents might be
* left by the time I/O completes for the loser of the race. In that
......
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