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-rw-r--r--fs/xfs/xfs_bmap_util.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 2efd78a9719e..e62fb5216341 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -992,6 +992,7 @@ xfs_prepare_shift(
struct xfs_inode *ip,
loff_t offset)
{
+ struct xfs_mount *mp = ip->i_mount;
int error;
/*
@@ -1005,6 +1006,17 @@ xfs_prepare_shift(
}
/*
+ * Shift operations must stabilize the start block offset boundary along
+ * with the full range of the operation. If we don't, a COW writeback
+ * completion could race with an insert, front merge with the start
+ * extent (after split) during the shift and corrupt the file. Start
+ * with the block just prior to the start to stabilize the boundary.
+ */
+ offset = round_down(offset, 1 << mp->m_sb.sb_blocklog);
+ if (offset)
+ offset -= (1 << mp->m_sb.sb_blocklog);
+
+ /*
* Writeback and invalidate cache for the remainder of the file as we're
* about to shift down every extent from offset to EOF.
*/