5.15-stable review patch. If anyone has any objections, please let me know.
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From: Deepanshu Kartikey kartikey406@gmail.com
commit 78a63493f8e352296dbc7cb7b3f4973105e8679e upstream.
The extent map cache can become stale when extents are moved or defragmented, causing subsequent operations to see outdated extent flags. This triggers a BUG_ON in ocfs2_refcount_cal_cow_clusters().
The problem occurs when: 1. copy_file_range() creates a reflinked extent with OCFS2_EXT_REFCOUNTED 2. ioctl(FITRIM) triggers ocfs2_move_extents() 3. __ocfs2_move_extents_range() reads and caches the extent (flags=0x2) 4. ocfs2_move_extent()/ocfs2_defrag_extent() calls __ocfs2_move_extent() which clears OCFS2_EXT_REFCOUNTED flag on disk (flags=0x0) 5. The extent map cache is not invalidated after the move 6. Later write() operations read stale cached flags (0x2) but disk has updated flags (0x0), causing a mismatch 7. BUG_ON(!(rec->e_flags & OCFS2_EXT_REFCOUNTED)) triggers
Fix by clearing the extent map cache after each extent move/defrag operation in __ocfs2_move_extents_range(). This ensures subsequent operations read fresh extent data from disk.
Link: https://lore.kernel.org/all/20251009142917.517229-1-kartikey406@gmail.com/T/ Link: https://lkml.kernel.org/r/20251009154903.522339-1-kartikey406@gmail.com Fixes: 53069d4e7695 ("Ocfs2/move_extents: move/defrag extents within a certain range.") Signed-off-by: Deepanshu Kartikey kartikey406@gmail.com Reported-by: syzbot+6fdd8fa3380730a4b22c@syzkaller.appspotmail.com Tested-by: syzbot+6fdd8fa3380730a4b22c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?id=2959889e1f6e216585ce522f7e8bc002b46ad9e... Reviewed-by: Mark Fasheh mark@fasheh.com Reviewed-by: Joseph Qi joseph.qi@linux.alibaba.com Cc: Joel Becker jlbec@evilplan.org Cc: Junxiao Bi junxiao.bi@oracle.com Cc: Changwei Ge gechangwei@live.cn Cc: Jun Piao piaojun@huawei.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ocfs2/move_extents.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/fs/ocfs2/move_extents.c +++ b/fs/ocfs2/move_extents.c @@ -868,6 +868,11 @@ static int __ocfs2_move_extents_range(st mlog_errno(ret); goto out; } + /* + * Invalidate extent cache after moving/defragging to prevent + * stale cached data with outdated extent flags. + */ + ocfs2_extent_map_trunc(inode, cpos);
context->clusters_moved += alloc_size; next: