From 67c362b810aa63979a6816435c56b1a0cf14103f Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 29 Jan 2025 10:47:10 -0800 Subject: [PATCH] xfs: only remap the written blocks in xfs_reflink_end_cow_extent [ Upstream commit 55f669f34184ecb25b8353f29c7f6f1ae5b313d1 ] xfs_reflink_end_cow_extent looks up the COW extent and the data fork extent at offset_fsb, and then proceeds to remap the common subset between the two. It does however not limit the remapped extent to the passed in [*offset_fsbm end_fsb] range and thus potentially remaps more blocks than the one handled by the current I/O completion. This means that with sufficiently large data and COW extents we could be remapping COW fork mappings that have not been written to, leading to a stale data exposure on a powerfail event. We use to have a xfs_trim_range to make the remap fit the I/O completion range, but that got (apparently accidentally) removed in commit df2fd88f8ac7 ("xfs: rewrite xfs_reflink_end_cow to use intents"). Note that I've only found this by code inspection, and a test case would probably require very specific delay and error injection. Fixes: df2fd88f8ac7 ("xfs: rewrite xfs_reflink_end_cow to use intents") Signed-off-by: Christoph Hellwig Reviewed-by: "Darrick J. Wong" Signed-off-by: Chandan Babu R Signed-off-by: Leah Rumancik Signed-off-by: Greg Kroah-Hartman --- fs/xfs/xfs_reflink.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index 004f5a0444be..cbdc23217a42 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -783,6 +783,7 @@ xfs_reflink_end_cow_extent( } } del = got; + xfs_trim_extent(&del, *offset_fsb, end_fsb - *offset_fsb); /* Grab the corresponding mapping in the data fork. */ nmaps = 1;