6.1-stable review patch. If anyone has any objections, please let me know.
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From: Christoph Hellwig hch@lst.de
[ 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 hch@lst.de Reviewed-by: "Darrick J. Wong" djwong@kernel.org Signed-off-by: Chandan Babu R chandanbabu@kernel.org Signed-off-by: Leah Rumancik leah.rumancik@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/xfs/xfs_reflink.c | 1 + 1 file changed, 1 insertion(+)
--- 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;