Patch "xfs: only remap the written blocks in xfs_reflink_end_cow_extent" has been added to the 6.1-stable tree

This is a note to let you know that I've just added the patch titled

    xfs: only remap the written blocks in xfs_reflink_end_cow_extent

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     xfs-only-remap-the-written-blocks-in-xfs_reflink_end_cow_extent.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.


From [email protected] Wed Jan 29 19:48:00 2025
From: Leah Rumancik <[email protected]>
Date: Wed, 29 Jan 2025 10:47:10 -0800
Subject: xfs: only remap the written blocks in xfs_reflink_end_cow_extent
To: [email protected]
Cc: [email protected], [email protected], [email protected], [email protected], Christoph Hellwig <[email protected]>, "Darrick J. Wong" <[email protected]>, Chandan Babu R <[email protected]>, Leah Rumancik <[email protected]>
Message-ID: <[email protected]>

From: Christoph Hellwig <[email protected]>

[ 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 <[email protected]>
Reviewed-by: "Darrick J. Wong" <[email protected]>
Signed-off-by: Chandan Babu R <[email protected]>
Signed-off-by: Leah Rumancik <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 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;


Patches currently in stable-queue which might be from [email protected] are

queue-6.1/xfs-allow-read-io-and-ficlone-to-run-concurrently.patch
queue-6.1/xfs-hoist-freeing-of-rt-data-fork-extent-mappings.patch
queue-6.1/xfs-make-sure-maxlen-is-still-congruent-with-prod-when-rounding-down.patch
queue-6.1/xfs-only-remap-the-written-blocks-in-xfs_reflink_end_cow_extent.patch
queue-6.1/xfs-dquot-recovery-does-not-validate-the-recovered-dquot.patch
queue-6.1/xfs-clean-up-dqblk-extraction.patch
queue-6.1/xfs-abort-intent-items-when-recovery-intents-fail.patch
queue-6.1/xfs-up-ic_sema-if-flushing-data-device-fails.patch
queue-6.1/xfs-fix-internal-error-from-agfl-exhaustion.patch
queue-6.1/xfs-factor-out-xfs_defer_pending_abort.patch
queue-6.1/xfs-fix-units-conversion-error-in-xfs_bmap_del_extent_delay.patch
queue-6.1/xfs-bump-max-fsgeom-struct-version.patch
queue-6.1/xfs-handle-nimaps-0-from-xfs_bmapi_write-in-xfs_alloc_file_space.patch
queue-6.1/xfs-rt-stubs-should-return-negative-errnos-when-rt-disabled.patch
queue-6.1/xfs-clean-up-fs_xflag_realtime-handling-in-xfs_ioctl_setattr_xflags.patch
queue-6.1/xfs-respect-the-stable-writes-flag-on-the-rt-device.patch
queue-6.1/xfs-introduce-protection-for-drop-nlink.patch
queue-6.1/xfs-prevent-rt-growfs-when-quota-is-enabled.patch
queue-6.1/xfs-inode-recovery-does-not-validate-the-recovered-inode.patch