wireguard-linux/fs/xfs, branch stable

xfs: fix wild memcpy access when formatting ondisk rtrefcount btree roots

2026-09-17T09:27:41Z

LOLLM noticed that the inode btree root formatting methods copy too many bytes -- there's only one set of keys in node blocks, not two. This causes memory corruption of whatever's beyond the buffers. Cc: stable@vger.kernel.org # v6.14 Fixes: f0415af60f482a ("xfs: wire up a new metafile type for the realtime refcount") Signed-off-by: Darrick J. Wong Assisted-by: LOLLM # finding obvious bugs Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino

xfs: don't let hidden_space go negative in xfs_metafile_resv_init

2026-09-17T09:27:41Z

LOLLM points out that if the amount of fdblocks that we can reserve for a metadata btree file goes below the space already used by that file, then the hidden_space subtraction can underflow, causing xfs_dec_fdblocks to subtract a huge amount of space. We never want the target to be less than the used sapce, so fix the logic that adjusts dblocks_avail downwards. Also fix an error in the adjacent comment. Cc: stable@vger.kernel.org # v6.15 Fixes: 1df8d75030b787 ("xfs: make metabtree reservations global") Signed-off-by: Darrick J. Wong Assisted-by: LOLLM # finding obvious bugs Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino

xfs: drop dquot flush lock when we can't find a buffer to flush

2026-09-17T09:27:41Z

LOLLM noticed that xfs_qm_flush_one fails to drop the dquot flush lock if it can't grab the buffer associated with the dquot. Since there's no buffer, nobody else is going to drop the dqflock, so we need to do it ourselves. Cc: stable@vger.kernel.org # v6.13 Fixes: ca378189fdfa89 ("xfs: convert quotacheck to attach dquot buffers") Signed-off-by: Darrick J. Wong Assisted-by: LOLLM # finding obvious bugs Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino

xfs: fix cursor and pointer handling when recovering iunlink buckets

2026-09-17T09:27:41Z

LOLLM pointed out a bug in xlog_recover_iunlink_bucket: 1. We don't null out prev_ip after releasing it, which can lead to UAF problems if the inodegc flush call in the loop fails. at which point I noticed even more bugs: 2. If the inodegc flush inside the loop fails, we also leak @ip. 3. We set prev_agino to agino having already advanced agino, which results in inodes with i_prev_unlinked set to itself. 4. If we exit the bottom of the loop with prev_ip set, then prev_ip aliases ip and we also set its i_prev_unlinked to itself. Bugs 3 and 4 introduce loops into the unlinked list, though these loops don't surface because we immediately flush each unlinked inode after loading it. Fix all of these issues. Cc: stable@vger.kernel.org # v6.0 Fixes: 04755d2e5821b3 ("xfs: refactor xlog_recover_process_iunlinks()") Signed-off-by: Darrick J. Wong Assisted-by: LOLLM # finding obvious bugs Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino

xfs: fix blockgc group quota scanning when usrquota isn't enforced

2026-09-17T09:27:41Z

LOLLM noticed the copy-paste error here -- if user quotas aren't enforced but we're near the group quota limit, we fail to set FLAG_GID and hence we might not actually free any preallocations, causing unnecessary EDQUOT. Fix that. Cc: stable@vger.kernel.org # v5.12 Fixes: c237dd7c709432 ("xfs: flush eof/cowblocks if we can't reserve quota for inode creation") Signed-off-by: Darrick J. Wong Assisted-by: LOLLM # finding obvious bugs Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino

xfs: don't merge different file IO error types

2026-09-17T09:27:41Z

LOLLM noticed that we can accidentally merge file range health monitoring events even if they have different errors. We shouldn't do that. Cc: stable@vger.kernel.org # v7.0 Fixes: dfa8bad3a8796c ("xfs: convey file I/O errors to the health monitor") Signed-off-by: Darrick J. Wong Assisted-by: LOLLM # finding obvious bugs Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino

xfs: don't let memory failures leak blocks and kill repairs

2026-09-17T09:27:41Z

LOLLM complains that a memory allocation failure in xrep_newbt_add_blocks results in online repair leaking blocks that were previously allocated to write a new btree, but the problem is worse than that -- a limitation of the codebase is that the callers cannot undo the transaction /and/ return the error -- either you undo all changes and commit the transaction, or you error out and the filesystem goes down. However, the new btree space reservation object isn't that big (~48 bytes). Let's just do a NOFAIL allocation and the problem goes away. Cc: stable@vger.kernel.org # v6.8 Fixes: be408417630427 ("xfs: implement block reservation accounting for btrees we're staging") Signed-off-by: Darrick J. Wong Assisted-by: LOLLM # finding obvious bugs Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino

xfs: don't cross reference rmapbt with bitmaps if they're incomplete

2026-09-17T09:27:41Z

LOLLM points out that runtime errors (e.g. ENOMEM) when we're trying to compute space usag bitmaps are silently dropped by the rmapbt scrubber. We ought to flag that as an incomplete scrub instead of reporting cross-referencing errors based on faulty data. Cc: stable@vger.kernel.org # v6.4 Fixes: fed050f3452da0 ("xfs: cross-reference rmap records with ag btrees") Signed-off-by: Darrick J. Wong Assisted-by: LOLLM # finding obvious bugs Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino

xfs: fix rtgroup repair estimations

2026-09-17T09:27:41Z

When I added online fsck for realtime reflink, I forgot to update xrep_calc_rtgroup_resblks to factor in the size of the refcount btree when it guesses how much space we need to start a repair. This hasn't been a huge problem in practice because there are few filesystems with (a) realtime, (b) rtgroups, (c) reflink, and (d) no rmap. But let's fix this before someone stumbles upon it, especially since LOLLM flagged this for me. Cc: stable@vger.kernel.org # v6.14 Fixes: 83ccffc489975d ("xfs: online repair of the realtime refcount btree") Signed-off-by: Darrick J. Wong Assisted-by: LOLLM # finding obvious bugs Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino

xfs: call xfs_dquot_set_prealloc_limits if we installed default rtb limits

2026-09-17T09:27:41Z

Now that we have quotas for the realtime volume, we also have precomputed watermark limits for the realtime block counts. These precomputations should be done any time we change the rtb limits, which means that xfs_qm_adjust_dqlimits needs to ensure that if we installed a default rtb limit. Cc: stable@vger.kernel.org # v6.13 Fixes: 5dd70852b03901 ("xfs: create quota preallocation watermarks for realtime quota") Signed-off-by: Darrick J. Wong Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino