[BUG] With crafted image, btrfs can panic at insert_inline_extent_backref(): kernel BUG at fs/btrfs/extent-tree.c:1857! invalid opcode: 0000 [#1] SMP PTI CPU: 0 PID: 1117 Comm: btrfs-transacti Not tainted 5.0.0-rc8+ #9 RIP: 0010:insert_inline_extent_backref+0xcc/0xe0 Code: 45 20 49 8b 7e 50 49 89 d8 4c 8b 4d 10 48 8b 55 c8 4c 89 e1 41 57 4c 89 ee 50 ff 75 18 e8 cc bf ff ff 31 c0 48 83 c4 18 eb b2 <0f> 0b e8 9d df bd ff 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 66 66 RSP: 0018:ffffac4dc1287be8 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 0000000000000007 RCX: 0000000000000001 RDX: 0000000000001000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffac4dc1287c28 R08: ffffac4dc1287ab8 R09: ffffac4dc1287ac0 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8febef88a540 R14: ffff8febeaa7bc30 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8febf7a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f663ace94c0 CR3: 0000000235698006 CR4: 00000000000206f0 Call Trace: ? _cond_resched+0x1a/0x50 __btrfs_inc_extent_ref.isra.64+0x7e/0x240 ? btrfs_merge_delayed_refs+0xa5/0x330 __btrfs_run_delayed_refs+0x653/0x1120 btrfs_run_delayed_refs+0xdb/0x1b0 btrfs_commit_transaction+0x52/0x950 ? start_transaction+0x94/0x450 transaction_kthread+0x163/0x190 kthread+0x105/0x140 ? btrfs_cleanup_transaction+0x560/0x560 ? kthread_destroy_worker+0x50/0x50 ret_from_fork+0x35/0x40 Modules linked in: ---[ end trace 2ad8b3de903cf825 ]---
[CAUSE] Due to extent tree corruption (still valid by itself, but bad cross ref), we can allocate an extent which is still in extent tree. Then we will try to insert/update inlined extent backref line for the existing tree block, and triggering the BUG_ON() where we don't expect to increase refs on non-subvolume tree block. [FIX] Replace that BUG_ON() with proper error message and leaf dump for debug build. Link: https://bugzilla.kernel.org/show_bug.cgi?id=202829 Signed-off-by: Qu Wenruo <w...@suse.com> --- fs/btrfs/extent-tree.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 199e4eed8f2d..72868d9ac58e 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -1856,7 +1856,24 @@ int insert_inline_extent_backref(struct btrfs_trans_handle *trans, num_bytes, parent, root_objectid, owner, offset, 1); if (ret == 0) { - BUG_ON(owner < BTRFS_FIRST_FREE_OBJECTID); + /* + * We're adding ref to an existing tree block, only happens + * when creating snapshots, not possible to other trees. + */ + if (owner < BTRFS_FIRST_FREE_OBJECTID) { + WARN(IS_ENABLED(CONFIG_BTRFS_DEBUG), KERN_ERR + "invalid operation for non-subvolume tree block"); + + btrfs_crit(trans->fs_info, +"invalid operation, adding refs to a non-subvolume tree block, bytenr=%llu num_bytes=%llu root_objectid=%llu", + bytenr, num_bytes, root_objectid); + if (IS_ENABLED(CONFIG_BTRFS_DEBUG)) { + btrfs_crit(trans->fs_info, + "path->slots[0]=%d path->nodes[0]:", path->slots[0]); + btrfs_print_leaf(path->nodes[0]); + } + return -EUCLEAN; + } update_inline_extent_backref(path, iref, refs_to_add, extent_op, NULL); } else if (ret == -ENOENT) { @@ -2073,6 +2090,9 @@ int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans, /* * __btrfs_inc_extent_ref - insert backreference for a given extent * + * The work is opposite as __btrfs_free_extent(). + * For more info about how it works or examples, refer to __btrfs_free_extent(). + * * @trans: Handle of transaction * * @node: The delayed ref node used to get the bytenr/length for @@ -2153,9 +2173,9 @@ static int __btrfs_inc_extent_ref(struct btrfs_trans_handle *trans, /* now insert the actual backref */ ret = insert_extent_backref(trans, path, bytenr, parent, root_objectid, owner, offset, refs_to_add); +out: if (ret) btrfs_abort_transaction(trans, ret); -out: btrfs_free_path(path); return ret; } -- 2.22.0
