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Qu Wenruo 1972f44c18 btrfs: reject new transactions if the fs is fully read-only
[BUG]
There is a bug report where a heavily fuzzed fs is mounted with all
rescue mount options, which leads to the following warnings during
unmount:

  BTRFS: Transaction aborted (error -22)
  Modules linked in:
  CPU: 0 UID: 0 PID: 9758 Comm: repro.out Not tainted
  6.19.0-rc5-00002-gb71e635feefc #7 PREEMPT(full)
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
  RIP: 0010:find_free_extent_update_loop fs/btrfs/extent-tree.c:4208 [inline]
  RIP: 0010:find_free_extent+0x52f0/0x5d20 fs/btrfs/extent-tree.c:4611
  Call Trace:
   <TASK>
   btrfs_reserve_extent+0x2cd/0x790 fs/btrfs/extent-tree.c:4705
   btrfs_alloc_tree_block+0x1e1/0x10e0 fs/btrfs/extent-tree.c:5157
   btrfs_force_cow_block+0x578/0x2410 fs/btrfs/ctree.c:517
   btrfs_cow_block+0x3c4/0xa80 fs/btrfs/ctree.c:708
   btrfs_search_slot+0xcad/0x2b50 fs/btrfs/ctree.c:2130
   btrfs_truncate_inode_items+0x45d/0x2350 fs/btrfs/inode-item.c:499
   btrfs_evict_inode+0x923/0xe70 fs/btrfs/inode.c:5628
   evict+0x5f4/0xae0 fs/inode.c:837
   __dentry_kill+0x209/0x660 fs/dcache.c:670
   finish_dput+0xc9/0x480 fs/dcache.c:879
   shrink_dcache_for_umount+0xa0/0x170 fs/dcache.c:1661
   generic_shutdown_super+0x67/0x2c0 fs/super.c:621
   kill_anon_super+0x3b/0x70 fs/super.c:1289
   btrfs_kill_super+0x41/0x50 fs/btrfs/super.c:2127
   deactivate_locked_super+0xbc/0x130 fs/super.c:474
   cleanup_mnt+0x425/0x4c0 fs/namespace.c:1318
   task_work_run+0x1d4/0x260 kernel/task_work.c:233
   exit_task_work include/linux/task_work.h:40 [inline]
   do_exit+0x694/0x22f0 kernel/exit.c:971
   do_group_exit+0x21c/0x2d0 kernel/exit.c:1112
   __do_sys_exit_group kernel/exit.c:1123 [inline]
   __se_sys_exit_group kernel/exit.c:1121 [inline]
   __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1121
   x64_sys_call+0x2210/0x2210 arch/x86/include/generated/asm/syscalls_64.h:232
   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0xe8/0xf80 arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x77/0x7f
  RIP: 0033:0x44f639
  Code: Unable to access opcode bytes at 0x44f60f.
  RSP: 002b:00007ffc15c4e088 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
  RAX: ffffffffffffffda RBX: 00000000004c32f0 RCX: 000000000044f639
  RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000001
  RBP: 0000000000000001 R08: ffffffffffffffc0 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004c32f0
  R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001
   </TASK>

Since rescue mount options will mark the full fs read-only, there should
be no new transaction triggered.

But during unmount we will evict all inodes, which can trigger a new
transaction, and triggers warnings on a heavily corrupted fs.

[CAUSE]
Btrfs allows new transaction even on a read-only fs, this is to allow
log replay happen even on read-only mounts, just like what ext4/xfs do.

However with rescue mount options, the fs is fully read-only and cannot
be remounted read-write, thus in that case we should also reject any new
transactions.

[FIX]
If we find the fs has rescue mount options, we should treat the fs as
error, so that no new transaction can be started.

Reported-by: Jiaming Zhang <r772577952@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CANypQFYw8Nt8stgbhoycFojOoUmt+BoZ-z8WJOZVxcogDdwm=Q@mail.gmail.com/
Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-01-20 17:18:47 +01:00
arch Fix perf CPU-clock counters, and address a static checker warning. 2025-11-23 08:20:15 -08:00
block vfs-6.18-rc7.fixes 2025-11-17 09:11:27 -08:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push contains the following changes: 2025-10-10 08:56:16 -07:00
Documentation Input updates for v6.18-rc6 2025-11-22 09:58:41 -08:00
drivers Fixes for the Allwinner clk driver: 2025-11-23 12:03:28 -08:00
fs btrfs: reject new transactions if the fs is fully read-only 2026-01-20 17:18:47 +01:00
include btrfs: fix NULL dereference on root when tracing inode eviction 2025-12-16 22:53:14 +01:00
init printk changes for 6.18 2025-10-04 11:13:11 -07:00
io_uring io_uring/cmd_net: fix wrong argument types for skb_queue_splice() 2025-11-20 11:40:15 -07:00
ipc namespace-6.18-rc1 2025-09-29 11:20:29 -07:00
kernel Miscellaneous fixes: 2025-11-23 08:23:30 -08:00
lib Crypto library fix for v6.18-rc7 2025-11-22 11:53:53 -08:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm slab fix for 6.18-rc7 2025-11-20 10:49:12 -08:00
net Including fixes from IPsec and wireless. 2025-11-20 08:52:07 -08:00
rust rust: Add -fno-isolate-erroneous-paths-dereference to bindgen_skip_c_flags 2025-11-10 08:37:06 +08:00
samples samples: work around glibc redefining some of our defines wrong 2025-11-21 09:29:02 -08:00
scripts Rust fixes for v6.18 (2nd) 2025-11-14 15:36:15 -08:00
security selinux/stable-6.18 PR 20251121 2025-11-22 09:24:36 -08:00
sound ALSA: usb-audio: Add native DSD quirks for PureAudio DAC series 2025-11-14 14:19:47 +01:00
tools RISC-V updates for v6.18-rc7 2025-11-22 09:44:50 -08:00
usr gen_init_cpio: Ignore fsync() returning EINVAL on pipes 2025-10-07 09:53:05 -07:00
virt KVM: guest_memfd: Remove bindings on memslot deletion when gmem is dying 2025-11-04 09:16:53 -08:00
.clang-format memblock: drop for_each_free_mem_pfn_range_in_zone_from() 2025-09-14 08:49:03 +03:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: ignore compile_commands.json globally 2025-08-12 15:53:55 -07:00
.mailmap soc: fixes for 6.18, part 3 2025-11-19 09:36:04 -08:00
.pylintrc tools: docs: parse-headers.py: move it from sphinx dir 2025-08-29 15:54:42 -06:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: mark ISDN subsystem as orphan 2025-10-27 17:49:45 -07:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS gpio fixes for v6.18-rc7 2025-11-21 10:43:58 -08:00
Makefile Linux 6.18-rc7 2025-11-23 14:53:16 -08:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.