linux/fs/btrfs
Qu Wenruo 2ba48b2004 btrfs: fix compat_ro checks against remount
[BUG]
Even with commit 81d5d61454 ("btrfs: enhance unsupported compat RO
flags handling"), btrfs can still mount a fs with unsupported compat_ro
flags read-only, then remount it RW:

  # btrfs ins dump-super /dev/loop0 | grep compat_ro_flags -A 3
  compat_ro_flags		0x403
			( FREE_SPACE_TREE |
			  FREE_SPACE_TREE_VALID |
			  unknown flag: 0x400 )

  # mount /dev/loop0 /mnt/btrfs
  mount: /mnt/btrfs: wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error.
         dmesg(1) may have more information after failed mount system call.
  ^^^ RW mount failed as expected ^^^

  # dmesg -t | tail -n5
  loop0: detected capacity change from 0 to 1048576
  BTRFS: device fsid cb5b82f5-0fdd-4d81-9b4b-78533c324afa devid 1 transid 7 /dev/loop0 scanned by mount (1146)
  BTRFS info (device loop0): using crc32c (crc32c-intel) checksum algorithm
  BTRFS info (device loop0): using free space tree
  BTRFS error (device loop0): cannot mount read-write because of unknown compat_ro features (0x403)
  BTRFS error (device loop0): open_ctree failed

  # mount /dev/loop0 -o ro /mnt/btrfs
  # mount -o remount,rw /mnt/btrfs
  ^^^ RW remount succeeded unexpectedly ^^^

[CAUSE]
Currently we use btrfs_check_features() to check compat_ro flags against
our current mount flags.

That function get reused between open_ctree() and btrfs_remount().

But for btrfs_remount(), the super block we passed in still has the old
mount flags, thus btrfs_check_features() still believes we're mounting
read-only.

[FIX]
Replace the existing @sb argument with @is_rw_mount.

As originally we only use @sb to determine if the mount is RW.

Now it's callers' responsibility to determine if the mount is RW, and
since there are only two callers, the check is pretty simple:

- caller in open_ctree()
  Just pass !sb_rdonly().

- caller in btrfs_remount()
  Pass !(*flags & SB_RDONLY), as our check should be against the new
  flags.

Now we can correctly reject the RW remount:

  # mount /dev/loop0 -o ro /mnt/btrfs
  # mount -o remount,rw /mnt/btrfs
  mount: /mnt/btrfs: mount point not mounted or bad option.
         dmesg(1) may have more information after failed mount system call.
  # dmesg -t | tail -n 1
  BTRFS error (device loop0: state M): cannot mount read-write because of unknown compat_ro features (0x403)

Reported-by: Chung-Chiang Cheng <shepjeng@gmail.com>
Fixes: 81d5d61454 ("btrfs: enhance unsupported compat RO flags handling")
CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-01-03 16:22:13 +01:00
..
tests btrfs: drop private_data parameter from extent_io_tree_init 2022-12-05 18:00:54 +01:00
accessors.c btrfs: add eb to btrfs_node_key_ptr_offset 2022-12-05 18:00:58 +01:00
accessors.h btrfs: add stack helpers for a few btrfs items 2022-12-05 18:00:58 +01:00
acl.c btrfs: move acl prototypes into acl.h 2022-12-05 18:00:46 +01:00
acl.h btrfs: move acl prototypes into acl.h 2022-12-05 18:00:46 +01:00
async-thread.c btrfs: simplify WQ_HIGHPRI handling in struct btrfs_workqueue 2022-05-16 17:03:15 +02:00
async-thread.h btrfs: remove unused typedefs get_extent_t and btrfs_work_func_t 2022-07-25 17:45:36 +02:00
backref.c btrfs: fix resolving backrefs for inline extent followed by prealloc 2022-12-20 19:43:43 +01:00
backref.h btrfs: send: skip resolution of our own backref when finding clone source 2022-12-05 18:00:50 +01:00
bio.c btrfs: handle case when repair happens with dev-replace 2023-01-03 15:53:18 +01:00
bio.h btrfs: split the bio submission path into a separate file 2022-12-05 18:00:57 +01:00
block-group.c btrfs: convert btrfs_block_group::needs_free_space to runtime flag 2022-12-05 18:00:51 +01:00
block-group.h btrfs: convert btrfs_block_group::seq_zone to runtime flag 2022-12-05 18:00:51 +01:00
block-rsv.c btrfs: simplify percent calculation helpers, rename div_factor 2022-12-05 18:00:48 +01:00
block-rsv.h btrfs: simplify percent calculation helpers, rename div_factor 2022-12-05 18:00:48 +01:00
btrfs_inode.h btrfs: pass btrfs_inode to btrfs_add_delayed_iput 2022-12-05 18:00:55 +01:00
check-integrity.c btrfs: use btrfs_dev_name() helper to handle missing devices better 2022-12-05 18:00:57 +01:00
check-integrity.h btrfs: check-integrity: split submit_bio from btrfsic checking 2022-05-16 17:03:12 +02:00
compression.c btrfs: split the bio submission path into a separate file 2022-12-05 18:00:57 +01:00
compression.h btrfs: constify input buffer parameter in compression code 2022-12-05 18:00:55 +01:00
ctree.c btrfs: add might_sleep() annotations 2022-12-05 18:00:59 +01:00
ctree.h btrfs: move the csum helpers into ctree.h 2022-12-05 18:00:58 +01:00
defrag.c btrfs: fix an error handling path in btrfs_defrag_leaves() 2022-12-15 19:16:50 +01:00
defrag.h btrfs: move defrag related prototypes to their own header 2022-12-05 18:00:46 +01:00
delalloc-space.c btrfs: update function comments 2022-12-05 18:00:45 +01:00
delalloc-space.h btrfs: move delalloc space related prototypes to delalloc-space.h 2022-12-05 18:00:44 +01:00
delayed-inode.c btrfs: pass btrfs_inode to btrfs_inode_unlock 2022-12-05 18:00:53 +01:00
delayed-inode.h btrfs: extend btrfs_dir_item type to store encryption status 2022-12-05 18:00:43 +01:00
delayed-ref.c btrfs: update function comments 2022-12-05 18:00:45 +01:00
delayed-ref.h btrfs: remove btrfs_delayed_extent_op::is_data 2022-05-16 17:17:31 +02:00
dev-replace.c btrfs: use btrfs_dev_name() helper to handle missing devices better 2022-12-05 18:00:57 +01:00
dev-replace.h btrfs: move dev-replace prototypes into dev-replace.h 2022-12-05 18:00:47 +01:00
dir-item.c btrfs: move dir-item prototypes into dir-item.h 2022-12-05 18:00:46 +01:00
dir-item.h btrfs: move dir-item prototypes into dir-item.h 2022-12-05 18:00:46 +01:00
discard.c btrfs: update function comments 2022-12-05 18:00:45 +01:00
discard.h btrfs: cleanup btrfs_discard_update_discardable usage 2020-12-08 15:54:02 +01:00
disk-io.c btrfs: fix compat_ro checks against remount 2023-01-03 16:22:13 +01:00
disk-io.h btrfs: fix compat_ro checks against remount 2023-01-03 16:22:13 +01:00
export.c btrfs: move super_block specific helpers into super.h 2022-12-05 18:00:47 +01:00
export.h btrfs: simplify generation check in btrfs_get_dentry 2022-12-05 18:00:41 +01:00
extent_io.c btrfs: fix false alert on bad tree level check 2023-01-03 15:53:18 +01:00
extent_io.h btrfs: move eb offset helpers into extent_io.h 2022-12-05 18:00:58 +01:00
extent_map.c btrfs: remove no longer used btrfs_next_extent_map() 2022-12-05 18:00:56 +01:00
extent_map.h btrfs: remove no longer used btrfs_next_extent_map() 2022-12-05 18:00:56 +01:00
extent-io-tree.c btrfs: fix off-by-one in delalloc search during lseek 2023-01-03 15:53:18 +01:00
extent-io-tree.h btrfs: allow passing a cached state record to count_range_bits() 2022-12-05 18:00:56 +01:00
extent-tree.c btrfs: always report error in run_one_delayed_ref() 2023-01-03 16:22:10 +01:00
extent-tree.h btrfs: move the snapshot drop related prototypes to extent-tree.h 2022-12-05 18:00:46 +01:00
file-item.c btrfs: split the bio submission path into a separate file 2022-12-05 18:00:57 +01:00
file-item.h btrfs: move file_extent_item helpers into file-item.h 2022-12-05 18:00:58 +01:00
file.c btrfs: fix off-by-one in delalloc search during lseek 2023-01-03 15:53:18 +01:00
file.h btrfs: use cached state when looking for delalloc ranges with fiemap 2022-12-05 18:00:56 +01:00
free-space-cache.c btrfs: pass btrfs_inode to btrfs_add_delayed_iput 2022-12-05 18:00:55 +01:00
free-space-cache.h btrfs: convert discard stat defs to enum 2022-12-05 18:00:45 +01:00
free-space-tree.c btrfs: convert btrfs_block_group::needs_free_space to runtime flag 2022-12-05 18:00:51 +01:00
free-space-tree.h btrfs: rename btrfs_block_group_cache 2019-11-18 17:51:51 +01:00
fs.c btrfs: move accessor helpers into accessors.h 2022-12-05 18:00:42 +01:00
fs.h btrfs: remove the unused endio_raid56_workers and btrfs_raid_bio::end_io_work 2022-12-05 18:00:49 +01:00
inode-item.c btrfs: move file-item prototypes into their own header 2022-12-05 18:00:46 +01:00
inode-item.h btrfs: use struct fscrypt_str instead of struct qstr 2022-12-05 18:00:43 +01:00
inode.c btrfs: fix ASSERT em->len condition in btrfs_get_extent 2023-01-03 15:53:18 +01:00
ioctl.c btrfs: replace strncpy() with strscpy() 2022-12-05 18:00:59 +01:00
ioctl.h btrfs: move ioctl prototypes into ioctl.h 2022-12-05 18:00:46 +01:00
Kconfig btrfs: use generic Kconfig option for 256kB page size limit 2022-01-20 08:52:55 +02:00
locking.c btrfs: move accessor helpers into accessors.h 2022-12-05 18:00:42 +01:00
locking.h btrfs: move the lockdep helpers into locking.h 2022-12-05 18:00:44 +01:00
lzo.c btrfs: constify input buffer parameter in compression code 2022-12-05 18:00:55 +01:00
Makefile btrfs: split the bio submission path into a separate file 2022-12-05 18:00:57 +01:00
messages.c btrfs: move super_block specific helpers into super.h 2022-12-05 18:00:47 +01:00
messages.h btrfs: print transaction aborted messages with an error level 2022-12-05 18:00:59 +01:00
misc.h btrfs: simplify percent calculation helpers, rename div_factor 2022-12-05 18:00:48 +01:00
ordered-data.c btrfs: pass btrfs_inode to btrfs_add_delayed_iput 2022-12-05 18:00:55 +01:00
ordered-data.h btrfs: use cached_state for btrfs_check_nocow_lock 2022-12-05 18:00:36 +01:00
orphan.c btrfs: move orphan prototypes into orphan.h 2022-12-05 18:00:47 +01:00
orphan.h btrfs: move orphan prototypes into orphan.h 2022-12-05 18:00:47 +01:00
print-tree.c btrfs: move struct btrfs_tree_parent_check out of disk-io.h 2022-12-05 18:00:57 +01:00
print-tree.h btrfs: print the actual offset in btrfs_root_name 2021-01-07 17:25:05 +01:00
props.c btrfs: move super_block specific helpers into super.h 2022-12-05 18:00:47 +01:00
props.h btrfs: make module init/exit match their sequence 2022-12-05 18:00:40 +01:00
qgroup.c btrfs: restore BTRFS_SEQ_LAST when looking up qgroup backref lookup 2022-12-15 19:16:57 +01:00
qgroup.h btrfs: sink gfp_t parameter to btrfs_qgroup_trace_extent 2022-12-05 18:00:43 +01:00
raid56.c btrfs: scrub: fix uninitialized return value in recover_scrub_rbio 2022-12-20 19:43:45 +01:00
raid56.h btrfs: raid56: prepare data checksums for later RMW verification 2022-12-05 18:00:57 +01:00
rcu-string.h btrfs: replace strncpy() with strscpy() 2022-12-05 18:00:59 +01:00
ref-verify.c btrfs: move accessor helpers into accessors.h 2022-12-05 18:00:42 +01:00
ref-verify.h btrfs: ref-verify: Use btrfs_ref to refactor btrfs_ref_tree_mod() 2019-04-29 19:02:49 +02:00
reflink.c btrfs: pass btrfs_inode to btrfs_inode_unlock 2022-12-05 18:00:53 +01:00
reflink.h Btrfs: move all reflink implementation code into its own file 2020-03-23 17:01:54 +01:00
relocation.c btrfs: split the bio submission path into a separate file 2022-12-05 18:00:57 +01:00
relocation.h btrfs: move relocation prototypes into relocation.h 2022-12-05 18:00:47 +01:00
root-tree.c btrfs: move orphan prototypes into orphan.h 2022-12-05 18:00:47 +01:00
root-tree.h btrfs: move root tree prototypes to their own header 2022-12-05 18:00:44 +01:00
scrub.c btrfs: introduce a bitmap based csum range search function 2022-12-05 18:00:57 +01:00
scrub.h btrfs: move scrub prototypes into scrub.h 2022-12-05 18:00:47 +01:00
send.c btrfs: send: bump the extent reference count limit for backref walking 2022-12-05 18:00:51 +01:00
send.h btrfs: send add define for v2 buffer size 2022-12-05 18:00:41 +01:00
space-info.c btrfs: simplify percent calculation helpers, rename div_factor 2022-12-05 18:00:48 +01:00
space-info.h btrfs: move btrfs_account_ro_block_groups_free_space into space-info.c 2022-12-05 18:00:44 +01:00
subpage.c btrfs: move the printk helpers out of ctree.h 2022-12-05 18:00:41 +01:00
subpage.h btrfs: make nodesize >= PAGE_SIZE case to reuse the non-subpage routine 2022-05-16 17:03:11 +02:00
super.c btrfs: fix compat_ro checks against remount 2023-01-03 16:22:13 +01:00
super.h btrfs: move super_block specific helpers into super.h 2022-12-05 18:00:47 +01:00
sysfs.c btrfs: simplify percent calculation helpers, rename div_factor 2022-12-05 18:00:48 +01:00
sysfs.h btrfs: split and refactor btrfs_sysfs_remove_devices_dir 2020-10-07 12:12:21 +02:00
transaction.c btrfs: drop private_data parameter from extent_io_tree_init 2022-12-05 18:00:54 +01:00
transaction.h btrfs: remove fs_info::pending_changes and related code 2022-12-05 18:00:42 +01:00
tree-checker.c btrfs: pass the extent buffer for the btrfs_item_nr helpers 2022-12-05 18:00:58 +01:00
tree-checker.h btrfs: move struct btrfs_tree_parent_check out of disk-io.h 2022-12-05 18:00:57 +01:00
tree-log.c btrfs: fix fscrypt name leak after failure to join log transaction 2022-12-20 19:43:47 +01:00
tree-log.h btrfs: use struct fscrypt_str instead of struct qstr 2022-12-05 18:00:43 +01:00
tree-mod-log.c btrfs: add eb to btrfs_node_key_ptr_offset 2022-12-05 18:00:58 +01:00
tree-mod-log.h btrfs: fix SPDX comment in tree-mod-log.h 2022-12-05 18:00:48 +01:00
ulist.c btrfs: constify ulist parameter of ulist_next() 2022-12-05 18:00:50 +01:00
ulist.h btrfs: constify ulist parameter of ulist_next() 2022-12-05 18:00:50 +01:00
uuid-tree.c btrfs: move uuid tree prototypes to uuid-tree.h 2022-12-05 18:00:46 +01:00
uuid-tree.h btrfs: move uuid tree prototypes to uuid-tree.h 2022-12-05 18:00:46 +01:00
verity.c btrfs: move orphan prototypes into orphan.h 2022-12-05 18:00:47 +01:00
verity.h btrfs: move verity prototypes into verity.h 2022-12-05 18:00:47 +01:00
volumes.c btrfs: fix extent map use-after-free when handling missing device in read_one_chunk 2022-12-05 18:00:59 +01:00
volumes.h btrfs: split the bio submission path into a separate file 2022-12-05 18:00:57 +01:00
xattr.c btrfs: move dir-item prototypes into dir-item.h 2022-12-05 18:00:46 +01:00
xattr.h
zlib.c btrfs: constify input buffer parameter in compression code 2022-12-05 18:00:55 +01:00
zoned.c btrfs: convert btrfs_block_group::seq_zone to runtime flag 2022-12-05 18:00:51 +01:00
zoned.h btrfs: move the printk helpers out of ctree.h 2022-12-05 18:00:41 +01:00
zstd.c btrfs: constify input buffer parameter in compression code 2022-12-05 18:00:55 +01:00