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Josef Bacik 339f26ffdf btrfs: fix lockdep splat in btrfs_recover_relocation 
commit fb286100974e7239af243bc2255a52f29442f9c8 upstream.

While testing the error paths of relocation I hit the following lockdep
splat:

  ======================================================
  WARNING: possible circular locking dependency detected
  5.10.0-rc6+ #217 Not tainted
  ------------------------------------------------------
  mount/779 is trying to acquire lock:
  ffffa0e676945418 (&fs_info->balance_mutex){+.+.}-{3:3}, at: btrfs_recover_balance+0x2f0/0x340

  but task is already holding lock:
  ffffa0e60ee31da8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x27/0x100

  which lock already depends on the new lock.

  the existing dependency chain (in reverse order) is:

  -> #2 (btrfs-root-00){++++}-{3:3}:
	 down_read_nested+0x43/0x130
	 __btrfs_tree_read_lock+0x27/0x100
	 btrfs_read_lock_root_node+0x31/0x40
	 btrfs_search_slot+0x462/0x8f0
	 btrfs_update_root+0x55/0x2b0
	 btrfs_drop_snapshot+0x398/0x750
	 clean_dirty_subvols+0xdf/0x120
	 btrfs_recover_relocation+0x534/0x5a0
	 btrfs_start_pre_rw_mount+0xcb/0x170
	 open_ctree+0x151f/0x1726
	 btrfs_mount_root.cold+0x12/0xea
	 legacy_get_tree+0x30/0x50
	 vfs_get_tree+0x28/0xc0
	 vfs_kern_mount.part.0+0x71/0xb0
	 btrfs_mount+0x10d/0x380
	 legacy_get_tree+0x30/0x50
	 vfs_get_tree+0x28/0xc0
	 path_mount+0x433/0xc10
	 __x64_sys_mount+0xe3/0x120
	 do_syscall_64+0x33/0x40
	 entry_SYSCALL_64_after_hwframe+0x44/0xa9

  -> #1 (sb_internal#2){.+.+}-{0:0}:
	 start_transaction+0x444/0x700
	 insert_balance_item.isra.0+0x37/0x320
	 btrfs_balance+0x354/0xf40
	 btrfs_ioctl_balance+0x2cf/0x380
	 __x64_sys_ioctl+0x83/0xb0
	 do_syscall_64+0x33/0x40
	 entry_SYSCALL_64_after_hwframe+0x44/0xa9

  -> #0 (&fs_info->balance_mutex){+.+.}-{3:3}:
	 __lock_acquire+0x1120/0x1e10
	 lock_acquire+0x116/0x370
	 __mutex_lock+0x7e/0x7b0
	 btrfs_recover_balance+0x2f0/0x340
	 open_ctree+0x1095/0x1726
	 btrfs_mount_root.cold+0x12/0xea
	 legacy_get_tree+0x30/0x50
	 vfs_get_tree+0x28/0xc0
	 vfs_kern_mount.part.0+0x71/0xb0
	 btrfs_mount+0x10d/0x380
	 legacy_get_tree+0x30/0x50
	 vfs_get_tree+0x28/0xc0
	 path_mount+0x433/0xc10
	 __x64_sys_mount+0xe3/0x120
	 do_syscall_64+0x33/0x40
	 entry_SYSCALL_64_after_hwframe+0x44/0xa9

  other info that might help us debug this:

  Chain exists of:
    &fs_info->balance_mutex --> sb_internal#2 --> btrfs-root-00

   Possible unsafe locking scenario:

	 CPU0                    CPU1
	 ----                    ----
    lock(btrfs-root-00);
				 lock(sb_internal#2);
				 lock(btrfs-root-00);
    lock(&fs_info->balance_mutex);

   *** DEADLOCK ***

  2 locks held by mount/779:
   #0: ffffa0e60dc040e0 (&type->s_umount_key#47/1){+.+.}-{3:3}, at: alloc_super+0xb5/0x380
   #1: ffffa0e60ee31da8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x27/0x100

  stack backtrace:
  CPU: 0 PID: 779 Comm: mount Not tainted 5.10.0-rc6+ #217
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
  Call Trace:
   dump_stack+0x8b/0xb0
   check_noncircular+0xcf/0xf0
   ? trace_call_bpf+0x139/0x260
   __lock_acquire+0x1120/0x1e10
   lock_acquire+0x116/0x370
   ? btrfs_recover_balance+0x2f0/0x340
   __mutex_lock+0x7e/0x7b0
   ? btrfs_recover_balance+0x2f0/0x340
   ? btrfs_recover_balance+0x2f0/0x340
   ? rcu_read_lock_sched_held+0x3f/0x80
   ? kmem_cache_alloc_trace+0x2c4/0x2f0
   ? btrfs_get_64+0x5e/0x100
   btrfs_recover_balance+0x2f0/0x340
   open_ctree+0x1095/0x1726
   btrfs_mount_root.cold+0x12/0xea
   ? rcu_read_lock_sched_held+0x3f/0x80
   legacy_get_tree+0x30/0x50
   vfs_get_tree+0x28/0xc0
   vfs_kern_mount.part.0+0x71/0xb0
   btrfs_mount+0x10d/0x380
   ? __kmalloc_track_caller+0x2f2/0x320
   legacy_get_tree+0x30/0x50
   vfs_get_tree+0x28/0xc0
   ? capable+0x3a/0x60
   path_mount+0x433/0xc10
   __x64_sys_mount+0xe3/0x120
   do_syscall_64+0x33/0x40
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

This is straightforward to fix, simply release the path before we setup
the balance_ctl.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-27 11:05:35 +01:00
..
tests
Btrfs: fix selftests failure due to uninitialized i_mode in test inodes
2020-08-05 10:06:00 +02:00
acl.c
Btrfs: setup a nofs context for memory allocation at __btrfs_set_acl
2019-03-23 20:10:00 +01:00
async-thread.c
Btrfs: fix crash during unmount due to race with delayed inode workers
2020-04-17 10:48:49 +02:00
async-thread.h
Btrfs: fix crash during unmount due to race with delayed inode workers
2020-04-17 10:48:49 +02:00
backref.c
btrfs: fix double free on ulist after backref resolution failure
2020-07-29 10:16:47 +02:00
backref.h
btrfs: replace GPL boilerplate by SPDX -- headers
2018-04-12 16:29:46 +02:00
btrfs_inode.h
btrfs: use tagged writepage to mitigate livelock of snapshot
2019-02-12 19:47:11 +01:00
check-integrity.c
btrfs: fix possible NULL-pointer dereference in integrity checks
2020-02-24 08:34:49 +01:00
check-integrity.h
btrfs: replace GPL boilerplate by SPDX -- headers
2018-04-12 16:29:46 +02:00
compression.c
btrfs: correctly validate compression type
2019-09-16 08:22:19 +02:00
compression.h
btrfs: correctly validate compression type
2019-09-16 08:22:19 +02:00
ctree.c
btrfs: cleanup cow block on error
2020-11-05 11:08:48 +01:00
ctree.h
btrfs: tree-checker: Verify inode item
2020-11-10 12:35:56 +01:00
dedupe.h
btrfs: replace GPL boilerplate by SPDX -- headers
2018-04-12 16:29:46 +02:00
delayed-inode.c
btrfs: qgroup: fix wrong qgroup metadata reserve for delayed inode
2020-11-05 11:08:47 +01:00
delayed-inode.h
btrfs: Remove fs_info from btrfs_delete_delayed_dir_index
2018-08-06 13:13:00 +02:00
delayed-ref.c
Btrfs: fix race between adding and putting tree mod seq elements and nodes
2020-02-11 04:34:06 -08:00
delayed-ref.h
btrfs: Remove fs_info from btrfs_add_delayed_data_ref
2018-08-06 13:12:34 +02:00
dev-replace.c
btrfs: dev-replace: fail mount if we don't have replace item with target device
2020-11-18 19:18:48 +01:00
dev-replace.h
btrfs: replace GPL boilerplate by SPDX -- headers
2018-04-12 16:29:46 +02:00
dir-item.c
btrfs: Remove fs_info from btrfs_insert_delayed_dir_index
2018-08-06 13:13:00 +02:00
disk-io.c
btrfs: fix space cache memory leak after transaction abort
2020-09-03 11:24:26 +02:00
disk-io.h
btrfs: Check the first key and level for cached extent buffer
2019-05-22 07:37:42 +02:00
export.c
btrfs: export helpers for subvolume name/id resolution
2020-08-26 10:30:58 +02:00
export.h
btrfs: export helpers for subvolume name/id resolution
2020-08-26 10:30:58 +02:00
extent_io.c
Btrfs: fix missing error return if writeback for extent buffer never started
2020-11-18 19:18:43 +01:00
extent_io.h
btrfs: fix potential deadlock in the search ioctl
2020-09-09 19:04:29 +02:00
extent_map.c
Btrfs: fix race between using extent maps and merging them
2020-02-19 19:51:56 +01:00
extent_map.h
btrfs: use fs_info for btrfs_handle_em_exist tracepoint
2018-05-28 18:07:17 +02:00
extent-tree.c
btrfs: don't force read-only after error in drop snapshot
2020-10-01 13:14:46 +02:00
file-item.c
btrfs: do not ignore error from btrfs_next_leaf() when inserting checksums
2020-06-22 09:05:11 +02:00
file.c
btrfs: file: reserve qgroup space after the hole punch range is locked
2020-09-03 11:24:22 +02:00
free-space-cache.c
btrfs: fix space cache memory leak after transaction abort
2020-09-03 11:24:26 +02:00
free-space-cache.h
btrfs: replace GPL boilerplate by SPDX -- headers
2018-04-12 16:29:46 +02:00
free-space-tree.c
btrfs: Remove fs_info from btrfs_del_root
2018-08-06 13:13:00 +02:00
free-space-tree.h
btrfs: Remove fs_info argument from add_to_free_space_tree
2018-05-28 18:07:36 +02:00
inode-item.c
btrfs: replace GPL boilerplate by SPDX -- sources
2018-04-12 16:29:51 +02:00
inode-map.c
Btrfs: fix inode cache waiters hanging on path allocation failure
2020-01-27 14:51:12 +01:00
inode-map.h
btrfs: replace GPL boilerplate by SPDX -- headers
2018-04-12 16:29:46 +02:00
inode.c
btrfs: qgroup: fix data leak caused by race between writeback and truncate
2020-10-01 13:14:49 +02:00
ioctl.c
btrfs: fix potential overflow in cluster_pages_for_defrag on 32bit arch
2020-11-18 19:18:49 +01:00
Kconfig
btrfs: add SPDX header to Kconfig
2018-04-12 16:29:55 +02:00
locking.c
btrfs: replace waitqueue_actvie with cond_wake_up
2018-05-28 18:23:09 +02:00
locking.h
btrfs: replace GPL boilerplate by SPDX -- headers
2018-04-12 16:29:46 +02:00
lzo.c
btrfs: lzo: Harden inline lzo compressed extent decompression
2018-05-30 16:46:43 +02:00
Makefile
btrfs: Remove custom crc32c init code
2018-03-26 15:09:39 +02:00
math.h
btrfs: replace GPL boilerplate by SPDX -- headers
2018-04-12 16:29:46 +02:00
ordered-data.c
Btrfs: fix btrfs_wait_ordered_range() so that it waits for all ordered extents
2020-02-28 16:38:58 +01:00
ordered-data.h
btrfs: remove remaing full_sync logic from btrfs_sync_file
2018-08-06 13:12:31 +02:00
orphan.c
btrfs: replace GPL boilerplate by SPDX -- sources
2018-04-12 16:29:51 +02:00
print-tree.c
btrfs: require only sector size alignment for parent eb bytenr
2020-09-17 13:45:28 +02:00
print-tree.h
btrfs: print-tree: debugging output enhancement
2018-04-20 19:18:16 +02:00
props.c
btrfs: correctly validate compression type
2019-09-16 08:22:19 +02:00
props.h
btrfs: replace GPL boilerplate by SPDX -- headers
2018-04-12 16:29:46 +02:00
qgroup.c
btrfs: fix transaction leak and crash after RO remount caused by qgroup rescan
2021-01-19 18:22:36 +01:00
qgroup.h
btrfs: qgroup: Avoid calling qgroup functions if qgroup is not enabled
2018-11-13 11:08:56 -08:00
raid56.c
btrfs: raid56: properly unmap parity page in finish_parity_scrub()
2019-04-03 06:26:21 +02:00
raid56.h
btrfs: replace GPL boilerplate by SPDX -- headers
2018-04-12 16:29:46 +02:00
rcu-string.h
btrfs: replace GPL boilerplate by SPDX -- headers
2018-04-12 16:29:46 +02:00
reada.c
btrfs: fix use-after-free on readahead extent after failure to create it
2020-11-05 11:08:48 +01:00
ref-verify.c
btrfs: ref-verify: fix memory leak in btrfs_ref_tree_mod
2020-11-18 19:18:48 +01:00
ref-verify.h
btrfs: replace GPL boilerplate by SPDX -- headers
2018-04-12 16:29:46 +02:00
relocation.c
btrfs: check commit root generation in should_ignore_root
2020-04-21 09:03:09 +02:00
root-tree.c
btrfs: do not delete mismatched root refs
2020-01-23 08:21:31 +01:00
scrub.c
btrfs: merge btrfs_find_device and find_device
2020-06-22 09:04:59 +02:00
send.c
btrfs: send: fix wrong file path when there is an inode with a pending rmdir
2021-01-12 20:10:24 +01:00
send.h
btrfs: replace GPL boilerplate by SPDX -- headers
2018-04-12 16:29:46 +02:00
struct-funcs.c
btrfs: prune unused includes
2018-08-06 13:12:43 +02:00
super.c
btrfs: fix transaction leak and crash after RO remount caused by qgroup rescan
2021-01-19 18:22:36 +01:00
sysfs.c
btrfs: sysfs: use NOFS for device creation
2020-08-26 10:30:59 +02:00
sysfs.h
btrfs: sysfs: Use enum/define value for feature array definitions
2018-05-28 18:23:39 +02:00
transaction.c
btrfs: transaction: Avoid deadlock due to bad initialization timing of fs_info::journal_info
2020-05-06 08:13:33 +02:00
transaction.h
Btrfs: fix deadlock between fiemap and transaction commits
2019-08-25 10:47:54 +02:00
tree-checker.c
btrfs: tree-checker: fix the error message for transid error
2020-11-10 12:35:57 +01:00
tree-checker.h
btrfs: Move btrfs_check_chunk_valid() to tree-check.[ch] and export it
2020-11-10 12:35:56 +01:00
tree-defrag.c
btrfs: replace GPL boilerplate by SPDX -- sources
2018-04-12 16:29:51 +02:00
tree-log.c
btrfs: reschedule if necessary when logging directory items
2020-11-05 11:08:48 +01:00
tree-log.h
Btrfs: sync log after logging new name
2018-08-23 17:37:26 +02:00
ulist.c
btrfs: replace GPL boilerplate by SPDX -- sources
2018-04-12 16:29:51 +02:00
ulist.h
btrfs: replace GPL boilerplate by SPDX -- headers
2018-04-12 16:29:46 +02:00
uuid-tree.c
btrfs: handle ENOENT in btrfs_uuid_tree_iterate
2019-12-31 16:34:44 +01:00
volumes.c
btrfs: fix lockdep splat in btrfs_recover_relocation
2021-01-27 11:05:35 +01:00
volumes.h
btrfs: tree-checker: Verify dev item
2020-11-10 12:35:56 +01:00
xattr.c
Btrfs: use nofs context when initializing security xattrs to avoid deadlock
2019-01-16 22:04:37 +01:00
xattr.h
btrfs: replace GPL boilerplate by SPDX -- headers
2018-04-12 16:29:46 +02:00
zlib.c
btrfs: replace GPL boilerplate by SPDX -- sources
2018-04-12 16:29:51 +02:00
zstd.c
btrfs: replace GPL boilerplate by SPDX -- sources
2018-04-12 16:29:51 +02:00