loop0: detected capacity change from 0 to 64
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.0/5318 is trying to acquire lock:
ffff88801267c0b0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x300 fs/hfs/bfind.c:-1

but task is already holding lock:
ffff88801267c0b0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x300 fs/hfs/bfind.c:-1

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&tree->tree_lock/1);
  lock(&tree->tree_lock/1);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

5 locks held by syz.0.0/5318:
 #0: ffff88801f4da420 (sb_writers#12){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2681 [inline]
 #0: ffff88801f4da420 (sb_writers#12){.+.+}-{0:0}, at: vfs_write+0x227/0xb90 fs/read_write.c:682
 #1: ffff888033709620 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
 #1: ffff888033709620 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: generic_file_write_iter+0x11e/0x680 mm/filemap.c:4454
 #2: ffff888033709478 (&HFS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xf2/0x15e0 fs/hfs/extent.c:397
 #3: ffff88801267c0b0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x300 fs/hfs/bfind.c:-1
 #4: ffff8880337080f8 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xf2/0x15e0 fs/hfs/extent.c:397

stack backtrace:
CPU: 0 UID: 0 PID: 5318 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041
 check_deadlock kernel/locking/lockdep.c:3093 [inline]
 validate_chain kernel/locking/lockdep.c:3895 [inline]
 __lock_acquire+0x253f/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:614 [inline]
 __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
 hfs_find_init+0x18e/0x300 fs/hfs/bfind.c:-1
 hfs_ext_read_extent fs/hfs/extent.c:200 [inline]
 hfs_extend_file+0x35c/0x15e0 fs/hfs/extent.c:401
 hfs_bmap_reserve+0x107/0x430 fs/hfs/btree.c:269
 __hfs_ext_write_extent+0x1fa/0x470 fs/hfs/extent.c:121
 __hfs_ext_cache_extent+0x6b/0x9b0 fs/hfs/extent.c:174
 hfs_ext_read_extent fs/hfs/extent.c:202 [inline]
 hfs_extend_file+0x39b/0x15e0 fs/hfs/extent.c:401
 hfs_get_block+0x412/0xc50 fs/hfs/extent.c:353
 __block_write_begin_int+0x6c6/0x1910 fs/buffer.c:2145
 block_write_begin fs/buffer.c:2256 [inline]
 cont_write_begin+0x737/0xae0 fs/buffer.c:2594
 hfs_write_begin+0x66/0xb0 fs/hfs/inode.c:53
 generic_perform_write+0x2e2/0x8f0 mm/filemap.c:4314
 generic_file_write_iter+0x14a/0x680 mm/filemap.c:4457
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x61d/0xb90 fs/read_write.c:686
 ksys_pwrite64 fs/read_write.c:793 [inline]
 __do_sys_pwrite64 fs/read_write.c:801 [inline]
 __se_sys_pwrite64 fs/read_write.c:798 [inline]
 __x64_sys_pwrite64+0x199/0x230 fs/read_write.c:798
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd8e659acb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd8e7416028 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007fd8e6815fa0 RCX: 00007fd8e659acb9
RDX: 00000000200000c1 RSI: 00002000000000c0 RDI: 0000000000000004
RBP: 00007fd8e6608bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000009000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd8e6816038 R14: 00007fd8e6815fa0 R15: 00007ffc97796d78
 </TASK>