loop0: detected capacity change from 0 to 64
============================================
WARNING: possible recursive locking detected
6.15.0-rc5-syzkaller-00043-gd76bb1ebb558 #0 Not tainted
--------------------------------------------
syz.0.0/5318 is trying to acquire lock:
ffff888034f4a0b0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x165/0x1e0 fs/hfs/bfind.c:-1

but task is already holding lock:
ffff888034f4a0b0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x165/0x1e0 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: ffff88803f40a420 (sb_writers#12){.+.+}-{0:0}, at: do_ftruncate+0x42a/0x540 fs/open.c:191
 #1: ffff888052a59ca0 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
 #1: ffff888052a59ca0 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: do_truncate+0x186/0x220 fs/open.c:63
 #2: ffff888052a59af8 (&HFS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xda/0x1230 fs/hfs/extent.c:397
 #3: ffff888034f4a0b0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x165/0x1e0 fs/hfs/bfind.c:-1
 #4: ffff888052a580f8 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xda/0x1230 fs/hfs/extent.c:397

stack backtrace:
CPU: 0 UID: 0 PID: 5318 Comm: syz.0.0 Not tainted 6.15.0-rc5-syzkaller-00043-gd76bb1ebb558 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_deadlock_bug+0x28b/0x2a0 kernel/locking/lockdep.c:3042
 check_deadlock kernel/locking/lockdep.c:3094 [inline]
 validate_chain+0x1a3f/0x2140 kernel/locking/lockdep.c:3896
 __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
 __mutex_lock_common kernel/locking/mutex.c:601 [inline]
 __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:746
 hfs_find_init+0x165/0x1e0 fs/hfs/bfind.c:-1
 hfs_ext_read_extent fs/hfs/extent.c:200 [inline]
 hfs_extend_file+0x2ee/0x1230 fs/hfs/extent.c:401
 hfs_bmap_reserve+0x107/0x430 fs/hfs/btree.c:234
 __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+0x316/0x1230 fs/hfs/extent.c:401
 hfs_get_block+0x3d7/0xbd0 fs/hfs/extent.c:353
 __block_write_begin_int+0x6b2/0x1900 fs/buffer.c:2151
 block_write_begin fs/buffer.c:2262 [inline]
 cont_write_begin+0x789/0xb50 fs/buffer.c:2601
 hfs_write_begin+0x66/0xb0 fs/hfs/inode.c:52
 cont_expand_zero fs/buffer.c:2528 [inline]
 cont_write_begin+0x2fa/0xb50 fs/buffer.c:2591
 hfs_write_begin+0x66/0xb0 fs/hfs/inode.c:52
 hfs_file_truncate+0x190/0x9c0 fs/hfs/extent.c:494
 hfs_inode_setattr+0x4a9/0x670 fs/hfs/inode.c:654
 notify_change+0xb33/0xe40 fs/attr.c:552
 do_truncate+0x19a/0x220 fs/open.c:65
 do_ftruncate+0x489/0x540 fs/open.c:192
 do_sys_ftruncate fs/open.c:207 [inline]
 __do_sys_ftruncate fs/open.c:212 [inline]
 __se_sys_ftruncate fs/open.c:210 [inline]
 __x64_sys_ftruncate+0x92/0xf0 fs/open.c:210
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff7b958e969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff7ba3d2038 EFLAGS: 00000246 ORIG_RAX: 000000000000004d
RAX: ffffffffffffffda RBX: 00007ff7b97b5fa0 RCX: 00007ff7b958e969
RDX: 0000000000000000 RSI: 0000000002007ffc RDI: 0000000000000008
RBP: 00007ff7b9610ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007ff7b97b5fa0 R15: 00007ffedd2ed218
 </TASK>