loop2: detected capacity change from 0 to 64
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.1318/12057 is trying to acquire lock:
ffff88801fa260b0 (&tree->tree_lock#2/1){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x2c0

but task is already holding lock:
ffff88803913cef8 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xda/0x14c0

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}:
       lock_acquire+0x120/0x360
       __mutex_lock+0x187/0x1350
       hfs_extend_file+0xda/0x14c0
       hfs_bmap_reserve+0x107/0x430
       __hfs_ext_write_extent+0x1fa/0x470
       __hfs_ext_cache_extent+0x6b/0x9b0
       hfs_extend_file+0x31e/0x14c0
       hfs_get_block+0x3d7/0xbd0
       __block_write_begin_int+0x6b5/0x1900
       cont_write_begin+0x789/0xb50
       hfs_write_begin+0x66/0xb0
       cont_write_begin+0x2fd/0xb50
       hfs_write_begin+0x66/0xb0
       hfs_file_truncate+0x19d/0xad0
       hfs_inode_setattr+0x4a9/0x670
       notify_change+0xb36/0xe40
       do_truncate+0x1a4/0x220
       do_ftruncate+0x489/0x540
       __x64_sys_ftruncate+0x92/0xf0
       do_syscall_64+0xfa/0x3b0
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&tree->tree_lock#2/1){+.+.}-{4:4}:
       validate_chain+0xb9b/0x2140
       __lock_acquire+0xab9/0xd20
       lock_acquire+0x120/0x360
       __mutex_lock+0x187/0x1350
       hfs_find_init+0x18e/0x2c0
       hfs_extend_file+0x2f6/0x14c0
       hfs_bmap_reserve+0x107/0x430
       hfs_cat_create+0x1c5/0x730
       hfs_mkdir+0x6c/0xe0
       vfs_mkdir+0x306/0x510
       do_mkdirat+0x247/0x590
       __x64_sys_mkdirat+0x87/0xa0
       do_syscall_64+0xfa/0x3b0
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&HFS_I(tree->inode)->extents_lock);
                               lock(&tree->tree_lock#2/1);
                               lock(&HFS_I(tree->inode)->extents_lock);
  lock(&tree->tree_lock#2/1);

 *** DEADLOCK ***

4 locks held by syz.2.1318/12057:
 #0: ffff88801b7b6428 (sb_writers#26){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90
 #1: ffff88803913ca20 (&type->i_mutex_dir_key#23/1){+.+.}-{4:4}, at: filename_create+0x1f8/0x3c0
 #2: ffff88810acca0b0 (&tree->tree_lock#2){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x2c0
 #3: ffff88803913cef8 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xda/0x14c0

stack backtrace:
CPU: 0 UID: 0 PID: 12057 Comm: syz.2.1318 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 print_circular_bug+0x2ee/0x310
 check_noncircular+0x134/0x160
 validate_chain+0xb9b/0x2140
 __lock_acquire+0xab9/0xd20
 lock_acquire+0x120/0x360
 __mutex_lock+0x187/0x1350
 hfs_find_init+0x18e/0x2c0
 hfs_extend_file+0x2f6/0x14c0
 hfs_bmap_reserve+0x107/0x430
 hfs_cat_create+0x1c5/0x730
 hfs_mkdir+0x6c/0xe0
 vfs_mkdir+0x306/0x510
 do_mkdirat+0x247/0x590
 __x64_sys_mkdirat+0x87/0xa0
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f76aff8d497
Code: 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 02 01 00 00 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:00007f76b0e6ae68 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f76b0e6aef0 RCX: 00007f76aff8d497
RDX: 00000000000001ff RSI: 00002000000001c0 RDI: 00000000ffffff9c
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00002000000001c0
R13: 00007f76b0e6aeb0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
