loop2: detected capacity change from 0 to 64
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.1603/14771 is trying to acquire lock:
ffff88802829e0b0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x184/0x200

but task is already holding lock:
ffff88810a9ecef8 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xda/0x1230

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/0x1230
       hfs_bmap_reserve+0x107/0x430
       __hfs_ext_write_extent+0x1fa/0x470
       hfs_ext_write_extent+0x161/0x1e0
       hfs_write_inode+0x91/0x7d0
       __writeback_single_inode+0x6f1/0xff0
       writeback_sb_inodes+0x6c7/0x1010
       wb_writeback+0x43b/0xaf0
       wb_workfn+0x409/0xef0
       process_scheduled_works+0xae1/0x17b0
       worker_thread+0x8a0/0xda0
       kthread+0x711/0x8a0
       ret_from_fork+0x439/0x7d0
       ret_from_fork_asm+0x1a/0x30

-> #0 (&tree->tree_lock/1){+.+.}-{4:4}:
       validate_chain+0xb9b/0x2140
       __lock_acquire+0xab9/0xd20
       lock_acquire+0x120/0x360
       __mutex_lock+0x187/0x1350
       hfs_find_init+0x184/0x200
       hfs_extend_file+0x2ee/0x1230
       hfs_bmap_reserve+0x107/0x430
       hfs_cat_create+0x1b3/0x640
       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/1);
                               lock(&HFS_I(tree->inode)->extents_lock);
  lock(&tree->tree_lock/1);

 *** DEADLOCK ***

4 locks held by syz.2.1603/14771:
 #0: ffff88803b48e428 (sb_writers#14){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90
 #1: ffff88810a9ef7a0 (&type->i_mutex_dir_key#11/1){+.+.}-{4:4}, at: filename_create+0x1f8/0x3c0
 #2: ffff88802829c0b0 (&tree->tree_lock){+.+.}-{4:4}, at: hfs_find_init+0x184/0x200
 #3: ffff88810a9ecef8 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xda/0x1230

stack backtrace:
CPU: 1 UID: 0 PID: 14771 Comm: syz.2.1603 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+0x184/0x200
 hfs_extend_file+0x2ee/0x1230
 hfs_bmap_reserve+0x107/0x430
 hfs_cat_create+0x1b3/0x640
 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: 0033:0x7f42a058d497
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:00007f42a14a1e68 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f42a14a1ef0 RCX: 00007f42a058d497
RDX: 00000000000001ff RSI: 00002000000001c0 RDI: 00000000ffffff9c
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00002000000001c0
R13: 00007f42a14a1eb0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
