======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.7.176/7274 is trying to acquire lock:
ffff88816bd6a0b0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x300

but task is already holding lock:
ffff8881be908778 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xf2/0x15e0

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}:
       __mutex_lock+0x19f/0x1300
       hfs_extend_file+0xf2/0x15e0
       hfs_bmap_reserve+0x107/0x430
       __hfs_ext_write_extent+0x1fa/0x470
       hfs_ext_write_extent+0x17e/0x210
       hfs_write_inode+0x117/0x960
       __writeback_single_inode+0x75a/0x11a0
       writeback_sb_inodes+0x992/0x1a20
       wb_writeback+0x456/0xb70
       wb_workfn+0x414/0xf50
       process_scheduled_works+0xb02/0x1830
       worker_thread+0xa50/0xfc0
       kthread+0x388/0x470
       ret_from_fork+0x51e/0xb90
       ret_from_fork_asm+0x1a/0x30

-> #0 (&tree->tree_lock/1){+.+.}-{4:4}:
       __lock_acquire+0x15a5/0x2cf0
       lock_acquire+0xf0/0x2e0
       __mutex_lock+0x19f/0x1300
       hfs_find_init+0x18e/0x300
       hfs_extend_file+0x35c/0x15e0
       hfs_bmap_reserve+0x107/0x430
       hfs_cat_create+0x20f/0x800
       hfs_create+0x75/0xe0
       path_openat+0x1395/0x3860
       do_file_open+0x23e/0x4a0
       do_sys_openat2+0x113/0x200
       __x64_sys_open+0x11e/0x150
       do_syscall_64+0x14d/0xf80
       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.7.176/7274:
 #0: ffff88816bd6c420 (sb_writers#20){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90
 #1: ffff8881be9082a0 (&type->i_mutex_dir_key#15){++++}-{4:4}, at: path_openat+0xb4c/0x3860
 #2: ffff88816bd680b0 (&tree->tree_lock){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x300
 #3: ffff8881be908778 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xf2/0x15e0

stack backtrace:
CPU: 1 UID: 0 PID: 7274 Comm: syz.7.176 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+0xe8/0x150
 print_circular_bug+0x2e1/0x300
 check_noncircular+0x12e/0x150
 __lock_acquire+0x15a5/0x2cf0
 lock_acquire+0xf0/0x2e0
 __mutex_lock+0x19f/0x1300
 hfs_find_init+0x18e/0x300
 hfs_extend_file+0x35c/0x15e0
 hfs_bmap_reserve+0x107/0x430
 hfs_cat_create+0x20f/0x800
 hfs_create+0x75/0xe0
 path_openat+0x1395/0x3860
 do_file_open+0x23e/0x4a0
 do_sys_openat2+0x113/0x200
 __x64_sys_open+0x11e/0x150
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f65ac39c799
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:00007f65ad2b7028 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f65ac616090 RCX: 00007f65ac39c799
RDX: 0000000000000022 RSI: 0000000000145142 RDI: 0000200000000000
RBP: 00007f65ac432c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f65ac616128 R14: 00007f65ac616090 R15: 00007ffccee18fd8
 </TASK>
