======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.2.7993/677 is trying to acquire lock:
ffff888178e2a0a8 (&tree->tree_lock#2/1){+.+.}-{4:4}, at: hfs_find_init+0x18d/0x300

but task is already holding lock:
ffff8881712dd4a0 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xf9/0x1680

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+0x19d/0x1550
       hfs_extend_file+0xf9/0x1680
       hfs_bmap_reserve+0x108/0x430
       __hfs_ext_write_extent+0x1fc/0x470
       __hfs_ext_cache_extent+0x6e/0x9b0
       hfs_extend_file+0x3ad/0x1680
       hfs_get_block+0x401/0xbf0
       __block_write_begin_int+0x6c2/0x1900
       cont_write_begin+0x71b/0xac0
       hfs_write_begin+0x123/0x1c0
       generic_perform_write+0x2d5/0x8f0
       generic_file_write_iter+0xae/0x330
       vfs_write+0x612/0xba0
       ksys_write+0x150/0x270
       do_syscall_64+0x166/0x520
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&tree->tree_lock#2/1){+.+.}-{4:4}:
       __lock_acquire+0x15ff/0x2e50
       lock_acquire+0x115/0x350
       __mutex_lock+0x19d/0x1550
       hfs_find_init+0x18d/0x300
       hfs_extend_file+0x367/0x1680
       hfs_bmap_reserve+0x108/0x430
       hfs_cat_create+0x23d/0x870
       hfs_mkdir+0x73/0xe0
       vfs_mkdir+0x40c/0x620
       filename_mkdirat+0x285/0x510
       __se_sys_mkdirat+0x35/0x150
       do_syscall_64+0x166/0x520
       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 ***

locks held by syz.2.7993/677: 4, last CPU#1:
 #0: ffff88817aaa0460 (sb_writers#21){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90
 #1: ffff8881712dd040 (&type->i_mutex_dir_key#18/1){+.+.}-{4:4}, at: filename_create+0x200/0x370
 #2: ffff888177b9c0a8 (&tree->tree_lock#2){+.+.}-{4:4}, at: hfs_find_init+0x18d/0x300
 #3: ffff8881712dd4a0 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xf9/0x1680

stack backtrace:
CPU: 1 UID: 0 PID: 677 Comm: syz.2.7993 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
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+0x2e2/0x300
 check_noncircular+0x12f/0x150
 __lock_acquire+0x15ff/0x2e50
 lock_acquire+0x115/0x350
 __mutex_lock+0x19d/0x1550
 hfs_find_init+0x18d/0x300
 hfs_extend_file+0x367/0x1680
 hfs_bmap_reserve+0x108/0x430
 hfs_cat_create+0x23d/0x870
 hfs_mkdir+0x73/0xe0
 vfs_mkdir+0x40c/0x620
 filename_mkdirat+0x285/0x510
 __se_sys_mkdirat+0x35/0x150
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f501c19cfc7
Code: 00 66 90 48 89 f2 b9 00 01 00 00 48 89 fe bf 9c ff ff ff e9 db f7 ff ff 66 2e 0f 1f 84 00 00 00 00 00 90 b8 02 01 00 00 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:00007f501d0aae58 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f501d0aaee0 RCX: 00007f501c19cfc7
RDX: 00000000000001ff RSI: 00002000000007c0 RDI: 00000000ffffff9c
RBP: 00002000000002c0 R08: 00002000000007c0 R09: 0000000000000000
R10: 00002000000002c0 R11: 0000000000000246 R12: 00002000000007c0
R13: 00007f501d0aaea0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
