loop0: detected capacity change from 0 to 64
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.626/9215 is trying to acquire lock:
ffff88803dd36278 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xda/0x1230

but task is already holding lock:
ffff88802b5b80b0 (&tree->tree_lock#2/1){+.+.}-{4:4}, at: hfs_find_init+0x184/0x200

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&tree->tree_lock#2/1){+.+.}-{4:4}:
       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_mkdir+0x6c/0x80
       do_syscall_64+0xfa/0x3b0
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}:
       validate_chain+0xb9b/0x2140
       __lock_acquire+0xab9/0xd20
       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_cache_extent+0x6b/0x9b0
       hfs_extend_file+0x316/0x1230
       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+0x190/0x9c0
       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

other info that might help us debug this:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

4 locks held by syz.0.626/9215:
 #0: ffff88810dd84428 (sb_writers#13){.+.+}-{0:0}, at: do_ftruncate+0x42a/0x540
 #1: ffff88803dd343a0 (&sb->s_type->i_mutex_key#21){+.+.}-{4:4}, at: do_truncate+0x171/0x220
 #2: ffff88803dd341f8 (&HFS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xda/0x1230
 #3: ffff88802b5b80b0 (&tree->tree_lock#2/1){+.+.}-{4:4}, at: hfs_find_init+0x184/0x200

stack backtrace:
CPU: 0 UID: 0 PID: 9215 Comm: syz.0.626 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_extend_file+0xda/0x1230
 hfs_bmap_reserve+0x107/0x430
 __hfs_ext_write_extent+0x1fa/0x470
 __hfs_ext_cache_extent+0x6b/0x9b0
 hfs_extend_file+0x316/0x1230
 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+0x190/0x9c0
 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
RIP: 0033:0x7f26c398eba9
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:00007f26c1bee038 EFLAGS: 00000246 ORIG_RAX: 000000000000004d
RAX: ffffffffffffffda RBX: 00007f26c3bd5fa0 RCX: 00007f26c398eba9
RDX: 0000000000000000 RSI: 00000000000081ff RDI: 0000000000000004
RBP: 00007f26c3a11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f26c3bd6038 R14: 00007f26c3bd5fa0 R15: 00007ffcdc369768
 </TASK>
