syzbot

loop0: detected capacity change from 0 to 1024
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.17/6079 is trying to acquire lock:
ffff888039021778 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_get_block+0x39a/0x15e0 fs/hfsplus/extents.c:260

but task is already holding lock:
ffff888039022df8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_truncate+0x2a4/0xc70 fs/hfsplus/extents.c:573

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&HFSPLUS_I(inode)->extents_lock);
  lock(&HFSPLUS_I(inode)->extents_lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

4 locks held by syz.0.17/6079:
 #0: ffff88803a2f6480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:508
 #1: ffff888039023058 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:985 [inline]
 #1: ffff888039023058 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: do_truncate+0x171/0x220 fs/open.c:63
 #2: ffff888039022df8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_truncate+0x2a4/0xc70 fs/hfsplus/extents.c:573
 #3: ffff88803585f0e8 (&sbi->alloc_mutex){+.+.}-{4:4}, at: hfsplus_block_free+0xc7/0x5f0 fs/hfsplus/bitmap.c:182

stack backtrace:
CPU: 0 UID: 0 PID: 6079 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_deadlock_bug+0x28b/0x2a0 kernel/locking/lockdep.c:3041
 check_deadlock kernel/locking/lockdep.c:3093 [inline]
 validate_chain+0x1a3f/0x2140 kernel/locking/lockdep.c:3895
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/rtmutex_api.c:535 [inline]
 mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:547
 hfsplus_get_block+0x39a/0x15e0 fs/hfsplus/extents.c:260
 block_read_full_folio+0x29f/0x830 fs/buffer.c:2420
 filemap_read_folio+0x117/0x380 mm/filemap.c:2444
 do_read_cache_folio+0x2ba/0x560 mm/filemap.c:4024
 do_read_cache_page mm/filemap.c:4090 [inline]
 read_cache_page+0x5d/0x170 mm/filemap.c:4099
 read_mapping_page include/linux/pagemap.h:993 [inline]
 hfsplus_block_free+0x134/0x5f0 fs/hfsplus/bitmap.c:185
 hfsplus_free_extents+0x121/0xa50 fs/hfsplus/extents.c:360
 hfsplus_file_truncate+0x754/0xc70 fs/hfsplus/extents.c:588
 hfsplus_setattr+0x1c4/0x270 fs/hfsplus/inode.c:266
 notify_change+0xc18/0xf60 fs/attr.c:546
 do_truncate+0x1a4/0x220 fs/open.c:68
 handle_truncate fs/namei.c:3596 [inline]
 do_open fs/namei.c:3979 [inline]
 path_openat+0x3078/0x3840 fs/namei.c:4134
 do_filp_open+0x1fa/0x410 fs/namei.c:4161
 do_sys_openat2+0x121/0x1c0 fs/open.c:1437
 do_sys_open fs/open.c:1452 [inline]
 __do_sys_openat fs/open.c:1468 [inline]
 __se_sys_openat fs/open.c:1463 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1463
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd1c5cbf6c9
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:00007fff39b3f588 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fd1c5f15fa0 RCX: 00007fd1c5cbf6c9
RDX: 0000000000183741 RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007fd1c5d41f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000042 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd1c5f15fa0 R14: 00007fd1c5f15fa0 R15: 0000000000000004
 </TASK>
hfsplus: unable to mark blocks free: error -5
hfsplus: can't free extent: start 134, count 1