syzbot

loop0: detected capacity change from 0 to 1024
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.17/5976 is trying to acquire lock:
ffff888033be22c8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_get_block+0x39e/0x1670 fs/hfsplus/extents.c:260

but task is already holding lock:
ffff888033be0e88 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_truncate+0x2b3/0xc30 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.0.17/5976:
 #0: ffff888033ca2420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:493
 #1: ffff888033be1078 (&sb->s_type->i_mutex_key#25){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1033 [inline]
 #1: ffff888033be1078 (&sb->s_type->i_mutex_key#25){+.+.}-{4:4}, at: do_truncate+0x18f/0x250 fs/open.c:63
 #2: ffff888033be0e88 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_truncate+0x2b3/0xc30 fs/hfsplus/extents.c:573
 #3: ffff8880335c58f8 (&sbi->alloc_mutex){+.+.}-{4:4}, at: hfsplus_block_free+0xc7/0x630 fs/hfsplus/bitmap.c:182

stack backtrace:
CPU: 1 UID: 0 PID: 5976 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041
 check_deadlock kernel/locking/lockdep.c:3093 [inline]
 validate_chain kernel/locking/lockdep.c:3895 [inline]
 __lock_acquire+0x253f/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:614 [inline]
 __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
 hfsplus_get_block+0x39e/0x1670 fs/hfsplus/extents.c:260
 block_read_full_folio+0x29f/0x830 fs/buffer.c:2417
 filemap_read_folio+0x137/0x3b0 mm/filemap.c:2501
 do_read_cache_folio+0x358/0x590 mm/filemap.c:4101
 do_read_cache_page mm/filemap.c:4167 [inline]
 read_cache_page+0x5d/0x170 mm/filemap.c:4176
 read_mapping_page include/linux/pagemap.h:1022 [inline]
 hfsplus_block_free+0x134/0x630 fs/hfsplus/bitmap.c:185
 hfsplus_free_extents+0x121/0xa50 fs/hfsplus/extents.c:360
 hfsplus_file_truncate+0x762/0xc30 fs/hfsplus/extents.c:588
 hfsplus_setattr+0x1c4/0x270 fs/hfsplus/inode.c:286
 notify_change+0xc1a/0xf40 fs/attr.c:556
 do_truncate+0x1c2/0x250 fs/open.c:68
 vfs_truncate+0x4b4/0x540 fs/open.c:118
 do_sys_truncate+0xf3/0x1c0 fs/open.c:142
 __do_sys_truncate fs/open.c:154 [inline]
 __se_sys_truncate fs/open.c:152 [inline]
 __x64_sys_truncate+0x5b/0x70 fs/open.c:152
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fce2039c799
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:00007ffd2b0cef88 EFLAGS: 00000246 ORIG_RAX: 000000000000004c
RAX: ffffffffffffffda RBX: 00007fce20615fa0 RCX: 00007fce2039c799
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000000
RBP: 00007fce20432c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fce20615fac R14: 00007fce20615fa0 R15: 00007fce20615fa0
 </TASK>
hfsplus: unable to mark blocks free: error -5
hfsplus: can't free extent: start 264, count 1