syzbot

loop0: detected capacity change from 0 to 1024
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.17/4421 is trying to acquire lock:
ffff88807c491548 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_get_block+0x39b/0x1530 fs/hfsplus/extents.c:260

but task is already holding lock:
ffff88807c492988 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_truncate+0x28f/0xb30 fs/hfsplus/extents.c:574

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.0.17/4421:
 #0: ffff888019af2460 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:393
 #1: ffff88807c492b80 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff88807c492b80 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at: do_truncate+0x183/0x220 fs/open.c:63
 #2: ffff88807c492988 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_truncate+0x28f/0xb30 fs/hfsplus/extents.c:574
 #3: ffff88802fe4d8f8 (&sbi->alloc_mutex){+.+.}-{3:3}, at: hfsplus_block_free+0xbf/0x4b0 fs/hfsplus/bitmap.c:182

stack backtrace:
CPU: 0 PID: 4421 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 __lock_acquire+0x122f/0x7c50 kernel/locking/lockdep.c:-1
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x120/0xaf0 kernel/locking/mutex.c:747
 hfsplus_get_block+0x39b/0x1530 fs/hfsplus/extents.c:260
 block_read_full_folio+0x3c9/0xed0 fs/buffer.c:2271
 filemap_read_folio+0x160/0x760 mm/filemap.c:2490
 do_read_cache_folio+0x2a0/0x760 mm/filemap.c:3627
 do_read_cache_page+0x32/0x220 mm/filemap.c:3669
 read_mapping_page include/linux/pagemap.h:791 [inline]
 hfsplus_block_free+0x128/0x4b0 fs/hfsplus/bitmap.c:185
 hfsplus_free_extents+0x10d/0xa50 fs/hfsplus/extents.c:360
 hfsplus_file_truncate+0x731/0xb30 fs/hfsplus/extents.c:589
 hfsplus_setattr+0x1c0/0x280 fs/hfsplus/inode.c:269
 notify_change+0xc74/0xf40 fs/attr.c:499
 do_truncate+0x197/0x220 fs/open.c:65
 vfs_truncate+0x262/0x2f0 fs/open.c:111
 do_sys_truncate+0xdc/0x190 fs/open.c:134
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f506a18eec9
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:00007ffdd55ddc38 EFLAGS: 00000246 ORIG_RAX: 000000000000004c
RAX: ffffffffffffffda RBX: 00007f506a3e5fa0 RCX: 00007f506a18eec9
RDX: 0000000000000000 RSI: 0008000000000000 RDI: 0000200000000080
RBP: 00007f506a211f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f506a3e5fa0 R14: 00007f506a3e5fa0 R15: 0000000000000002
 </TASK>
hfsplus: request for non-existent node 16777216 in B*Tree
hfsplus: request for non-existent node 16777216 in B*Tree
hfsplus: unable to mark blocks free: error -5
hfsplus: can't free extent