loop0: detected capacity change from 0 to 1024
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.17/5997 is trying to acquire lock:
ffff888079811548 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_get_block+0x272/0xaa0 fs/hfsplus/extents.c:260

but task is already holding lock:
ffff888079812988 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x1ca/0x12b0 fs/hfsplus/extents.c:453

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.0.17/5997:
 #0: ffff88802f7d6420 (sb_writers#12){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:738
 #1: ffff888079812b78 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:980 [inline]
 #1: ffff888079812b78 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: generic_file_write_iter+0x8c/0x3c0 mm/filemap.c:4394
 #2: ffff888079812988 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x1ca/0x12b0 fs/hfsplus/extents.c:453
 #3: ffff88802fc648f8 (&sbi->alloc_mutex){+.+.}-{4:4}, at: hfsplus_block_allocate+0xd2/0xc90 fs/hfsplus/bitmap.c:35

stack backtrace:
CPU: 0 UID: 0 PID: 5997 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_deadlock_bug+0x1e9/0x240 kernel/locking/lockdep.c:3041
 check_deadlock kernel/locking/lockdep.c:3093 [inline]
 validate_chain kernel/locking/lockdep.c:3895 [inline]
 __lock_acquire+0x1106/0x1c90 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825
 __mutex_lock_common kernel/locking/mutex.c:598 [inline]
 __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760
 hfsplus_get_block+0x272/0xaa0 fs/hfsplus/extents.c:260
 block_read_full_folio+0x457/0x850 fs/buffer.c:2420
 filemap_read_folio+0xc8/0x2a0 mm/filemap.c:2444
 do_read_cache_folio+0x263/0x5c0 mm/filemap.c:4036
 do_read_cache_page mm/filemap.c:4102 [inline]
 read_cache_page+0x5b/0x160 mm/filemap.c:4111
 read_mapping_page include/linux/pagemap.h:993 [inline]
 hfsplus_block_allocate+0x131/0xc90 fs/hfsplus/bitmap.c:37
 hfsplus_file_extend+0x459/0x12b0 fs/hfsplus/extents.c:464
 hfsplus_get_block+0x1a9/0xaa0 fs/hfsplus/extents.c:245
 get_more_blocks fs/direct-io.c:648 [inline]
 do_direct_IO fs/direct-io.c:936 [inline]
 __blockdev_direct_IO+0x2378/0x3c40 fs/direct-io.c:1243
 blockdev_direct_IO include/linux/fs.h:3511 [inline]
 hfsplus_direct_IO+0x106/0x2c0 fs/hfsplus/inode.c:131
 generic_file_direct_write+0x19a/0x410 mm/filemap.c:4188
 __generic_file_write_iter+0x11b/0x240 mm/filemap.c:4357
 generic_file_write_iter+0xe1/0x3c0 mm/filemap.c:4397
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x7d3/0x11d0 fs/read_write.c:686
 ksys_write+0x12a/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1ddad8f749
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:00007ffead3b0de8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1ddafe5fa0 RCX: 00007f1ddad8f749
RDX: 000000000003fe00 RSI: 0000200000004200 RDI: 0000000000000004
RBP: 00007f1ddae13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1ddafe5fa0 R14: 00007f1ddafe5fa0 R15: 0000000000000003
 </TASK>