loop3: detected capacity change from 0 to 1024
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.3.87/6270 is trying to acquire lock:
ffff88807dfb0e88 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_get_block+0x39f/0x1530 fs/hfsplus/extents.c:260

but task is already holding lock:
ffff88807dfb3048 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_extend+0x1fd/0x1990 fs/hfsplus/extents.c:455

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.3.87/6270:
 #0: ffff888077126418 (sb_writers#24){.+.+}-{0:0}, at: vfs_write+0x20e/0x940 fs/read_write.c:580
 #1: ffff88807dfb3250 (&sb->s_type->i_mutex_key#30){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #1: ffff88807dfb3250 (&sb->s_type->i_mutex_key#30){+.+.}-{3:3}, at: generic_file_write_iter+0x83/0x2e0 mm/filemap.c:4149
 #2: ffff88807dfb3048 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_extend+0x1fd/0x1990 fs/hfsplus/extents.c:455
 #3: ffff88807b8cc8f8 (&sbi->alloc_mutex){+.+.}-{3:3}, at: hfsplus_block_allocate+0x9d/0x8e0 fs/hfsplus/bitmap.c:35

stack backtrace:
CPU: 1 PID: 6270 Comm: syz.3.87 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_deadlock kernel/locking/lockdep.c:3062 [inline]
 validate_chain kernel/locking/lockdep.c:3856 [inline]
 __lock_acquire+0x5d40/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
 hfsplus_get_block+0x39f/0x1530 fs/hfsplus/extents.c:260
 block_read_full_folio+0x42e/0xf40 fs/buffer.c:2406
 filemap_read_folio+0x167/0x760 mm/filemap.c:2420
 do_read_cache_folio+0x470/0x7e0 mm/filemap.c:3804
 do_read_cache_page+0x32/0x250 mm/filemap.c:3870
 read_mapping_page include/linux/pagemap.h:892 [inline]
 hfsplus_block_allocate+0xff/0x8e0 fs/hfsplus/bitmap.c:37
 hfsplus_file_extend+0xae4/0x1990 fs/hfsplus/extents.c:466
 hfsplus_get_block+0x412/0x1530 fs/hfsplus/extents.c:245
 __block_write_begin_int+0x566/0x1ad0 fs/buffer.c:2124
 __block_write_begin fs/buffer.c:2173 [inline]
 block_write_begin+0x9a/0x1e0 fs/buffer.c:2234
 cont_write_begin+0x5c8/0x7e0 fs/buffer.c:2591
 hfsplus_write_begin+0x8b/0xd0 fs/hfsplus/inode.c:52
 cont_expand_zero fs/buffer.c:2518 [inline]
 cont_write_begin+0x2ad/0x7e0 fs/buffer.c:2581
 hfsplus_write_begin+0x8b/0xd0 fs/hfsplus/inode.c:52
 generic_perform_write+0x2fb/0x5b0 mm/filemap.c:4031
 generic_file_write_iter+0xaf/0x2e0 mm/filemap.c:4152
 call_write_iter include/linux/fs.h:2018 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x43b/0x940 fs/read_write.c:584
 ksys_pwrite64 fs/read_write.c:699 [inline]
 __do_sys_pwrite64 fs/read_write.c:709 [inline]
 __se_sys_pwrite64 fs/read_write.c:706 [inline]
 __x64_sys_pwrite64+0x195/0x220 fs/read_write.c:706
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f27f5d8f749
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:00007f27f6bc9038 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007f27f5fe5fa0 RCX: 00007f27f5d8f749
RDX: 0000000000000001 RSI: 00002000000005c0 RDI: 0000000000000004
RBP: 00007f27f5e13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000004fed0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f27f5fe6038 R14: 00007f27f5fe5fa0 R15: 00007fff8dc93618
 </TASK>