loop1: detected capacity change from 0 to 1024
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.1.168/5325 is trying to acquire lock:
ffff888056485208 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_get_block+0x39b/0x1530 fs/hfsplus/extents.c:260

but task is already holding lock:
ffff888056484b48 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_extend+0x1b3/0x1950 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.1.168/5325:
 #0: ffff888058258460 (sb_writers#18){.+.+}-{0:0}, at: vfs_write+0x256/0x960 fs/read_write.c:580
 #1: ffff888056484d40 (&sb->s_type->i_mutex_key#24){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff888056484d40 (&sb->s_type->i_mutex_key#24){+.+.}-{3:3}, at: generic_file_write_iter+0x7f/0x2e0 mm/filemap.c:3986
 #2: ffff888056484b48 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfsplus_file_extend+0x1b3/0x1950 fs/hfsplus/extents.c:455
 #3: ffff8880554118f8 (&sbi->alloc_mutex){+.+.}-{3:3}, at: hfsplus_block_allocate+0x99/0x8e0 fs/hfsplus/bitmap.c:35

stack backtrace:
CPU: 0 PID: 5325 Comm: syz.1.168 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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:3659
 do_read_cache_page+0x32/0x220 mm/filemap.c:3701
 read_mapping_page include/linux/pagemap.h:793 [inline]
 hfsplus_block_allocate+0xfb/0x8e0 fs/hfsplus/bitmap.c:37
 hfsplus_file_extend+0xa8e/0x1950 fs/hfsplus/extents.c:466
 hfsplus_get_block+0x40e/0x1530 fs/hfsplus/extents.c:245
 __block_write_begin_int+0x54b/0x1a70 fs/buffer.c:1991
 __block_write_begin fs/buffer.c:2041 [inline]
 block_write_begin+0x96/0x1e0 fs/buffer.c:2102
 cont_write_begin+0x5c4/0x7d0 fs/buffer.c:2456
 hfsplus_write_begin+0x87/0xd0 fs/hfsplus/inode.c:52
 cont_expand_zero fs/buffer.c:2383 [inline]
 cont_write_begin+0x2a9/0x7d0 fs/buffer.c:2446
 hfsplus_write_begin+0x87/0xd0 fs/hfsplus/inode.c:52
 generic_perform_write+0x2f7/0x5a0 mm/filemap.c:3862
 __generic_file_write_iter+0x148/0x2a0 mm/filemap.c:3960
 generic_file_write_iter+0xab/0x2e0 mm/filemap.c:3989
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x44c/0x960 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+0x191/0x220 fs/read_write.c:706
 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: 0033:0x7fb4ed18f749
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:00007fb4edfc4038 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007fb4ed3e5fa0 RCX: 00007fb4ed18f749
RDX: 000000000000ff10 RSI: 0000200000000140 RDI: 0000000000000007
RBP: 00007fb4ed213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000008000c61 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb4ed3e6038 R14: 00007fb4ed3e5fa0 R15: 00007ffc4da986f8
 </TASK>