loop0: detected capacity change from 0 to 1024
============================================
WARNING: possible recursive locking detected
6.15.0-rc5-syzkaller-00353-gcd802e7e5f1e #0 Not tainted
--------------------------------------------
syz.0.83/6399 is trying to acquire lock:
ffff88805b119548 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_get_block+0x39e/0x1530 fs/hfsplus/extents.c:260

but task is already holding lock:
ffff88805b11b048 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x1fc/0x1990 fs/hfsplus/extents.c:458

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.0.83/6399:
 #0: ffff888079f84420
 (sb_writers#20){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:3041 [inline]
 (sb_writers#20){.+.+}-{0:0}, at: vfs_write+0x211/0xa90 fs/read_write.c:680
 #1: ffff88805b11b238 (&sb->s_type->i_mutex_key#27){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
 #1: ffff88805b11b238 (&sb->s_type->i_mutex_key#27){+.+.}-{4:4}, at: generic_file_write_iter+0xe3/0x540 mm/filemap.c:4243
 #2: ffff88805b11b048 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x1fc/0x1990 fs/hfsplus/extents.c:458
 #3: ffff8880577118f8 (&sbi->alloc_mutex){+.+.}-{4:4}, at: hfsplus_block_allocate+0x9d/0x8e0 fs/hfsplus/bitmap.c:35

stack backtrace:
CPU: 1 UID: 0 PID: 6399 Comm: syz.0.83 Not tainted 6.15.0-rc5-syzkaller-00353-gcd802e7e5f1e #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_deadlock_bug+0x28b/0x2a0 kernel/locking/lockdep.c:3042
 check_deadlock kernel/locking/lockdep.c:3094 [inline]
 validate_chain+0x1a3f/0x2140 kernel/locking/lockdep.c:3896
 __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
 __mutex_lock_common kernel/locking/mutex.c:601 [inline]
 __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:746
 hfsplus_get_block+0x39e/0x1530 fs/hfsplus/extents.c:260
 block_read_full_folio+0x29c/0x830 fs/buffer.c:2427
 filemap_read_folio+0x114/0x380 mm/filemap.c:2401
 do_read_cache_folio+0x354/0x590 mm/filemap.c:3885
 do_read_cache_page mm/filemap.c:3951 [inline]
 read_cache_page+0x5d/0x170 mm/filemap.c:3960
 read_mapping_page include/linux/pagemap.h:989 [inline]
 hfsplus_block_allocate+0xff/0x8e0 fs/hfsplus/bitmap.c:37
 hfsplus_file_extend+0xae3/0x1990 fs/hfsplus/extents.c:469
 hfsplus_get_block+0x411/0x1530 fs/hfsplus/extents.c:245
 __block_write_begin_int+0x6b2/0x1900 fs/buffer.c:2151
 block_write_begin fs/buffer.c:2262 [inline]
 cont_write_begin+0x789/0xb50 fs/buffer.c:2601
 hfsplus_write_begin+0x66/0xb0 fs/hfsplus/inode.c:46
 cont_expand_zero fs/buffer.c:2528 [inline]
 cont_write_begin+0x2fa/0xb50 fs/buffer.c:2591
 hfsplus_write_begin+0x66/0xb0 fs/hfsplus/inode.c:46
 generic_perform_write+0x2c4/0x910 mm/filemap.c:4103
 generic_file_write_iter+0x10f/0x540 mm/filemap.c:4246
 new_sync_write fs/read_write.c:591 [inline]
 vfs_write+0x548/0xa90 fs/read_write.c:684
 ksys_pwrite64 fs/read_write.c:791 [inline]
 __do_sys_pwrite64 fs/read_write.c:799 [inline]
 __se_sys_pwrite64 fs/read_write.c:796 [inline]
 __x64_sys_pwrite64+0x193/0x220 fs/read_write.c:796
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7efea8d8e969
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:00007efea9c19038 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007efea8fb5fa0 RCX: 00007efea8d8e969
RDX: 0000000000000001 RSI: 0000200000000000 RDI: 0000000000000006
RBP: 00007efea8e10ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000004fed0 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007efea8fb5fa0 R15: 00007ffe53d3e7e8
 </TASK>