syzbot

loop0: detected capacity change from 0 to 32768
BUG at fs/jfs/jfs_dmap.c:2972 assert(n < 4)
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kernel BUG at fs/jfs/jfs_dmap.c:2972!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 3545 Comm: syz-executor412 Not tainted 6.1.69-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
RIP: 0010:dbFindLeaf+0x4de/0x4e0 fs/jfs/jfs_dmap.c:2972
Code: fe e9 55 ff ff ff e8 41 b3 84 fe 48 c7 c7 60 57 24 8b 48 c7 c6 a0 54 24 8b ba 9c 0b 00 00 48 c7 c1 20 62 24 8b e8 5b 19 82 07 <0f> 0b 55 41 57 41 56 41 55 41 54 53 48 83 ec 68 48 89 fb 49 be 00
RSP: 0018:ffffc90003a0f138 EFLAGS: 00010246
RAX: 000000000000002b RBX: 00000000ffffffff RCX: a6ca299fba489200
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000011 R08: ffffffff816e161c R09: fffff52000741dc9
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000155
R13: 0000000000000003 R14: 0000000000000014 R15: 0000000000000000
FS:  0000555557031380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020ea0000 CR3: 0000000073724000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 dbAllocDmapLev+0xcf/0x490 fs/jfs/jfs_dmap.c:1967
 dbAllocCtl+0x113/0x920 fs/jfs/jfs_dmap.c:1823
 dbAllocAG+0x28b/0x10b0 fs/jfs/jfs_dmap.c:1364
 dbAlloc+0x654/0xc90 fs/jfs/jfs_dmap.c:888
 extBalloc fs/jfs/jfs_extent.c:326 [inline]
 extAlloc+0x4f4/0x1000 fs/jfs/jfs_extent.c:122
 jfs_get_block+0x417/0xe50 fs/jfs/inode.c:248
 __block_write_begin_int+0x544/0x1a30 fs/buffer.c:1991
 __block_write_begin fs/buffer.c:2041 [inline]
 block_write_begin+0x98/0x1f0 fs/buffer.c:2102
 jfs_write_begin+0x2d/0x60 fs/jfs/inode.c:304
 generic_perform_write+0x2fc/0x5e0 mm/filemap.c:3808
 __generic_file_write_iter+0x176/0x400 mm/filemap.c:3936
 generic_file_write_iter+0xab/0x310 mm/filemap.c:3968
 do_iter_write+0x6e6/0xc50 fs/read_write.c:861
 vfs_writev fs/read_write.c:934 [inline]
 do_pwritev+0x216/0x360 fs/read_write.c:1031
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f34a8311139
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 17 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc5cac8ff8 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 00007ffc5cac91d8 RCX: 00007f34a8311139
RDX: 0000000000000001 RSI: 0000000020000100 RDI: 0000000000000004
RBP: 00007f34a838a610 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000005405 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffc5cac91c8 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dbFindLeaf+0x4de/0x4e0 fs/jfs/jfs_dmap.c:2972
Code: fe e9 55 ff ff ff e8 41 b3 84 fe 48 c7 c7 60 57 24 8b 48 c7 c6 a0 54 24 8b ba 9c 0b 00 00 48 c7 c1 20 62 24 8b e8 5b 19 82 07 <0f> 0b 55 41 57 41 56 41 55 41 54 53 48 83 ec 68 48 89 fb 49 be 00
RSP: 0018:ffffc90003a0f138 EFLAGS: 00010246
RAX: 000000000000002b RBX: 00000000ffffffff RCX: a6ca299fba489200
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000011 R08: ffffffff816e161c R09: fffff52000741dc9
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000155
R13: 0000000000000003 R14: 0000000000000014 R15: 0000000000000000
FS:  0000555557031380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005581f476db40 CR3: 0000000073724000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400