[Bug Report] crash in the path of direct IO

[Changwei Ge]

Hi,

We encountered a crash issue days ago.

The call trace follows as below:

>From the call trace, we can see that a direct read request caused this
crash issue, which triggered a BUG_ON check point.

With the help of debugfs.ocfs2 tool, I can see that clusters owned by
the target file are extremely scattered . Most of them are not

continuous.

Does anyone have ideas about this issue?

[10628085.052236] RIP: 0010:[<ffffffff81240ba0>]  [<ffffffff81240ba0>]
do_blockdev_direct_IO+0x1e10/0x1eb0
[10628085.052248] RSP: 0018:ffff88018038fa38  EFLAGS: 00010246
[10628085.052252] RAX: 0000000000000000 RBX: ffff8800ae579680 RCX:
0000000000000009
[10628085.052258] RDX: 0000000000000000 RSI: 000000000fb25900 RDI:
000000007d92c800
[10628085.052265] RBP: ffff88018038fc68 R08: ffff8805e042a298 R09:
0000000000000001
[10628085.052271] R10: 0000000000000003 R11: 0000000000000000 R12:
0000000000000000
[10628085.052277] R13: 0000000000000a00 R14: ffff8800ae5796a8 R15:
ffffea0014865280
[10628085.052284] FS:  00007f7f517fa700(0000) GS:ffff8806276c0000(0000)
knlGS:0000000000000000
[10628085.052290] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[10628085.052294] CR2: 000000001fbc0000 CR3: 0000000bdb8f7000 CR4:
00000000001426e0
[10628085.052300] Stack:
[10628085.052304]  ffff88018038fc60 ffff880626c18d00 0000000000117c00
ffff8800ae5796e8
[10628085.052311]  ffff88018038fb90 ffff8800ae5796b4 0000000000000200
0000000000131000
[10628085.052318]  000000007d92c5fb ffff88052194a000 0000000117c00000
fffffffffffffe00
[10628085.052326] Call Trace:
[10628085.052371]  [<ffffffffc06ea3c0>] ?
ocfs2_zero_new_buffers+0x130/0x130 [ocfs2]
[10628085.052379]  [<ffffffff81240c83>] __blockdev_direct_IO+0x43/0x50
[10628085.052395]  [<ffffffffc06e9af0>] ? ocfs2_zero_tail+0x50/0x50 [ocfs2]
[10628085.052411]  [<ffffffffc06e933f>] ocfs2_direct_IO+0x8f/0xa0 [ocfs2]
[10628085.052426]  [<ffffffffc06e9af0>] ? ocfs2_zero_tail+0x50/0x50 [ocfs2]
[10628085.052432]  [<ffffffff8118ba1a>] generic_file_read_iter+0x56a/0x610
[10628085.052449]  [<ffffffffc070004b>] ?
__ocfs2_cluster_unlock.isra.36+0xab/0xf0 [ocfs2]
[10628085.052469]  [<ffffffffc070a2da>] ocfs2_file_read_iter+0xca/0x410
[ocfs2]
[10628085.052476]  [<ffffffff810ffe44>] ? do_futex+0x304/0xbc0
[10628085.052481]  [<ffffffff8120263b>] __vfs_read+0xab/0xf0
[10628085.052487]  [<ffffffff812039d5>] vfs_read+0x95/0x130
[10628085.052491]  [<ffffffff81203c62>] SyS_pread64+0x92/0xa0
[10628085.052498]  [<ffffffff817f81b2>] system_call_fastpath+0x16/0x75


Br.

Thanks.

Changwei.