[Ocfs2-devel] [PATCH] ocfs2: fix ocfs2 read inode data panic in ocfs2_iget
sunny.s.zhang
sunny.s.zhang at oracle.com
Sun Mar 24 23:15:59 PDT 2019
Hi Gang,
在 2019年03月25日 11:11, Gang He 写道:
> Hi Sunny,
>
>
>>>> On 2019/3/25 at 10:18, in message
> <ab0a6ca7-2f6a-b738-72ce-4ffb6787aad2 at oracle.com>, "sunny.s.zhang"
> <sunny.s.zhang at oracle.com> wrote:
>
>> 在 2019年03月25日 09:31, Joseph Qi 写道:
>>> On 19/3/25 09:26, Shuning Zhang wrote:
>>>> In some cases, the function ocfs2_iget read the data of inode, which has
>>>> been deleted for some reason. That will make the system panic. So We
>>>> should judge whether this inode has been deleted, and tell the caller
>>>> that the inode is a bad inode.
>>>>
>>>> [283465.542049] OCFS2: ERROR (device sdp): ocfs2_validate_inode_block:
>>>> Invalid dinode #580640: OCFS2_VALID_FL not set
>>>>
>>> Looks like it is a filesystem corruption bug.
>>> So we'd better find where it is introduced and try to fix it there.
>> Thank you for reviewing
>> In that case, the ocfs2 was used as rear end of NFS(V3), which is
>> stateless as we know. NFS can't protect parent
>> directory from being deleted, when child is being accessed. We can find
>> the description at Documentation/filesystems/nfs/Exporting.
>> I have reproduced this issue by adding some delay codes. This issue can
>> be reproduced in the production environment in case of heavy load .
>> Of course this is a defect of NFS(V3), But I think ocfs2 should have
>> some fault tolerance. ocfs2 should not panic, if it try to get a
>> nonexistent inode.
> I feel ocfs2_test_inode_bit() can avoid the problem, but why do we still encounter this problem?
> Maybe there are some potential logic(or race condition) problem.
ocfs2_test_inode_bit() can test whether the inode have been deleted, but
can't avoid this issue.
The key of this issue is ocfs2_get_parent() calls ocfs2_iget(inode) ,
but does not check if the inode exists.
I think this issue alse can be fixed, If ocfs2_get_parent() call
ocfs2_test_inode_bit before calling ocfs2_iget().
But this will have a little impact on performance.
This issue can be reproduce by the following steps.
on the nfs server side,
..../patha/pathb
Step 1: The process A was scheduled before calling the function fh_verify.
Step 2: The process B is removing the 'pathb', and just completed the
call to
function dput.
Then the dentry of 'pathb' has been deleted from the dcache, and all
ancestors have been deleted also.
The relationship of dentry and inode was deleted through the function
hlist_del_init. The following is the call stack.
dentry_iput->hlist_del_init(&dentry->d_u.d_alias)
At this time, the inode is still in the dcache.
Step 3: The process A call the function ocfs2_get_dentry, which get the
inode
from dcache. Then the refcount of inode is 1. The following is the call
stack.
nfsd3_proc_getacl->fh_verify->exportfs_decode_fh->fh_to_dentry(ocfs2_get_dentr
y)
Step 4: Dirty pages are flushed by bdi threads. So the inode of 'patha' is
evicted, and this directory was deleted.
But the inode of 'pathb' can't be evicted, because the refcount of the
inode
was 1.
Step 5: The process A keep running, and call the function
reconnect_path(in exportfs_decode_fh),
which call function ocfs2_get_parent of ocfs2. Get the block number of
parent
directory(patha) by the name of "..". Then read the data from disk by the
block number. Bug this inode has been deleted, so the system panic.
Process A Process B
1. in nfsd3_proc_getacl |
2. | dput
3. fh_to_dentry(ocfs2_get_dentry) |
4. bdi flush dirty cache |
5. ocfs2_iget |
Thanks,
Sunny
> Thanks
> Gang
>
>
>> Thanks,
>> Sunny
>>> Thanks,
>>> Joseph
>>>
>>>> [283465.545490] Kernel panic - not syncing: OCFS2: (device sdp): panic
>> forced
>>>> after error
>>>>
>>>> [283465.546889] CPU: 5 PID: 12416 Comm: nfsd Tainted: G W
>>>> 4.1.12-124.18.6.el6uek.bug28762940v3.x86_64 #2
>>>> [283465.548382] Hardware name: VMware, Inc. VMware Virtual Platform/440BX
>>>> Desktop Reference Platform, BIOS 6.00 09/21/2015
>>>> [283465.549657] 0000000000000000 ffff8800a56fb7b8 ffffffff816e839c
>>>> ffffffffa0514758
>>>> [283465.550392] 000000000008dc20 ffff8800a56fb838 ffffffff816e62d3
>>>> 0000000000000008
>>>> [283465.551056] ffff880000000010 ffff8800a56fb848 ffff8800a56fb7e8
>>>> ffff88005df9f000
>>>> [283465.551710] Call Trace:
>>>> [283465.552516] [<ffffffff816e839c>] dump_stack+0x63/0x81
>>>> [283465.553291] [<ffffffff816e62d3>] panic+0xcb/0x21b
>>>> [283465.554037] [<ffffffffa04e66b0>] ocfs2_handle_error+0xf0/0xf0 [ocfs2]
>>>> [283465.554882] [<ffffffffa04e7737>] __ocfs2_error+0x67/0x70 [ocfs2]
>>>> [283465.555768] [<ffffffffa049c0f9>] ocfs2_validate_inode_block+0x229/0x230
>>>> [ocfs2]
>>>> [283465.556683] [<ffffffffa047bcbc>] ocfs2_read_blocks+0x46c/0x7b0 [ocfs2]
>>>> [283465.557408] [<ffffffffa049bed0>] ? ocfs2_inode_cache_io_unlock+0x20/0x20
>>>> [ocfs2]
>>>> [283465.557973] [<ffffffffa049f0eb>] ocfs2_read_inode_block_full+0x3b/0x60
>>>> [ocfs2]
>>>> [283465.558525] [<ffffffffa049f5ba>] ocfs2_iget+0x4aa/0x880 [ocfs2]
>>>> [283465.559082] [<ffffffffa049146e>] ocfs2_get_parent+0x9e/0x220 [ocfs2]
>>>> [283465.559622] [<ffffffff81297c05>] reconnect_path+0xb5/0x300
>>>> [283465.560156] [<ffffffff81297f46>] exportfs_decode_fh+0xf6/0x2b0
>>>> [283465.560708] [<ffffffffa062faf0>] ? nfsd_proc_getattr+0xa0/0xa0 [nfsd]
>>>> [283465.561262] [<ffffffff810a8196>] ? prepare_creds+0x26/0x110
>>>> [283465.561932] [<ffffffffa0630860>] fh_verify+0x350/0x660 [nfsd]
>>>> [283465.562862] [<ffffffffa0637804>] ? nfsd_cache_lookup+0x44/0x630 [nfsd]
>>>> [283465.563697] [<ffffffffa063a8b9>] nfsd3_proc_getattr+0x69/0xf0 [nfsd]
>>>> [283465.564510] [<ffffffffa062cf60>] nfsd_dispatch+0xe0/0x290 [nfsd]
>>>> [283465.565358] [<ffffffffa05eb892>] ? svc_tcp_adjust_wspace+0x12/0x30
>>>> [sunrpc]
>>>> [283465.566272] [<ffffffffa05ea652>] svc_process_common+0x412/0x6a0 [sunrpc]
>>>> [283465.567155] [<ffffffffa05eaa03>] svc_process+0x123/0x210 [sunrpc]
>>>> [283465.568020] [<ffffffffa062c90f>] nfsd+0xff/0x170 [nfsd]
>>>> [283465.568962] [<ffffffffa062c810>] ? nfsd_destroy+0x80/0x80 [nfsd]
>>>> [283465.570112] [<ffffffff810a622b>] kthread+0xcb/0xf0
>>>> [283465.571099] [<ffffffff810a6160>] ? kthread_create_on_node+0x180/0x180
>>>> [283465.572114] [<ffffffff816f11b8>] ret_from_fork+0x58/0x90
>>>> [283465.573156] [<ffffffff810a6160>] ? kthread_create_on_node+0x180/0x180
>>>> ---
>>>> fs/ocfs2/inode.c | 22 ++++++++++++++++++++++
>>>> 1 files changed, 22 insertions(+), 0 deletions(-)
>>>>
>>>> diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
>>>> index b254416..a7f8160 100644
>>>> --- a/fs/ocfs2/inode.c
>>>> +++ b/fs/ocfs2/inode.c
>>>> @@ -513,6 +513,16 @@ static int ocfs2_read_locked_inode(struct inode *inode,
>>>> status = -EINVAL;
>>>> fe = (struct ocfs2_dinode *) bh->b_data;
>>>>
>>>> + /*
>>>> + * In some cases, this inode has been deleted, but the data of
>>>> + * inode is read directly. So We should judge whether this inode
>>>> + * has been deleted.
>>>> + * */
>>>> + if (unlikely(fe->i_dtime != 0)) {
>>>> + mlog(ML_NOTICE, "The inode %llu has been deleted\n",
>>>> + le64_to_cpu(fe->i_blkno));
>>>> + goto bail;
>>>> + }
>>>> /*
>>>> * This is a code bug. Right now the caller needs to
>>>> * understand whether it is asking for a system file inode or
>>>> @@ -1331,6 +1341,18 @@ int ocfs2_validate_inode_block(struct super_block
>> *sb,
>>>>
>>>> BUG_ON(!buffer_uptodate(bh));
>>>>
>>>> + /*
>>>> + * In some cases, this inode has been deleted, but the data of
>>>> + * inode is read directly. This is not a data corruption.So
>>>> + * We should judge whether this inode has been deleted.
>>>> + * */
>>>> + if (unlikely(di->i_dtime != 0)) {
>>>> + rc = -EINVAL;
>>>> + mlog(ML_NOTICE, "The inode %llu has been deleted\n",
>>>> + le64_to_cpu(di->i_blkno));
>>>> + goto bail;
>>>> + }
>>>> +
>>>> /*
>>>> * If the ecc fails, we return the error but otherwise
>>>> * leave the filesystem running. We know any error is
>>>>
>>
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