Re: BUG: warning at fs/ext3/inode.c:1016/ext3_getblk()

Badari Pulavarty
2006-09-05T20:14:05Z

Dave Kleikamp wrote:
> On Tue, 2006-09-05 at 11:09 -0700, Badari Pulavarty wrote:
>
>> On Tue, 2006-09-05 at 13:10 -0400, Will Simoneau wrote:
>>
>>> Has anyone seen this before? These three traces occured at different times
>>> today when three new user accounts (and associated quotas) were created. This
>>> machine is an NFS server which uses quotas on an ext3 fs (dir_index is on).
>>> Kernel is 2.6.17.11 on an x86 smp w/64G highmem; 4G ram is installed. The
>>> affected filesystem is on a software raid1 of two hardware raid0 volumes from a
>>> megaraid card.
>>>
>>> BUG: warning at fs/ext3/inode.c:1016/ext3_getblk()
>>> <c01c5140> ext3_getblk+0x98/0x2a6 <c03b2806> md_wakeup_thread+0x26/0x2a
>>> <c01c536d> ext3_bread+0x1f/0x88 <c01cedf9> ext3_quota_read+0x136/0x1ae
>>> <c018b683> v1_read_dqblk+0x61/0xac <c0188f32> dquot_acquire+0xf6/0x107
>>> <c01ceaba> ext3_acquire_dquot+0x46/0x68 <c01897d4> dqget+0x155/0x1e7
>>> <c018a97b> dquot_transfer+0x3e0/0x3e9 <c016fe52> dput+0x23/0x13e
>>> <c01c7986> ext3_setattr+0xc3/0x240 <c0120f66> current_fs_time+0x52/0x6a
>>> <c017320e> notify_change+0x2bd/0x30d <c0159246> chown_common+0x9c/0xc5
>>> <c02a222c> strncpy_from_user+0x3b/0x68 <c0167fe6> do_path_lookup+0xdf/0x266
>>> <c016841b> __user_walk_fd+0x44/0x5a <c01592b9> sys_chown+0x4a/0x55
>>> <c015a43c> vfs_write+0xe7/0x13c <c01695d4> sys_mkdir+0x1f/0x23
>>> <c0102a97> syscall_call+0x7/0xb
>>>
>> I think its a bogus warning.
>>
>> ext3_getblk() is calling ext3_get_blocks_handle() to map "1" block for
>> read. But for *some* reason ext3_get_blocks_handle() more than 1 block.
>> ext3_get_blocks_handle() return "positive #of blocks" is a valid case.
>> So needs to be fixed.
>>
>
> I'm having a hard time figuring out exactly what ext3_get_blocks_handle
> is trying to return, but it looks to me like if it is allocating one
> data block, and needs to allocate an indirect block as well, then it
> will return 2 rather than 1. Is this expected, or am I just confused?
>
>

It would return "1" in that case.. (data block)

> 0 means get_block() suceeded and indicates the number of blocks mapped
= 0 lookup failed
< 0 mean error case

>> I did search for callers of ext3_get_blocks_handle() and found that
>> ext3_readdir() seems to do wrong thing all the time with error check :(
>> Need to take a closer look..
>>
>> err = ext3_get_blocks_handle(NULL, inode, blk, 1,
>> &map_bh, 0, 0);
>> if (err > 0) { <<<< BAD
>> page_cache_readahead(sb->s_bdev->bd_inode->i_mapping,
>> &filp->f_ra,
>> filp,
>> map_bh.b_blocknr >>
>> (PAGE_CACHE_SHIFT - inode->i_blkbits),
>> 1);
>> bh = ext3_bread(NULL, inode, blk, 0, &err);
>> }
>>
>
> Bad to do this what it's doing, or bad to call name the variable "err"?
> I think if it looked like this:
>
> count = ext3_get_blocks_handle(NULL, inode, blk, 1,
> &map_bh, 0, 0);
> if (count > 0) {
>
> it would be a lot less confusing.
>
I am sorry !! it is doing the right thing :(

Thanks,
Badari