Re: [V9fs-developer] [PATCH] [fs/9p] Let the read retry on short reads.

["Venkateswararao Jujjuri (JV)" <jvrao@linux.vnet.ibm.com>]

Latchesar Ionkov wrote:
> What problem does that change solve? It adds an additional call when
> EOF is reached. The way most user apps are written, that'll mean two
> calls that return Rread count 0.
> 
> I was thinking of doing a similar change, but decided against it.

Yeah I ran into the issue when tried with o_direct and dd.

Can we depend on the application retrying?
Yes I also observed the behavior you are mentioning (2 Rreads returning 0)
Wondering if we have a better way to address this.

Thanks,
JV

> 
> Thanks,
>     Lucho
> 
> On Tue, Aug 17, 2010 at 12:46 PM, Venkateswararao Jujjuri (JV)
> <jvrao@linux.vnet.ibm.com> wrote:
>> A simple fix to retry on short reads.
>>
>> Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
>> ---
>>  fs/9p/vfs_file.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
>> index 2695491..cae984d 100644
>> --- a/fs/9p/vfs_file.c
>> +++ b/fs/9p/vfs_file.c
>> @@ -166,7 +166,7 @@ v9fs_file_readn(struct file *filp, char *data, char __user *udata, u32 count,
>>                offset += n;
>>                count -= n;
>>                total += n;
>> -       } while (count > 0 && n == size);
>> +       } while (count > 0);
>>
>>        if (n < 0)
>>                total = n;
>> --
>> 1.6.5.2
>>
>>
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