Re: Subject: [PATCH] SQUASHME: Move a check from nfs_pageio_do_add_request to nfs_generic_pg_test

[Boaz Harrosh <bharrosh@panasas.com>]

On 05/26/2011 11:11 PM, Trond Myklebust wrote:
> On Thu, 2011-05-26 at 22:58 +0300, Boaz Harrosh wrote: 
>> On 05/26/2011 10:17 PM, Boaz Harrosh wrote:
>>>
>>> desc->pg_bsize is negotiated with the MDS. But if we are doing
>>> pnfs-IO it is not relevant.
>>>
>>> While at it cleanup nfs_pageio_do_add_request() in light of the
>>> less things it needs to do.
>>>
>>> Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
>>> ---
>>>  fs/nfs/pagelist.c |   28 ++++++++++++++--------------
>>>  1 files changed, 14 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
>>> index c795660..130b683 100644
>>> --- a/fs/nfs/pagelist.c
>>> +++ b/fs/nfs/pagelist.c
>>> @@ -206,6 +206,16 @@ nfs_wait_on_request(struct nfs_page *req)
>>>  
>>>  static bool nfs_generic_pg_test(struct nfs_pageio_descriptor *desc, struct nfs_page *prev, struct nfs_page *req)
>>>  {
>>> +	/*
>>> +	* FIXME: ideally we should be able to coalesce all requests
>>> +	* that are not block boundary aligned, but currently this
>>> +	* is problematic for the case of bsize < PAGE_CACHE_SIZE,
>>> +	* since nfs_flush_multi and nfs_pagein_multi assume you
>>> +	* can have only one struct nfs_page.
>>> +	*/
>>> +	if (desc->pg_bsize < PAGE_SIZE)
>>> +		return 0;
>>> +
>>>  	return desc->pg_count + req->wb_bytes <= desc->pg_bsize;
>>>  }
>>>  
>>> @@ -278,29 +288,19 @@ static bool nfs_can_coalesce_requests(struct nfs_page *prev,
>>>  static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
>>>  				     struct nfs_page *req)
>>>  {
>>> -	size_t newlen = req->wb_bytes;
>>> -
>>>  	if (desc->pg_count != 0) {
>>>  		struct nfs_page *prev;
>>>  
>>> -		/*
>>> -		 * FIXME: ideally we should be able to coalesce all requests
>>> -		 * that are not block boundary aligned, but currently this
>>> -		 * is problematic for the case of bsize < PAGE_CACHE_SIZE,
>>> -		 * since nfs_flush_multi and nfs_pagein_multi assume you
>>> -		 * can have only one struct nfs_page.
>>> -		 */
>>> -		if (desc->pg_bsize < PAGE_SIZE)
>>> -			return 0;
>>> -		newlen += desc->pg_count;
>>> +		desc->pg_count += req->wb_bytes;
>>
>> - 		desc->pg_count += req->wb_bytes;
>>
>>>  		prev = nfs_list_entry(desc->pg_list.prev);
>>>  		if (!nfs_can_coalesce_requests(prev, req, desc))
>>>  			return 0;
>>
>> + 		desc->pg_count += req->wb_bytes;
>>
>>> -	} else
>>> +	} else {
>>>  		desc->pg_base = req->wb_pgbase;
>>> +		desc->pg_count = req->wb_bytes;
>>> +	}
>>>  	nfs_list_remove_request(req);
>>>  	nfs_list_add_request(req, &desc->pg_list);
>>> -	desc->pg_count = newlen;
> 
> Wait. Why not just replace this line with
> 
> desc->pg_count += req->wb_bytes;
> 
> That should always be correct.
> 
Sure, OK, since desc->pg_count should be zero.
Benny could you make the change before you submit/squash.

Thanks
Boaz