On Wed, Nov 30, 2011 at 9:01 PM, Benny Halevy <bhalevy@xxxxxxxxxx> wrote:
> On 2011-12-03 06:52, Peng Tao wrote:
>> This gives LD option not to ask for layout in pg_init.
>>
>> Signed-off-by: Peng Tao <peng_tao@xxxxxxx>
>> ---
>> fs/nfs/pnfs.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
>> 1 files changed, 46 insertions(+), 0 deletions(-)
>>
>> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
>> index 734e670..c8dc0b1 100644
>> --- a/fs/nfs/pnfs.c
>> +++ b/fs/nfs/pnfs.c
>> @@ -1254,6 +1254,7 @@ pnfs_do_multiple_writes(struct nfs_pageio_descriptor *desc, struct list_head *he
>> struct nfs_write_data *data;
>> const struct rpc_call_ops *call_ops = desc->pg_rpc_callops;
>> struct pnfs_layout_segment *lseg = desc->pg_lseg;
>> + const bool has_lseg = !!lseg;
>
> nit: "has_lseg = (lseg != NULL)" would be more straight forward IMO
>
>>
>> desc->pg_lseg = NULL;
>> while (!list_empty(head)) {
>> @@ -1262,7 +1263,29 @@ pnfs_do_multiple_writes(struct nfs_pageio_descriptor *desc, struct list_head *he
>> data = list_entry(head->next, struct nfs_write_data, list);
>> list_del_init(&data->list);
>>
>> + if (!has_lseg) {
>> + struct nfs_page *req = nfs_list_entry(data->pages.next);
>> + __u64 length = data->npages << PAGE_CACHE_SHIFT;
>> +
>> + lseg = pnfs_update_layout(desc->pg_inode,
>> + req->wb_context,
>> + req_offset(req),
>> + length,
>> + IOMODE_RW,
>> + GFP_NOFS);
>> + if (!lseg || length > (lseg->pls_range.length)) {
>
> I'm concerned about the 'length' part of this condition.
> pnfs_try_to_write_data should handle short writes/reads and
> we should be able to iterate through the I/O using different
> layout segments.
Trond has suggested moving all these back inside block layout. And I
think I can handle short reads/writes situation there.
>
>> + put_lseg(lseg);
>> + lseg = NULL;
>> + pnfs_write_through_mds(desc,data);
>> + continue;
>> + }
>> + }
>> +
>> trypnfs = pnfs_try_to_write_data(data, call_ops, lseg, how);
>> + if (!has_lseg) {
>> + put_lseg(lseg);
>> + lseg = NULL;
>> + }
>
> We had an implementation in the past that saved the most recent lseg in 'desc'
> so it could be used for the remaining requests. Once exhausted, you can
> look for a new one.
Yes, the desc->lseg is what I'm going to use in blocklayout private pg_doio.
>
>> if (trypnfs == PNFS_NOT_ATTEMPTED)
>> pnfs_write_through_mds(desc, data);
>> }
>> @@ -1350,6 +1373,7 @@ pnfs_do_multiple_reads(struct nfs_pageio_descriptor *desc, struct list_head *hea
>> struct nfs_read_data *data;
>> const struct rpc_call_ops *call_ops = desc->pg_rpc_callops;
>> struct pnfs_layout_segment *lseg = desc->pg_lseg;
>> + const bool has_lseg = !!lseg;
>
> ditto
>
>>
>> desc->pg_lseg = NULL;
>> while (!list_empty(head)) {
>> @@ -1358,7 +1382,29 @@ pnfs_do_multiple_reads(struct nfs_pageio_descriptor *desc, struct list_head *hea
>> data = list_entry(head->next, struct nfs_read_data, list);
>> list_del_init(&data->list);
>>
>> + if (!has_lseg) {
>> + struct nfs_page *req = nfs_list_entry(data->pages.next);
>> + __u64 length = data->npages << PAGE_CACHE_SHIFT;
>> +
>> + lseg = pnfs_update_layout(desc->pg_inode,
>> + req->wb_context,
>> + req_offset(req),
>> + length,
>> + IOMODE_READ,
>> + GFP_KERNEL);
>> + if (!lseg || length > lseg->pls_range.length) {
>> + put_lseg(lseg);
>> + lseg = NULL;
>> + pnfs_read_through_mds(desc, data);
>> + continue;
>> + }
>> + }
>> +
>> trypnfs = pnfs_try_to_read_data(data, call_ops, lseg);
>> + if (!has_lseg) {
>> + put_lseg(lseg);
>> + lseg = NULL;
>> + }
>
> ditto
>
> Benny
>
>> if (trypnfs == PNFS_NOT_ATTEMPTED)
>> pnfs_read_through_mds(desc, data);
>> }
--
Thanks,
Tao
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