On 2010-09-21 21:25, Fred Isaman wrote:
> On Tue, Sep 21, 2010 at 3:00 PM, Benny Halevy <bhalevy@xxxxxxxxxxx> wrote:
>> Base the LAYOUTGET arguments on the actual required byte ranges
>> rather than asking for the whole file layout.
>>
>> Add a check in readpage_async_filler that the layout segment
>> retrieved in pnfs_pageio_init_read still covers the current page
>> and if not, try getting a new one.
>>
>> Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx>
>> ---
>> fs/nfs/file.c | 2 +-
>> fs/nfs/pnfs.c | 13 ++++++-------
>> fs/nfs/pnfs.h | 21 ++++++++-------------
>> fs/nfs/read.c | 17 ++++++++++++++++-
>> 4 files changed, 31 insertions(+), 22 deletions(-)
>>
>> diff --git a/fs/nfs/file.c b/fs/nfs/file.c
>> index b05c1ff..228f41e 100644
>> --- a/fs/nfs/file.c
>> +++ b/fs/nfs/file.c
>> @@ -390,7 +390,7 @@ static int nfs_write_begin(struct file *file, struct address_space *mapping,
>>
>> pnfs_update_layout(mapping->host,
>> nfs_file_open_context(file),
>> - 0, NFS4_MAX_UINT64, IOMODE_RW,
>> + pos, len, IOMODE_RW,
>> &lseg);
>> start:
>> /*
>> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
>> index e6261a3..de716f6 100644
>> --- a/fs/nfs/pnfs.c
>> +++ b/fs/nfs/pnfs.c
>> @@ -600,11 +600,10 @@ send_layoutget(struct inode *ino,
>> pnfs_layout_release(lo, NULL);
>> return -ENOMEM;
>> }
>> - lgp->args.minlength = NFS4_MAX_UINT64;
>> + lgp->args.minlength = PAGE_CACHE_SIZE -
>> + (range->offset & (PAGE_CACHE_SIZE-1));
>> lgp->args.maxcount = PNFS_LAYOUT_MAXSIZE;
>> - lgp->args.range.iomode = range->iomode;
>> - lgp->args.range.offset = 0;
>> - lgp->args.range.length = NFS4_MAX_UINT64;
>> + lgp->args.range = *range;
>> lgp->args.type = server->pnfs_curr_ld->id;
>> lgp->args.inode = ino;
>> lgp->lsegpp = lsegpp;
>> @@ -1028,8 +1027,8 @@ _pnfs_update_layout(struct inode *ino,
>> {
>> struct pnfs_layout_range arg = {
>> .iomode = iomode,
>> - .offset = 0,
>> - .length = NFS4_MAX_UINT64,
>> + .offset = pos,
>> + .length = count,
>> };
>> struct nfs_inode *nfsi = NFS_I(ino);
>> struct pnfs_layout_hdr *lo;
>> @@ -1330,7 +1329,7 @@ pnfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
>> readahead_range(inode, pages, &loff, &count);
>>
>> if (count > 0) {
>> - _pnfs_update_layout(inode, ctx, loff, count, IOMODE_READ,
>> + pnfs_update_layout(inode, ctx, loff, count, IOMODE_READ,
>
>
> Why this change? the pnfs_enabled_sb check has already been done at
> the top of the function, hasn't it?
>
Actually, it's for the dprintk, but this is not crucial.
>
>> &pgio->pg_lseg);
>> if (!pgio->pg_lseg)
>> return;
>> diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
>> index 81534aa..b666f53 100644
>> --- a/fs/nfs/pnfs.h
>> +++ b/fs/nfs/pnfs.h
>> @@ -188,19 +188,14 @@ static inline int pnfs_return_layout(struct inode *ino,
>> return 0;
>> }
>>
>> -static inline void pnfs_update_layout(struct inode *ino,
>> - struct nfs_open_context *ctx,
>> - loff_t pos, u64 count, enum pnfs_iomode access_type,
>> - struct pnfs_layout_segment **lsegpp)
>> -{
>> - struct nfs_server *nfss = NFS_SERVER(ino);
>> -
>> - if (pnfs_enabled_sb(nfss))
>> - _pnfs_update_layout(ino, ctx, pos, count, access_type, lsegpp);
>> - else {
>> - if (lsegpp)
>> - *lsegpp = NULL;
>> - }
>> +#define pnfs_update_layout(ino, ctx, pos, count, access_type, lsegpp) { \
>> + if (pnfs_enabled_sb(NFS_SERVER(ino))) { \
>> + dprintk("%s: updating %s layout pos %llu count %llu\n", __func__, \
>> + (access_type) == IOMODE_READ ? "READ" : "WRITE", \
>> + (unsigned long long)(pos), (unsigned long long)(count)); \
>> + _pnfs_update_layout(ino, ctx, pos, count, access_type, lsegpp); \
>> + } else \
>> + *lsegpp = NULL; \
>> }
>
>
> Why this change? I much prefer the inline version to the define, and
> I thought that this was generally being pushed.
>
dprintk again.
I think I'll just do this as a debug-only patch, just so we have the extra debugging
in the development tree.
>
>>
>> static inline int pnfs_get_write_status(struct nfs_write_data *data)
>> diff --git a/fs/nfs/read.c b/fs/nfs/read.c
>> index dde7996..36eef5e 100644
>> --- a/fs/nfs/read.c
>> +++ b/fs/nfs/read.c
>> @@ -121,12 +121,14 @@ int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
>> LIST_HEAD(one_request);
>> struct nfs_page *new;
>> unsigned int len;
>> + loff_t pgoffs;
>> struct pnfs_layout_segment *lseg;
>>
>> len = nfs_page_length(page);
>> if (len == 0)
>> return nfs_return_empty_page(page);
>> - pnfs_update_layout(inode, ctx, 0, NFS4_MAX_UINT64, IOMODE_READ, &lseg);
>> + pgoffs = (loff_t)page->index << PAGE_CACHE_SHIFT;
>> + pnfs_update_layout(inode, ctx, pgoffs, len, IOMODE_READ, &lseg);
>> new = nfs_create_request(ctx, inode, page, 0, len, lseg);
>> put_lseg(lseg);
>> if (IS_ERR(new)) {
>> @@ -603,14 +605,27 @@ readpage_async_filler(void *data, struct page *page)
>> {
>> struct nfs_readdesc *desc = (struct nfs_readdesc *)data;
>> struct inode *inode = page->mapping->host;
>> + struct pnfs_layout_range *range;
>> struct nfs_page *new;
>> unsigned int len;
>> + loff_t pgoff;
>> int error;
>>
>> len = nfs_page_length(page);
>> if (len == 0)
>> return nfs_return_empty_page(page);
>>
>> + pgoff = (loff_t)page->index << PAGE_CACHE_SHIFT;
>> + range = desc->pgio->pg_lseg ? &desc->pgio->pg_lseg->range : NULL;
>> + if (!range ||
>> + (range->offset > pgoff + len) ||
>> + (range->offset + range->length < pgoff)) {
>> + put_lseg(desc->pgio->pg_lseg);
>> + desc->pgio->pg_lseg = NULL;
>> + pnfs_update_layout(inode, desc->ctx, pgoff, len, IOMODE_READ,
>> + &desc->pgio->pg_lseg);
>> + }
>> +
>> new = nfs_create_request(desc->ctx, inode, page, 0, len,
>> desc->pgio->pg_lseg);
>> if (IS_ERR(new))
>> --
>
>
> Wouldn't it be easier to just trim any returned layout to page
> boundaries, and then pnfs_can_coalesce_requests will handle this
> automatically.
Trimming the returned layout to page boundaries sounds like a good idea,
but in this case it's not the page alignment I'm worried about, but
working in layout segments in general. The first segment we end with
after pnfs_pageio_init_read and that we store in desc->pgio->pg_lseg
may cover only part of the whole I/O so we need this check to see if
it's exhausted and we need another layout segment to continue, otherwise
we'll be using a layout segment that does not cover the page in hand.
Benny
>
> Fred
>
>> 1.7.2.3
>>
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