On 04/23/2014 12:29 AM, Weston Andros Adamson wrote:
> Now that pg_test can change the size of the request (by returning a non-zero
> size smaller than the request), pg_test functions that call other
> pg_test functions must return the minimum of the result - or 0 if any fail.
>
> Also clean up the logic of some pg_test functions so that all checks are
> for contitions where coalescing is not possible.
>
> Signed-off-by: Weston Andros Adamson <[email protected]>
> ---
> fs/nfs/nfs4filelayout.c | 27 ++++++++++++++-------------
> fs/nfs/objlayout/objio_osd.c | 12 ++++++++----
> fs/nfs/pnfs.c | 15 ++++++++++-----
> 3 files changed, 32 insertions(+), 22 deletions(-)
>
> diff --git a/fs/nfs/nfs4filelayout.c b/fs/nfs/nfs4filelayout.c
> index 3b32c95..cfd76bd 100644
> --- a/fs/nfs/nfs4filelayout.c
> +++ b/fs/nfs/nfs4filelayout.c
> @@ -930,26 +930,27 @@ static size_t
> filelayout_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
> struct nfs_page *req)
> {
> + unsigned int size;
> u64 p_stripe, r_stripe;
> u32 stripe_unit;
>
> - if (!pnfs_generic_pg_test(pgio, prev, req) ||
> - !nfs_generic_pg_test(pgio, prev, req))
> + /* calls nfs_generic_pg_test */
> + size = pnfs_generic_pg_test(pgio, prev, req);
> + if (!size)
> return 0;
>
> - if (!prev)
> - return req->wb_bytes;
> + if (prev) {
> + p_stripe = (u64)req_offset(prev);
> + r_stripe = (u64)req_offset(req);
> + stripe_unit = FILELAYOUT_LSEG(pgio->pg_lseg)->stripe_unit;
>
> - p_stripe = (u64)req_offset(prev);
> - r_stripe = (u64)req_offset(req);
> - stripe_unit = FILELAYOUT_LSEG(pgio->pg_lseg)->stripe_unit;
> + do_div(p_stripe, stripe_unit);
> + do_div(r_stripe, stripe_unit);
>
> - do_div(p_stripe, stripe_unit);
> - do_div(r_stripe, stripe_unit);
> -
> - if (p_stripe == r_stripe)
> - return req->wb_bytes;
> - return 0;
> + if (p_stripe != r_stripe)
> + return 0;
> + }
> + return min(size, req->wb_bytes);
> }
>
> static void
> diff --git a/fs/nfs/objlayout/objio_osd.c b/fs/nfs/objlayout/objio_osd.c
> index c20352a..31de29e 100644
> --- a/fs/nfs/objlayout/objio_osd.c
> +++ b/fs/nfs/objlayout/objio_osd.c
> @@ -571,13 +571,17 @@ int objio_write_pagelist(struct nfs_write_data *wdata, int how)
> static size_t objio_pg_test(struct nfs_pageio_descriptor *pgio,
> struct nfs_page *prev, struct nfs_page *req)
> {
> - if (!pnfs_generic_pg_test(pgio, prev, req))
> + unsigned int size;
> +
> + size = pnfs_generic_pg_test(pgio, prev, req);
> +
> + if (!size)
> return 0;
>
> - if (pgio->pg_count + req->wb_bytes <=
> + if (pgio->pg_count + req->wb_bytes >
> (unsigned long)pgio->pg_layout_private)
> - return req->wb_bytes;
> - return 0;
> + return 0;

objio_osd can enjoy the new facility by returning the
remainder here:

max_io = (unsigned long)pgio->pg_layout_private);

wb_bytes = min(size, req->wb_bytes);

if (pgio->pg_count + req->wb_bytes > max_io)
wb_bytes = max_io - pgio->pg_count;

return wb_bytes;

Which reminds me that this code sucks and I need to fix it. I will do
so after you send your changes.

[I promise to test these guys soon. Can you please put them on a public tree?]

Thanks
Boaz

> + return min(size, req->wb_bytes);
> }
>
> static void objio_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
> index 6201bf6..7c89385 100644
> --- a/fs/nfs/pnfs.c
> +++ b/fs/nfs/pnfs.c
> @@ -1469,8 +1469,12 @@ size_t
> pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
> struct nfs_page *req)
> {
> - if (pgio->pg_lseg == NULL)
> - return nfs_generic_pg_test(pgio, prev, req);
> + unsigned int size;
> +
> + size = nfs_generic_pg_test(pgio, prev, req);
> +
> + if (!size)
> + return 0;
>
> /*
> * Test if a nfs_page is fully contained in the pnfs_layout_range.
> @@ -1486,10 +1490,11 @@ pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
> * first byte that lies outside the pnfs_layout_range. FIXME?
> *
> */
> - if (req_offset(req) < end_offset(pgio->pg_lseg->pls_range.offset,
> + if (req_offset(req) >= end_offset(pgio->pg_lseg->pls_range.offset,
> pgio->pg_lseg->pls_range.length))
> - return req->wb_bytes;
> - return 0;
> + return 0;
> +
> + return min(size, req->wb_bytes);
> }
> EXPORT_SYMBOL_GPL(pnfs_generic_pg_test);
>
>