user/sven/linux.git/include/linux/nfs_page.h, branch v3.16.1

nfs: page group syncing in write path

2014-05-29T15:11:45Z

Operations that modify state for a whole page must be syncronized across all requests within a page group. In the write path, this is calling end_page_writeback and removing the head request from an inode. Both of these operations should not be called until all requests in a page group have reached the point where they would call them. This patch should have no effect yet since all page groups currently have one request, but will come into play when pg_test functions are modified to split pages into sub-page regions. Signed-off-by: Weston Andros Adamson Signed-off-by: Trond Myklebust

nfs: page group syncing in read path

2014-05-29T15:11:45Z

Operations that modify state for a whole page must be syncronized across all requests within a page group. In the read path, this is calling unlock_page and SetPageUptodate. Both of these functions should not be called until all requests in a page group have reached the point where they would call them. This patch should have no effect yet since all page groups currently have one request, but will come into play when pg_test functions are modified to split pages into sub-page regions. Signed-off-by: Weston Andros Adamson Signed-off-by: Trond Myklebust

nfs: add support for multiple nfs reqs per page

2014-05-29T15:11:44Z

Add "page groups" - a circular list of nfs requests (struct nfs_page) that all reference the same page. This gives nfs read and write paths the ability to account for sub-page regions independently. This somewhat follows the design of struct buffer_head's sub-page accounting. Only "head" requests are ever added/removed from the inode list in the buffered write path. "head" and "sub" requests are treated the same through the read path and the rest of the write/commit path. Requests are given an extra reference across the life of the list. Page groups are never rejoined after being split. If the read/write request fails and the client falls back to another path (ie revert to MDS in PNFS case), the already split requests are pushed through the recoalescing code again, which may split them further and then coalesce them into properly sized requests on the wire. Fragmentation shouldn't be a problem with the current design, because we flush all requests in page group when a non-contiguous request is added, so the only time resplitting should occur is on a resend of a read or write. This patch lays the groundwork for sub-page splitting, but does not actually do any splitting. For now all page groups have one request as pg_test functions don't yet split pages. There are several related patches that are needed support multiple requests per page group. Signed-off-by: Weston Andros Adamson Signed-off-by: Trond Myklebust

nfs: modify pg_test interface to return size_t

2014-05-29T15:11:43Z

This is a step toward allowing pg_test to inform the the coalescing code to reduce the size of requests so they may fit in whatever scheme the pg_test callback wants to define. For now, just return the size of the request if there is space, or 0 if there is not. This shouldn't change any behavior as it acts the same as when the pg_test functions returned bool. Signed-off-by: Weston Andros Adamson Signed-off-by: Trond Myklebust

nfs: remove unused arg from nfs_create_request

2014-05-29T15:11:43Z

@inode is passed but not used. Signed-off-by: Weston Andros Adamson Signed-off-by: Trond Myklebust

nfs: clean up PG_* flags

2014-05-29T15:11:42Z

Remove unused flags PG_NEED_COMMIT and PG_NEED_RESCHED. Add comments describing how each flag is used. Signed-off-by: Weston Andros Adamson Signed-off-by: Trond Myklebust

NFS: Create a common initiate_pgio() function

2014-05-29T15:11:40Z

Most of this code is the same for both the read and write paths, so combine everything and use the rw_ops when necessary. Signed-off-by: Anna Schumaker Signed-off-by: Trond Myklebust

NFS: Create a common nfs_pgio_result_common function

2014-05-28T22:40:36Z

Combining these functions will let me make a single nfs_rw_common_ops struct (see the next patch). Signed-off-by: Anna Schumaker Signed-off-by: Trond Myklebust

NFS: Create a common pgio_rpc_prepare function

2014-05-28T22:40:28Z

The read and write paths do exactly the same thing for the rpc_prepare rpc_op. This patch combines them together into a single function. Signed-off-by: Anna Schumaker Signed-off-by: Trond Myklebust

NFS: Create a common rw_header_alloc and rw_header_free function

2014-05-28T22:40:04Z

I create a new struct nfs_rw_ops to decide the differences between reads and writes. This struct will be set when initializing a new nfs_pgio_descriptor, and then passed on to the nfs_rw_header when a new header is allocated. Signed-off-by: Anna Schumaker Signed-off-by: Trond Myklebust