NFS: create common nfs_pgio_header for both read and write

In order to avoid duplicating all the data in nfs_read_data whenever we
split it up into multiple RPC calls (either due to a short read result
or due to rsize < PAGE_SIZE), we split out the bits that are the same
per RPC call into a separate "header" structure.

The goal this patch moves towards is to have a single header
refcounted by several rpc_data structures.  Thus, want to always refer
from rpc_data to the header, and not the other way.  This patch comes
close to that ideal, but the directio code currently needs some
special casing, isolated in the nfs_direct_[read_write]hdr_release()
functions.  This will be dealt with in a future patch.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

2 files changed, 20 insertions, 15 deletions

diff --git a/fs/nfs/objlayout/objio_osd.c b/fs/nfs/objlayout/objio_osd.c
index 4bff4a3dab46..fbf4874ec252 100644
--- a/fs/nfs/objlayout/objio_osd.c
+++ b/fs/nfs/objlayout/objio_osd.c
@@ -440,11 +440,12 @@ static void _read_done(struct ore_io_state *ios, void *private)
 
 int objio_read_pagelist(struct nfs_read_data *rdata)
 {
+        struct nfs_pgio_header *hdr = rdata->header;
         struct objio_state *objios;
         int ret;
 
-        ret = objio_alloc_io_state(NFS_I(rdata->inode)->layout, true,
-                        rdata->lseg, rdata->args.pages, rdata->args.pgbase,
+        ret = objio_alloc_io_state(NFS_I(hdr->inode)->layout, true,
+                        hdr->lseg, rdata->args.pages, rdata->args.pgbase,
                         rdata->args.offset, rdata->args.count, rdata,
                         GFP_KERNEL, &objios);
         if (unlikely(ret))
@@ -483,12 +484,12 @@ static struct page *__r4w_get_page(void *priv, u64 offset, bool *uptodate)
 {
         struct objio_state *objios = priv;
         struct nfs_write_data *wdata = objios->oir.rpcdata;
+        struct address_space *mapping = wdata->header->inode->i_mapping;
         pgoff_t index = offset / PAGE_SIZE;
-        struct page *page = find_get_page(wdata->inode->i_mapping, index);
+        struct page *page = find_get_page(mapping, index);
 
         if (!page) {
-                page = find_or_create_page(wdata->inode->i_mapping,
-                                                index, GFP_NOFS);
+                page = find_or_create_page(mapping, index, GFP_NOFS);
                 if (unlikely(!page)) {
                         dprintk("%s: grab_cache_page Failed index=0x%lx\n",
                                 __func__, index);
@@ -518,11 +519,12 @@ static const struct _ore_r4w_op _r4w_op = {
 
 int objio_write_pagelist(struct nfs_write_data *wdata, int how)
 {
+        struct nfs_pgio_header *hdr = wdata->header;
         struct objio_state *objios;
         int ret;
 
-        ret = objio_alloc_io_state(NFS_I(wdata->inode)->layout, false,
-                        wdata->lseg, wdata->args.pages, wdata->args.pgbase,
+        ret = objio_alloc_io_state(NFS_I(hdr->inode)->layout, false,
+                        hdr->lseg, wdata->args.pages, wdata->args.pgbase,
                         wdata->args.offset, wdata->args.count, wdata, GFP_NOFS,
                         &objios);
         if (unlikely(ret))
diff --git a/fs/nfs/objlayout/objlayout.c b/fs/nfs/objlayout/objlayout.c
index 595c5fc21a19..874613545301 100644
--- a/fs/nfs/objlayout/objlayout.c
+++ b/fs/nfs/objlayout/objlayout.c
@@ -258,7 +258,7 @@ objlayout_read_done(struct objlayout_io_res *oir, ssize_t status, bool sync)
         if (status >= 0)
                 rdata->res.count = status;
         else
-                rdata->pnfs_error = status;
+                rdata->header->pnfs_error = status;
         objlayout_iodone(oir);
         /* must not use oir after this point */
 
@@ -279,12 +279,14 @@ objlayout_read_done(struct objlayout_io_res *oir, ssize_t status, bool sync)
 enum pnfs_try_status
 objlayout_read_pagelist(struct nfs_read_data *rdata)
 {
+        struct nfs_pgio_header *hdr = rdata->header;
+        struct inode *inode = hdr->inode;
         loff_t offset = rdata->args.offset;
         size_t count = rdata->args.count;
         int err;
         loff_t eof;
 
-        eof = i_size_read(rdata->inode);
+        eof = i_size_read(inode);
         if (unlikely(offset + count > eof)) {
                 if (offset >= eof) {
                         err = 0;
@@ -297,17 +299,17 @@ objlayout_read_pagelist(struct nfs_read_data *rdata)
         }
 
         rdata->res.eof = (offset + count) >= eof;
-        _fix_verify_io_params(rdata->lseg, &rdata->args.pages,
+        _fix_verify_io_params(hdr->lseg, &rdata->args.pages,
                               &rdata->args.pgbase,
                               rdata->args.offset, rdata->args.count);
 
         dprintk("%s: inode(%lx) offset 0x%llx count 0x%Zx eof=%d\n",
-                __func__, rdata->inode->i_ino, offset, count, rdata->res.eof);
+                __func__, inode->i_ino, offset, count, rdata->res.eof);
 
         err = objio_read_pagelist(rdata);
  out:
         if (unlikely(err)) {
-                rdata->pnfs_error = err;
+                hdr->pnfs_error = err;
                 dprintk("%s: Returned Error %d\n", __func__, err);
                 return PNFS_NOT_ATTEMPTED;
         }
@@ -340,7 +342,7 @@ objlayout_write_done(struct objlayout_io_res *oir, ssize_t status, bool sync)
                 wdata->res.count = status;
                 wdata->verf.committed = oir->committed;
         } else {
-                wdata->pnfs_error = status;
+                wdata->header->pnfs_error = status;
         }
         objlayout_iodone(oir);
         /* must not use oir after this point */
@@ -363,15 +365,16 @@ enum pnfs_try_status
 objlayout_write_pagelist(struct nfs_write_data *wdata,
                          int how)
 {
+        struct nfs_pgio_header *hdr = wdata->header;
         int err;
 
-        _fix_verify_io_params(wdata->lseg, &wdata->args.pages,
+        _fix_verify_io_params(hdr->lseg, &wdata->args.pages,
                               &wdata->args.pgbase,
                               wdata->args.offset, wdata->args.count);
 
         err = objio_write_pagelist(wdata, how);
         if (unlikely(err)) {
-                wdata->pnfs_error = err;
+                hdr->pnfs_error = err;
                 dprintk("%s: Returned Error %d\n", __func__, err);
                 return PNFS_NOT_ATTEMPTED;
         }