NFS: Another cleanup of the read/write request coalescing code

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

3 files changed, 113 insertions, 73 deletions

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 7017eb0e0bc8..528128545d66 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -225,14 +225,26 @@ out:
 /**
  * nfs_pageio_init - initialise a page io descriptor
  * @desc: pointer to descriptor
- * @iosize: io block size
+ * @inode: pointer to inode
+ * @doio: pointer to io function
+ * @bsize: io block size
+ * @io_flags: extra parameters for the io function
  */
-void nfs_pageio_init(struct nfs_pageio_descriptor *desc, unsigned int bsize)
+void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
+                     struct inode *inode,
+                     int (*doio)(struct inode *, struct list_head *, size_t, int),
+                     unsigned int bsize,
+                     int io_flags)
 {
         INIT_LIST_HEAD(&desc->pg_list);
+        desc->pg_bytes_written = 0;
         desc->pg_count = 0;
         desc->pg_bsize = bsize;
         desc->pg_base = 0;
+        desc->pg_inode = inode;
+        desc->pg_doio = doio;
+        desc->pg_ioflags = io_flags;
+        desc->pg_error = 0;
 }
 
 /**
@@ -265,15 +277,15 @@ static int nfs_can_coalesce_requests(struct nfs_page *prev,
 }
 
 /**
- * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
+ * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
  * @desc: destination io descriptor
  * @req: request
  *
  * Returns true if the request 'req' was successfully coalesced into the
  * existing list of pages 'desc'.
  */
-static int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
-                                  struct nfs_page *req)
+static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
+                                     struct nfs_page *req)
 {
         size_t newlen = req->wb_bytes;
 
@@ -301,6 +313,46 @@ static int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
         return 1;
 }
 
+/*
+ * Helper for nfs_pageio_add_request and nfs_pageio_complete
+ */
+static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
+{
+        if (!list_empty(&desc->pg_list)) {
+                int error = desc->pg_doio(desc->pg_inode,
+                                          &desc->pg_list,
+                                          desc->pg_count,
+                                          desc->pg_ioflags);
+                if (error < 0)
+                        desc->pg_error = error;
+                else
+                        desc->pg_bytes_written += desc->pg_count;
+        }
+        if (list_empty(&desc->pg_list)) {
+                desc->pg_count = 0;
+                desc->pg_base = 0;
+        }
+}
+
+/**
+ * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
+ * @desc: destination io descriptor
+ * @req: request
+ *
+ * Returns true if the request 'req' was successfully coalesced into the
+ * existing list of pages 'desc'.
+ */
+static int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
+                                  struct nfs_page *req)
+{
+        while (!nfs_pageio_do_add_request(desc, req)) {
+                nfs_pageio_doio(desc);
+                if (desc->pg_error < 0)
+                        return 0;
+        }
+        return 1;
+}
+
 /**
  * nfs_pageio_add_list - Split coalesced requests out from a list.
  * @desc: destination io descriptor
@@ -320,6 +372,15 @@ void nfs_pageio_add_list(struct nfs_pageio_descriptor *desc,
         }
 }
 
+/**
+ * nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
+ * @desc: pointer to io descriptor
+ */
+void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
+{
+        nfs_pageio_doio(desc);
+}
+
 #define NFS_SCAN_MAXENTRIES 16
 /**
  * nfs_scan_dirty - Scan the radix tree for dirty requests
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 97f0f42e136d..0effa74992df 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -27,7 +27,8 @@
 
 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
 
-static int nfs_pagein_one(struct list_head *, struct inode *);
+static int nfs_pagein_multi(struct inode *, struct list_head *, size_t, int);
+static int nfs_pagein_one(struct inode *, struct list_head *, size_t, int);
 static const struct rpc_call_ops nfs_read_partial_ops;
 static const struct rpc_call_ops nfs_read_full_ops;
 
@@ -133,7 +134,10 @@ static int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
                 memclear_highpage_flush(page, len, PAGE_CACHE_SIZE - len);
 
         nfs_list_add_request(new, &one_request);
-        nfs_pagein_one(&one_request, inode);
+        if (NFS_SERVER(inode)->rsize < PAGE_CACHE_SIZE)
+                nfs_pagein_multi(inode, &one_request, len, 0);
+        else
+                nfs_pagein_one(inode, &one_request, len, 0);
         return 0;
 }
 
@@ -230,7 +234,7 @@ static void nfs_execute_read(struct nfs_read_data *data)
  * won't see the new data until our attribute cache is updated.  This is more
  * or less conventional NFS client behavior.
  */
-static int nfs_pagein_multi(struct list_head *head, struct inode *inode)
+static int nfs_pagein_multi(struct inode *inode, struct list_head *head, size_t count, int flags)
 {
         struct nfs_page *req = nfs_list_entry(head->next);
         struct page *page = req->wb_page;
@@ -242,7 +246,7 @@ static int nfs_pagein_multi(struct list_head *head, struct inode *inode)
 
         nfs_list_remove_request(req);
 
-        nbytes = req->wb_bytes;
+        nbytes = count;
         do {
                 size_t len = min(nbytes,rsize);
 
@@ -258,23 +262,19 @@ static int nfs_pagein_multi(struct list_head *head, struct inode *inode)
 
         ClearPageError(page);
         offset = 0;
-        nbytes = req->wb_bytes;
+        nbytes = count;
         do {
                 data = list_entry(list.next, struct nfs_read_data, pages);
                 list_del_init(&data->pages);
 
                 data->pagevec[0] = page;
 
-                if (nbytes > rsize) {
-                        nfs_read_rpcsetup(req, data, &nfs_read_partial_ops,
-                                        rsize, offset);
-                        offset += rsize;
-                        nbytes -= rsize;
-                } else {
-                        nfs_read_rpcsetup(req, data, &nfs_read_partial_ops,
-                                        nbytes, offset);
-                        nbytes = 0;
-                }
+                if (nbytes < rsize)
+                        rsize = nbytes;
+                nfs_read_rpcsetup(req, data, &nfs_read_partial_ops,
+                                  rsize, offset);
+                offset += rsize;
+                nbytes -= rsize;
                 nfs_execute_read(data);
         } while (nbytes != 0);
 
@@ -291,30 +291,24 @@ out_bad:
         return -ENOMEM;
 }
 
-static int nfs_pagein_one(struct list_head *head, struct inode *inode)
+static int nfs_pagein_one(struct inode *inode, struct list_head *head, size_t count, int flags)
 {
         struct nfs_page         *req;
         struct page             **pages;
         struct nfs_read_data    *data;
-        unsigned int            count;
-
-        if (NFS_SERVER(inode)->rsize < PAGE_CACHE_SIZE)
-                return nfs_pagein_multi(head, inode);
 
-        data = nfs_readdata_alloc(NFS_SERVER(inode)->rsize);
+        data = nfs_readdata_alloc(count);
         if (!data)
                 goto out_bad;
 
         INIT_LIST_HEAD(&data->pages);
         pages = data->pagevec;
-        count = 0;
         while (!list_empty(head)) {
                 req = nfs_list_entry(head->next);
                 nfs_list_remove_request(req);
                 nfs_list_add_request(req, &data->pages);
                 ClearPageError(req->wb_page);
                 *pages++ = req->wb_page;
-                count += req->wb_bytes;
         }
         req = nfs_list_entry(data->pages.next);
 
@@ -328,22 +322,20 @@ out_bad:
 }
 
 static int
-nfs_pagein_list(struct list_head *head, unsigned int rsize)
+nfs_pagein_list(struct inode *inode, struct list_head *head, unsigned int rsize)
 {
         struct nfs_pageio_descriptor desc;
-        struct nfs_page *req;
         unsigned int pages = 0;
         int error = 0;
 
-        while (!list_empty(head)) {
-                nfs_pageio_init(&desc, rsize);
-                nfs_pageio_add_list(&desc, head);
-                req = nfs_list_entry(desc.pg_list.next);
-                error = nfs_pagein_one(&desc.pg_list, req->wb_context->dentry->d_inode);
-                if (error < 0)
-                        break;
-                pages += (desc.pg_count + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
-        }
+        if (rsize < PAGE_CACHE_SIZE)
+                nfs_pageio_init(&desc, inode, nfs_pagein_multi, rsize, 0);
+        else
+                nfs_pageio_init(&desc, inode, nfs_pagein_one, rsize, 0);
+
+        nfs_pageio_add_list(&desc, head);
+        nfs_pageio_complete(&desc);
+        pages += (desc.pg_bytes_written + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 
         nfs_async_read_error(head);
         if (error >= 0)
@@ -597,7 +589,7 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
                                 filp->private_data);
         ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
         if (!list_empty(&head)) {
-                int err = nfs_pagein_list(&head, server->rsize);
+                int err = nfs_pagein_list(inode, &head, server->rsize);
                 if (!ret)
                         nfs_add_stats(inode, NFSIOS_READPAGES, err);
                         ret = err;
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index b03ec1ba4d75..b6749967eead 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -835,7 +835,7 @@ static void nfs_execute_write(struct nfs_write_data *data)
  * Generate multiple small requests to write out a single
  * contiguous dirty area on one page.
  */
-static int nfs_flush_multi(struct inode *inode, struct list_head *head, int how)
+static int nfs_flush_multi(struct inode *inode, struct list_head *head, size_t count, int how)
 {
         struct nfs_page *req = nfs_list_entry(head->next);
         struct page *page = req->wb_page;
@@ -847,7 +847,7 @@ static int nfs_flush_multi(struct inode *inode, struct list_head *head, int how)
 
         nfs_list_remove_request(req);
 
-        nbytes = req->wb_bytes;
+        nbytes = count;
         do {
                 size_t len = min(nbytes, wsize);
 
@@ -862,23 +862,19 @@ static int nfs_flush_multi(struct inode *inode, struct list_head *head, int how)
 
         ClearPageError(page);
         offset = 0;
-        nbytes = req->wb_bytes;
+        nbytes = count;
         do {
                 data = list_entry(list.next, struct nfs_write_data, pages);
                 list_del_init(&data->pages);
 
                 data->pagevec[0] = page;
 
-                if (nbytes > wsize) {
-                        nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
-                                        wsize, offset, how);
-                        offset += wsize;
-                        nbytes -= wsize;
-                } else {
-                        nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
-                                        nbytes, offset, how);
-                        nbytes = 0;
-                }
+                if (nbytes < wsize)
+                        wsize = nbytes;
+                nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
+                                   wsize, offset, how);
+                offset += wsize;
+                nbytes -= wsize;
                 nfs_execute_write(data);
         } while (nbytes != 0);
 
@@ -904,26 +900,23 @@ out_bad:
  * This is the case if nfs_updatepage detects a conflicting request
  * that has been written but not committed.
  */
-static int nfs_flush_one(struct inode *inode, struct list_head *head, int how)
+static int nfs_flush_one(struct inode *inode, struct list_head *head, size_t count, int how)
 {
         struct nfs_page         *req;
         struct page             **pages;
         struct nfs_write_data   *data;
-        unsigned int            count;
 
-        data = nfs_writedata_alloc(NFS_SERVER(inode)->wsize);
+        data = nfs_writedata_alloc(count);
         if (!data)
                 goto out_bad;
 
         pages = data->pagevec;
-        count = 0;
         while (!list_empty(head)) {
                 req = nfs_list_entry(head->next);
                 nfs_list_remove_request(req);
                 nfs_list_add_request(req, &data->pages);
                 ClearPageError(req->wb_page);
                 *pages++ = req->wb_page;
-                count += req->wb_bytes;
         }
         req = nfs_list_entry(data->pages.next);
 
@@ -946,28 +939,22 @@ static int nfs_flush_one(struct inode *inode, struct list_head *head, int how)
 static int nfs_flush_list(struct inode *inode, struct list_head *head, int npages, int how)
 {
         struct nfs_pageio_descriptor desc;
-        int (*flush_one)(struct inode *, struct list_head *, int);
         int wpages = NFS_SERVER(inode)->wpages;
         int wsize = NFS_SERVER(inode)->wsize;
-        int error;
 
-        flush_one = nfs_flush_one;
-        if (wsize < PAGE_CACHE_SIZE)
-                flush_one = nfs_flush_multi;
         /* For single writes, FLUSH_STABLE is more efficient */
         if (npages <= wpages && npages == NFS_I(inode)->npages
                         && nfs_list_entry(head->next)->wb_bytes <= wsize)
                 how |= FLUSH_STABLE;
 
-        do {
-                nfs_pageio_init(&desc, wsize);
-                nfs_pageio_add_list(&desc, head);
-                error = flush_one(inode, &desc.pg_list, how);
-                if (error < 0)
-                        goto out_err;
-        } while (!list_empty(head));
-        return 0;
-out_err:
+        if (wsize < PAGE_CACHE_SIZE)
+                nfs_pageio_init(&desc, inode, nfs_flush_multi, wsize, how);
+        else
+                nfs_pageio_init(&desc, inode, nfs_flush_one, wsize, how);
+        nfs_pageio_add_list(&desc, head);
+        nfs_pageio_complete(&desc);
+        if (desc.pg_error == 0)
+                return 0;
         while (!list_empty(head)) {
                 struct nfs_page *req = nfs_list_entry(head->next);
                 nfs_list_remove_request(req);
@@ -975,7 +962,7 @@ out_err:
                 nfs_end_page_writeback(req->wb_page);
                 nfs_clear_page_writeback(req);
         }
-        return error;
+        return desc.pg_error;
 }
 
 /*