NFS: Add nfs_commit_file()

Copy will use this to set up a commit request for a generic range.  I
don't want to allocate a new pagecache entry for the file, so I needed
to change parts of the commit path to handle requests with a null
wb_page.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

3 files changed, 42 insertions, 6 deletions

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index f1d1d2c472e9..5154fa65a2f2 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -477,6 +477,7 @@ void nfs_mark_request_commit(struct nfs_page *req,
                              u32 ds_commit_idx);
 int nfs_write_need_commit(struct nfs_pgio_header *);
 void nfs_writeback_update_inode(struct nfs_pgio_header *hdr);
+int nfs_commit_file(struct file *file, struct nfs_write_verifier *verf);
 int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
                             int how, struct nfs_commit_info *cinfo);
 void nfs_retry_commit(struct list_head *page_list,
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 1f6db4231057..174dd4cf5747 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -341,8 +341,10 @@ nfs_create_request(struct nfs_open_context *ctx, struct page *page,
          * long write-back delay. This will be adjusted in
          * update_nfs_request below if the region is not locked. */
         req->wb_page    = page;
-        req->wb_index   = page_file_index(page);
-        get_page(page);
+        if (page) {
+                req->wb_index = page_file_index(page);
+                get_page(page);
+        }
         req->wb_offset  = offset;
         req->wb_pgbase  = offset;
         req->wb_bytes   = count;
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 9283a96b9fb8..e18a97aab275 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -737,7 +737,7 @@ static void nfs_inode_remove_request(struct nfs_page *req)
                 head = req->wb_head;
 
                 spin_lock(&inode->i_lock);
-                if (likely(!PageSwapCache(head->wb_page))) {
+                if (likely(head->wb_page && !PageSwapCache(head->wb_page))) {
                         set_page_private(head->wb_page, 0);
                         ClearPagePrivate(head->wb_page);
                         smp_mb__after_atomic();
@@ -759,7 +759,8 @@ static void nfs_inode_remove_request(struct nfs_page *req)
 static void
 nfs_mark_request_dirty(struct nfs_page *req)
 {
-        __set_page_dirty_nobuffers(req->wb_page);
+        if (req->wb_page)
+                __set_page_dirty_nobuffers(req->wb_page);
 }
 
 /*
@@ -835,7 +836,8 @@ nfs_request_add_commit_list(struct nfs_page *req, struct nfs_commit_info *cinfo)
         spin_lock(&cinfo->inode->i_lock);
         nfs_request_add_commit_list_locked(req, &cinfo->mds->list, cinfo);
         spin_unlock(&cinfo->inode->i_lock);
-        nfs_mark_page_unstable(req->wb_page, cinfo);
+        if (req->wb_page)
+                nfs_mark_page_unstable(req->wb_page, cinfo);
 }
 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list);
 
@@ -1724,6 +1726,36 @@ nfs_commit_list(struct inode *inode, struct list_head *head, int how,
         return -ENOMEM;
 }
 
+int nfs_commit_file(struct file *file, struct nfs_write_verifier *verf)
+{
+        struct inode *inode = file_inode(file);
+        struct nfs_open_context *open;
+        struct nfs_commit_info cinfo;
+        struct nfs_page *req;
+        int ret;
+
+        open = get_nfs_open_context(nfs_file_open_context(file));
+        req  = nfs_create_request(open, NULL, NULL, 0, i_size_read(inode));
+        if (!req) {
+                ret = -ENOMEM;
+                goto out_put;
+        }
+
+        nfs_init_cinfo_from_inode(&cinfo, inode);
+
+        memcpy(&req->wb_verf, verf, sizeof(struct nfs_write_verifier));
+        nfs_request_add_commit_list(req, &cinfo);
+        ret = nfs_commit_inode(inode, FLUSH_SYNC);
+        if (ret > 0)
+                ret = 0;
+
+        nfs_free_request(req);
+out_put:
+        put_nfs_open_context(open);
+        return ret;
+}
+EXPORT_SYMBOL_GPL(nfs_commit_file);
+
 /*
  * COMMIT call returned
  */
@@ -1748,7 +1780,8 @@ static void nfs_commit_release_pages(struct nfs_commit_data *data)
         while (!list_empty(&data->pages)) {
                 req = nfs_list_entry(data->pages.next);
                 nfs_list_remove_request(req);
-                nfs_clear_page_commit(req->wb_page);
+                if (req->wb_page)
+                        nfs_clear_page_commit(req->wb_page);
 
                 dprintk("NFS:       commit (%s/%llu %d@%lld)",
                         req->wb_context->dentry->d_sb->s_id,