NFS: Optimise nfs_vm_page_mkwrite()
The current model locks the page twice for no good reason. Optimise by
inlining the parts of nfs_write_begin()/nfs_write_end() that we care about.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index b3bb89f..4560fc2 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -392,35 +392,27 @@
struct file *filp = vma->vm_file;
unsigned pagelen;
int ret = -EINVAL;
- void *fsdata;
struct address_space *mapping;
- loff_t offset;
lock_page(page);
mapping = page->mapping;
- if (mapping != vma->vm_file->f_path.dentry->d_inode->i_mapping) {
- unlock_page(page);
- return -EINVAL;
- }
+ if (mapping != vma->vm_file->f_path.dentry->d_inode->i_mapping)
+ goto out_unlock;
+
+ ret = 0;
pagelen = nfs_page_length(page);
- offset = (loff_t)page->index << PAGE_CACHE_SHIFT;
+ if (pagelen == 0)
+ goto out_unlock;
+
+ ret = nfs_flush_incompatible(filp, page);
+ if (ret != 0)
+ goto out_unlock;
+
+ ret = nfs_updatepage(filp, page, 0, pagelen);
+ if (ret == 0)
+ ret = pagelen;
+out_unlock:
unlock_page(page);
-
- /*
- * we can use mapping after releasing the page lock, because:
- * we hold mmap_sem on the fault path, which should pin the vma
- * which should pin the file, which pins the dentry which should
- * hold a reference on inode.
- */
-
- if (pagelen) {
- struct page *page2 = NULL;
- ret = nfs_write_begin(filp, mapping, offset, pagelen,
- 0, &page2, &fsdata);
- if (!ret)
- ret = nfs_write_end(filp, mapping, offset, pagelen,
- pagelen, page2, fsdata);
- }
return ret;
}