NFS: Minor read optimisation...
Since PG_uptodate may now end up getting set during the call to
nfs_wb_page(), we can avoid putting a read request on the wire in those
situations.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 7bd7cb9..c07d0d1 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -483,17 +483,19 @@
*/
error = nfs_wb_page(inode, page);
if (error)
- goto out_error;
+ goto out_unlock;
+ if (PageUptodate(page))
+ goto out_unlock;
error = -ESTALE;
if (NFS_STALE(inode))
- goto out_error;
+ goto out_unlock;
if (file == NULL) {
error = -EBADF;
ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
if (ctx == NULL)
- goto out_error;
+ goto out_unlock;
} else
ctx = get_nfs_open_context((struct nfs_open_context *)
file->private_data);
@@ -502,8 +504,7 @@
put_nfs_open_context(ctx);
return error;
-
-out_error:
+out_unlock:
unlock_page(page);
return error;
}
@@ -520,21 +521,32 @@
struct inode *inode = page->mapping->host;
struct nfs_page *new;
unsigned int len;
+ int error;
- nfs_wb_page(inode, page);
+ error = nfs_wb_page(inode, page);
+ if (error)
+ goto out_unlock;
+ if (PageUptodate(page))
+ goto out_unlock;
+
len = nfs_page_length(page);
if (len == 0)
return nfs_return_empty_page(page);
+
new = nfs_create_request(desc->ctx, inode, page, 0, len);
- if (IS_ERR(new)) {
- SetPageError(page);
- unlock_page(page);
- return PTR_ERR(new);
- }
+ if (IS_ERR(new))
+ goto out_error;
+
if (len < PAGE_CACHE_SIZE)
zero_user_page(page, len, PAGE_CACHE_SIZE - len, KM_USER0);
nfs_pageio_add_request(desc->pgio, new);
return 0;
+out_error:
+ error = PTR_ERR(new);
+ SetPageError(page);
+out_unlock:
+ unlock_page(page);
+ return error;
}
int nfs_readpages(struct file *filp, struct address_space *mapping,
