nfs: use GFP_NOFS preloads for radix-tree insertion

NFS should use GFP_NOFS mode radix tree preloads rather than GFP_ATOMIC
allocations at radix-tree insertion-time.  This is important to reduce the
atomic memory requirement.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index f55c437124a2287e1ae80834af5059c0f3388d38..7be42e6eb63a52cd18d1fd1f3b8ce7927d9304b3 100644 (file)
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -360,15 +360,13 @@ int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 /*
  * Insert a write request into an inode
  */
-static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
+static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 {
        struct nfs_inode *nfsi = NFS_I(inode);
        int error;
 
        error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
-       BUG_ON(error == -EEXIST);
-       if (error)
-               return error;
+       BUG_ON(error);
        if (!nfsi->npages) {
                igrab(inode);
                if (nfs_have_delegation(inode, FMODE_WRITE))
@@ -378,8 +376,8 @@ static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
        set_page_private(req->wb_page, (unsigned long)req);
        nfsi->npages++;
        kref_get(&req->wb_kref);
-       radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_LOCKED);
-       return 0;
+       radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index,
+                               NFS_PAGE_TAG_LOCKED);
 }
 
 /*
@@ -591,6 +589,13 @@ static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
                /* Loop over all inode entries and see if we find
                 * A request for the page we wish to update
                 */
+               if (new) {
+                       if (radix_tree_preload(GFP_NOFS)) {
+                               nfs_release_request(new);
+                               return ERR_PTR(-ENOMEM);
+                       }
+               }
+
                spin_lock(&inode->i_lock);
                req = nfs_page_find_request_locked(page);
                if (req) {
@@ -601,28 +606,27 @@ static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
                                error = nfs_wait_on_request(req);
                                nfs_release_request(req);
                                if (error < 0) {
-                                       if (new)
+                                       if (new) {
+                                               radix_tree_preload_end();
                                                nfs_release_request(new);
+                                       }
                                        return ERR_PTR(error);
                                }
                                continue;
                        }
                        spin_unlock(&inode->i_lock);
-                       if (new)
+                       if (new) {
+                               radix_tree_preload_end();
                                nfs_release_request(new);
+                       }
                        break;
                }
 
                if (new) {
-                       int error;
                        nfs_lock_request_dontget(new);
-                       error = nfs_inode_add_request(inode, new);
-                       if (error) {
-                               spin_unlock(&inode->i_lock);
-                               nfs_unlock_request(new);
-                               return ERR_PTR(error);
-                       }
+                       nfs_inode_add_request(inode, new);
                        spin_unlock(&inode->i_lock);
+                       radix_tree_preload_end();
                        req = new;
                        goto zero_page;
                }