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>

1 files changed, 19 insertions, 15 deletions

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index f55c437124a2..7be42e6eb63a 100644
--- 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;
                 }