Merge branch 'work.symlinks' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull vfs RCU symlink updates from Al Viro:
 "Replacement of ->follow_link/->put_link, allowing to stay in RCU mode
  even if the symlink is not an embedded one.

  No changes since the mailbomb on Jan 1"

* 'work.symlinks' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  switch ->get_link() to delayed_call, kill ->put_link()
  kill free_page_put_link()
  teach nfs_get_link() to work in RCU mode
  teach proc_self_get_link()/proc_thread_self_get_link() to work in RCU mode
  teach shmem_get_link() to work in RCU mode
  teach page_get_link() to work in RCU mode
  replace ->follow_link() with new method that could stay in RCU mode
  don't put symlink bodies in pagecache into highmem
  namei: page_getlink() and page_follow_link_light() are the same thing
  ufs: get rid of ->setattr() for symlinks
  udf: don't duplicate page_symlink_inode_operations
  logfs: don't duplicate page_symlink_inode_operations
  switch befs long symlinks to page_symlink_operations

2 files changed, 50 insertions, 15 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index c7e8b87da5b2..bdb4dc7b4ecd 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -408,9 +408,10 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr, st
 				inode->i_fop = NULL;
 				inode->i_flags |= S_AUTOMOUNT;
 			}
-		} else if (S_ISLNK(inode->i_mode))
+		} else if (S_ISLNK(inode->i_mode)) {
 			inode->i_op = &nfs_symlink_inode_operations;
-		else
+			inode_nohighmem(inode);
+		} else
 			init_special_inode(inode, inode->i_mode, fattr->rdev);
 
 		memset(&inode->i_atime, 0, sizeof(inode->i_atime));
@@ -1086,6 +1087,27 @@ static bool nfs_mapping_need_revalidate_inode(struct inode *inode)
 		|| NFS_STALE(inode);
 }
 
+int nfs_revalidate_mapping_rcu(struct inode *inode)
+{
+	struct nfs_inode *nfsi = NFS_I(inode);
+	unsigned long *bitlock = &nfsi->flags;
+	int ret = 0;
+
+	if (IS_SWAPFILE(inode))
+		goto out;
+	if (nfs_mapping_need_revalidate_inode(inode)) {
+		ret = -ECHILD;
+		goto out;
+	}
+	spin_lock(&inode->i_lock);
+	if (test_bit(NFS_INO_INVALIDATING, bitlock) ||
+	    (nfsi->cache_validity & NFS_INO_INVALID_DATA))
+		ret = -ECHILD;
+	spin_unlock(&inode->i_lock);
+out:
+	return ret;
+}
+
 /**
  * __nfs_revalidate_mapping - Revalidate the pagecache
  * @inode - pointer to host inode
diff --git a/fs/nfs/symlink.c b/fs/nfs/symlink.c
index b6de433da5db..4fe3eead3868 100644
--- a/fs/nfs/symlink.c
+++ b/fs/nfs/symlink.c
@@ -42,21 +42,35 @@ error:
 	return -EIO;
 }
 
-static const char *nfs_follow_link(struct dentry *dentry, void **cookie)
+static const char *nfs_get_link(struct dentry *dentry,
+				struct inode *inode,
+				struct delayed_call *done)
 {
-	struct inode *inode = d_inode(dentry);
 	struct page *page;
 	void *err;
 
-	err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping));
-	if (err)
-		return err;
-	page = read_cache_page(&inode->i_data, 0,
-				(filler_t *)nfs_symlink_filler, inode);
-	if (IS_ERR(page))
-		return ERR_CAST(page);
-	*cookie = page;
-	return kmap(page);
+	if (!dentry) {
+		err = ERR_PTR(nfs_revalidate_mapping_rcu(inode));
+		if (err)
+			return err;
+		page = find_get_page(inode->i_mapping, 0);
+		if (!page)
+			return ERR_PTR(-ECHILD);
+		if (!PageUptodate(page)) {
+			put_page(page);
+			return ERR_PTR(-ECHILD);
+		}
+	} else {
+		err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping));
+		if (err)
+			return err;
+		page = read_cache_page(&inode->i_data, 0,
+					(filler_t *)nfs_symlink_filler, inode);
+		if (IS_ERR(page))
+			return ERR_CAST(page);
+	}
+	set_delayed_call(done, page_put_link, page);
+	return page_address(page);
 }
 
 /*
@@ -64,8 +78,7 @@ static const char *nfs_follow_link(struct dentry *dentry, void **cookie)
  */
 const struct inode_operations nfs_symlink_inode_operations = {
 	.readlink	= generic_readlink,
-	.follow_link	= nfs_follow_link,
-	.put_link	= page_put_link,
+	.get_link	= nfs_get_link,
 	.getattr	= nfs_getattr,
 	.setattr	= nfs_setattr,
 };