ocfs: simplify symlink handling

seeing that "fast" symlinks still get allocation + copy, we might as
well simply switch them to pagecache-based variant of ->follow_link();
just need an appropriate ->readpage() for them...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/ocfs2/inode.c

@@ -273,11 +273,13 @@ void ocfs2_populate_inode(struct inode *inode, struct ocfs2_dinode *fe,
 	inode->i_gid = le32_to_cpu(fe->i_gid);
 
 	/* Fast symlinks will have i_size but no allocated clusters. */
-	if (S_ISLNK(inode->i_mode) && !fe->i_clusters)
+	if (S_ISLNK(inode->i_mode) && !fe->i_clusters) {
 		inode->i_blocks = 0;
-	else
+		inode->i_mapping->a_ops = &ocfs2_fast_symlink_aops;
+	} else {
 		inode->i_blocks = ocfs2_inode_sector_count(inode);
-	inode->i_mapping->a_ops = &ocfs2_aops;
+		inode->i_mapping->a_ops = &ocfs2_aops;
+	}
 	inode->i_atime.tv_sec = le64_to_cpu(fe->i_atime);
 	inode->i_atime.tv_nsec = le32_to_cpu(fe->i_atime_nsec);
 	inode->i_mtime.tv_sec = le64_to_cpu(fe->i_mtime);
@@ -331,10 +333,7 @@ void ocfs2_populate_inode(struct inode *inode, struct ocfs2_dinode *fe,
 		    OCFS2_I(inode)->ip_dir_lock_gen = 1;
 		    break;
 	    case S_IFLNK:
-		    if (ocfs2_inode_is_fast_symlink(inode))
-			inode->i_op = &ocfs2_fast_symlink_inode_operations;
-		    else
-			inode->i_op = &ocfs2_symlink_inode_operations;
+		    inode->i_op = &ocfs2_symlink_inode_operations;
 		    i_size_write(inode, le64_to_cpu(fe->i_size));
 		    break;
 	    default:

fs/ocfs2/namei.c

@@ -1724,15 +1724,16 @@ static int ocfs2_symlink(struct inode *dir,
 	fe = (struct ocfs2_dinode *) new_fe_bh->b_data;
 	inode->i_rdev = 0;
 	newsize = l - 1;
+	inode->i_op = &ocfs2_symlink_inode_operations;
 	if (l > ocfs2_fast_symlink_chars(sb)) {
 		u32 offset = 0;
 
-		inode->i_op = &ocfs2_symlink_inode_operations;
 		status = dquot_alloc_space_nodirty(inode,
 		    ocfs2_clusters_to_bytes(osb->sb, 1));
 		if (status)
 			goto bail;
 		did_quota = 1;
+		inode->i_mapping->a_ops = &ocfs2_aops;
 		status = ocfs2_add_inode_data(osb, inode, &offset, 1, 0,
 					      new_fe_bh,
 					      handle, data_ac, NULL,
@@ -1750,7 +1751,7 @@ static int ocfs2_symlink(struct inode *dir,
 		i_size_write(inode, newsize);
 		inode->i_blocks = ocfs2_inode_sector_count(inode);
 	} else {
-		inode->i_op = &ocfs2_fast_symlink_inode_operations;
+		inode->i_mapping->a_ops = &ocfs2_fast_symlink_aops;
 		memcpy((char *) fe->id2.i_symlink, symname, l);
 		i_size_write(inode, newsize);
 		inode->i_blocks = 0;

fs/ocfs2/symlink.c

@@ -54,101 +54,40 @@
 #include "buffer_head_io.h"
 
 
-static char *ocfs2_fast_symlink_getlink(struct inode *inode,
-					struct buffer_head **bh)
+static int ocfs2_fast_symlink_readpage(struct file *unused, struct page *page)
 {
-	int status;
-	char *link = NULL;
+	struct inode *inode = page->mapping->host;
+	struct buffer_head *bh;
+	int status = ocfs2_read_inode_block(inode, &bh);
 	struct ocfs2_dinode *fe;
+	const char *link;
+	void *kaddr;
+	size_t len;
 
-	status = ocfs2_read_inode_block(inode, bh);
 	if (status < 0) {
 		mlog_errno(status);
-		link = ERR_PTR(status);
-		goto bail;
+		return status;
 	}
 
-	fe = (struct ocfs2_dinode *) (*bh)->b_data;
+	fe = (struct ocfs2_dinode *) bh->b_data;
 	link = (char *) fe->id2.i_symlink;
-bail:
-
-	return link;
-}
-
-static int ocfs2_readlink(struct dentry *dentry,
-			  char __user *buffer,
-			  int buflen)
-{
-	int ret;
-	char *link;
-	struct buffer_head *bh = NULL;
-	struct inode *inode = dentry->d_inode;
-
-	link = ocfs2_fast_symlink_getlink(inode, &bh);
-	if (IS_ERR(link)) {
-		ret = PTR_ERR(link);
-		goto out;
-	}
-
-	/*
-	 * Without vfsmount we can't update atime now,
-	 * but we will update atime here ultimately.
-	 */
-	ret = vfs_readlink(dentry, buffer, buflen, link);
-
+	/* will be less than a page size */
+	len = strnlen(link, ocfs2_fast_symlink_chars(inode->i_sb));
+	kaddr = kmap_atomic(page);
+	memcpy(kaddr, link, len + 1);
+	kunmap_atomic(kaddr);
+	SetPageUptodate(page);
+	unlock_page(page);
 	brelse(bh);
-out:
-	if (ret < 0)
-		mlog_errno(ret);
-	return ret;
+	return 0;
 }
 
-static void *ocfs2_fast_follow_link(struct dentry *dentry,
-				    struct nameidata *nd)
-{
-	int status = 0;
-	int len;
-	char *target, *link = ERR_PTR(-ENOMEM);
-	struct inode *inode = dentry->d_inode;
-	struct buffer_head *bh = NULL;
-
-	BUG_ON(!ocfs2_inode_is_fast_symlink(inode));
-	target = ocfs2_fast_symlink_getlink(inode, &bh);
-	if (IS_ERR(target)) {
-		status = PTR_ERR(target);
-		mlog_errno(status);
-		goto bail;
-	}
-
-	/* Fast symlinks can't be large */
-	len = strnlen(target, ocfs2_fast_symlink_chars(inode->i_sb));
-	link = kzalloc(len + 1, GFP_NOFS);
-	if (!link) {
-		status = -ENOMEM;
-		mlog_errno(status);
-		goto bail;
-	}
-
-	memcpy(link, target, len);
-
-bail:
-	nd_set_link(nd, status ? ERR_PTR(status) : link);
-	brelse(bh);
-
-	if (status)
-		mlog_errno(status);
-	return NULL;
-}
-
-static void ocfs2_fast_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
-{
-	char *link = nd_get_link(nd);
-	if (!IS_ERR(link))
-		kfree(link);
-}
+const struct address_space_operations ocfs2_fast_symlink_aops = {
+	.readpage		= ocfs2_fast_symlink_readpage,
+};
 
 const struct inode_operations ocfs2_symlink_inode_operations = {
-	.readlink	= page_readlink,
+	.readlink	= generic_readlink,
 	.follow_link	= page_follow_link_light,
 	.put_link	= page_put_link,
 	.getattr	= ocfs2_getattr,
@@ -159,15 +98,3 @@ const struct inode_operations ocfs2_symlink_inode_operations = {
 	.removexattr	= generic_removexattr,
 	.fiemap		= ocfs2_fiemap,
 };
-const struct inode_operations ocfs2_fast_symlink_inode_operations = {
-	.readlink	= ocfs2_readlink,
-	.follow_link	= ocfs2_fast_follow_link,
-	.put_link	= ocfs2_fast_put_link,
-	.getattr	= ocfs2_getattr,
-	.setattr	= ocfs2_setattr,
-	.setxattr	= generic_setxattr,
-	.getxattr	= generic_getxattr,
-	.listxattr	= ocfs2_listxattr,
-	.removexattr	= generic_removexattr,
-	.fiemap		= ocfs2_fiemap,
-};

fs/ocfs2/symlink.h

@@ -27,7 +27,7 @@
 #define OCFS2_SYMLINK_H
 
 extern const struct inode_operations ocfs2_symlink_inode_operations;
-extern const struct inode_operations ocfs2_fast_symlink_inode_operations;
+extern const struct address_space_operations ocfs2_fast_symlink_aops;
 
 /*
  * Test whether an inode is a fast symlink.