sysv: fix handling of delete_entry and set_link failures

similar to minixfs series - make sysv_set_link() report failures,
lift dir_put_page() into the callers of sysv_set_link() and
sysv_delete_entry(), make sysv_rename() handle failures in both.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/sysv/dir.c

@@ -249,10 +249,12 @@ int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
 
 	lock_page(page);
 	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
-	BUG_ON(err);
+	if (err) {
+		unlock_page(page);
+		return err;
+	}
 	de->inode = 0;
 	dir_commit_chunk(page, pos, SYSV_DIRSIZE);
-	dir_put_page(page, de);
 	inode->i_ctime = inode->i_mtime = current_time(inode);
 	mark_inode_dirty(inode);
 	return sysv_handle_dirsync(inode);
@@ -335,7 +337,7 @@ int sysv_empty_dir(struct inode * inode)
 }
 
 /* Releases the page */
-void sysv_set_link(struct sysv_dir_entry *de, struct page *page,
+int sysv_set_link(struct sysv_dir_entry *de, struct page *page,
 	struct inode *inode)
 {
 	struct inode *dir = page->mapping->host;
@@ -344,13 +346,15 @@ void sysv_set_link(struct sysv_dir_entry *de, struct page *page,
 
 	lock_page(page);
 	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
-	BUG_ON(err);
+	if (err) {
+		unlock_page(page);
+		return err;
+	}
 	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
 	dir_commit_chunk(page, pos, SYSV_DIRSIZE);
-	dir_put_page(page, de);
 	dir->i_mtime = dir->i_ctime = current_time(dir);
 	mark_inode_dirty(dir);
-	sysv_handle_dirsync(inode);
+	return sysv_handle_dirsync(inode);
 }
 
 /*

fs/sysv/namei.c

@@ -153,19 +153,18 @@ static int sysv_unlink(struct inode * dir, struct dentry * dentry)
 	struct inode * inode = d_inode(dentry);
 	struct page * page;
 	struct sysv_dir_entry * de;
-	int err = -ENOENT;
+	int err;
 
 	de = sysv_find_entry(dentry, &page);
 	if (!de)
-		goto out;
-
-	err = sysv_delete_entry (de, page);
-	if (err)
-		goto out;
+		return -ENOENT;
 
-	inode->i_ctime = dir->i_ctime;
-	inode_dec_link_count(inode);
-out:
+	err = sysv_delete_entry(de, page);
+	if (!err) {
+		inode->i_ctime = dir->i_ctime;
+		inode_dec_link_count(inode);
+	}
+	dir_put_page(page, de);
 	return err;
 }
 
@@ -227,7 +226,10 @@ static int sysv_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 		new_de = sysv_find_entry(new_dentry, &new_page);
 		if (!new_de)
 			goto out_dir;
-		sysv_set_link(new_de, new_page, old_inode);
+		err = sysv_set_link(new_de, new_page, old_inode);
+		dir_put_page(new_page, new_de);
+		if (err)
+			goto out_dir;
 		new_inode->i_ctime = current_time(new_inode);
 		if (dir_de)
 			drop_nlink(new_inode);
@@ -240,14 +242,17 @@ static int sysv_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 			inode_inc_link_count(new_dir);
 	}
 
-	sysv_delete_entry(old_de, old_page);
+	err = sysv_delete_entry(old_de, old_page);
+	if (err)
+		goto out_dir;
+
 	mark_inode_dirty(old_inode);
 
 	if (dir_de) {
-		sysv_set_link(dir_de, dir_page, new_dir);
-		inode_dec_link_count(old_dir);
+		err = sysv_set_link(dir_de, dir_page, new_dir);
+		if (!err)
+			inode_dec_link_count(old_dir);
 	}
-	return 0;
 
 out_dir:
 	if (dir_de)

fs/sysv/sysv.h

@@ -154,7 +154,7 @@ extern int sysv_add_link(struct dentry *, struct inode *);
 extern int sysv_delete_entry(struct sysv_dir_entry *, struct page *);
 extern int sysv_make_empty(struct inode *, struct inode *);
 extern int sysv_empty_dir(struct inode *);
-extern void sysv_set_link(struct sysv_dir_entry *, struct page *,
+extern int sysv_set_link(struct sysv_dir_entry *, struct page *,
 			struct inode *);
 extern struct sysv_dir_entry *sysv_dotdot(struct inode *, struct page **);
 extern ino_t sysv_inode_by_name(struct dentry *);