powerpc/spufs: only add ".ctx" file with "debug" mount option

Currently, the .ctx debug file in spu context directories is always
present.

We'd prefer to prevent users from relying on this file, so add a
"debug" mount option to spufs. The .ctx file will only be added to
the context directories when this option is present.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

arch/powerpc/platforms/cell/spufs/file.c

@@ -2645,7 +2645,6 @@ struct spufs_tree_descr spufs_dir_contents[] = {
 	{ "tid", &spufs_tid_fops, 0444, },
 	{ "stat", &spufs_stat_fops, 0444, },
 	{ "switch_log", &spufs_switch_log_fops, 0444 },
-	{ ".ctx", &spufs_ctx_fops, 0444, },
 	{},
 };
 
@@ -2671,6 +2670,10 @@ struct spufs_tree_descr spufs_dir_nosched_contents[] = {
 	{ "object-id", &spufs_object_id_ops, 0666, },
 	{ "tid", &spufs_tid_fops, 0444, },
 	{ "stat", &spufs_stat_fops, 0444, },
+	{},
+};
+
+struct spufs_tree_descr spufs_dir_debug_contents[] = {
 	{ ".ctx", &spufs_ctx_fops, 0444, },
 	{},
 };

arch/powerpc/platforms/cell/spufs/inode.c

@@ -42,10 +42,19 @@
 
 #include "spufs.h"
 
+struct spufs_sb_info {
+	int debug;
+};
+
 static struct kmem_cache *spufs_inode_cache;
 char *isolated_loader;
 static int isolated_loader_size;
 
+static struct spufs_sb_info *spufs_get_sb_info(struct super_block *sb)
+{
+	return sb->s_fs_info;
+}
+
 static struct inode *
 spufs_alloc_inode(struct super_block *sb)
 {
@@ -280,6 +289,13 @@ spufs_mkdir(struct inode *dir, struct dentry *dentry, unsigned int flags,
 	if (ret)
 		goto out_free_ctx;
 
+	if (spufs_get_sb_info(dir->i_sb)->debug)
+		ret = spufs_fill_dir(dentry, spufs_dir_debug_contents,
+				mode, ctx);
+
+	if (ret)
+		goto out_free_ctx;
+
 	d_instantiate(dentry, inode);
 	dget(dentry);
 	dir->i_nlink++;
@@ -640,18 +656,19 @@ long spufs_create(struct nameidata *nd, unsigned int flags, mode_t mode,
 
 /* File system initialization */
 enum {
-	Opt_uid, Opt_gid, Opt_mode, Opt_err,
+	Opt_uid, Opt_gid, Opt_mode, Opt_debug, Opt_err,
 };
 
 static match_table_t spufs_tokens = {
 	{ Opt_uid,   "uid=%d" },
 	{ Opt_gid,   "gid=%d" },
 	{ Opt_mode,  "mode=%o" },
+	{ Opt_debug, "debug" },
 	{ Opt_err,    NULL  },
 };
 
 static int
-spufs_parse_options(char *options, struct inode *root)
+spufs_parse_options(struct super_block *sb, char *options, struct inode *root)
 {
 	char *p;
 	substring_t args[MAX_OPT_ARGS];
@@ -679,6 +696,9 @@ spufs_parse_options(char *options, struct inode *root)
 				return 0;
 			root->i_mode = option | S_IFDIR;
 			break;
+		case Opt_debug:
+			spufs_get_sb_info(sb)->debug = 1;
+			break;
 		default:
 			return 0;
 		}
@@ -737,7 +757,7 @@ spufs_create_root(struct super_block *sb, void *data)
 	SPUFS_I(inode)->i_ctx = NULL;
 
 	ret = -EINVAL;
-	if (!spufs_parse_options(data, inode))
+	if (!spufs_parse_options(sb, data, inode))
 		goto out_iput;
 
 	ret = -ENOMEM;
@@ -755,6 +775,7 @@ spufs_create_root(struct super_block *sb, void *data)
 static int
 spufs_fill_super(struct super_block *sb, void *data, int silent)
 {
+	struct spufs_sb_info *info;
 	static struct super_operations s_ops = {
 		.alloc_inode = spufs_alloc_inode,
 		.destroy_inode = spufs_destroy_inode,
@@ -766,11 +787,16 @@ spufs_fill_super(struct super_block *sb, void *data, int silent)
 
 	save_mount_options(sb, data);
 
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
 	sb->s_maxbytes = MAX_LFS_FILESIZE;
 	sb->s_blocksize = PAGE_CACHE_SIZE;
 	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 	sb->s_magic = SPUFS_MAGIC;
 	sb->s_op = &s_ops;
+	sb->s_fs_info = info;
 
 	return spufs_create_root(sb, data);
 }

arch/powerpc/platforms/cell/spufs/spufs.h

@@ -244,6 +244,7 @@ struct spufs_tree_descr {
 
 extern struct spufs_tree_descr spufs_dir_contents[];
 extern struct spufs_tree_descr spufs_dir_nosched_contents[];
+extern struct spufs_tree_descr spufs_dir_debug_contents[];
 
 /* system call implementation */
 extern struct spufs_calls spufs_calls;