[PATCH] (2/14) resync

FS_NOMOUNT is gone, initialization for pseudo-filesystems
(bdev, pipe, sock) switched to use of a common helper.

Documentation/filesystems/porting

@@ -215,3 +215,9 @@ not protected by the conditions above is risky even in the old tree - you
 had been relying on BKL and that's prone to screwups.  Old tree had quite
 a few holes of that kind - unprotected access to ->d_parent leading to
 anything from oops to silent memory corruption.
+
+---
+[mandatory]
+
+	FS_NOMOUNT is gone.  If you use it - just set MS_NOUSER in flags
+(see rootfs for one kind of solution and bdev/socket/pipe for another).

fs/block_dev.c

@@ -181,44 +181,16 @@ static int block_fsync(struct file *filp, struct dentry *dentry, int datasync)
  * pseudo-fs
  */
 
-static int bd_fill_super(struct super_block *sb, void *data, int silent)
-{
-	static struct super_operations sops = {};
-	struct inode *root;
-
-	sb->s_maxbytes = ~0ULL;
-	sb->s_blocksize = 1024;
-	sb->s_blocksize_bits = 10;
-	sb->s_magic = 0x62646576;
-	sb->s_op = &sops;
-	root = new_inode(sb);
-	if (!root)
-		return -ENOMEM;
-	root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
-	root->i_uid = root->i_gid = 0;
-	root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
-	sb->s_root = d_alloc(NULL, &(const struct qstr) { "bdev:", 5, 0 });
-	if (!sb->s_root) {
-		iput(root);
-		return -ENOMEM;
-	}
-	sb->s_root->d_sb = sb;
-	sb->s_root->d_parent = sb->s_root;
-	d_instantiate(sb->s_root, root);
-	return 0;
-}
-
 static struct super_block *bd_get_sb(struct file_system_type *fs_type,
 	int flags, char *dev_name, void *data)
 {
-	return get_sb_nodev(fs_type, flags, data, bd_fill_super);
+	return get_sb_pseudo(fs_type, "bdev:", NULL, 0x62646576);
 }
 
 static struct file_system_type bd_type = {
 	name:		"bdev",
 	get_sb:		bd_get_sb,
 	kill_sb:	kill_anon_super,
-	fs_flags:	FS_NOMOUNT,
 };
 
 static struct vfsmount *bd_mnt;

fs/libfs.c

@@ -155,3 +155,50 @@ struct file_operations simple_dir_operations = {
 struct inode_operations simple_dir_inode_operations = {
 	lookup:		simple_lookup,
 };
+
+/*
+ * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
+ * will never be mountable)
+ */
+struct super_block *
+get_sb_pseudo(struct file_system_type *fs_type, char *name,
+	struct super_operations *ops, unsigned long magic)
+{
+	struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
+	static struct super_operations default_ops = {statfs: simple_statfs};
+	struct dentry *dentry;
+	struct inode *root;
+	struct qstr d_name = {name:name, len:strlen(name)};
+
+	if (IS_ERR(s))
+		return s;
+
+	s->s_flags = MS_NOUSER;
+	s->s_maxbytes = ~0ULL;
+	s->s_blocksize = 1024;
+	s->s_blocksize_bits = 10;
+	s->s_magic = magic;
+	s->s_op = ops ? ops : &default_ops;
+	root = new_inode(s);
+	if (!root)
+		goto Enomem;
+	root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
+	root->i_uid = root->i_gid = 0;
+	root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
+	dentry = d_alloc(NULL, &d_name);
+	if (!dentry) {
+		iput(root);
+		goto Enomem;
+	}
+	dentry->d_sb = s;
+	dentry->d_parent = dentry;
+	d_instantiate(dentry, root);
+	s->s_root = dentry;
+	s->s_flags |= MS_ACTIVE;
+	return s;
+
+Enomem:
+	up_write(&s->s_umount);
+	deactivate_super(s);
+	return ERR_PTR(-ENOMEM);
+}

fs/pipe.c

@@ -665,46 +665,16 @@ int do_pipe(int *fd)
  * d_name - pipe: will go nicely and kill the special-casing in procfs.
  */
 
-static struct super_operations pipefs_ops = {
-	statfs:		simple_statfs,
-};
-
-static int pipefs_fill_super(struct super_block *sb, void *data, int silent)
-{
-	struct inode *root;
-
-	sb->s_blocksize = 1024;
-	sb->s_blocksize_bits = 10;
-	sb->s_magic = PIPEFS_MAGIC;
-	sb->s_op	= &pipefs_ops;
-	root = new_inode(sb);
-	if (!root)
-		return -ENOMEM;
-	root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
-	root->i_uid = root->i_gid = 0;
-	root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
-	sb->s_root = d_alloc(NULL, &(const struct qstr) { "pipe:", 5, 0 });
-	if (!sb->s_root) {
-		iput(root);
-		return -ENOMEM;
-	}
-	sb->s_root->d_sb = sb;
-	sb->s_root->d_parent = sb->s_root;
-	d_instantiate(sb->s_root, root);
-	return 0;
-}
-
 static struct super_block *pipefs_get_sb(struct file_system_type *fs_type,
 	int flags, char *dev_name, void *data)
 {
-	return get_sb_nodev(fs_type, flags, data, pipefs_fill_super);
+	return get_sb_pseudo(fs_type, "pipe:", NULL, PIPEFS_MAGIC);
 }
 
 static struct file_system_type pipe_fs_type = {
 	name:		"pipefs",
 	get_sb:		pipefs_get_sb,
 	kill_sb:	kill_anon_super,
-	fs_flags:	FS_NOMOUNT,
 };
 
 static int __init init_pipe_fs(void)

fs/ramfs/inode.c

@@ -308,6 +308,12 @@ static struct super_block *ramfs_get_sb(struct file_system_type *fs_type,
 	return get_sb_nodev(fs_type, flags, data, ramfs_fill_super);
 }
 
+static struct super_block *rootfs_get_sb(struct file_system_type *fs_type,
+	int flags, char *dev_name, void *data)
+{
+	return get_sb_nodev(fs_type, flags|MS_NOUSER, data, ramfs_fill_super);
+}
+
 static struct file_system_type ramfs_fs_type = {
 	name:		"ramfs",
 	get_sb:		ramfs_get_sb,
@@ -315,9 +321,8 @@ static struct file_system_type ramfs_fs_type = {
 };
 static struct file_system_type rootfs_fs_type = {
 	name:		"rootfs",
-	get_sb:		ramfs_get_sb,
+	get_sb:		rootfs_get_sb,
 	kill_sb:	kill_litter_super,
-	fs_flags:	FS_NOMOUNT,
 };
 
 static int __init init_ramfs_fs(void)
@@ -339,4 +344,3 @@ int __init init_rootfs(void)
 }
 
 MODULE_LICENSE("GPL");
-

fs/super.c

@@ -618,8 +618,6 @@ do_kern_mount(const char *fstype, int flags, char *name, void *data)
 	sb = type->get_sb(type, flags, name, data);
 	if (IS_ERR(sb))
 		goto out_mnt;
-	if (type->fs_flags & FS_NOMOUNT)
-		sb->s_flags |= MS_NOUSER;
 	mnt->mnt_sb = sb;
 	mnt->mnt_root = dget(sb->s_root);
 	mnt->mnt_mountpoint = sb->s_root;

include/linux/fs.h

@@ -89,11 +89,6 @@ extern int leases_enable, dir_notify_enable, lease_break_time;
 
 /* public flags for file_system_type */
 #define FS_REQUIRES_DEV 1 
-#define FS_NO_DCACHE	2 /* Only dcache the necessary things. */
-#define FS_NO_PRELIM	4 /* prevent preloading of dentries, even if
-			   * FS_NO_DCACHE is not set.
-			   */
-#define FS_NOMOUNT	16 /* Never mount from userland */
 #define FS_ODD_RENAME	32768	/* Temporary stuff; will go away as soon
 				  * as nfs_rename() will be cleaned up
 				  */
@@ -969,6 +964,8 @@ struct super_block *sget(struct file_system_type *type,
 			int (*test)(struct super_block *,void *),
 			int (*set)(struct super_block *,void *),
 			void *data);
+struct super_block *get_sb_pseudo(struct file_system_type *, char *,
+			struct super_operations *ops, unsigned long);
 
 /* Alas, no aliases. Too much hassle with bringing module.h everywhere */
 #define fops_get(fops) \

mm/shmem.c

@@ -1358,6 +1358,8 @@ static int shmem_fill_super(struct super_block * sb, void * data, int silent)
 		err = -EINVAL;
 		goto failed;
 	}
+#else
+	sb->s_flags |= MS_NOUSER;
 #endif
 
 	spin_lock_init (&sbinfo->stat_lock);
@@ -1505,21 +1507,13 @@ static struct file_system_type shmem_fs_type = {
 	get_sb:		shmem_get_sb,
 	kill_sb:	kill_litter_super,
 };
+#endif
 static struct file_system_type tmpfs_fs_type = {
 	owner:		THIS_MODULE,
 	name:		"tmpfs",
 	get_sb:		shmem_get_sb,
 	kill_sb:	kill_litter_super,
 };
-#else
-static struct file_system_type tmpfs_fs_type = {
-	owner:		THIS_MODULE,
-	name:		"tmpfs",
-	get_sb:		shmem_get_sb,
-	kill_sb:	kill_litter_super,
-	fs_flags:	FS_NOMOUNT,
-};
-#endif
 static struct vfsmount *shm_mnt;
 
 static int __init init_shmem_fs(void)

net/socket.c

@@ -317,34 +317,10 @@ static struct super_operations sockfs_ops = {
 	statfs:		simple_statfs,
 };
 
-static int sockfs_fill_super(struct super_block *sb, void *data, int silent)
-{
-	struct inode *root;
-	sb->s_blocksize = 1024;
-	sb->s_blocksize_bits = 10;
-	sb->s_magic = SOCKFS_MAGIC;
-	sb->s_op = &sockfs_ops;
-	root = new_inode(sb);
-	if (!root)
-		return -ENOMEM;
-	root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
-	root->i_uid = root->i_gid = 0;
-	root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
-	sb->s_root = d_alloc(NULL, &(const struct qstr) { "socket:", 7, 0 });
-	if (!sb->s_root) {
-		iput(root);
-		return -ENOMEM;
-	}
-	sb->s_root->d_sb = sb;
-	sb->s_root->d_parent = sb->s_root;
-	d_instantiate(sb->s_root, root);
-	return 0;
-}
-
 static struct super_block *sockfs_get_sb(struct file_system_type *fs_type,
 	int flags, char *dev_name, void *data)
 {
-	return get_sb_nodev(fs_type, flags, data, sockfs_fill_super);
+	return get_sb_pseudo(fs_type, "socket:", &sockfs_ops, SOCKFS_MAGIC);
 }
 
 static struct vfsmount *sock_mnt;
@@ -353,7 +329,6 @@ static struct file_system_type sock_fs_type = {
 	name:		"sockfs",
 	get_sb:		sockfs_get_sb,
 	kill_sb:	kill_anon_super,
-	fs_flags:	FS_NOMOUNT,
 };
 static int sockfs_delete_dentry(struct dentry *dentry)
 {