ANDROID: vfs: Allow filesystems to access their private mount data

Now we pass the vfsmount when mounting and remounting.
This allows the filesystem to actually set up the mount
specific data, although we can't quite do anything with
it yet. show_options is expanded to include data that
lives with the mount.

To avoid changing existing filesystems, these have
been added as new vfs functions.

Change-Id: If80670bfad9f287abb8ac22457e1b034c9697097
Signed-off-by: Daniel Rosenberg <drosen@google.com>

diff --git a/fs/internal.h b/fs/internal.h
index 71859c4d0b41b820dfe22bca4d30d8863ad86df7..6387b35a1c0d13b0aa13fafff5d1889bac580038 100644 (file)
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -84,9 +84,11 @@ extern struct file *get_empty_filp(void);
  * super.c
  */
 extern int do_remount_sb(struct super_block *, int, void *, int);
+extern int do_remount_sb2(struct vfsmount *, struct super_block *, int,
+                                                               void *, int);
 extern bool trylock_super(struct super_block *sb);
 extern struct dentry *mount_fs(struct file_system_type *,
-                              int, const char *, void *);
+                              int, const char *, struct vfsmount *, void *);
 extern struct super_block *user_get_super(dev_t);
 
 /*

diff --git a/fs/namespace.c b/fs/namespace.c
index 06f1b23ffd5b1677be7095a67501bc38b81d58f1..4aad64ad9ad0a38a0f021ab943849290dd59f475 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -979,7 +979,7 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void
        if (flags & MS_KERNMOUNT)
                mnt->mnt.mnt_flags = MNT_INTERNAL;
 
-       root = mount_fs(type, flags, name, data);
+       root = mount_fs(type, flags, name, &mnt->mnt, data);
        if (IS_ERR(root)) {
                kfree(mnt->mnt.data);
                mnt_free_id(mnt);
@@ -2255,7 +2255,7 @@ static int do_remount(struct path *path, int flags, int mnt_flags,
        else if (!capable(CAP_SYS_ADMIN))
                err = -EPERM;
        else {
-               err = do_remount_sb(sb, flags, data, 0);
+               err = do_remount_sb2(path->mnt, sb, flags, data, 0);
                namespace_lock();
                lock_mount_hash();
                propagate_remount(mnt);

diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c
index 87645955990d15a9df03df7b0c4b4b82100f1543..961e597acfc6633b5f4fa32d0366664092b5dbb5 100644 (file)
--- a/fs/proc_namespace.c
+++ b/fs/proc_namespace.c
@@ -118,7 +118,9 @@ static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
        if (err)
                goto out;
        show_mnt_opts(m, mnt);
-       if (sb->s_op->show_options)
+       if (sb->s_op->show_options2)
+                       err = sb->s_op->show_options2(mnt, m, mnt_path.dentry);
+       else if (sb->s_op->show_options)
                err = sb->s_op->show_options(m, mnt_path.dentry);
        seq_puts(m, " 0 0\n");
 out:
@@ -178,7 +180,9 @@ static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
        err = show_sb_opts(m, sb);
        if (err)
                goto out;
-       if (sb->s_op->show_options)
+       if (sb->s_op->show_options2) {
+               err = sb->s_op->show_options2(mnt, m, mnt->mnt_root);
+       } else if (sb->s_op->show_options)
                err = sb->s_op->show_options(m, mnt->mnt_root);
        seq_putc(m, '\n');
 out:

diff --git a/fs/super.c b/fs/super.c
index b938b14f6041b97a8f8b2681016dcb08a8438ce6..c96434ea71e25a78bd5bab4c446119e3fdb44d1a 100644 (file)
--- a/fs/super.c
+++ b/fs/super.c
@@ -703,7 +703,8 @@ rescan:
 }
 
 /**
- *     do_remount_sb - asks filesystem to change mount options.
+ *     do_remount_sb2 - asks filesystem to change mount options.
+ *     @mnt:   mount we are looking at
  *     @sb:    superblock in question
  *     @flags: numeric part of options
  *     @data:  the rest of options
@@ -711,7 +712,7 @@ rescan:
  *
  *     Alters the mount options of a mounted file system.
  */
-int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
+int do_remount_sb2(struct vfsmount *mnt, struct super_block *sb, int flags, void *data, int force)
 {
        int retval;
        int remount_ro;
@@ -753,7 +754,16 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
                }
        }
 
-       if (sb->s_op->remount_fs) {
+       if (mnt && sb->s_op->remount_fs2) {
+               retval = sb->s_op->remount_fs2(mnt, sb, &flags, data);
+               if (retval) {
+                       if (!force)
+                               goto cancel_readonly;
+                       /* If forced remount, go ahead despite any errors */
+                       WARN(1, "forced remount of a %s fs returned %i\n",
+                            sb->s_type->name, retval);
+               }
+       } else if (sb->s_op->remount_fs) {
                retval = sb->s_op->remount_fs(sb, &flags, data);
                if (retval) {
                        if (!force)
@@ -785,6 +795,11 @@ cancel_readonly:
        return retval;
 }
 
+int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
+{
+       return do_remount_sb2(NULL, sb, flags, data, force);
+}
+
 static void do_emergency_remount(struct work_struct *work)
 {
        struct super_block *sb, *p = NULL;
@@ -1104,7 +1119,7 @@ struct dentry *mount_single(struct file_system_type *fs_type,
 EXPORT_SYMBOL(mount_single);
 
 struct dentry *
-mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
+mount_fs(struct file_system_type *type, int flags, const char *name, struct vfsmount *mnt, void *data)
 {
        struct dentry *root;
        struct super_block *sb;
@@ -1121,7 +1136,10 @@ mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
                        goto out_free_secdata;
        }
 
-       root = type->mount(type, flags, name, data);
+       if (type->mount2)
+               root = type->mount2(mnt, type, flags, name, data);
+       else
+               root = type->mount(type, flags, name, data);
        if (IS_ERR(root)) {
                error = PTR_ERR(root);
                goto out_free_secdata;

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 87858f72a1436c0208917dc35d83bb69725b5ee3..e26cf250d97dedbe4aa9346ddd0370355cc7e95a 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1733,11 +1733,13 @@ struct super_operations {
        int (*unfreeze_fs) (struct super_block *);
        int (*statfs) (struct dentry *, struct kstatfs *);
        int (*remount_fs) (struct super_block *, int *, char *);
+       int (*remount_fs2) (struct vfsmount *, struct super_block *, int *, char *);
        void *(*clone_mnt_data) (void *);
        void (*copy_mnt_data) (void *, void *);
        void (*umount_begin) (struct super_block *);
 
        int (*show_options)(struct seq_file *, struct dentry *);
+       int (*show_options2)(struct vfsmount *,struct seq_file *, struct dentry *);
        int (*show_devname)(struct seq_file *, struct dentry *);
        int (*show_path)(struct seq_file *, struct dentry *);
        int (*show_stats)(struct seq_file *, struct dentry *);
@@ -1969,6 +1971,8 @@ struct file_system_type {
 #define FS_RENAME_DOES_D_MOVE  32768   /* FS will handle d_move() during rename() internally. */
        struct dentry *(*mount) (struct file_system_type *, int,
                       const char *, void *);
+       struct dentry *(*mount2) (struct vfsmount *, struct file_system_type *, int,
+                              const char *, void *);
        void *(*alloc_mnt_data) (void);
        void (*kill_sb) (struct super_block *);
        struct module *owner;