EXPORT_SYMBOL(generic_shutdown_super);
+/**
+ * sget_fc - Find or create a superblock
+ * @fc: Filesystem context.
+ * @test: Comparison callback
+ * @set: Setup callback
+ *
+ * Find or create a superblock using the parameters stored in the filesystem
+ * context and the two callback functions.
+ *
+ * If an extant superblock is matched, then that will be returned with an
+ * elevated reference count that the caller must transfer or discard.
+ *
+ * If no match is made, a new superblock will be allocated and basic
+ * initialisation will be performed (s_type, s_fs_info and s_id will be set and
+ * the set() callback will be invoked), the superblock will be published and it
+ * will be returned in a partially constructed state with SB_BORN and SB_ACTIVE
+ * as yet unset.
+ */
+struct super_block *sget_fc(struct fs_context *fc,
+ int (*test)(struct super_block *, struct fs_context *),
+ int (*set)(struct super_block *, struct fs_context *))
+{
+ struct super_block *s = NULL;
+ struct super_block *old;
+ struct user_namespace *user_ns = fc->global ? &init_user_ns : fc->user_ns;
+ int err;
+
+ if (!(fc->sb_flags & SB_KERNMOUNT) &&
+ fc->purpose != FS_CONTEXT_FOR_SUBMOUNT) {
+ /* Don't allow mounting unless the caller has CAP_SYS_ADMIN
+ * over the namespace.
+ */
+ if (!(fc->fs_type->fs_flags & FS_USERNS_MOUNT)) {
+ if (!capable(CAP_SYS_ADMIN))
+ return ERR_PTR(-EPERM);
+ } else {
+ if (!ns_capable(fc->user_ns, CAP_SYS_ADMIN))
+ return ERR_PTR(-EPERM);
+ }
+ }
+
+retry:
+ spin_lock(&sb_lock);
+ if (test) {
+ hlist_for_each_entry(old, &fc->fs_type->fs_supers, s_instances) {
+ if (test(old, fc))
+ goto share_extant_sb;
+ }
+ }
+ if (!s) {
+ spin_unlock(&sb_lock);
+ s = alloc_super(fc->fs_type, fc->sb_flags, user_ns);
+ if (!s)
+ return ERR_PTR(-ENOMEM);
+ goto retry;
+ }
+
+ s->s_fs_info = fc->s_fs_info;
+ err = set(s, fc);
+ if (err) {
+ s->s_fs_info = NULL;
+ spin_unlock(&sb_lock);
+ destroy_unused_super(s);
+ return ERR_PTR(err);
+ }
+ fc->s_fs_info = NULL;
+ s->s_type = fc->fs_type;
+ strlcpy(s->s_id, s->s_type->name, sizeof(s->s_id));
+ list_add_tail(&s->s_list, &super_blocks);
+ hlist_add_head(&s->s_instances, &s->s_type->fs_supers);
+ spin_unlock(&sb_lock);
+ get_filesystem(s->s_type);
+ register_shrinker_prepared(&s->s_shrink);
+ return s;
+
+share_extant_sb:
+ if (user_ns != old->s_user_ns) {
+ spin_unlock(&sb_lock);
+ destroy_unused_super(s);
+ return ERR_PTR(-EBUSY);
+ }
+ if (!grab_super(old))
+ goto retry;
+ destroy_unused_super(s);
+ return old;
+}
+EXPORT_SYMBOL(sget_fc);
+
/**
* sget_userns - find or create a superblock
* @type: filesystem type superblock should belong to
}
}
- retval = legacy_reconfigure(fc);
- 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);
+ if (fc->ops->reconfigure) {
+ retval = fc->ops->reconfigure(fc);
+ 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);
+ }
}
WRITE_ONCE(sb->s_flags, ((sb->s_flags & ~fc->sb_flags_mask) |
EXPORT_SYMBOL(mount_ns);
+int set_anon_super_fc(struct super_block *sb, struct fs_context *fc)
+{
+ return set_anon_super(sb, NULL);
+}
+EXPORT_SYMBOL(set_anon_super_fc);
+
+static int test_keyed_super(struct super_block *sb, struct fs_context *fc)
+{
+ return sb->s_fs_info == fc->s_fs_info;
+}
+
+static int test_single_super(struct super_block *s, struct fs_context *fc)
+{
+ return 1;
+}
+
+/**
+ * vfs_get_super - Get a superblock with a search key set in s_fs_info.
+ * @fc: The filesystem context holding the parameters
+ * @keying: How to distinguish superblocks
+ * @fill_super: Helper to initialise a new superblock
+ *
+ * Search for a superblock and create a new one if not found. The search
+ * criterion is controlled by @keying. If the search fails, a new superblock
+ * is created and @fill_super() is called to initialise it.
+ *
+ * @keying can take one of a number of values:
+ *
+ * (1) vfs_get_single_super - Only one superblock of this type may exist on the
+ * system. This is typically used for special system filesystems.
+ *
+ * (2) vfs_get_keyed_super - Multiple superblocks may exist, but they must have
+ * distinct keys (where the key is in s_fs_info). Searching for the same
+ * key again will turn up the superblock for that key.
+ *
+ * (3) vfs_get_independent_super - Multiple superblocks may exist and are
+ * unkeyed. Each call will get a new superblock.
+ *
+ * A permissions check is made by sget_fc() unless we're getting a superblock
+ * for a kernel-internal mount or a submount.
+ */
+int vfs_get_super(struct fs_context *fc,
+ enum vfs_get_super_keying keying,
+ int (*fill_super)(struct super_block *sb,
+ struct fs_context *fc))
+{
+ int (*test)(struct super_block *, struct fs_context *);
+ struct super_block *sb;
+
+ switch (keying) {
+ case vfs_get_single_super:
+ test = test_single_super;
+ break;
+ case vfs_get_keyed_super:
+ test = test_keyed_super;
+ break;
+ case vfs_get_independent_super:
+ test = NULL;
+ break;
+ default:
+ BUG();
+ }
+
+ sb = sget_fc(fc, test, set_anon_super_fc);
+ if (IS_ERR(sb))
+ return PTR_ERR(sb);
+
+ if (!sb->s_root) {
+ int err = fill_super(sb, fc);
+ if (err) {
+ deactivate_locked_super(sb);
+ return err;
+ }
+
+ sb->s_flags |= SB_ACTIVE;
+ }
+
+ BUG_ON(fc->root);
+ fc->root = dget(sb->s_root);
+ return 0;
+}
+EXPORT_SYMBOL(vfs_get_super);
+
#ifdef CONFIG_BLOCK
static int set_bdev_super(struct super_block *s, void *data)
{
struct super_block *sb;
int error;
- error = legacy_get_tree(fc);
+ if (fc->fs_type->fs_flags & FS_REQUIRES_DEV && !fc->source) {
+ errorf(fc, "Filesystem requires source device");
+ return -ENOENT;
+ }
+
+ if (fc->root)
+ return -EBUSY;
+
+ /* Get the mountable root in fc->root, with a ref on the root and a ref
+ * on the superblock.
+ */
+ error = fc->ops->get_tree(fc);
if (error < 0)
return error;
+ if (!fc->root) {
+ pr_err("Filesystem %s get_tree() didn't set fc->root\n",
+ fc->fs_type->name);
+ /* We don't know what the locking state of the superblock is -
+ * if there is a superblock.
+ */
+ BUG();
+ }
+
sb = fc->root->d_sb;
WARN_ON(!sb->s_bdi);
projects / linux.git / blobdiff