#include <linux/magic.h>
#include <linux/slab.h>
#include <linux/cleancache.h>
+#include <linux/mnt_namespace.h>
#include "compat.h"
#include "delayed-inode.h"
#include "ctree.h"
#include <trace/events/btrfs.h>
static const struct super_operations btrfs_super_ops;
+static struct file_system_type btrfs_fs_type;
static const char *btrfs_decode_error(struct btrfs_fs_info *fs_info, int errno,
char nbuf[16])
int intarg;
if (!options)
- goto out;
+ return 0;
/*
* strsep changes the string, duplicate it because parse_options
error = btrfs_scan_one_device(match_strdup(&args[0]),
flags, holder, fs_devices);
if (error)
- goto out_free_opts;
+ goto out;
break;
default:
break;
}
}
- out_free_opts:
+out:
kfree(orig);
- out:
- /*
- * If no subvolume name is specified we use the default one. Allocate
- * a copy of the string "." here so that code later in the
- * mount path doesn't care if it's the default volume or another one.
- */
- if (!*subvol_name) {
- *subvol_name = kstrdup(".", GFP_KERNEL);
- if (!*subvol_name)
- return -ENOMEM;
- }
return error;
}
return set_anon_super(s, data);
}
+/*
+ * This will strip out the subvol=%s argument for an argument string and add
+ * subvolid=0 to make sure we get the actual tree root for path walking to the
+ * subvol we want.
+ */
+static char *setup_root_args(char *args)
+{
+ unsigned copied = 0;
+ unsigned len = strlen(args) + 2;
+ char *pos;
+ char *ret;
+
+ /*
+ * We need the same args as before, but minus
+ *
+ * subvol=a
+ *
+ * and add
+ *
+ * subvolid=0
+ *
+ * which is a difference of 2 characters, so we allocate strlen(args) +
+ * 2 characters.
+ */
+ ret = kzalloc(len * sizeof(char), GFP_NOFS);
+ if (!ret)
+ return NULL;
+ pos = strstr(args, "subvol=");
+
+ /* This shouldn't happen, but just in case.. */
+ if (!pos) {
+ kfree(ret);
+ return NULL;
+ }
+
+ /*
+ * The subvol=<> arg is not at the front of the string, copy everybody
+ * up to that into ret.
+ */
+ if (pos != args) {
+ *pos = '\0';
+ strcpy(ret, args);
+ copied += strlen(args);
+ pos++;
+ }
+
+ strncpy(ret + copied, "subvolid=0", len - copied);
+
+ /* Length of subvolid=0 */
+ copied += 10;
+
+ /*
+ * If there is no , after the subvol= option then we know there's no
+ * other options and we can just return.
+ */
+ pos = strchr(pos, ',');
+ if (!pos)
+ return ret;
+
+ /* Copy the rest of the arguments into our buffer */
+ strncpy(ret + copied, pos, len - copied);
+ copied += strlen(pos);
+
+ return ret;
+}
+
+static struct dentry *mount_subvol(const char *subvol_name, int flags,
+ const char *device_name, char *data)
+{
+ struct super_block *s;
+ struct dentry *root;
+ struct vfsmount *mnt;
+ struct mnt_namespace *ns_private;
+ char *newargs;
+ struct path path;
+ int error;
+
+ newargs = setup_root_args(data);
+ if (!newargs)
+ return ERR_PTR(-ENOMEM);
+ mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name,
+ newargs);
+ kfree(newargs);
+ if (IS_ERR(mnt))
+ return ERR_CAST(mnt);
+
+ ns_private = create_mnt_ns(mnt);
+ if (IS_ERR(ns_private)) {
+ mntput(mnt);
+ return ERR_CAST(ns_private);
+ }
+
+ /*
+ * This will trigger the automount of the subvol so we can just
+ * drop the mnt we have here and return the dentry that we
+ * found.
+ */
+ error = vfs_path_lookup(mnt->mnt_root, mnt, subvol_name,
+ LOOKUP_FOLLOW, &path);
+ put_mnt_ns(ns_private);
+ if (error)
+ return ERR_PTR(error);
+
+ /* Get a ref to the sb and the dentry we found and return it */
+ s = path.mnt->mnt_sb;
+ atomic_inc(&s->s_active);
+ root = dget(path.dentry);
+ path_put(&path);
+ down_write(&s->s_umount);
+
+ return root;
+}
/*
* Find a superblock for the given device / mount point.
if (error)
return ERR_PTR(error);
+ if (subvol_name) {
+ root = mount_subvol(subvol_name, flags, device_name, data);
+ kfree(subvol_name);
+ return root;
+ }
+
error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
if (error)
- goto error_free_subvol_name;
+ return ERR_PTR(error);
error = btrfs_open_devices(fs_devices, mode, fs_type);
if (error)
- goto error_free_subvol_name;
+ return ERR_PTR(error);
if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
error = -EACCES;
bdev = fs_devices->latest_bdev;
s = sget(fs_type, btrfs_test_super, btrfs_set_super, tree_root);
- if (IS_ERR(s))
- goto error_s;
+ if (IS_ERR(s)) {
+ error = PTR_ERR(s);
+ goto error_close_devices;
+ }
if (s->s_root) {
if ((flags ^ s->s_flags) & MS_RDONLY) {
deactivate_locked_super(s);
- error = -EBUSY;
- goto error_close_devices;
+ return ERR_PTR(-EBUSY);
}
btrfs_close_devices(fs_devices);
flags & MS_SILENT ? 1 : 0);
if (error) {
deactivate_locked_super(s);
- goto error_free_subvol_name;
+ return ERR_PTR(error);
}
btrfs_sb(s)->fs_info->bdev_holder = fs_type;
s->s_flags |= MS_ACTIVE;
}
- /* if they gave us a subvolume name bind mount into that */
- if (strcmp(subvol_name, ".")) {
- struct dentry *new_root;
-
- root = get_default_root(s, subvol_rootid);
- if (IS_ERR(root)) {
- error = PTR_ERR(root);
- deactivate_locked_super(s);
- goto error_free_subvol_name;
- }
-
- mutex_lock(&root->d_inode->i_mutex);
- new_root = lookup_one_len(subvol_name, root,
- strlen(subvol_name));
- mutex_unlock(&root->d_inode->i_mutex);
-
- if (IS_ERR(new_root)) {
- dput(root);
- deactivate_locked_super(s);
- error = PTR_ERR(new_root);
- goto error_free_subvol_name;
- }
- if (!new_root->d_inode) {
- dput(root);
- dput(new_root);
- deactivate_locked_super(s);
- error = -ENXIO;
- goto error_free_subvol_name;
- }
- dput(root);
- root = new_root;
- } else {
- root = get_default_root(s, subvol_objectid);
- if (IS_ERR(root)) {
- error = PTR_ERR(root);
- deactivate_locked_super(s);
- goto error_free_subvol_name;
- }
+ root = get_default_root(s, subvol_objectid);
+ if (IS_ERR(root)) {
+ deactivate_locked_super(s);
+ return root;
}
- kfree(subvol_name);
return root;
-error_s:
- error = PTR_ERR(s);
error_close_devices:
btrfs_close_devices(fs_devices);
kfree(fs_info);
kfree(tree_root);
-error_free_subvol_name:
- kfree(subvol_name);
return ERR_PTR(error);
}
projects / linux-2.6-block.git / commitdiff