diff options
| -rw-r--r-- | fs/btrfs/super.c | 199 |
1 files changed, 135 insertions, 64 deletions
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 244fa46c50b8..934789f7fd33 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -40,6 +40,7 @@ #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" @@ -58,6 +59,7 @@ #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]) @@ -411,7 +413,7 @@ static int btrfs_parse_early_options(const char *options, fmode_t flags, int intarg; if (!options) - goto out; + return 0; /* * strsep changes the string, duplicate it because parse_options @@ -460,26 +462,15 @@ static int btrfs_parse_early_options(const char *options, fmode_t flags, 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; } @@ -730,6 +721,118 @@ static int btrfs_set_super(struct super_block *s, void *data) 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. @@ -761,13 +864,19 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags, 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; @@ -792,14 +901,15 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags, 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); @@ -814,64 +924,25 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags, 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); } |
