Hi, > -----Original Message----- > From: linux-btrfs-owner@xxxxxxxxxxxxxxx [mailto:linux-btrfs-owner@xxxxxxxxxxxxxxx] On Behalf Of Tomohiro Misono > Sent: Friday, May 11, 2018 3:26 PM > To: linux-btrfs@xxxxxxxxxxxxxxx > Subject: [PATCH v4 1/3] btrfs: Add unprivileged ioctl which returns subvolume information > > Add new unprivileged ioctl BTRFS_IOC_GET_SUBVOL_INFO which returns the information of subvolume containing this inode. > (i.e. returns the information in ROOT_ITEM and ROOT_BACKREF.) > > Signed-off-by: Tomohiro Misono <misono.tomohiro@xxxxxxxxxxxxxx> > --- > fs/btrfs/ioctl.c | 129 +++++++++++++++++++++++++++++++++++++++++++++ > include/uapi/linux/btrfs.h | 51 ++++++++++++++++++ > 2 files changed, 180 insertions(+) > > diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 48e2ddff32bd..64b23e22852f 100644 > --- a/fs/btrfs/ioctl.c > +++ b/fs/btrfs/ioctl.c > @@ -2242,6 +2242,133 @@ static noinline int btrfs_ioctl_ino_lookup(struct file *file, > return ret; > } > > +/* Get the subvolume information in BTRFS_ROOT_ITEM and > +BTRFS_ROOT_BACKREF */ static noinline int btrfs_ioctl_get_subvol_info(struct file *file, > + void __user *argp) > +{ > + struct btrfs_ioctl_get_subvol_info_args *subvol_info; > + struct btrfs_root *root; > + struct btrfs_path *path; > + struct btrfs_key key; > + > + struct btrfs_root_item root_item; > + struct btrfs_root_ref *rref; > + struct extent_buffer *l; > + int slot; > + > + unsigned long item_off; > + unsigned long item_len; > + > + struct inode *inode; > + int ret; > + > + path = btrfs_alloc_path(); > + if (!path) > + return -ENOMEM; > + > + subvol_info = kzalloc(sizeof(*subvol_info), GFP_KERNEL); > + if (!subvol_info) { > + btrfs_free_path(path); > + return -ENOMEM; > + } > + inode = file_inode(file); > + > + root = BTRFS_I(inode)->root->fs_info->tree_root; > + key.objectid = BTRFS_I(inode)->root->root_key.objectid; > + key.type = BTRFS_ROOT_ITEM_KEY; > + key.offset = 0; > + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); > + if (ret < 0) { > + goto out; > + } else if (ret > 0) { > + u64 objectid = key.objectid; > + > + if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) { > + ret = btrfs_next_leaf(root, path); > + if (ret < 0) > + return ret; Should goto out; to free subvol_info and path. > + } > + > + /* If the subvolume is a snapshot, offset is not zero */ > + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); > + if (key.objectid != objectid || > + key.type != BTRFS_ROOT_ITEM_KEY) { > + ret = -ENOENT; > + goto out; > + } > + } > + > + l = path->nodes[0]; > + slot = path->slots[0]; > + item_off = btrfs_item_ptr_offset(l, slot); > + item_len = btrfs_item_size_nr(l, slot); > + read_extent_buffer(l, &root_item, item_off, item_len); > + > + subvol_info->id = key.objectid; > + > + subvol_info->generation = btrfs_root_generation(&root_item); > + subvol_info->flags = btrfs_root_flags(&root_item); > + > + memcpy(subvol_info->uuid, root_item.uuid, BTRFS_UUID_SIZE); > + memcpy(subvol_info->parent_uuid, root_item.parent_uuid, > + BTRFS_UUID_SIZE); > + memcpy(subvol_info->received_uuid, root_item.received_uuid, > + BTRFS_UUID_SIZE); > + > + subvol_info->ctransid = btrfs_root_ctransid(&root_item); > + subvol_info->ctime.sec = btrfs_stack_timespec_sec(&root_item.ctime); > + subvol_info->ctime.nsec = btrfs_stack_timespec_nsec(&root_item.ctime); > + > + subvol_info->otransid = btrfs_root_otransid(&root_item); > + subvol_info->otime.sec = btrfs_stack_timespec_sec(&root_item.otime); > + subvol_info->otime.nsec = btrfs_stack_timespec_nsec(&root_item.otime); > + > + subvol_info->stransid = btrfs_root_stransid(&root_item); > + subvol_info->stime.sec = btrfs_stack_timespec_sec(&root_item.stime); > + subvol_info->stime.nsec = btrfs_stack_timespec_nsec(&root_item.stime); > + > + subvol_info->rtransid = btrfs_root_rtransid(&root_item); > + subvol_info->rtime.sec = btrfs_stack_timespec_sec(&root_item.rtime); > + subvol_info->rtime.nsec = btrfs_stack_timespec_nsec(&root_item.rtime); > + > + btrfs_release_path(path); > + key.type = BTRFS_ROOT_BACKREF_KEY; > + key.offset = 0; > + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); > + if (ret < 0) { > + goto out; > + } else if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) { > + ret = btrfs_next_leaf(root, path); > + if (ret < 0) > + return ret; Should goto out; to free subvol_info and path. > + } > + > + l = path->nodes[0]; > + slot = path->slots[0]; > + btrfs_item_key_to_cpu(l, &key, slot); > + if (key.objectid == subvol_info->id && > + key.type == BTRFS_ROOT_BACKREF_KEY){ > + subvol_info->parent_id = key.offset; > + > + rref = btrfs_item_ptr(l, slot, struct btrfs_root_ref); > + subvol_info->dirid = btrfs_root_ref_dirid(l, rref); > + > + item_off = btrfs_item_ptr_offset(l, slot) > + + sizeof(struct btrfs_root_ref); > + item_len = btrfs_item_size_nr(l, slot) > + - sizeof(struct btrfs_root_ref); > + read_extent_buffer(l, subvol_info->name, item_off, item_len); > + } If this if is not correct(ex. corrupt filesystem without backref), should it return -ENOENT, or its be ok without parent_id, dirid and name. Suggest to add logic of else. > + > + if (copy_to_user(argp, subvol_info, sizeof(*subvol_info))) > + ret = -EFAULT; > + > +out: > + kzfree(subvol_info); > + btrfs_free_path(path); > + return ret; > +} > + > static noinline int btrfs_ioctl_snap_destroy(struct file *file, > void __user *arg) > { > @@ -5374,6 +5501,8 @@ long btrfs_ioctl(struct file *file, unsigned int > return btrfs_ioctl_get_features(file, argp); > case BTRFS_IOC_SET_FEATURES: > return btrfs_ioctl_set_features(file, argp); > + case BTRFS_IOC_GET_SUBVOL_INFO: > + return btrfs_ioctl_get_subvol_info(file, argp); > } > > return -ENOTTY; > diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h index c8d99b9ca550..ed053852c71f 100644 > --- a/include/uapi/linux/btrfs.h > +++ b/include/uapi/linux/btrfs.h > @@ -725,6 +725,55 @@ struct btrfs_ioctl_send_args { > __u64 reserved[4]; /* in */ > }; > > +struct btrfs_ioctl_get_subvol_info_args { > + /* All filed is out */ > + /* Id of this subvolume */ > + __u64 id; > + /* Name of this subvolume, used to get the real name at mount point */ > + char name[BTRFS_VOL_NAME_MAX + 1]; > + /* > + * Id of the subvolume which contains this subvolume. > + * Zero for top-level subvolume or deleted subvolume > + */ > + __u64 parent_id; > + /* > + * Inode number of the directory which contains this subvolume. > + * Zero for top-level subvolume or deleted subvolume > + */ > + __u64 dirid; > + > + /* Latest transaction id of this subvolume */ > + __u64 generation; > + /* Flags of this subvolume */ > + __u64 flags; > + > + /* uuid of this subvolume */ > + __u8 uuid[BTRFS_UUID_SIZE]; > + /* > + * uuid of the subvolume of which this subvolume is a snapshot. > + * All zero for non-snapshot subvolume > + */ > + __u8 parent_uuid[BTRFS_UUID_SIZE]; > + /* > + * uuid of the subvolume from which this subvolume is received. > + * All zero for non-received subvolume > + */ > + __u8 received_uuid[BTRFS_UUID_SIZE]; > + > + /* Transaction id indicates when change/create/send/receive happens */ > + __u64 ctransid; > + __u64 otransid; > + __u64 stransid; > + __u64 rtransid; > + /* Time corresponds to c/o/s/rtransid */ > + struct btrfs_ioctl_timespec ctime; > + struct btrfs_ioctl_timespec otime; > + struct btrfs_ioctl_timespec stime; > + struct btrfs_ioctl_timespec rtime; > + > + __u64 reserved[8]; > +}; > + > /* Error codes as returned by the kernel */ enum btrfs_err_code { > BTRFS_ERROR_DEV_RAID1_MIN_NOT_MET = 1, @@ -843,5 +892,7 @@ enum btrfs_err_code { > struct btrfs_ioctl_vol_args_v2) > #define BTRFS_IOC_LOGICAL_INO_V2 _IOWR(BTRFS_IOCTL_MAGIC, 59, \ > struct btrfs_ioctl_logical_ino_args) > +#define BTRFS_IOC_GET_SUBVOL_INFO _IOR(BTRFS_IOCTL_MAGIC, 60, \ > + struct btrfs_ioctl_get_subvol_info_args) > > #endif /* _UAPI_LINUX_BTRFS_H */ > -- > 2.14.3 > Reviewed-by: Gu Jinxiang <gujx@xxxxxxxxxxxxxx> > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > ?韬{.n?????%??檩??w?{.n???{饼?~镶?^n?■???h?璀?｛?夸z罐?+€?zf＂?????i?????_璁?:+v??撸?
