From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mgwkm02.jp.fujitsu.com ([202.219.69.169]:42808 "EHLO mgwkm02.jp.fujitsu.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752161AbeEUBHK (ORCPT ); Sun, 20 May 2018 21:07:10 -0400 Received: from g01jpfmpwkw02.exch.g01.fujitsu.local (g01jpfmpwkw02.exch.g01.fujitsu.local [10.0.193.56]) by kw-mxq.gw.nic.fujitsu.com (Postfix) with ESMTP id A46F0AC00F6 for ; Mon, 21 May 2018 10:07:01 +0900 (JST) Received: from G01JPEXCHKW18.g01.fujitsu.local (G01JPEXCHKW18.g01.fujitsu.local [10.0.194.57]) by g01jpfmpwkw02.exch.g01.fujitsu.local (Postfix) with ESMTP id CF4583285D1 for ; Mon, 21 May 2018 10:07:00 +0900 (JST) From: Tomohiro Misono To: Subject: [PATCH v7 1/3] btrfs: Add unprivileged ioctl which returns subvolume information Date: Mon, 21 May 2018 10:09:42 +0900 Message-ID: <62581a7c24e450ae49ed561686a6007c3726b4f7.1526863497.git.misono.tomohiro@jp.fujitsu.com> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain Sender: linux-btrfs-owner@vger.kernel.org List-ID: 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.) Reviewed-by: Gu Jinxiang Tested-by: Gu Jinxiang Signed-off-by: Tomohiro Misono --- v5 -> v6 - Use brfs_read_fs_root_no_name() to get subvolume root and simplify code v4 -> v5 - Update error handling of btrfs_next_leaf() to cover all cases - Return error if ROOT_BACKREF is not found (except top-level) fs/btrfs/ioctl.c | 125 +++++++++++++++++++++++++++++++++++++++++++++ include/uapi/linux/btrfs.h | 51 ++++++++++++++++++ 2 files changed, 176 insertions(+) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 8f7c1b9a2db7..a395c6d51dd6 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2387,6 +2387,129 @@ 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_fs_info *fs_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 = 0; + + 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); + fs_info = BTRFS_I(inode)->root->fs_info; + + /* Get root_item of inode's subvolume */ + key.objectid = BTRFS_I(inode)->root->root_key.objectid; + key.type = BTRFS_ROOT_ITEM_KEY; + key.offset = (u64)-1; + root = btrfs_read_fs_root_no_name(fs_info, &key); + if (IS_ERR(root)) { + ret = PTR_ERR(root); + goto out; + } + root_item = &root->root_item; + + 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); + + if (key.objectid != BTRFS_FS_TREE_OBJECTID) { + /* Search root tree for ROOT_BACKREF of this subvolume */ + root = fs_info->tree_root; + + 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) { + goto out; + } else if (ret > 0) { + ret = -EUCLEAN; + goto out; + } + } + + 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); + } else { + ret = -ENOENT; + goto out; + } + } + + 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) { @@ -5545,6 +5668,8 @@ long btrfs_ioctl(struct file *file, unsigned int return btrfs_ioctl_fsgetxattr(file, argp); case FS_IOC_FSSETXATTR: return btrfs_ioctl_fssetxattr(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..02cd1f1994e8 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 field 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