RE: [PATCH v6 1/3] btrfs: Add unprivileged ioctl which returns subvolume information

[Gu, Jinxiang]

> -Original Message-
> From: linux-btrfs-ow...@vger.kernel.org 
> [mailto:linux-btrfs-ow...@vger.kernel.org] On Behalf Of Tomohiro Misono
> Sent: Friday, May 18, 2018 10:55 AM
> To: linux-btrfs@vger.kernel.org
> Subject: [PATCH v6 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 
> ---
>  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 
> 48e2ddff32bd..31af6e91c614 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -2242,6 +2242,129 @@ 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, );
> + if (IS_ERR(root)) {
> + ret = PTR_ERR(root);
> + goto out;
> + }
> + root_item = >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(_item->otime);
> + subvol_info->ctime.nsec =
> +btrfs_stack_timespec_nsec(_item->ctime);
> +
> + subvol_info->otransid = btrfs_root_otransid(root_item);
> + subvol_info->otime.sec = btrfs_stack_timespec_sec(_item->otime);
> + subvol_info->otime.nsec =
> +btrfs_stack_timespec_nsec(_item->otime);
> +
> + subvol_info->stransid = btrfs_root_stransid(root_item);
> + subvol_info->stime.sec = btrfs_stack_timespec_sec(_item->stime);
> + subvol_info->stime.nsec =
> +btrfs_stack_timespec_nsec(_item->stime);
> +
> + subvol_info->rtransid = btrfs_root_rtransid(root_item);
> + subvol_info->rtime.sec = btrfs_stack_timespec_sec(_item->rtime);
> + subvol_info->rtime.nsec =
> +btrfs_stack_timespec_nsec(_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, , 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];
> +  

RE: [PATCH v6 1/3] btrfs: Add unprivileged ioctl which returns subvolume information

[Gu, Jinxiang]

> -Original Message-
> From: linux-btrfs-ow...@vger.kernel.org 
> [mailto:linux-btrfs-ow...@vger.kernel.org] On Behalf Of Tomohiro Misono
> Sent: Friday, May 18, 2018 10:55 AM
> To: linux-btrfs@vger.kernel.org
> Subject: [PATCH v6 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 
> ---
>  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 
> 48e2ddff32bd..31af6e91c614 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -2242,6 +2242,129 @@ 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, );
> + if (IS_ERR(root)) {
> + ret = PTR_ERR(root);
> + goto out;
> + }
> + root_item = >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(_item->otime);
> + subvol_info->ctime.nsec =
> +btrfs_stack_timespec_nsec(_item->ctime);
> +
> + subvol_info->otransid = btrfs_root_otransid(root_item);
> + subvol_info->otime.sec = btrfs_stack_timespec_sec(_item->otime);
> + subvol_info->otime.nsec =
> +btrfs_stack_timespec_nsec(_item->otime);
> +
> + subvol_info->stransid = btrfs_root_stransid(root_item);
> + subvol_info->stime.sec = btrfs_stack_timespec_sec(_item->stime);
> + subvol_info->stime.nsec =
> +btrfs_stack_timespec_nsec(_item->stime);
> +
> + subvol_info->rtransid = btrfs_root_rtransid(root_item);
> + subvol_info->rtime.sec = btrfs_stack_timespec_sec(_item->rtime);
> + subvol_info->rtime.nsec =
> +btrfs_stack_timespec_nsec(_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, , 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];
> +  

Re: [PATCH v6 1/3] btrfs: Add unprivileged ioctl which returns subvolume information

[Misono Tomohiro]

On 2018/05/18 11:54, Tomohiro Misono wrote:
> 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 
> ---
>  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 48e2ddff32bd..31af6e91c614 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -2242,6 +2242,129 @@ 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, );
> + if (IS_ERR(root)) {
> + ret = PTR_ERR(root);
> + goto out;
> + }
> + root_item = >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(_item->otime);
  obviously ->ctime, 
sorry for messed up.

> + subvol_info->ctime.nsec = btrfs_stack_timespec_nsec(_item->ctime);
> +
> + subvol_info->otransid = btrfs_root_otransid(root_item);
> + subvol_info->otime.sec = btrfs_stack_timespec_sec(_item->otime);
> + subvol_info->otime.nsec = btrfs_stack_timespec_nsec(_item->otime);
> +
> + subvol_info->stransid = btrfs_root_stransid(root_item);
> + subvol_info->stime.sec = btrfs_stack_timespec_sec(_item->stime);
> + subvol_info->stime.nsec = btrfs_stack_timespec_nsec(_item->stime);
> +
> + subvol_info->rtransid = btrfs_root_rtransid(root_item);
> + subvol_info->rtime.sec = btrfs_stack_timespec_sec(_item->rtime);
> + subvol_info->rtime.nsec = btrfs_stack_timespec_nsec(_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, , 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, , slot);
> + if (key.objectid == subvol_info->id &&
> + key.type == BTRFS_ROOT_BACKREF_KEY) {
> +