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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.) Reviewed-by: Gu Jinxiang <gujx@cn.fujitsu.com> Tested-by: Gu Jinxiang <gujx@cn.fujitsu.com> Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com> [ minor style fixes, update struct comments ] Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Tomohiro Misono
David Sterba
parent
ad7e1a740d
commit
b64ec075bd
121
fs/btrfs/ioctl.c
121
fs/btrfs/ioctl.c
@ -2383,6 +2383,125 @@ out:
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return ret;
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}
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/* Get the subvolume information in BTRFS_ROOT_ITEM and BTRFS_ROOT_BACKREF */
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static int btrfs_ioctl_get_subvol_info(struct file *file, void __user *argp)
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{
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struct btrfs_ioctl_get_subvol_info_args *subvol_info;
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struct btrfs_fs_info *fs_info;
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struct btrfs_root *root;
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struct btrfs_path *path;
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struct btrfs_key key;
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struct btrfs_root_item *root_item;
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struct btrfs_root_ref *rref;
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struct extent_buffer *leaf;
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unsigned long item_off;
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unsigned long item_len;
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struct inode *inode;
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int slot;
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int ret = 0;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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subvol_info = kzalloc(sizeof(*subvol_info), GFP_KERNEL);
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if (!subvol_info) {
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btrfs_free_path(path);
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return -ENOMEM;
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}
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inode = file_inode(file);
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fs_info = BTRFS_I(inode)->root->fs_info;
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/* Get root_item of inode's subvolume */
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key.objectid = BTRFS_I(inode)->root->root_key.objectid;
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key.type = BTRFS_ROOT_ITEM_KEY;
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key.offset = (u64)-1;
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root = btrfs_read_fs_root_no_name(fs_info, &key);
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if (IS_ERR(root)) {
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ret = PTR_ERR(root);
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goto out;
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}
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root_item = &root->root_item;
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subvol_info->treeid = key.objectid;
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subvol_info->generation = btrfs_root_generation(root_item);
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subvol_info->flags = btrfs_root_flags(root_item);
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memcpy(subvol_info->uuid, root_item->uuid, BTRFS_UUID_SIZE);
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memcpy(subvol_info->parent_uuid, root_item->parent_uuid,
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BTRFS_UUID_SIZE);
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memcpy(subvol_info->received_uuid, root_item->received_uuid,
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BTRFS_UUID_SIZE);
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subvol_info->ctransid = btrfs_root_ctransid(root_item);
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subvol_info->ctime.sec = btrfs_stack_timespec_sec(&root_item->ctime);
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subvol_info->ctime.nsec = btrfs_stack_timespec_nsec(&root_item->ctime);
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subvol_info->otransid = btrfs_root_otransid(root_item);
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subvol_info->otime.sec = btrfs_stack_timespec_sec(&root_item->otime);
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subvol_info->otime.nsec = btrfs_stack_timespec_nsec(&root_item->otime);
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subvol_info->stransid = btrfs_root_stransid(root_item);
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subvol_info->stime.sec = btrfs_stack_timespec_sec(&root_item->stime);
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subvol_info->stime.nsec = btrfs_stack_timespec_nsec(&root_item->stime);
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subvol_info->rtransid = btrfs_root_rtransid(root_item);
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subvol_info->rtime.sec = btrfs_stack_timespec_sec(&root_item->rtime);
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subvol_info->rtime.nsec = btrfs_stack_timespec_nsec(&root_item->rtime);
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if (key.objectid != BTRFS_FS_TREE_OBJECTID) {
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/* Search root tree for ROOT_BACKREF of this subvolume */
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root = fs_info->tree_root;
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key.type = BTRFS_ROOT_BACKREF_KEY;
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key.offset = 0;
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ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
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if (ret < 0) {
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goto out;
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} else if (path->slots[0] >=
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btrfs_header_nritems(path->nodes[0])) {
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ret = btrfs_next_leaf(root, path);
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if (ret < 0) {
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goto out;
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} else if (ret > 0) {
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ret = -EUCLEAN;
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goto out;
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}
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}
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leaf = path->nodes[0];
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slot = path->slots[0];
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btrfs_item_key_to_cpu(leaf, &key, slot);
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if (key.objectid == subvol_info->treeid &&
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key.type == BTRFS_ROOT_BACKREF_KEY) {
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subvol_info->parent_id = key.offset;
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rref = btrfs_item_ptr(leaf, slot, struct btrfs_root_ref);
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subvol_info->dirid = btrfs_root_ref_dirid(leaf, rref);
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item_off = btrfs_item_ptr_offset(leaf, slot)
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+ sizeof(struct btrfs_root_ref);
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item_len = btrfs_item_size_nr(leaf, slot)
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- sizeof(struct btrfs_root_ref);
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read_extent_buffer(leaf, subvol_info->name,
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item_off, item_len);
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} else {
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ret = -ENOENT;
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goto out;
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}
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}
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if (copy_to_user(argp, subvol_info, sizeof(*subvol_info)))
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ret = -EFAULT;
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out:
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btrfs_free_path(path);
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kzfree(subvol_info);
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return ret;
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}
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static noinline int btrfs_ioctl_snap_destroy(struct file *file,
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void __user *arg)
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{
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@ -5545,6 +5664,8 @@ long btrfs_ioctl(struct file *file, unsigned int
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return btrfs_ioctl_fsgetxattr(file, argp);
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case FS_IOC_FSSETXATTR:
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return btrfs_ioctl_fssetxattr(file, argp);
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case BTRFS_IOC_GET_SUBVOL_INFO:
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return btrfs_ioctl_get_subvol_info(file, argp);
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}
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return -ENOTTY;
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@ -725,6 +725,66 @@ struct btrfs_ioctl_send_args {
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__u64 reserved[4]; /* in */
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};
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/*
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* Information about a fs tree root.
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*
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* All items are filled by the ioctl
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*/
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struct btrfs_ioctl_get_subvol_info_args {
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/* Id of this subvolume */
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__u64 treeid;
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/* Name of this subvolume, used to get the real name at mount point */
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char name[BTRFS_VOL_NAME_MAX + 1];
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/*
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* Id of the subvolume which contains this subvolume.
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* Zero for top-level subvolume or a deleted subvolume.
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*/
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__u64 parent_id;
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/*
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* Inode number of the directory which contains this subvolume.
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* Zero for top-level subvolume or a deleted subvolume
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*/
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__u64 dirid;
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/* Latest transaction id of this subvolume */
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__u64 generation;
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/* Flags of this subvolume */
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__u64 flags;
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/* UUID of this subvolume */
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__u8 uuid[BTRFS_UUID_SIZE];
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/*
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* UUID of the subvolume of which this subvolume is a snapshot.
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* All zero for a non-snapshot subvolume.
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*/
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__u8 parent_uuid[BTRFS_UUID_SIZE];
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/*
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* UUID of the subvolume from which this subvolume was received.
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* All zero for non-received subvolume.
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*/
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__u8 received_uuid[BTRFS_UUID_SIZE];
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/* Transaction id indicating when change/create/send/receive happened */
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__u64 ctransid;
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__u64 otransid;
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__u64 stransid;
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__u64 rtransid;
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/* Time corresponding to c/o/s/rtransid */
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struct btrfs_ioctl_timespec ctime;
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struct btrfs_ioctl_timespec otime;
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struct btrfs_ioctl_timespec stime;
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struct btrfs_ioctl_timespec rtime;
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/* Must be zero */
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__u64 reserved[8];
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};
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/* Error codes as returned by the kernel */
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enum btrfs_err_code {
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BTRFS_ERROR_DEV_RAID1_MIN_NOT_MET = 1,
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@ -843,5 +903,7 @@ enum btrfs_err_code {
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struct btrfs_ioctl_vol_args_v2)
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#define BTRFS_IOC_LOGICAL_INO_V2 _IOWR(BTRFS_IOCTL_MAGIC, 59, \
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struct btrfs_ioctl_logical_ino_args)
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#define BTRFS_IOC_GET_SUBVOL_INFO _IOR(BTRFS_IOCTL_MAGIC, 60, \
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struct btrfs_ioctl_get_subvol_info_args)
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#endif /* _UAPI_LINUX_BTRFS_H */
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