qemu /
qemu /
d6092e085d23ee2884eb9df3ffb5306ff625e937 linux-user: Add support for a group of btrfs ioctls used for subvolumes
This patch implements functionality of following ioctls:
BTRFS_IOC_SUBVOL_CREATE - Creating a btrfs subvolume
Create a btrfs subvolume. The subvolume is created using the ioctl's
third argument which represents a pointer to a following structure
type:
struct btrfs_ioctl_vol_args {
__s64 fd;
char name[BTRFS_PATH_NAME_MAX + 1];
};
Before calling this ioctl, the fields of this structure should be filled
with aproppriate values. The fd field represents the file descriptor
value of the subvolume and the name field represents the subvolume
path.
BTRFS_IOC_SUBVOL_GETFLAGS - Getting subvolume flags
Read the flags of the btrfs subvolume. The flags are read using
the ioctl's third argument that is a pointer of __u64 (unsigned long).
The third argument represents a bit mask that can be composed of following
values:
BTRFS_SUBVOL_RDONLY (1ULL << 1)
BTRFS_SUBVOL_QGROUP_INHERIT (1ULL << 2)
BTRFS_DEVICE_SPEC_BY_ID (1ULL << 3)
BTRFS_SUBVOL_SPEC_BY_ID (1ULL << 4)
BTRFS_IOC_SUBVOL_SETFLAGS - Setting subvolume flags
Set the flags of the btrfs subvolume. The flags are set using the
ioctl's third argument that is a pointer of __u64 (unsigned long).
The third argument represents a bit mask that can be composed of same
values as in the case of previous ioctl (BTRFS_IOC_SUBVOL_GETFLAGS).
BTRFS_IOC_SUBVOL_GETINFO - Getting subvolume information
Read information about the subvolume. The subvolume information is
returned in the ioctl's third argument which represents a pointer to
a following structure type:
struct btrfs_ioctl_get_subvol_info_args {
/* Id of this subvolume */
__u64 treeid;
/* 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 a deleted subvolume.
*/
__u64 parent_id;
/*
* Inode number of the directory which contains this subvolume.
* Zero for top-level subvolume or a 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 a non-snapshot subvolume.
*/
__u8 parent_uuid[BTRFS_UUID_SIZE];
/*
* UUID of the subvolume from which this subvolume was received.
* All zero for non-received subvolume.
*/
__u8 received_uuid[BTRFS_UUID_SIZE];
/* Transaction id indicating when change/create/send/receive happened */
__u64 ctransid;
__u64 otransid;
__u64 stransid;
__u64 rtransid;
/* Time corresponding 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;
/* Must be zero */
__u64 reserved[8];
};
All of the fields of this structure are filled after the ioctl call.
Implementation notes:
Ioctls BTRFS_IOC_SUBVOL_CREATE and BTRFS_IOC_SUBVOL_GETINFO have structure
types as third arguments. That is the reason why a corresponding definition
are added in file 'linux-user/syscall_types.h'.
The line '#include <linux/btrfs.h>' is added in file 'linux-user/syscall.c' to
recognise preprocessor definitions for these ioctls. Since the file "linux/btrfs.h"
was added in the kernel version 3.9, it is enwrapped in an #ifdef statement
with parameter CONFIG_BTRFS which is defined in 'configure' if the
header file is present.
Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Tested-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200823195014.116226-2-Filip.Bozuta@syrmia.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
5 files changed
