From e0eab99255d34c9dbaac7b73a1a2a79f823a7da9 Mon Sep 17 00:00:00 2001

From: Filip Bozuta <Filip.Bozuta@syrmia.com>

Date: Thu, 3 Sep 2020 01:26:54 +0200

Subject: [PATCH 2/9] linux-user: Add support for a group of btrfs ioctls used

 for subvolumes

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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>

---

 configure                  |  9 +++++++++

 linux-user/ioctls.h        | 15 +++++++++++++++

 linux-user/syscall.c       |  3 +++

 linux-user/syscall_defs.h  |  8 ++++++++

 linux-user/syscall_types.h | 32 ++++++++++++++++++++++++++++++++

 5 files changed, 67 insertions(+)

diff --git a/configure b/configure

index 2acc4d1465..1cba4e0b80 100755

--- a/configure

+++ b/configure

@@ -5079,6 +5079,12 @@ if check_include sys/kcov.h ; then

     kcov=yes

 fi

+# check for btrfs filesystem support (kernel must be 3.9+)

+btrfs=no

+if check_include linux/btrfs.h ; then

+    btrfs=yes

+fi

+

 # If we're making warnings fatal, apply this to Sphinx runs as well

 sphinx_werror=""

 if test "$werror" = "yes"; then

@@ -7330,6 +7336,9 @@ fi

 if test "$kcov" = "yes" ; then

   echo "CONFIG_KCOV=y" >> $config_host_mak

 fi

+if test "$btrfs" = "yes" ; then

+  echo "CONFIG_BTRFS=y" >> $config_host_mak

+fi

 if test "$inotify" = "yes" ; then

   echo "CONFIG_INOTIFY=y" >> $config_host_mak

 fi

diff --git a/linux-user/ioctls.h b/linux-user/ioctls.h

index 0713ae1311..12d1444224 100644

--- a/linux-user/ioctls.h

+++ b/linux-user/ioctls.h

@@ -174,6 +174,21 @@

      IOCTL(FS_IOC32_GETVERSION, IOC_R, MK_PTR(TYPE_INT))

      IOCTL(FS_IOC32_SETVERSION, IOC_W, MK_PTR(TYPE_INT))

+#ifdef BTRFS_IOC_SUBVOL_CREATE

+     IOCTL(BTRFS_IOC_SUBVOL_CREATE, IOC_W,

+           MK_PTR(MK_STRUCT(STRUCT_btrfs_ioctl_vol_args)))

+#endif

+#ifdef BTRFS_IOC_SUBVOL_GETFLAGS

+     IOCTL(BTRFS_IOC_SUBVOL_GETFLAGS, IOC_R, MK_PTR(TYPE_ULONGLONG))

+#endif

+#ifdef BTRFS_IOC_SUBVOL_SETFLAGS

+     IOCTL(BTRFS_IOC_SUBVOL_SETFLAGS, IOC_W, MK_PTR(TYPE_ULONGLONG))

+#endif

+#ifdef BTRFS_IOC_GET_SUBVOL_INFO

+     IOCTL(BTRFS_IOC_GET_SUBVOL_INFO, IOC_R,

+           MK_PTR(MK_STRUCT(STRUCT_btrfs_ioctl_get_subvol_info_args)))

+#endif

+

 #ifdef CONFIG_USBFS

   /* USB ioctls */

   IOCTL(USBDEVFS_CONTROL, IOC_RW,

diff --git a/linux-user/syscall.c b/linux-user/syscall.c

index 945fc25279..36777c91b0 100644

--- a/linux-user/syscall.c

+++ b/linux-user/syscall.c

@@ -112,6 +112,9 @@

 #include <linux/if_alg.h>

 #include <linux/rtc.h>

 #include <sound/asound.h>

+#ifdef CONFIG_BTRFS

+#include <linux/btrfs.h>

+#endif

 #ifdef HAVE_DRM_H

 #include <libdrm/drm.h>

 #endif

diff --git a/linux-user/syscall_defs.h b/linux-user/syscall_defs.h

index 3c261cff0e..2757956dfa 100644

--- a/linux-user/syscall_defs.h

+++ b/linux-user/syscall_defs.h

@@ -967,6 +967,14 @@ struct target_rtc_pll_info {

 #define TARGET_FS_IOC32_GETVERSION TARGET_IOR('v', 1, int)

 #define TARGET_FS_IOC32_SETVERSION TARGET_IOW('v', 2, int)

+/* btrfs ioctls */

+#define TARGET_BTRFS_IOC_SUBVOL_CREATE          TARGET_IOWU(BTRFS_IOCTL_MAGIC, 14)

+#define TARGET_BTRFS_IOC_SUBVOL_GETFLAGS        TARGET_IOR(BTRFS_IOCTL_MAGIC, 25,\

+                                                           abi_ullong)

+#define TARGET_BTRFS_IOC_SUBVOL_SETFLAGS        TARGET_IOW(BTRFS_IOCTL_MAGIC, 26,\

+                                                           abi_ullong)

+#define TARGET_BTRFS_IOC_GET_SUBVOL_INFO        TARGET_IORU(BTRFS_IOCTL_MAGIC, 60)

+

 /* usb ioctls */

 #define TARGET_USBDEVFS_CONTROL TARGET_IOWRU('U', 0)

 #define TARGET_USBDEVFS_BULK TARGET_IOWRU('U', 2)

diff --git a/linux-user/syscall_types.h b/linux-user/syscall_types.h

index 3f1f033464..db61dbc1b3 100644

--- a/linux-user/syscall_types.h

+++ b/linux-user/syscall_types.h

@@ -354,6 +354,38 @@ STRUCT(blkpg_partition,

        MK_ARRAY(TYPE_CHAR, BLKPG_DEVNAMELTH), /* devname */

        MK_ARRAY(TYPE_CHAR, BLKPG_VOLNAMELTH)) /* volname */

+#ifdef BTRFS_IOC_SUBVOL_CREATE

+STRUCT(btrfs_ioctl_vol_args,

+       TYPE_LONGLONG, /* fd */

+       MK_ARRAY(TYPE_CHAR, BTRFS_PATH_NAME_MAX + 1)) /* name */

+#endif

+

+#ifdef BTRFS_IOC_GET_SUBVOL_INFO

+STRUCT(btrfs_ioctl_timespec,

+       TYPE_ULONGLONG, /* sec */

+       TYPE_INT) /* nsec */

+

+STRUCT(btrfs_ioctl_get_subvol_info_args,

+       TYPE_ULONGLONG, /* treeid */

+       MK_ARRAY(TYPE_CHAR, BTRFS_VOL_NAME_MAX + 1),

+       TYPE_ULONGLONG, /* parentid */

+       TYPE_ULONGLONG, /* dirid */

+       TYPE_ULONGLONG, /* generation */

+       TYPE_ULONGLONG, /* flags */

+       MK_ARRAY(TYPE_CHAR, BTRFS_UUID_SIZE), /* uuid */

+       MK_ARRAY(TYPE_CHAR, BTRFS_UUID_SIZE), /* parent_uuid */

+       MK_ARRAY(TYPE_CHAR, BTRFS_UUID_SIZE), /* received_uuid */

+       TYPE_ULONGLONG, /* ctransid */

+       TYPE_ULONGLONG, /* otransid */

+       TYPE_ULONGLONG, /* stransid */

+       TYPE_ULONGLONG, /* rtransid */

+       MK_STRUCT(STRUCT_btrfs_ioctl_timespec), /* ctime */

+       MK_STRUCT(STRUCT_btrfs_ioctl_timespec), /* otime */

+       MK_STRUCT(STRUCT_btrfs_ioctl_timespec), /* stime */

+       MK_STRUCT(STRUCT_btrfs_ioctl_timespec), /* rtime */

+       MK_ARRAY(TYPE_ULONGLONG, 8)) /* reserved */

+#endif

+

 STRUCT(rtc_time,

        TYPE_INT, /* tm_sec */

        TYPE_INT, /* tm_min */

-- 

2.26.2