This patch implements functionality of following ioctls:
BTRFS_IOC_INO_LOOKUP - Reading tree root id and path
Read tree root id and path for a given file or directory.
The name and tree root id are returned in an ioctl's third
argument that represents a pointer to a following type:
struct btrfs_ioctl_ino_lookup_args {
__u64 treeid;
__u64 objectid;
char name[BTRFS_INO_LOOKUP_PATH_MAX];
};
Before calling this ioctl, field 'objectid' should be filled
with the object id value for which the tree id and path are
to be read. Value 'BTRFS_FIRST_FREE_OBJECTID' represents the
object id for the first available btrfs object (directory or
file).
BTRFS_IOC_INO_PATHS - Reading paths to all files
Read path to all files with a certain inode number. The paths
are returned in the ioctl's third argument which represents
a pointer to a following type:
struct btrfs_ioctl_ino_path_args {
__u64 inum; /* in */
__u64 size; /* in */
__u64 reserved[4];
/* struct btrfs_data_container *fspath; out */
__u64 fspath; /* out */
};
Before calling this ioctl, the 'inum' and 'size' field should
be filled with the aproppriate inode number and size of the
directory where file paths should be looked for. For now, the
paths are returned in an '__u64' (unsigned long long) value
'fspath'.
BTRFS_IOC_LOGICAL_INO - Reading inode numbers
Read inode numbers for files on a certain logical adress. The
inode numbers are returned in the ioctl's third argument which
represents a pointer to a following type:
struct btrfs_ioctl_logical_ino_args {
__u64 logical; /* in */
__u64 size; /* in */
__u64 reserved[3]; /* must be 0 for now */
__u64 flags; /* in, v2 only */
/* struct btrfs_data_container *inodes; out */
__u64 inodes;
};
Before calling this ioctl, the 'logical' and 'size' field should
be filled with the aproppriate logical adress and size of where
the inode numbers of files should be looked for. For now, the
inode numbers are returned in an '__u64' (unsigned long long)
value 'inodes'.
BTRFS_IOC_LOGICAL_INO_V2 - Reading inode numbers
Same as the above mentioned ioctl except that it allows passing
a flags 'BTRFS_LOGICAL_INO_ARGS_IGNORE_OFFSET'.
BTRFS_IOC_INO_LOOKUP_USER - Reading subvolume name and path
Read name and path of a subvolume. The tree root id and
path are read in an ioctl's third argument which represents a
pointer to a following type:
struct btrfs_ioctl_ino_lookup_user_args {
/* in, inode number containing the subvolume of 'subvolid' */
__u64 dirid;
/* in */
__u64 treeid;
/* out, name of the subvolume of 'treeid' */
char name[BTRFS_VOL_NAME_MAX + 1];
/*
* out, constructed path from the directory with which the ioctl is
* called to dirid
*/
char path[BTRFS_INO_LOOKUP_USER_PATH_MAX];
};
Before calling this ioctl, the 'dirid' and 'treeid' field should
be filled with aproppriate values which represent the inode number
of the directory that contains the subvolume and treeid of the
subvolume.
Implementation notes:
All of the ioctls in this patch use structure types as third arguments.
That is the reason why aproppriate thunk definitions were added in file
'syscall_types.h'.
Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Tested-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200823195014.116226-6-Filip.Bozuta@syrmia.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
===========
QEMU README
===========
QEMU is a generic and open source machine & userspace emulator and
virtualizer.
QEMU is capable of emulating a complete machine in software without any
need for hardware virtualization support. By using dynamic translation,
it achieves very good performance. QEMU can also integrate with the Xen
and KVM hypervisors to provide emulated hardware while allowing the
hypervisor to manage the CPU. With hypervisor support, QEMU can achieve
near native performance for CPUs. When QEMU emulates CPUs directly it is
capable of running operating systems made for one machine (e.g. an ARMv7
board) on a different machine (e.g. an x86_64 PC board).
QEMU is also capable of providing userspace API virtualization for Linux
and BSD kernel interfaces. This allows binaries compiled against one
architecture ABI (e.g. the Linux PPC64 ABI) to be run on a host using a
different architecture ABI (e.g. the Linux x86_64 ABI). This does not
involve any hardware emulation, simply CPU and syscall emulation.
QEMU aims to fit into a variety of use cases. It can be invoked directly
by users wishing to have full control over its behaviour and settings.
It also aims to facilitate integration into higher level management
layers, by providing a stable command line interface and monitor API.
It is commonly invoked indirectly via the libvirt library when using
open source applications such as oVirt, OpenStack and virt-manager.
QEMU as a whole is released under the GNU General Public License,
version 2. For full licensing details, consult the LICENSE file.
Building
========
QEMU is multi-platform software intended to be buildable on all modern
Linux platforms, OS-X, Win32 (via the Mingw64 toolchain) and a variety
of other UNIX targets. The simple steps to build QEMU are:
.. code-block:: shell
mkdir build
cd build
../configure
make
Additional information can also be found online via the QEMU website:
* `<https://qemu.org/Hosts/Linux>`_
* `<https://qemu.org/Hosts/Mac>`_
* `<https://qemu.org/Hosts/W32>`_
Submitting patches
==================
The QEMU source code is maintained under the GIT version control system.
.. code-block:: shell
git clone https://git.qemu.org/git/qemu.git
When submitting patches, one common approach is to use 'git
format-patch' and/or 'git send-email' to format & send the mail to the
qemu-devel@nongnu.org mailing list. All patches submitted must contain
a 'Signed-off-by' line from the author. Patches should follow the
guidelines set out in the CODING_STYLE.rst file.
Additional information on submitting patches can be found online via
the QEMU website
* `<https://qemu.org/Contribute/SubmitAPatch>`_
* `<https://qemu.org/Contribute/TrivialPatches>`_
The QEMU website is also maintained under source control.
.. code-block:: shell
git clone https://git.qemu.org/git/qemu-web.git
* `<https://www.qemu.org/2017/02/04/the-new-qemu-website-is-up/>`_
A 'git-publish' utility was created to make above process less
cumbersome, and is highly recommended for making regular contributions,
or even just for sending consecutive patch series revisions. It also
requires a working 'git send-email' setup, and by default doesn't
automate everything, so you may want to go through the above steps
manually for once.
For installation instructions, please go to
* `<https://github.com/stefanha/git-publish>`_
The workflow with 'git-publish' is:
.. code-block:: shell
$ git checkout master -b my-feature
$ # work on new commits, add your 'Signed-off-by' lines to each
$ git publish
Your patch series will be sent and tagged as my-feature-v1 if you need to refer
back to it in the future.
Sending v2:
.. code-block:: shell
$ git checkout my-feature # same topic branch
$ # making changes to the commits (using 'git rebase', for example)
$ git publish
Your patch series will be sent with 'v2' tag in the subject and the git tip
will be tagged as my-feature-v2.
Bug reporting
=============
The QEMU project uses Launchpad as its primary upstream bug tracker. Bugs
found when running code built from QEMU git or upstream released sources
should be reported via:
* `<https://bugs.launchpad.net/qemu/>`_
If using QEMU via an operating system vendor pre-built binary package, it
is preferable to report bugs to the vendor's own bug tracker first. If
the bug is also known to affect latest upstream code, it can also be
reported via launchpad.
For additional information on bug reporting consult:
* `<https://qemu.org/Contribute/ReportABug>`_
Contact
=======
The QEMU community can be contacted in a number of ways, with the two
main methods being email and IRC
* `<mailto:qemu-devel@nongnu.org>`_
* `<https://lists.nongnu.org/mailman/listinfo/qemu-devel>`_
* #qemu on irc.oftc.net
Information on additional methods of contacting the community can be
found online via the QEMU website:
* `<https://qemu.org/Contribute/StartHere>`_