btrfs: defrag: extend ioctl to accept compression levels

The zstd and zlib compression types support setting compression levels.
Enhance the defrag interface to specify the levels as well. For zstd

btrfs: defrag: extend ioctl to accept compression levels

The zstd and zlib compression types support setting compression levels.
Enhance the defrag interface to specify the levels as well. For zstd the
negative (realtime) levels are also accepted.

Reviewed-by: Qu Wenruo <[email protected]>
Signed-off-by: Daniel Vacek <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: add new ioctl to wait for cleaned subvolumes

Add a new unprivileged ioctl that will let the command
'btrfs subvolume sync' work without the (privileged) SEARCH_TREE ioctl.

There are several

btrfs: add new ioctl to wait for cleaned subvolumes

Add a new unprivileged ioctl that will let the command
'btrfs subvolume sync' work without the (privileged) SEARCH_TREE ioctl.

There are several modes of operation, where the most common ones are to
wait on a specific subvolume or all currently queued for cleaning. This
is utilized e.g. in backup applications that delete subvolumes and wait
until they're cleaned to check for remaining space.

The other modes are for flexibility, e.g. for monitoring or
checkpoints in the queue of deleted subvolumes, again without the need
to use SEARCH_TREE.

Notes:

- waiting is interruptible, the timeout is set to 1 second and is not
configurable

- repeated calls to the ioctl see a different state, so this is
inherently racy when using e.g. the count or peek next/last

Use cases:

- a subvolume A was deleted, wait for cleaning (WAIT_FOR_ONE)

- a bunch of subvolumes were deleted, wait for all (WAIT_FOR_QUEUED or
PEEK_LAST + WAIT_FOR_ONE)

- count how many are queued (not blocking), for monitoring purposes

- report progress (PEEK_NEXT), may miss some if cleaning is quick

- own waiting in user space (PEEK_LAST until it's 0)

Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: qgroup: validate btrfs_qgroup_inherit parameter

[BUG]
Currently btrfs can create subvolume with an invalid qgroup inherit
without triggering any error:

# mkfs.btrfs -O quota -f $dev
# mo

btrfs: qgroup: validate btrfs_qgroup_inherit parameter

[BUG]
Currently btrfs can create subvolume with an invalid qgroup inherit
without triggering any error:

# mkfs.btrfs -O quota -f $dev
# mount $dev $mnt
# btrfs subvolume create -i 2/0 $mnt/subv1
# btrfs qgroup show -prce --sync $mnt
Qgroupid Referenced Exclusive Path
-------- ---------- --------- ----
0/5 16.00KiB 16.00KiB <toplevel>
0/256 16.00KiB 16.00KiB subv1

[CAUSE]
We only do a very basic size check for btrfs_qgroup_inherit structure,
but never really verify if the values are correct.

Thus in btrfs_qgroup_inherit() function, we have to skip non-existing
qgroups, and never return any error.

[FIX]
Fix the behavior and introduce extra checks:

- Introduce early check for btrfs_qgroup_inherit structure
Not only the size, but also all the qgroup ids would be verified.

And the timing is very early, so we can return error early.
This early check is very important for snapshot creation, as snapshot
is delayed to transaction commit.

- Drop support for btrfs_qgroup_inherit::num_ref_copies and
num_excl_copies
Those two members are used to specify to copy refr/excl numbers from
other qgroups.
This would definitely mark qgroup inconsistent, and btrfs-progs has
dropped the support for them for a long time.
It's time to drop the support for kernel.

- Verify the supported btrfs_qgroup_inherit::flags
Just in case we want to add extra flags for btrfs_qgroup_inherit.

Now above subvolume creation would fail with -ENOENT other than silently
ignore the non-existing qgroup.

CC: [email protected] # 6.7+
Signed-off-by: Qu Wenruo <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: defrag: reject unknown flags of btrfs_ioctl_defrag_range_args

Add extra sanity check for btrfs_ioctl_defrag_range_args::flags.

This is not really to enhance fuzzing tests, but as a preparati

btrfs: defrag: reject unknown flags of btrfs_ioctl_defrag_range_args

Add extra sanity check for btrfs_ioctl_defrag_range_args::flags.

This is not really to enhance fuzzing tests, but as a preparation for
future expansion on btrfs_ioctl_defrag_range_args.

In the future we're going to add new members, allowing more fine tuning
for btrfs defrag. Without the -ENONOTSUPP error, there would be no way
to detect if the kernel supports those new defrag features.

CC: [email protected] # 4.14+
Reviewed-by: Filipe Manana <[email protected]>
Signed-off-by: Qu Wenruo <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: qgroup: add new quota mode for simple quotas

Add a new quota mode called "simple quotas". It can be enabled by the
existing quota enable ioctl via a new command, and sets an incompat
bit, as

btrfs: qgroup: add new quota mode for simple quotas

Add a new quota mode called "simple quotas". It can be enabled by the
existing quota enable ioctl via a new command, and sets an incompat
bit, as the implementation of simple quotas will make backwards
incompatible changes to the disk format of the extent tree.

Signed-off-by: Boris Burkov <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: read raid stripe tree from disk

If we find the raid-stripe-tree on mount, read it from disk. This is
a backward incompatible feature. The rescue=ignorebadroots mount option
will skip this tre

btrfs: read raid stripe tree from disk

If we find the raid-stripe-tree on mount, read it from disk. This is
a backward incompatible feature. The rescue=ignorebadroots mount option
will skip this tree.

Signed-off-by: Johannes Thumshirn <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: scrub: reject unsupported scrub flags

Since the introduction of scrub interface, the only flag that we support
is BTRFS_SCRUB_READONLY. Thus there is no sanity checks, if there are
some unde

btrfs: scrub: reject unsupported scrub flags

Since the introduction of scrub interface, the only flag that we support
is BTRFS_SCRUB_READONLY. Thus there is no sanity checks, if there are
some undefined flags passed in, we just ignore them.

This is problematic if we want to introduce new scrub flags, as we have
no way to determine if such flags are supported.

Address the problem by introducing a check for the flags, and if
unsupported flags are set, return -EOPNOTSUPP to inform the user space.

This check should be backported for all supported kernels before any new
scrub flags are introduced.

CC: [email protected] # 4.14+
Reviewed-by: Anand Jain <[email protected]>
Signed-off-by: Qu Wenruo <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: ioctl: return device fsid from DEV_INFO ioctl

Currently user space utilizes dev info ioctl to grab the info of a
certain devid, this includes its device uuid. But the returned info is
not en

btrfs: ioctl: return device fsid from DEV_INFO ioctl

Currently user space utilizes dev info ioctl to grab the info of a
certain devid, this includes its device uuid. But the returned info is
not enough to determine if a device is a seed.

Commit a26d60dedf9a ("btrfs: sysfs: add devinfo/fsid to retrieve actual
fsid from the device") exports the same value in sysfs so this is for
parity with ioctl. Add a new member, fsid, into
btrfs_ioctl_dev_info_args, and populate the member with fsid value.

This should not cause any compatibility problem, following the
combinations:

- Old user space, old kernel
- Old user space, new kernel
User space tool won't even check the new member.

- New user space, old kernel
The kernel won't touch the new member, and user space tool should
zero out its argument, thus the new member is all zero.

User space tool can then know the kernel doesn't support this fsid
reporting, and falls back to whatever they can.

- New user space, new kernel
Go as planned.

Would find the fsid member is no longer zero, and trust its value.

Reviewed-by: Anand Jain <[email protected]>
Signed-off-by: Qu Wenruo <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: sync some cleanups from progs into uapi/btrfs.h

When syncing this code into btrfs-progs Dave noticed there's some things
we were losing in the sync that are needed. This syncs those changes

btrfs: sync some cleanups from progs into uapi/btrfs.h

When syncing this code into btrfs-progs Dave noticed there's some things
we were losing in the sync that are needed. This syncs those changes
into the kernel, which include a few comments that weren't in the
kernel, some whitespace changes, an attribute, and the cplusplus bit.

Signed-off-by: Josef Bacik <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: separate BLOCK_GROUP_TREE compat RO flag from EXTENT_TREE_V2

The problem of long mount time caused by block group item search is
already known for some time, and the solution of block group t

btrfs: separate BLOCK_GROUP_TREE compat RO flag from EXTENT_TREE_V2

The problem of long mount time caused by block group item search is
already known for some time, and the solution of block group tree has
been proposed.

There is really no need to bound this feature into extent tree v2, just
introduce compat RO flag, BLOCK_GROUP_TREE, to correctly solve the
problem.

All the code handling block group root is already in the upstream
kernel, thus this patch really only needs to introduce the new compat RO
flag.

This patch introduces one extra artificial limitation on block group
tree feature, that free space cache v2 and no-holes feature must be
enabled to use this new compat RO feature.

This artificial requirement is mostly to reduce the test combinations,
and can be a guideline for future features, to mostly rely on the latest
default features.

Signed-off-by: Qu Wenruo <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: send: enable support for stream v2 and compressed writes

Now that the new support is implemented, allow the ioctl to accept v2
and the compressed flag, and update the version in sysfs.

Signe

btrfs: send: enable support for stream v2 and compressed writes

Now that the new support is implemented, allow the ioctl to accept v2
and the compressed flag, and update the version in sysfs.

Signed-off-by: Omar Sandoval <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: send: add stream v2 definitions

This adds the definitions of the new commands for send stream version 2
and their respective attributes: fallocate, FS_IOC_SETFLAGS (a.k.a.
chattr), and encode

btrfs: send: add stream v2 definitions

This adds the definitions of the new commands for send stream version 2
and their respective attributes: fallocate, FS_IOC_SETFLAGS (a.k.a.
chattr), and encoded writes. It also documents two changes to the send
stream format in v2: the receiver shouldn't assume a maximum command
size, and the DATA attribute is encoded differently to allow for writes
larger than 64k. These will be implemented in subsequent changes, and
then the ioctl will accept the new version and flag.

Reviewed-by: Josef Bacik <[email protected]>
Signed-off-by: Omar Sandoval <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

treewide: uapi: Replace zero-length arrays with flexible-array members

There is a regular need in the kernel to provide a way to declare
having a dynamically sized set of trailing elements in a stru

treewide: uapi: Replace zero-length arrays with flexible-array members

There is a regular need in the kernel to provide a way to declare
having a dynamically sized set of trailing elements in a structure.
Kernel code should always use “flexible array members”[1] for these
cases. The older style of one-element or zero-length arrays should
no longer be used[2].

This code was transformed with the help of Coccinelle:
(linux-5.19-rc2$ spatch --jobs $(getconf _NPROCESSORS_ONLN) --sp-file script.cocci --include-headers --dir . > output.patch)

@@
identifier S, member, array;
type T1, T2;
@@

struct S {
...
T1 member;
T2 array[
- 0
];
};

-fstrict-flex-arrays=3 is coming and we need to land these changes
to prevent issues like these in the short future:

../fs/minix/dir.c:337:3: warning: 'strcpy' will always overflow; destination buffer has size 0,
but the source string has length 2 (including NUL byte) [-Wfortify-source]
strcpy(de3->name, ".");
^

Since these are all [0] to [] changes, the risk to UAPI is nearly zero. If
this breaks anything, we can use a union with a new member name.

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/78
Build-tested-by: kernel test robot <[email protected]>
Link: https://lore.kernel.org/lkml/62b675ec.wKX6AOZ6cbE71vtF%[email protected]/
Acked-by: Dan Williams <[email protected]> # For ndctl.h
Signed-off-by: Gustavo A. R. Silva <[email protected]>

show more ...

btrfs: add definitions and documentation for encoded I/O ioctls

In order to allow sending and receiving compressed data without
decompressing it, we need an interface to write pre-compressed data
di

btrfs: add definitions and documentation for encoded I/O ioctls

In order to allow sending and receiving compressed data without
decompressing it, we need an interface to write pre-compressed data
directly to the filesystem and the matching interface to read compressed
data without decompressing it. This adds the definitions for ioctls to
do that and detailed explanations of how to use them.

Reviewed-by: Nikolay Borisov <[email protected]>
Signed-off-by: Omar Sandoval <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: add definition for EXTENT_TREE_V2

This adds the initial definition of the EXTENT_TREE_V2 incompat feature
flag. This also hides the support behind CONFIG_BTRFS_DEBUG.

THIS IS A IN DEVELOPME

btrfs: add definition for EXTENT_TREE_V2

This adds the initial definition of the EXTENT_TREE_V2 incompat feature
flag. This also hides the support behind CONFIG_BTRFS_DEBUG.

THIS IS A IN DEVELOPMENT FORMAT CHANGE, DO NOT USE UNLESS YOU ARE A
DEVELOPER OR A TESTER.

The format is in flux and will be added in stages, any fs will need to
be re-made between updates to the format.

Signed-off-by: Josef Bacik <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: send: prepare for v2 protocol

This is preparatory work for send protocol update to version 2 and
higher.

We have many pending protocol update requests but still don't have the
basic protocol

btrfs: send: prepare for v2 protocol

This is preparatory work for send protocol update to version 2 and
higher.

We have many pending protocol update requests but still don't have the
basic protocol rev in place, the first thing that must happen is to do
the actual versioning support.

The protocol version is u32 and is a new member in the send ioctl
struct. Validity of the version field is backed by a new flag bit. Old
kernels would fail when a higher version is requested. Version protocol
0 will pick the highest supported version, BTRFS_SEND_STREAM_VERSION,
that's also exported in sysfs.

The version is still unchanged and will be increased once we have new
incompatible commands or stream updates.

Reviewed-by: Nikolay Borisov <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: initial fsverity support

Add support for fsverity in btrfs. To support the generic interface in
fs/verity, we add two new item types in the fs tree for inodes with
verity enabled. One stores

btrfs: initial fsverity support

Add support for fsverity in btrfs. To support the generic interface in
fs/verity, we add two new item types in the fs tree for inodes with
verity enabled. One stores the per-file verity descriptor and btrfs
verity item and the other stores the Merkle tree data itself.

Verity checking is done in end_page_read just before a page is marked
uptodate. This naturally handles a variety of edge cases like holes,
preallocated extents, and inline extents. Some care needs to be taken to
not try to verity pages past the end of the file, which are accessed by
the generic buffered file reading code under some circumstances like
reading to the end of the last page and trying to read again. Direct IO
on a verity file falls back to buffered reads.

Verity relies on PageChecked for the Merkle tree data itself to avoid
re-walking up shared paths in the tree. For this reason, we need to
cache the Merkle tree data. Since the file is immutable after verity is
turned on, we can cache it at an index past EOF.

Use the new inode ro_flags to store verity on the inode item, so that we
can enable verity on a file, then rollback to an older kernel and still
mount the file system and read the file. Since we can't safely write the
file anymore without ruining the invariants of the Merkle tree, we mark
a ro_compat flag on the file system when a file has verity enabled.

Acked-by: Eric Biggers <[email protected]>
Co-developed-by: Chris Mason <[email protected]>
Signed-off-by: Chris Mason <[email protected]>
Signed-off-by: Boris Burkov <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: fix typos in comments

Fix typos that have snuck in since the last round. Found by codespell.

Signed-off-by: David Sterba <[email protected]>

btrfs: introduce ZONED feature flag

This patch introduces the ZONED incompat flag. The flag indicates that
the volume management will satisfy the constraints imposed by
host-managed zoned block devi

btrfs: introduce ZONED feature flag

This patch introduces the ZONED incompat flag. The flag indicates that
the volume management will satisfy the constraints imposed by
host-managed zoned block devices (aligned chunk allocation, append-only
updates, reset zone after filled).

As the zoned support will happen incrementally due to enhancing some
core infrastructure like super block writes, tree-log, raid support, the
feature will appear in sysfs only on debug builds. It will be enabled
once the support is feature complete and applications can reliably check
whether zoned support is present or not.

Reviewed-by: Anand Jain <[email protected]>
Reviewed-by: Johannes Thumshirn <[email protected]>
Signed-off-by: Damien Le Moal <[email protected]>
Signed-off-by: Naohiro Aota <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: add metadata_uuid to FS_INFO ioctl

Add retrieval of the filesystem's metadata UUID to the fsinfo ioctl.
This is driven by setting the BTRFS_FS_INFO_FLAG_METADATA_UUID flag in
btrfs_ioctl_fs_i

btrfs: add metadata_uuid to FS_INFO ioctl

Add retrieval of the filesystem's metadata UUID to the fsinfo ioctl.
This is driven by setting the BTRFS_FS_INFO_FLAG_METADATA_UUID flag in
btrfs_ioctl_fs_info_args::flags.

Reviewed-by: Nikolay Borisov <[email protected]>
Signed-off-by: Johannes Thumshirn <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: add filesystem generation to FS_INFO ioctl

Add retrieval of the filesystem's generation to the fsinfo ioctl. This is
driven by setting the BTRFS_FS_INFO_FLAG_GENERATION flag in
btrfs_ioctl_fs

btrfs: add filesystem generation to FS_INFO ioctl

Add retrieval of the filesystem's generation to the fsinfo ioctl. This is
driven by setting the BTRFS_FS_INFO_FLAG_GENERATION flag in
btrfs_ioctl_fs_info_args::flags.

Reviewed-by: Nikolay Borisov <[email protected]>
Signed-off-by: Johannes Thumshirn <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: pass checksum type via BTRFS_IOC_FS_INFO ioctl

With the recent addition of filesystem checksum types other than CRC32c,
it is not anymore hard-coded which checksum type a btrfs filesystem use

btrfs: pass checksum type via BTRFS_IOC_FS_INFO ioctl

With the recent addition of filesystem checksum types other than CRC32c,
it is not anymore hard-coded which checksum type a btrfs filesystem uses.

Up to now there is no good way to read the filesystem checksum, apart from
reading the filesystem UUID and then query sysfs for the checksum type.

Add a new csum_type and csum_size fields to the BTRFS_IOC_FS_INFO ioctl
command which usually is used to query filesystem features. Also add a
flags member indicating that the kernel responded with a set csum_type and
csum_size field.

For compatibility reasons, only return the csum_type and csum_size if
the BTRFS_FS_INFO_FLAG_CSUM_INFO flag was passed to the kernel. Also
clear any unknown flags so we don't pass false positives to user-space
newer than the kernel.

To simplify further additions to the ioctl, also switch the padding to a
u8 array. Pahole was used to verify the result of this switch:

The csum members are added before flags, which might look odd, but this
is to keep the alignment requirements and not to introduce holes in the
structure.

$ pahole -C btrfs_ioctl_fs_info_args fs/btrfs/btrfs.ko
struct btrfs_ioctl_fs_info_args {
__u64 max_id; /* 0 8 */
__u64 num_devices; /* 8 8 */
__u8 fsid[16]; /* 16 16 */
__u32 nodesize; /* 32 4 */
__u32 sectorsize; /* 36 4 */
__u32 clone_alignment; /* 40 4 */
__u16 csum_type; /* 44 2 */
__u16 csum_size; /* 46 2 */
__u64 flags; /* 48 8 */
__u8 reserved[968]; /* 56 968 */

/* size: 1024, cachelines: 16, members: 10 */
};

Fixes: 3951e7f050ac ("btrfs: add xxhash64 to checksumming algorithms")
Fixes: 3831bf0094ab ("btrfs: add sha256 to checksumming algorithm")
CC: [email protected] # 5.5+
Signed-off-by: Johannes Thumshirn <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: re-instantiate the removed BTRFS_SUBVOL_CREATE_ASYNC definition

The commit 9c1036fdb1d1ff1b ("btrfs: Remove BTRFS_SUBVOL_CREATE_ASYNC
support") breaks strace build with the kernel headers fro

btrfs: re-instantiate the removed BTRFS_SUBVOL_CREATE_ASYNC definition

The commit 9c1036fdb1d1ff1b ("btrfs: Remove BTRFS_SUBVOL_CREATE_ASYNC
support") breaks strace build with the kernel headers from git:

btrfs.c: In function "btrfs_test_subvol_ioctls":
btrfs.c:531:23: error: "BTRFS_SUBVOL_CREATE_ASYNC" undeclared (first use
in this function)
vol_args_v2.flags = BTRFS_SUBVOL_CREATE_ASYNC;

Moreover, it is improper to break UAPI, strace uses the definitions to
decode ioctls that are considered part of public API.

Restore the macro definition and put it under "#ifndef __KERNEL__"
in order to prevent inadvertent in-kernel usage.

Fixes: 9c1036fdb1d1ff1b ("btrfs: Remove BTRFS_SUBVOL_CREATE_ASYNC support")
Reviewed-by: Nikolay Borisov <[email protected]>
Signed-off-by: Eugene Syromiatnikov <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: Remove BTRFS_SUBVOL_CREATE_ASYNC support

This functionality was deprecated in kernel 5.4. Since no one has
complained of the impending removal it's time we did so.

Signed-off-by: Nikolay Bor

btrfs: Remove BTRFS_SUBVOL_CREATE_ASYNC support

This functionality was deprecated in kernel 5.4. Since no one has
complained of the impending removal it's time we did so.

Signed-off-by: Nikolay Borisov <[email protected]>
Reviewed-by: David Sterba <[email protected]>
[ add comment ]
Signed-off-by: David Sterba <[email protected]>

show more ...

btrfs: add new BTRFS_IOC_SNAP_DESTROY_V2 ioctl

This ioctl will be responsible for deleting a subvolume using its id.
This can be used when a system has a file system mounted from a
subvolume, rather

btrfs: add new BTRFS_IOC_SNAP_DESTROY_V2 ioctl

This ioctl will be responsible for deleting a subvolume using its id.
This can be used when a system has a file system mounted from a
subvolume, rather than the root file system, like below:

/
@subvol1/
@subvol2/
@subvol_default/

If only @subvol_default is mounted, we have no path to reach @subvol1
and @subvol2, thus no way to delete them. Current subvolume delete ioctl
takes a file handle point as argument, and if @subvol_default is
mounted, we can't reach @subvol1 and @subvol2 from the same mount point.

This patch introduces a new ioctl BTRFS_IOC_SNAP_DESTROY_V2 that takes
the extended structure with flags to allow to delete subvolume using
subvolid.

Now, we can use this new ioctl specifying the subvolume id and refer to
the same mount point. It doesn't matter which subvolume was mounted,
since we can reach to the desired one using the subvolume id, and then
delete it.

The full path to the subvolume id is resolved internally and access is
verified as if the subvolume was accessed by path.

The volume args v2 structure is extended to use the existing union for
subvolume id specification, that's valid in case the
BTRFS_SUBVOL_SPEC_BY_ID is set.

Signed-off-by: Marcos Paulo de Souza <[email protected]>
Reviewed-by: David Sterba <[email protected]>
[ update changelog ]
Signed-off-by: David Sterba <[email protected]>

show more ...