Right now, grabbing blockinfo always calls stat on the disk, then
opens the image to determine the capacity, using a throw-away
virStorageSourcePtr. This has a couple of drawbacks:
1. We are calling stat and opening a file on every invocation of
the API. However, there are cases where the stats should NOT be
changing between successive calls (if a domain is running, no
one should be changing the physical size of a block device or raw
image behind our backs; capacity of read-only files should not
be changing; and we are the gateway to the block-resize command
to know when the capacity of read-write files should be changing).
True, we still have to use stat in some cases (a sparse raw file
changes allocation if it is read-write and the amount of holes is
changing, and a read-write qcow2 image stored in a file changes
physical size if it was not fully pre-allocated). But for
read-only images, even this should be something we can remember
from the previous time, rather than repeating every call.
2. We want to enhance the power of virDomainListGetStats, by
sharing code. But we already have a virStorageSourcePtr for
each disk, and it would be easier to reuse the common structure
than to have to worry about the one-off virDomainBlockInfoPtr.
While this patch does not optimize reuse of information in point
1, it does get us closer to being able to do so; by updating a
structure that survives between consecutive calls.
* src/util/virstoragefile.h (_virStorageSource): Add physical, to
mirror virDomainBlockInfo; rearrange fields to match public struct.
(virStorageSourceCopy): Copy the new field.
* src/qemu/qemu_driver.c (qemuDomainGetBlockInfo): Store into
storage source, then copy to block info.
Signed-off-by: Eric Blake <eblake@redhat.com>
To be able to express some use cases of the RBD backing with libvirt, we
need to be able to specify a config file for the RBD client to qemu as
that is one of the commonly used options.
Some storage systems have internal support for snapshots. Libvirt should
be able to select a correct snapshot when starting a VM.
This patch adds a XML element to select a storage source snapshot for
the RBD protocol which supports this feature.
To allow reuse this non-trivial parser code in the backing store parser
this part of the command line parser needs to be split out into a
separate funciton.
As we now have a deep copy function for struct virStorageSource add a
notice that extensions of the structure require also appropriate changes
to the virStorageSourceCopy func.
To express empty drive we historically use storage source with empty
path. Unfortunately NBD disks may be declared without a path.
Add a helper to wrap this logic.
https://bugzilla.redhat.com/show_bug.cgi?id=1091866
Add a new boolean 'sparse'. This will be used by the logical backend
storage driver to determine whether the target volume is sparse or not
(also known by a snapshot or thin logical volume). Although setting sparse
to true at creation could be seen as duplicitous to setting during
virStorageBackendLogicalMakeVol() in case there are ever other code paths
between Create and FindLVs that need to know about the volume be sparse.
Use the 'sparse' in a new virStorageBackendLogicalVolWipe() to decide whether
to attempt to wipe the logical volume or not. For now, I have found no
means to wipe the volume without writing to it. Writing to the sparse
volume causes it to be filled. A sparse logical volume is not completely
writeable as there exists metadata which if overwritten will cause the
sparse lv to go INACTIVE which means pool-refresh will not find it.
Access to whatever lvm uses to manage data blocks is not provided by
any API I could find.
Add 'nocow' to storage volume xml so that user can have an option
to set NOCOW flag to the newly created volume. It's useful on btrfs
file system to enhance performance.
Btrfs has low performance when hosting VM images, even more when the guest
in those VM are also using btrfs as file system. One way to mitigate this
bad performance is to turn off COW attributes on VM files. Generally, there
are two ways to turn off COW on btrfs: a) by mounting fs with nodatacow,
then all newly created files will be NOCOW. b) per file. Add the NOCOW file
attribute. It could only be done to empty or new files.
This patch tries the second way, according to 'nocow' option, it could set
NOCOW flag per file:
for raw file images, handle 'nocow' in libvirt code; for non-raw file images,
pass 'nocow=on' option to qemu-img, and let qemu-img to handle that (requires
qemu-img version >= 2.1).
Signed-off-by: Chunyan Liu <cyliu@suse.com>
The commit referenced above changed function arguments of
virStorageFileGetMetadataFromBuf() but didn't tweak the
ATTRIBUTE_NONNULL tied to them. This was caught by coverity as it
actually obeys them. We disabled them for GCC and thus it didn't show
up.
Additionally in commit 3ea661deea I passed
NULL to the backingFormat argument which was also marked as nonnull. Use
a dummy int's address when the argument isn't supplied so that the code
doesn't need to change much.
We are going to modify storage source chains in place. Add a helper that
will copy relevant information such as security labels to the new
element if that doesn't contain it.
In the future we might need to track state of individual images. Move
the readonly and shared flags to the virStorageSource struct so that we
can keep them in a per-image basis.
The qemu block info function relied on working with local storage. Break
this assumption by adding support for remote volumes. Unfortunately we
still need to take a hybrid approach as some of the operations require a
filedescriptor.
Previously you'd get:
$ virsh domblkinfo gl vda
error: cannot stat file '/img10': Bad file descriptor
Now you get some stats:
$ virsh domblkinfo gl vda
Capacity: 10485760
Allocation: 197120
Physical: 197120
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1110198
To allow reusing this function in the qemu driver we need to allow
specifying the storage format. Also separate return of the backing store
path now isn't necessary.
There's a lot of places where we skip doing actions based on the
locality of given storage type. The usual pattern is to skip it if:
virStorageSourceGetActualType(src) == VIR_STORAGE_TYPE_NETWORK
Add a simple helper to simplify the pattern to
virStorageSourceIsLocalStorage(src)
Replace the inline "auth" struct in virStorageSource with a pointer
to a virStorageAuthDefPtr and utilize between the domain_conf, qemu_conf,
and qemu_command sources for finding the auth data for a domain disk
Introduce virStorageAuthDef and friends. Future patches will merge/utilize
their view of storage source/pool auth/secret definitions.
New API's include:
virStorageAuthDefParse: Parse the "<auth/>" XML data for either the
domain disk or storage pool returning a
virStorageAuthDefPtr
virStorageAuthDefCopy: Copy a virStorageAuthDefPtr - to be used by
the qemuTranslateDiskSourcePoolAuth when it
copies storage pool auth data into domain
disk auth data
virStorageAuthDefFormat: Common output of the "<auth" in the domain
disk or storage pool XML
virStorageAuthDefFree: Free memory associated with virStorageAuthDef
Subsequent patches will utilize the new functions for the domain disk and
storage pools.
Future work in the hostdev pass through can then make use of common data
structures and code.
The parent directory doesn't necessarily need to be stored after we
don't mangle the path stored in the image. Remove it and tweak the code
to avoid using it.
Now that we store only relative names in virStorageSource's member
relPath the backingRelative member is obsolete. Remove it and adapt the
code to the removal.
Due to various refactors and compatibility with the virstoragetest the
relPath field of the virStorageSource structure was always filled either
with the relative name or the full path in case of absolutely backed
storage. Return its original purpose to store only the relative name of
the disk if it is backed relatively and tweak the tests.
This patch introduces a function that will allow us to resolve a
relative difference between two elements of a disk backing chain. This
function will be used to allow relative block commit and block pull
where we need to specify the new relative name of the image to qemu.
This patch also adds unit tests for the function to verify that it works
correctly.
Introduce a common function that will take a callback to resolve links
that will be used to canonicalize paths on various storage systems and
add extensive tests.
The image labels are stored in the virStorageSource struct. Convert the
virDomainDiskDefGetSecurityLabelDef helper not to use the full disk def
and move it appropriately.
Add parsers for relative and absolute backing names for local and remote
storage files.
This parser parses relative paths as relative to their parents and
absolute paths according to the protocol or local access.
For remote storage volumes, all URI based backing file names are
supported and for the qemu colon syntax the NBD protocol is supported.
Use virStorageFileReadHeader() to read headers of storage files possibly
on remote storage to retrieve the image metadata.
The backend information is now parsed by
virStorageFileGetMetadataInternal which is now exported from the util
source and virStorageFileGetMetadataFromFDInternal now doesn't need to
be exported.
My future work will modify the metadata crawler function to use the
storage driver file APIs to access the files instead of accessing them
directly so that we will be able to request the metadata for remote
files too. To avoid linking the storage driver to every helper file
using the utils code, the backing chain traversal function needs to be
moved to the storage driver source.
Additionally the virt-aa-helper and virstoragetest programs need to be
linked with the storage driver as a result of this change.
Add argument to return backing file format of a file probed by
virStorageFileGetMetadataFromFD so that it can be used in place of
virStorageFileGetMetadataFromBuf.
Currently the protocol type with index 0 was NBD which made it hard to
distinguish whether the protocol type was actually assigned. Add a new
protocol type with index 0 to distinguish it explicitly.
The gluster volume name was previously stored as part of the source path
string. This is unfortunate when we want to do operations on the path as
the volume is used separately.
Parse and store the volume name separately for gluster storage volumes
and use the newly stored variable appropriately.
This partially reverts commits b279e52f7 and ea18f8b2.
It turns out our code base is full of:
if ((struct.member = virBlahFromString(str)) < 0)
goto error;
Meanwhile, the C standard says it is up to the compiler whether
an enum is signed or unsigned when all of its declared values
happen to be positive. In my testing (Fedora 20, gcc 4.8.2),
the compiler picked signed, and nothing changed. But others
testing with gcc 4.7 got compiler warnings, because it picked
the enum to be unsigned, but no unsigned value is less than 0.
Even worse:
if ((struct.member = virBlahFromString(str)) <= 0)
goto error;
is silently compiled without warning, but incorrectly treats -1
from a bad parse as a large positive number with no warning; and
without the compiler's help to find these instances, it is a
nightmare to maintain correctly. We could force signed enums
with a dummy negative declaration in each enum, or cast the
result of virBlahFromString back to int after assigning to an
enum value, or use a temporary int for collecting results from
virBlahFromString, but those actions are all uglier than what we
were trying to cure by directly using enum types for struct
values in the first place. It's better off to just live with int
members, and use 'switch ((virFoo) struct.member)' where we want
the compiler to help, than to track down all the conversions from
string to enum and ensure they don't suffer from type problems.
* src/util/virstorageencryption.h: Revert back to int declarations
with comment about enum usage.
* src/util/virstoragefile.h: Likewise.
* src/conf/domain_conf.c: Restore back to casts in switches.
* src/qemu/qemu_driver.c: Likewise.
* src/qemu/qemu_command.c: Add cast rather than revert.
Signed-off-by: Eric Blake <eblake@redhat.com>
Add VIR_STORAGE_FILE_PLOOP format. This format is used
to store disk images for virtual machines in PCS and containers
in PCS, OpenVZ and also in Parallels Desktop for Mac.
This format is described on OpenVZ site -
https://openvz.org/Ploop (together with ploop devices). It
consists of XML descriptor and one or more image files: base
image and deltas. Format of the image files described here:
https://openvz.org/Ploop/format.
This patch only adds VIR_STORAGE_FILE_PLOOP constant, consequent
patches will use it in parallels driver.
Signed-off-by: Dmitry Guryanov <dguryanov@parallels.com>
For internal structs, we might as well be type-safe and let the
compiler help us with less typing required on our part (getting
rid of casts is always nice). In trying to use enums directly,
I noticed two problems in virstoragefile.h that can't be fixed
without more invasive refactoring: virStorageSource.format is
used as more of a union of multiple enums in storage volume
code (so it has to remain an int), and virStorageSourcePoolDef
refers to pooltype whose enum is declared in src/conf, but where
src/util can't pull in headers from src/conf.
* src/util/virstoragefile.h (virStorageNetHostDef)
(virStorageSourcePoolDef, virStorageSource): Use enums instead of
int for fields of internal types.
* src/qemu/qemu_command.c (qemuParseCommandLine): Cover all values.
* src/conf/domain_conf.c (virDomainDiskSourceParse)
(virDomainDiskSourceFormat): Simplify clients.
* src/qemu/qemu_driver.c
(qemuDomainSnapshotCreateSingleDiskActive)
(qemuDomainSnapshotPrepareDiskExternalBackingInactive)
(qemuDomainSnapshotPrepareDiskExternalOverlayActive)
(qemuDomainSnapshotPrepareDiskInternal): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
In "src/conf/" there are many enumeration (enum) declarations.
Similar to the recent cleanup to "src/util" directory, it's
better to use a typedef for variable types, function types and
other usages. Other enumeration and folders will be changed to
typedef's in the future. Most of the files changed in this
commit are related to storage (storage_conf) enums.
Signed-off-by: Julio Faracco <jcfaracco@gmail.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
In "src/util/" there are many enumeration (enum) declarations.
Sometimes, it's better using a typedef for variable types,
function types and other usages. Other enumeration will be
changed to typedef's in the future.
Signed-off-by: Julio Faracco <jcfaracco@gmail.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
All callers of virStorageFileGetMetadataFromBuf were first calling
virStorageFileProbeFormatFromBuf, to learn what format to pass in.
But this function is already wired to do the exact same probe if
the incoming format is VIR_STORAGE_FILE_AUTO, so it's simpler to
just refactor the probing into the central function.
* src/util/virstoragefile.h (virStorageFileGetMetadataFromBuf):
Drop parameter.
(virStorageFileProbeFormatFromBuf): Drop declaration.
* src/util/virstoragefile.c (virStorageFileGetMetadataFromBuf):
Do probe here instead of in callers.
(virStorageFileProbeFormatFromBuf): Make static.
* src/libvirt_private.syms (virstoragefile.h): Drop function.
* src/storage/storage_backend_fs.c (virStorageBackendProbeTarget):
Update caller.
* src/storage/storage_backend_gluster.c
(virStorageBackendGlusterRefreshVol): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
To avoid memory leak of the "backingStoreRaw" field when reparsing
backing chains a new function is being introduced by this patch that
shall be used to clear backing store information.
The memory leak was introduced in commit 8823272d41.
Each backing store of a given disk is associated with a unique index
(which is also formatted in domain XML) for easier addressing of any
particular backing store. With this patch, any backing store can be
addressed by its disk target and the index. For example, "vdc[4]"
addresses the backing store with index equal to 4 of the disk identified
by "vdc" target. Such shorthand can be used in any API in place for a
backing file path:
virsh blockcommit domain vda --base vda[3] --top vda[2]
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
To avoid having the root of a backing chain present twice in the list we
need to invert the working of virStorageFileGetMetadataRecurse.
Until now the recursive worker created a new backing chain element from
the name and other information passed as arguments. This required us to
pass the data of the parent in a deconstructed way and the worker
created a new entry for the parent.
This patch converts this function so that it just fills in metadata
about the parent and creates a backing chain element from those. This
removes the duplication of the first element.
To avoid breaking the test suite, virstoragetest now calls a wrapper
that creates the parent structure explicitly and pre-fills it with the
test data with same function signature as previously used.
Add the required fields that are missing from the new structure that
will allow us to switch the storage file metadata code entirely to the
new structure.
Add "relPath" and "relDir" and the raw backing store name. Also allow
creating linked lists of virStorageSourcePtrs to express backing chains.
Remove the obsolete field replaced by data in "path".
The testsuite requires tweaking as the name of the backing file is now
stored one layer deeper in the backing chain linked list.
As for the previous patch, this change is needed to achieve
compatibility with all the existing code, where we expect a fully
qualified path of local files to be present.
To allow future change of virStorageFileMetadata to virStorageSource we
need to store a full path in the "path" variable as rest of the code
expects it to be a full path. Rename the "path" field to "relPath" to
keep tracking the info but allowing a real "path" field.
Domain snapshots should only permit an external snapshot into
a storage format that permits a backing chain, since the new
snapshot file necessarily must be backed by the existing file.
The C code for the qemu driver is a little bit stricter in
currently enforcing only qcow2 or qed, but at the XML parser
level, including virt-xml-validate, it is fairly easy to
enforce that a user can't request a 'raw' external snapshot.
* docs/schemas/storagecommon.rng (storageFormat): Split out...
(storageFormatBacking): ...new sublist.
* docs/schemas/domainsnapshot.rng (disksnapshotdriver): Use new
type.
* src/util/virstoragefile.h (virStorageFileFormat): Rearrange for
easier code management.
* src/util/virstoragefile.c (virStorageFileFormat, fileTypeInfo):
Likewise.
* src/conf/snapshot_conf.c (virDomainSnapshotDiskDefParseXML): Use
new marker to limit selection of formats.
Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
