If the storage device type is parsed as network our parser still allows
it to omit the <source> element. The empty drive check would not trigger
on such device as it expects that every network storage source is valid.
Use VIR_STORAGE_NET_PROTOCOL_NONE as a marker that the storage source is
empty.
The gluster volume name extraction code was copied from the XML parser
without changing the VIR_ERR_XML_ERROR error code. Use
VIR_ERR_CONFIG_UNSUPPORTED instead.
Similar to commit fdb80ed4f6 libvirtd
would crash if a gluster URI without path would be used in the backing
chain of a volume. The crash happens in the gluster specific part of the
parser that extracts the gluster volume name from the path.
Fix the crash by checking that the PATH is NULL.
This patch does not contain a test case as it's not possible to test it
with the current infrastructure as the test suite would attempt to
contact the gluster server in the URI. I'm working on the test suite
addition but that will be post-release material.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1196528
If a storage file would be backed with a NBD device without path
(nbd://localhost) libvirt would crash when parsing the backing path for
the disk as the URI structure's path element is NULL in such case but
the NBD parser would access it shamelessly.
Remove the resize flag and use the same code path for all callers.
This flag was added by commit 18f0316 to allow virStorageFileResize
use 'safezero' while preserving the behavior.
Explicitly return -2 when a fallback to a different method should
be done, to make the code path more obvious.
Fail immediately when ftruncate fails in the mmap method,
as we did before commit 18f0316.
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>
Currently virStorageFileResize() function uses build conditionals to
choose either the posix_fallocate() or syscall(SYS_fallocate) with no
fallback in order to preallocate the space in the newly resized file.
Since the safezero code has a similar set of conditionals modify the
resize and safezero code in order to allow the resize logic to make use
of safezero to unify the look/feel of the code paths.
Add a new boolean (resize) to safezero() to make the optional decision
whether to try syscall(SYS_fallocate) if the posix_fallocate fails because
HAVE_POSIX_FALLOCATE is not defined (eg, return -1 and errno == 0).
Create a local safezero_sys_fallocate in order to handle the resize
code paths that support that. If not present, the set errno = ENOSYS
in order to allow the caller to handle the failure scenarios.
Signed-off-by: John Ferlan <jferlan@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.
As we now have a common function to parse backing store string for RBD
backing store we can reuse it in the backing store walker so that we
don't fail on files backed by RBD storage.
This patch also adds a few tests to verify that the parsing works as
expected.
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.
If there are no hosts for a storage source virStorageSourceCopy and
virStorageSourceNewFromBackingRelative would try to copy them anyways.
As the success of virStorageNetHostDefCopy is determined by returning
a pointer and malloc of 0 elements might return NULL according to the
implementation, the result of the copy function may vary.
Fix this by copying the hosts array only if there are hosts defined.
When creating a disk image snapshot the libvirt code would blindly copy
the parents label to the newly created image. This runs into problems
when you start a VM from an image hosted on NFS (or other storage system
that doesn't support selinux labels) and the snapshot destination is on
a storage system that does support selinux labels. Libvirt's code in
that case generates a different security label for the image hosted on
NFS. This label is valid only for NFS images and doesn't allow access in
case of a locally stored image.
To fix this issue libvirt needs to refrain from copying security
information in cases where the default domain seclabel is a better
choice.
This patch repurposes the now unused @force argument of
virStorageSourceInitChainElement to denote whether a copy of the
security labelling stuff should be attempted or not. This allows to
fine-control the copy operation for cases where we need to keep the
label of the old disk vs. the cases where we need to keep the label
unset to use the default domain imagelabel.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1151718
The code that parses the schema from the URI touches the "hosts[0]"
member of the storage file source structure in case the URI contains a
schema. The hosts array was not yet allocated at the point in the code
where the transport protocol was parsed and set. This lead to a crash of
libvirtd.
Fix the code by allocating the "hosts" array upfront and add a test case
to verify this scenario. (Unfortunately this requires shuffling the test
case numbers too).
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1156288
virStorageSourceInitChainElement initializes a new storage chain element
for use as a new disk source. If the new element doesn't contain the
driver name, copy it from the old source.
This fixes issue where a disk would forget the driver after a snapshot.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1140984
The backing store string location offset 0 determines that the file
isn't present. The string size shouldn't be then checked:
from qemu.git/docs/specs/qcow2.txt
== Header ==
The first cluster of a qcow2 image contains the file header:
Byte 0 - 3: magic
QCOW magic string ("QFI\xfb")
4 - 7: version
Version number (valid values are 2 and 3)
8 - 15: backing_file_offset
Offset into the image file at which the backing file name
is stored (NB: The string is not null terminated). 0 if the
image doesn't have a backing file.
16 - 19: backing_file_size
Length of the backing file name in bytes. Must not be
longer than 1023 bytes. Undefined if the image doesn't have
a backing file. ^^^^^^^^^
This patch intentionally leaves the backing file string size check in
place in case a malformatted file would be presented to libvirt. Also
according to the docs the string size is maximum 1023 bytes, thus this
patch adds a check to verify that.
I was also able to verify that the check was done the same way in the
legacy qcow fromat (in qemu's code).
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.
Valgrind caught a memory leak:
==2018== 9 bytes in 1 blocks are definitely lost in loss record 143 of 927
==2018== at 0x4A0645D: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==2018== by 0x8C42369: strdup (strdup.c:42)
==2018== by 0x50EACC9: virStrdup (virstring.c:676)
==2018== by 0x50E79E5: virStorageSourceCopy (virstoragefile.c:1845)
==2018== by 0x20A3FAA7: qemuDomainBlockCommit (qemu_driver.c:15620)
==2018== by 0x51DC6B2: virDomainBlockCommit (libvirt.c:20092)
I traced it to the fact that blockcopy and blockcommit end up
reparsing a backing chain on pivot, but the chain parsing code
doesn't gracefully handle the case where the backing file is
already known.
I'm not exactly sure when this was introduced, but suspect that the
refactoring in commit 9944b71 and friends that moved towards probing
in-place rather than into a temporary structure are part of the cause.
* src/util/virstoragefile.c (virStorageFileGetMetadataInternal):
Don't leak any prior value.
Signed-off-by: Eric Blake <eblake@redhat.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.
When discovering a disk backing chain the parent disk's metadata need to
be populated into the guest images so that each piece of the backing
chain contains a copy of those. This will allow us to refactor the
security driver so that it will not need to carry around the original
disk definition.
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.
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.
Replace:
if (virBufferError(&buf)) {
virBufferFreeAndReset(&buf);
virReportOOMError();
...
}
with:
if (virBufferCheckError(&buf) < 0)
...
This should not be a functional change (unless some callers
misused the virBuffer APIs - a different error would be reported
then)
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.
Store backing chain paths as non-canonical. The canonicalization step
will be already taken. This will allow to avoid storing unnecessary
amounts of data.
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.
The block commit code looks for an explicit base file relative
to the discovered top file; so for a chain of:
base <- snap1 <- snap2 <- snap3
and a command of:
virsh blockcommit $dom vda --base snap2 --top snap1
we got a sane message (here from libvirt 1.0.5):
error: invalid argument: could not find base 'snap2' below 'snap1' in chain for 'vda'
Meanwhile, recent refactoring has slightly reduced the quality of the
libvirt error messages, by losing the phrase 'below xyz':
error: invalid argument: could not find image 'snap2' in chain for 'snap3'
But we had a one-off, where we were not excluding the top file
itself in searching for the base; thankfully qemu still reports
the error, but the quality is worse:
virsh blockcommit $dom vda --base snap2 --top snap2
error: internal error unable to execute QEMU command 'block-commit': Base '/snap2' not found
Fix the one-off in blockcommit by changing the semantics of name
lookup - if a starting point is specified, then the result must
be below that point, rather than including that point. The only
other call to chain lookup was blockpull code, which was already
forcing the lookup to omit the active layer and only needs a
tweak to use the new semantics.
This also fixes the bug exposed in the testsuite, where when doing
a lookup pinned to an intermediate point in the chain, we were
unable to return the name of the parent also in the chain.
* src/util/virstoragefile.c (virStorageFileChainLookup): Change
semantics for non-NULL startFrom.
* src/qemu/qemu_driver.c (qemuDomainBlockJobImpl): Adjust caller,
to keep existing semantics.
* tests/virstoragetest.c (mymain): Adjust to expose new semantics.
Signed-off-by: Eric Blake <eblake@redhat.com>
Jim Fehlig reported a regression found by libvirt-TCK tests:
> ~ # perl /usr/share/libvirt-tck/tests/qemu/100-disk-encryption.t
...
> ok 4 - defined persistent domain config
> # Starting inactive domain config
> libvirt error code: 1, message: internal error: unable to execute QEMU command
> 'cont': 'drive-ide0-0-1'
> (/var/cache/libvirt-tck/300-disk-encryption/demo.qcow2) is encrypted
Commit 2279d560 converted a boolean into a pointer with the intent of
transferring that pointer out of a temporary object into the caller's
data structure. The temporary structure meant that meta->encryption
was always NULL on entry, so we could get away with blindly allocating
the pointer when the header said so. But later, commit 8823272d
tweaked things to do backing chain detection in-place, rather than via
a temporary object; this has the net result that meta->encryption can
be non-NULL on entry. Not only did this turn the latent behavior into
a memory leak, it is also a behavior regression: blindly allocating a
new pointer wipes out what secrets we already knew about the chain,
making it impossible to restart the domain.
Of course, no one in their right mind should be relying on qcow2
encryption - it is fundamentally flawed. And sadly, the TCK tests
don't get run often enough, and this shows that our virstoragetest
does not exercise encrypted images at all. Otherwise, we could
have avoided a release containing this regression.
* src/util/virstoragefile.c (virStorageFileGetMetadataInternal):
Don't nuke an already-existing encryption.
Signed-off-by: Eric Blake <eblake@redhat.com>
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.
For guests backed by gluster volumes (or other network storage) we don't
fill the backing chain (see qemuDomainDetermineDiskChain). This leaves
the "relPath" field of the top image NULL. This causes a crash in
virStorageFileChainLookup() when looking up a backing element for such a
disk.
Since I'm working on adding support for network storage and one of the
steps will make the "relPath" field optional let's use STREQ_NULLABLE
instead of STREQ in virStorageFileChainLookup() to avoid the problem.
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.
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>
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>
Commit f22b7899 stumbled across a difference between 32-bit and
64-bit platforms when parsing "-1" as an int. Now that we've
fixed that difference, it's time to fix the testsuite.
* src/util/virstoragefile.c (virStorageFileParseChainIndex):
Require a positive index.
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.
Commit 5c43e2e introduced a NULL deref if there is a failure
in virStorageFileGetMetadataInternal.
* src/util/virstoragefile.c (virStorageFileGetMetadataFromBuf):
Fix error handling.
Signed-off-by: Eric Blake <eblake@redhat.com>
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 a temporary step to allow killing of the "backingStore" field of
struct virStorageFileMetadata the recursive metadata retrieval function
will be converted not to use the field in the lookup process.
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.
Avoid passing lot of arguments into guts of metadata retrieval to fill
the actual structure. Temporarily fill the structure before passing it
down to the actual metadata extractor.
This will later help the inversion of the steps taken to extract the
metadata so that this function can be fully converted to
virStorageSource as the data struct.
This patch also fixes regression when starting a gluster storage pool
where the volumes don't have local representation so that the
canonicalization of the volume's file name failed. Broken by commit
79f11b35
Move the code checking the presence of the backing file to the recursive
worker function instead of the metadata parser. The recursive worker
will later be changed to parse more than just local files and this
change will help the separation.
As we already pass the whole structure down the call path there's no
need to return some stuff in a separate argument. Remove the argument
and tweak callers to avoid breaking semantics.
virStorageFileGetMetadataFromBuf will be refactored later along with the
storage driver.
Don't use the backingStoreRaw as a indication of broken chains. Fill it
always and tweak the broken image chain detector to avoid changing the
semantics.
The new semantics to detect a broken chain is the presence of string in
backingStoreRaw but the lack of the backing chain metadata structure in
the chain.
Now that the raw backing store name is always filled there's no need to
pass the raw name variable separately to fill in case the backing is not
a file. Tweak the function so that it can handle a NULL in that case.
While running virstoragetest, valgrind pointed out the following
memory leak:
==8142== 2 bytes in 1 blocks are definitely lost in loss record 1 of 92
==8142== at 0x4A069EE: malloc (vg_replace_malloc.c:270)
==8142== by 0x4E7B53E: mdir_name (dirname-lgpl.c:78)
==8142== by 0x4CBE2B0: virStorageFileGetMetadataInternal (virstoragefile.c:595)
==8142== by 0x4CBE651: virStorageFileGetMetadataFromFDInternal (virstoragefile.c:1086)
==8142== by 0x4CBEEB4: virStorageFileGetMetadataRecurse (virstoragefile.c:1175)
==8142== by 0x4CBF1DE: virStorageFileGetMetadata (virstoragefile.c:1270)
==8142== by 0x4028AD: testStorageChain (virstoragetest.c:275)
==8142== by 0x407B91: virtTestRun (testutils.c:201)
==8142== by 0x4039D7: mymain (virstoragetest.c:534)
==8142== by 0x40830D: virtTestMain (testutils.c:789)
==8142== by 0x3E6CE1ED1C: (below main) (libc-start.c:226)
...62 times
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>
Another field no longer needed, getting us one step closer to
merging virStorageFileMetadata and virStorageSource.
* src/util/virstoragefile.h (_virStorageFileMetadata): Drop
field.
* src/util/virstoragefile.c (virStorageFileGetMetadataInternal)
(virStorageFileGetMetadataFromFDInternal): Alter signature.
(virStorageFileFreeMetadata, virStorageFileGetMetadataFromBuf)
(virStorageFileGetMetadataFromFD): Adjust clients.
* tests/virstoragetest.c (_testFileData, testStorageChain)
(mymain): Simplify test.
Signed-off-by: Eric Blake <eblake@redhat.com>
Thanks to the testsuite, I feel quite confident that this rewrite
is correct; it gives the same results for all cases except for one.
I can make the argument that _that_ case was a pre-existing bug:
when looking up relative names, the lookup is supposed to be
pegged to the directory that contains the parent qcow2 file. Thus,
this resolves the fixme first mentioned in commit 367cd69 (even
though I accidentally removed the fixme comment early in 74430fe).
* src/util/virstoragefile.c (virStorageFileChainLookup): Depend on
new rather than old fields.
* tests/virstoragetest.c (mymain): Adjust test to match fix.
Signed-off-by: Eric Blake <eblake@redhat.com>
The original chain lookup code had to pass in the starting name,
because it was not available in the chain. But now that we have
added fields to the struct, this parameter is redundant.
* src/util/virstoragefile.h (virStorageFileChainLookup): Alter
signature.
* src/util/virstoragefile.c (virStorageFileChainLookup): Adjust
handling of top of chain.
* src/qemu/qemu_driver.c (qemuDomainBlockCommit): Adjust caller.
* tests/virstoragetest.c (testStorageLookup, mymain): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
The chain lookup function was inconsistent on whether it left
a message in the log when looking up a name that is not found
on the chain (leaving a message for OOM or if name was
relative but not part of the chain), and could litter the log
even when successful (when name was relative but deep in the
chain, use of virFindBackingFile early in the chain would complain
about a file not found). It's easier to make the function
consistently emit a message exactly once on failure, and to let
all callers rely on the clean semantics.
* src/util/virstoragefile.c (virStorageFileChainLookup): Always
report error on failure. Simplify relative lookups.
* src/qemu/qemu_driver.c (qemuDomainBlockCommit): Avoid
overwriting error.
Signed-off-by: Eric Blake <eblake@redhat.com>
Drop another redundant field from virStorageFileMetadata.
* src/util/virstoragefile.h (_virStorageFileMetadata): Drop
field.
* src/util/virstoragefile.c
(virStorageFileGetMetadataFromFDInternal)
(virStorageFileGetMetadataFromFD)
(virStorageFileGetMetadataRecurse): Adjust callers.
* tests/virstoragetest.c (_testFileData, testStorageChain)
(mymain): Simplify test.
Signed-off-by: Eric Blake <eblake@redhat.com>
A couple pieces of virStorageFileMetadata are used only while
collecting information about the chain, and don't need to
live permanently in the struct. This patch refactors external
callers to collect the information separately, so that the
next patch can remove the fields.
* src/util/virstoragefile.h (virStorageFileGetMetadataFromBuf):
Alter signature.
* src/util/virstoragefile.c (virStorageFileGetMetadataInternal):
Likewise.
(virStorageFileGetMetadataFromFDInternal): Adjust callers.
* src/storage/storage_backend_fs.c (virStorageBackendProbeTarget):
Likewise.
* src/storage/storage_backend_gluster.c
(virStorageBackendGlusterRefreshVol): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
Finally starting to prune away some of the old fields that have
been made redundant by the new fields, on my way towards directly
reusing virStorageSource.
* src/util/virstoragefile.h (_virStorageFileMetadata): Drop
field.
* src/util/virstoragefile.c (virStorageFileGetMetadataInternal)
(virStorageFileChainLookup): Adjust callers.
* tests/virstoragetest.c (_testFileData, testStorageChain)
(mymain): Simplify test.
Signed-off-by: Eric Blake <eblake@redhat.com>
Deciding if a user string represents a local file instead of a
network path is an operation worth exposing directly, particularly
since the next patch will be removing a redundant variable that
was caching the information.
* src/util/virstoragefile.h (virStorageIsFile): New declaration.
* src/util/virstoragefile.c (virBackingStoreIsFile): Rename...
(virStorageIsFile): ...export, and allow NULL input.
(virStorageFileGetMetadataInternal)
(virStorageFileGetMetadataRecurse, virStorageFileGetMetadata):
Update callers.
* src/conf/domain_conf.c (virDomainDiskDefForeachPath): Use it.
* src/storage/storage_backend_fs.c (virStorageBackendProbeTarget):
Likewise.
* src/libvirt_private.syms (virstoragefile.h): Export function.
Signed-off-by: Eric Blake <eblake@redhat.com>
So far, my work has been merely preserving the status quo of
backing file analysis. But this patch starts to tread in the
territory of making the backing chain code more powerful - we
will eventually support network storage containing non-raw
formats. Here, we expose metadata information about a network
backing store, even if that information is still hardcoded to
a raw format for now.
* src/util/virstoragefile.c (virStorageFileGetMetadataRecurse):
Also populate struct for non-file backing.
(virStorageFileGetMetadata, virStorageFileGetMetadatainternal):
Recognize non-file top image.
(virFindBackingFile): Add comment.
(virStorageFileChainGetBroken): Adjust comment, ensure output
is set.
* tests/virstoragetest.c (mymain): Update test to reflect it.
Signed-off-by: Eric Blake <eblake@redhat.com>
The current use of virStorageFileMetadata is awkward; to learn
some of the information about a child node, you have to read
fields in the parent node. This does not lend itself well to
modifying backing chains (whether inserting a new node in the
chain, or consolidating existing nodes); better would be to
learn about a child node directly in that node. This patch
sets up some new fields which contain redundant information,
although not necessarily in the final desired state for the
new fields (see the next patch for actual tests of what is there
now). Then later patches will do any refactoring necessary to
get the fields to their desired states, and update clients to
get the information from the new fields, so we can finally
delete the fields that are tracking information about the wrong
node.
More concretely, compare these three example backing chains:
good <- one
missing <- two
gluster://server/vol/img <- three
Pre-patch, querying the chains gives:
{ .backingStore = "/path/to/good",
.backingStoreRaw = "good",
.backingStoreIsFile = true,
.backingStoreFormat = VIR_STORAGE_FILE_RAW,
.backingMeta = {
.backingStore = NULL,
.backingStoreRaw = NULL,
.backingStoreIsFile = false,
.backingMeta = NULL,
}
}
{ .backingStore = NULL,
.backingStoreRaw = "missing",
.backingStoreIsFile = false,
.backingStoreFormat = VIR_STORAGE_FILE_NONE,
.backingMeta = NULL,
}
{ .backingStore = "gluster://server/vol/img",
.backingStoreRaw = NULL,
.backingStoreIsFile = false,
.backingStoreFormat = VIR_STORAGE_FILE_RAW,
.backingMeta = NULL,
}
Deciding whether to ignore a missing backing file (as in virsh
vol-dumpxml) or report an error (as in security manager sVirt
labeling) requires reading multiple fields. Plus, the format
is hard-coded to treat all network protocols as end-of-the-chain,
as if they were raw. By the end of this patch series, the goal
is to instead represent these three situations as:
{ .path = "one",
.canonPath = "/path/to/one",
.type = VIR_STORAGE_TYPE_FILE,
.format = VIR_STORAGE_FILE_QCOW2,
.backingStoreRaw = "good",
.backingMeta = {
.path = "good",
.canonPath = "/path/to/good",
.type = VIR_STORAGE_TYPE_FILE,
.format = VIR_STORAGE_FILE_RAW,
.backingStoreRaw = NULL,
.backingMeta = NULL,
}
}
{ .path = "two",
.canonPath = "/path/to/two",
.type = VIR_STORAGE_TYPE_FILE,
.format = VIR_STORAGE_FILE_QCOW2,
.backingStoreRaw = "missing",
.backingMeta = NULL,
}
{ .path = "three",
.canonPath = "/path/to/three",
.type = VIR_STORAGE_TYPE_FILE,
.format = VIR_STORAGE_FILE_QCOW2,
.backingStoreRaw = "gluster://server/vol/img",
.backingMeta = {
.path = "gluster://server/vol/img",
.canonPath = "gluster://server/vol/img",
.type = VIR_STORAGE_TYPE_NETWORK,
.format = VIR_STORAGE_FILE_RAW,
.backingStoreRaw = NULL,
.backingMeta = NULL,
}
}
or, for the second file, maybe also allowing:
{ .path = "two",
.canonPath = "/path/to/two",
.type = VIR_STORAGE_TYPE_FILE,
.format = VIR_STORAGE_FILE_QCOW2,
.backingStoreRaw = "missing",
.backingMeta = {
.path = "missing",
.canonPath = NULL,
.type = VIR_STORAGE_TYPE_NONE,
.format = VIR_STORAGE_FILE_NONE,
.backingStoreRaw = NULL,
.backingMeta = NULL,
}
}
* src/util/virstoragefile.h (_virStorageFileMetadata): Add
path, canonPath, relDir, type, and format fields. Reorder
existing fields, and add lots of comments.
* src/util/virstoragefile.c (virStorageFileFreeMetadata): Clean
new fields.
(virStorageFileGetMetadataInternal)
(virStorageFileGetMetadataFromFDInternal): Start populating new
fields.
Signed-off-by: Eric Blake <eblake@redhat.com>
Right now, we are allocating virStorageFileMetadata near the bottom
of the callchain, only after we have identified that we are visiting
a file (and not a network resource). I'm hoping to eventually
support parsing the backing chain from XML, where the backing chain
crawl then validates what was parsed rather than allocating a fresh
structure. Likewise, I'm working towards a setup where we have a
backing element even for networks. Both of these use cases are
easier to code if the allocation is hoisted earlier.
* src/util/virstoragefile.c (virStorageFileGetMetadataInternal)
(virStorageFileGetMetadataFromFDInternal): Change signature.
(virStorageFileGetMetadataFromBuf)
(virStorageFileGetMetadataRecurse, virStorageFileGetMetadata):
Update callers.
Signed-off-by: Eric Blake <eblake@redhat.com>
The previous patch started a separation of error messages
reported against the user-specified name, vs. tracking the
canonical path that was actually opened. This patch extends
that notion, by hoisting directory detection up front, passing
the canonical path through the entire call chain, and
simplifying lower-level functions that can now assume that
a canonical path and directory have been supplied.
* src/util/virstoragefile.c
(virStorageFileGetMetadataFromFDInternal)
(virStorageFileGetMetadataInternal): Add parameter, require
directory.
(virFindBackingFile): Require directory.
(virStorageFileGetMetadataFromFD): Pass canonical path.
(virStorageFileGetMetadataFromBuf): Likewise.
(virStorageFileGetMetadata): Determine initial directory.
Signed-off-by: Eric Blake <eblake@redhat.com>
While trying to refactor the backing file chain, I noticed that
if you have a self-referential qcow2 file via a relative name:
qemu-img create -f qcow2 loop 10M
qemu-img rebase -u -f qcow2 -F qcow2 -b loop loop
then libvirt was creating a chain 2 deep before realizing it
had hit a loop; furthermore, virStorageFileChainCheckBroken
was not identifying the chain as broken. With this patch,
the loop is detected when the chain is only 1 deep; still
enough for storage volume XML to display the file, but now
with a proper error report about where the loop was found.
This patch adds a parameter to virStorageFileGetMetadataRecurse,
so that errors at the top of the chain remain unchanged; messages
issued for backing files now use the name provided by the user
instead of the canonical name (for VDSM, which uses relative
symlinks to device mapper block devices, this is actually more
useful).
* src/util/virstoragefile.c (virStorageFileGetMetadataRecurse):
Add parameter, require canonical path up front. Mark chain
broken on OOM or loop detection.
(virStorageFileGetMetadata): Pass in canonical name.
Signed-off-by: Eric Blake <eblake@redhat.com>
I noticed that the apparmor code could request metadata even
for a cdrom with no media, which would cause a memory leak of
the hash table used to look for loops in the backing chain.
But even before that, we blindly dereferenced the path for
printing a debug statement, so it is just better to enforce
that this is only used on non-NULL names.
* src/util/virstoragefile.c (virStorageFileGetMetadata): Assume
non-NULL path.
* src/util/virstoragefile.h: Annotate this.
* src/security/virt-aa-helper.c (get_files): Fix caller.
Signed-off-by: Eric Blake <eblake@redhat.com>
Right now, virStorageFileMetadata tracks bool backingStoreIsFile
for whether the backing string specified in metadata can be
resolved as a file (covering both block and regular file
resources) or is treated as a network protocol. But when
merging this struct with virStorageSource, it will be easier
to just actually track which type of resource it is, as well
as have a reserved value for the case where the resource type
is unknown (or had an error during probing).
* src/util/virstoragefile.h (virStorageType): Add a placeholder
value, swap order to match similar public enum.
* src/util/virstoragefile.c (virStorage): Update string mapping.
* src/conf/domain_conf.c (virDomainDiskSourceParse)
(virDomainDiskDefParseXML, virDomainDiskDefFormat)
(virDomainDiskSourceFormat): Adjust clients.
* src/conf/snapshot_conf.c (virDomainSnapshotDiskDefParseXML):
Likewise.
* src/qemu/qemu_driver.c
(qemuDomainSnapshotPrepareDiskExternalBackingInactive)
(qemuDomainSnapshotPrepareDiskExternalOverlayActive)
(qemuDomainSnapshotPrepareDiskExternalOverlayInactive)
(qemuDomainSnapshotPrepareDiskInternal)
(qemuDomainSnapshotCreateSingleDiskActive): Likewise.
* src/qemu/qemu_command.c (qemuGetDriveSourceString): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
A future patch will merge virStorageFileMetadata and virStorageSource,
but I found it easier to do if both structs use the same information
for tracking whether a source file needs encryption keys.
* src/util/virstoragefile.h (_virStorageFileMetadata): Prepare
full encryption struct instead of just a bool.
* src/storage/storage_backend_fs.c (virStorageBackendProbeTarget):
Use transfer semantics.
* src/storage/storage_backend_gluster.c
(virStorageBackendGlusterRefreshVol): Likewise.
* src/util/virstoragefile.c (virStorageFileGetMetadataInternal):
Populate struct.
(virStorageFileFreeMetadata): Adjust clients.
* tests/virstoragetest.c (testStorageChain): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
Another step towards unification of structures. While we might
not expose everything in XML via domain disk as we do for
storage volume pointer, both places want to deal with (at least
part of) the backing chain; therefore, moving towards a single
struct usable from both contexts will make the backing chain
code more reusable.
* src/conf/storage_conf.h (_virStoragePerms)
(virStorageTimestamps): Move...
* src/util/virstoragefile.h: ...here.
(_virStorageSource): Add more fields.
* src/util/virstoragefile.c (virStorageSourceClear): Clean
additional fields.
Signed-off-by: Eric Blake <eblake@redhat.com>
Move some functions out of domain_conf for use in the next
patch where snapshot starts to directly use structs in
virstoragefile.
* src/conf/domain_conf.c (virDomainDiskDefFree)
(virDomainDiskSourcePoolDefParse): Adjust callers.
(virDomainDiskSourceDefClear, virDomainDiskSourcePoolDefFree)
(virDomainDiskAuthClear): Move...
* src/util/virstoragefile.c (virStorageSourceClear)
(virStorageSourcePoolDefFree, virStorageSourceAuthClear): ...and
rename.
* src/conf/domain_conf.h (virDomainDiskAuthClear): Drop
declaration.
* src/qemu/qemu_conf.c (qemuTranslateDiskSourcePool): Adjust
caller.
* src/util/virstoragefile.h: Declare them.
* src/libvirt_private.syms (virstoragefile.h): Export them.
Signed-off-by: Eric Blake <eblake@redhat.com>
The code in virstoragefile.c is getting more complex as I
consolidate backing chain handling code. But for the setuid
virt-login-shell, we don't need to crawl backing chains. It's
easier to audit things for setuid security if there are fewer
files involved, so this patch moves the one function that
virFileOpen() was actually relying on to also live in virfile.c.
* src/util/virstoragefile.c (virStorageFileIsSharedFS)
(virStorageFileIsSharedFSType): Move...
* src/util/virfile.c (virFileIsSharedFS, virFileIsSharedFSType):
...to here, and rename.
(virFileOpenAs): Update caller.
* src/security/security_selinux.c
(virSecuritySELinuxSetFileconHelper)
(virSecuritySELinuxSetSecurityAllLabel)
(virSecuritySELinuxRestoreSecurityImageLabelInt): Likewise.
* src/security/security_dac.c
(virSecurityDACRestoreSecurityImageLabelInt): Likewise.
* src/qemu/qemu_driver.c (qemuOpenFileAs): Likewise.
* src/qemu/qemu_migration.c (qemuMigrationIsSafe): Likewise.
* src/util/virstoragefile.h: Adjust declarations.
* src/util/virfile.h: Likewise.
* src/libvirt_private.syms (virfile.h, virstoragefile.h): Move
symbols as appropriate.
Signed-off-by: Eric Blake <eblake@redhat.com>
Another struct being moved to util. This one doesn't have as
much use yet, thankfully.
* src/conf/domain_conf.h (virDomainDiskSourcePoolMode)
(virDomainDiskSourcePoolDef): Move...
* src/util/virstoragefile.h (virStorageSourcePoolMode)
(virStorageSourcePoolDef): ...and rename.
* src/conf/domain_conf.c (virDomainDiskSourcePoolDefFree)
(virDomainDiskSourceDefClear, virDomainDiskSourcePoolDefParse)
(virDomainDiskDefParseXML, virDomainDiskSourceDefParse)
(virDomainDiskSourceDefFormatInternal)
(virDomainDiskDefForeachPath, virDomainDiskSourceIsBlockType):
Adjust clients.
* src/qemu/qemu_conf.c (qemuTranslateDiskSourcePool): Likewise.
* src/libvirt_private.syms (domain_conf.h): Move symbols...
(virstoragefile.h): ...as appropriate.
Signed-off-by: Eric Blake <eblake@redhat.com>
When virStorageFileGetMetadata is called with NULL path argument, the
invalid pointer boils down through the recursive worker and is caught by
virHashAddEntry which is thankfully resistant to NULL arguments. As it
doesn't make sense to pursue backing chains of NULL volumes, exit
earlier.
This was noticed in the virt-aahelper-test with a slightly modified
codebase.
Any source file which calls the logging APIs now needs
to have a VIR_LOG_INIT("source.name") declaration at
the start of the file. This provides a static variable
of the virLogSource type.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
This gets rid of another stat() per volume, as well as cutting
bytes read in half, when populating the volumes of a directory
pool during a pool refresh. Not to mention that it provides an
interface that can let gluster pools also probe file types.
* src/util/virstoragefile.h (virStorageFileProbeFormatFromFD):
Delete.
(virStorageFileProbeFormatFromBuf): New prototype.
(VIR_STORAGE_MAX_HEADER): New constant, based on...
* src/util/virstoragefile.c (STORAGE_MAX_HEAD): ...old name.
(vmdk4GetBackingStore, virStorageFileGetMetadataInternal)
(virStorageFileProbeFormat): Adjust clients.
(virStorageFileProbeFormatFromFD): Delete.
(virStorageFileProbeFormatFromBuf): Export.
* src/storage/storage_backend_fs.c (virStorageBackendProbeTarget):
Adjust client.
* src/libvirt_private.syms (virstoragefile.h): Adjust exports.
Signed-off-by: Eric Blake <eblake@redhat.com>
Future patches will want to learn metadata about a file using
a buffer that was already parsed in order to probe the file's
format. Rather than reopening and re-reading the file, it makes
sense to separate getting file contents from actually parsing
those contents.
* src/util/virstoragefile.c (virStorageFileGetMetadataFromBuf)
(virStorageFileGetMetadataFromFDInternal): New functions.
(virStorageFileGetMetadataInternal): Hoist fstat() and read() into
callers.
(virStorageFileGetMetadataFromFD)
(virStorageFileGetMetadataRecurse): Rework clients.
* src/util/virstoragefile.h (virStorageFileGetMetadataFromBuf):
New prototype.
* src/libvirt_private.syms (virstoragefile.h): Export it.
Signed-off-by: Eric Blake <eblake@redhat.com>
Our backing file chain code was not very robust to an ill-timed
EINTR, which could lead to a short read causing us to randomly
treat metadata differently than usual. But the existing
virFileReadLimFD forces an error if we don't read the entire
file, even though we only care about the header of the file.
So add a new virFile function that does what we want.
* src/util/virfile.h (virFileReadHeaderFD): New prototype.
* src/util/virfile.c (virFileReadHeaderFD): New function.
* src/libvirt_private.syms (virfile.h): Export it.
* src/util/virstoragefile.c (virStorageFileGetMetadataInternal)
(virStorageFileProbeFormatFromFD): Use it.
Signed-off-by: Eric Blake <eblake@redhat.com>
'unsigned char *' makes sense if you are doing math on bytes and
don't want to worry about wraparound from a signed 'char'; but
since all we are doing is memcmp() or virReadBufInt*[LB]E(), which
are both safe on either type of char, and since read() prefers to
operate on 'char *', it's simpler to avoid casts by just typing
things as 'char *' from the get-go. [Technically, read can
operate on an 'unsigned char *' thanks to the C rule that any
pointer can be implicitly converted to 'char *' for legacy K&R
compatibility; but where this patch saves us is if we try to use
virfile.h functions that take 'char **' in order to allocate the
buffer, where the compiler would barf on type mismatch.]
* src/util/virstoragefile.c (FileTypeInfo): Avoid unsigned char.
(cowGetBackingStore, qcow2GetBackingStoreFormat)
(qcowXGetBackingStore, qcow1GetBackingStore)
(qcow2GetBackingStore, vmdk4GetBackingStore, qedGetBackingStore)
(virStorageFileMatchesMagic, virStorageFileMatchesVersion)
(virStorageFileProbeFormatFromBuf, qcow2GetFeatures)
(virStorageFileGetMetadataInternal)
(virStorageFileProbeFormatFromFD): Simplify clients.
Signed-off-by: Eric Blake <eblake@redhat.com>
A qcow2 file with a backing file of 'gluster://host/vol/file' should
not try to look for a directory named './gluster:/' in the file system.
* src/util/virstoragefile.c (virBackingStoreIsFile): Broaden check
to include all protocols.
Signed-off-by: Eric Blake <eblake@redhat.com>
Most of the usage of getuid()/getgid() is in cases where we are
considering what privileges we have. As such the code should be
using the effective IDs, not real IDs.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
This should resolve:
https://bugzilla.redhat.com/show_bug.cgi?id=1012085
libvirt previously recognized NFS, GFS2, OCFS2, and AFS filesystems as
"shared", and thus eligible for exceptions to certain rules/actions
about chowning image files before handing them off to a guest. This
patch widens the definition of "shared filesystem" to include SMB and
CIFS filesystems (aka "Windows file sharing"); both of these use the
same protocol, but different drivers so there are different magic
numbers for each.
*src/util/virstoragefile.c: Add a helper function to get
the first name of missing backing files, if the name is NULL,
it means the diskchain is not broken.
*src/qemu/qemu_domain.c: qemuDiskChainCheckBroken(disk) to
check if its chain is broken
Convert the type of loop iterators named 'i', 'j', k',
'ii', 'jj', 'kk', to be 'size_t' instead of 'int' or
'unsigned int', also santizing 'ii', 'jj', 'kk' to use
the normal 'i', 'j', 'k' naming
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Detect qcow2 images with version 3 in the image header as
VIR_STORAGE_FILE_QCOW2.
These images have a feature bitfield, with just one feature supported
so far: lazy_refcounts.
The header length changed too, moving the location of the backing
format name.
Such as on FreeBSD. Broken in commit aa2a4cff7.
* src/util/virstoragefile.c (virStorageFileResize): Add missing ';',
mark conditionally unused variables.
Signed-off-by: Eric Blake <eblake@redhat.com>
The document for "vol-resize" says the new capacity will be sparse
unless "--allocate" is specified, however, the "--allocate" flag
is never implemented. This implements the "--allocate" flag for
fs backend's raw type volume, based on posix_fallocate and the
syscall SYS_fallocate.
This resolves:
https://bugzilla.redhat.com/show_bug.cgi?id=851411https://bugzilla.redhat.com/show_bug.cgi?id=955500
The first problem was that virFileOpenAs was returning fd (-1) in one
of the error cases rather than ret (-errno), so the caller thought
that the error was EPERM rather than ENOENT.
The second problem was that some log messages in the general purpose
qemuOpenFile() function would always say "Failed to create" even if
the caller hadn't included O_CREAT (i.e. they were trying to open an
existing file).
This fixes virFileOpenAs to jump down to the error return (which
returns ret instead of fd) in the previously mentioned incorrect
failure case of virFileOpenAs(), removes all error logging from
virFileOpenAs() (since the callers report it), and modifies
qemuOpenFile to appropriately use "open" or "create" in its log
messages.
NB: I seriously considered removing logging from all callers of
virFileOpenAs(), but there is at least one case where the caller
doesn't want virFileOpenAs() to log any errors, because it's just
going to try again (qemuOpenFile()). We can't simply make a silent
variation of virFileOpenAs() though, because qemuOpenFile() can't make
the decision about whether or not it wants to retry until after
virFileOpenAs() has already returned an error code.
Likewise, I also considered changing virFileOpenAs() to return -1 with
errno set on return, and may still do that, but only as a separate
patch, as it obscures the intent of this patch too much.
The source code base needs to be adapted as well. Some files
include virutil.h just for the string related functions (here,
the include is substituted to match the new file), some include
virutil.h without any need (here, the include is removed), and
some require both.
If you have a qcow2 file /path1/to/file pointed to by symlink
/path2/symlink, and pass qemu /path2/symlink, then qemu treats
a relative backing file in the qcow2 metadata as being relative
to /path2, not /path1/to. Yes, this means that it is possible
to create a qcow2 file where the choice of WHICH directory and
symlink you access its contents from will then determine WHICH
backing file (if any) you actually find; the results can be
rather screwy, but we have to match what qemu does.
Libvirt and qemu default to creating absolute backing file
names, so most users don't hit this. But at least VDSM uses
symlinks and relative backing names alongside the
--reuse-external flags to libvirt snapshot operations, with the
result that libvirt was failing to follow the intended chain of
backing files, and then backing files were not granted the
necessary sVirt permissions to be opened by qemu.
See https://bugzilla.redhat.com/show_bug.cgi?id=903248 for
more gory details. This fixes a regression introduced in
commit 8250783.
I tested this patch by creating the following chain:
ls /home/eblake/Downloads/Fedora.iso # raw file for base
cd /var/lib/libvirt/images
qemu-img create -f qcow2 \
-obacking_file=/home/eblake/Downloads/Fedora.iso,backing_fmt=raw one
mkdir sub
cd sub
ln -s ../one onelink
qemu-img create -f qcow2 \
-obacking_file=../sub/onelink,backing_fmt=qcow2 two
mv two ..
ln -s ../two twolink
qemu-img create -f qcow2 \
-obacking_file=../sub/twolink,backing_fmt=qcow2 three
mv three ..
ln -s ../three threelink
then pointing my domain at /var/lib/libvirt/images/sub/threelink.
Prior to this patch, I got complaints about missing backing
files; afterwards, I was able to verify that the backing chain
(and hence DAC and SELinux relabels) of the entire chain worked.
* src/util/virstoragefile.h (_virStorageFileMetadata): Add
directory member.
* src/util/virstoragefile.c (absolutePathFromBaseFile): Drop,
replaced by...
(virFindBackingFile): ...better function.
(virStorageFileGetMetadataInternal): Add an argument.
(virStorageFileGetMetadataFromFD, virStorageFileChainLookup)
(virStorageFileGetMetadata): Update callers.
Prior to this patch, we had the callchains:
external users
\-> virStorageFileGetMetadataFromFD
\-> virStorageFileGetMetadataFromBuf
virStorageFileGetMetadataRecurse
\-> virStorageFileGetMetadataFromFD
\-> virStorageFileGetMetadataFromBuf
However, a future patch wants to add an additional parameter to
the bottom of the chain, for use by virStorageFileGetMetadataRecurse,
without affecting existing external callers. Since there is only a
single caller of the internal function, we can repurpose it to fit
our needs, with this patch giving us:
external users
\-> virStorageFileGetMetadataFromFD
\-> virStorageFileGetMetadataInternal
virStorageFileGetMetadataRecurse /
\-> virStorageFileGetMetadataInternal
* src/util/virstoragefile.c (virStorageFileGetMetadataFromFD):
Move most of the guts...
(virStorageFileGetMetadataFromBuf): ...here, and rename...
(virStorageFileGetMetadataInternal): ...to this.
(virStorageFileGetMetadataRecurse): Use internal helper.
virStorageFileGetMetadataFromFD is the only caller of
virStorageFileGetMetadataFromBuf; and it doesn't care about the
difference between a return of 0 (total success) or 1
(metadata was inconsistent, but pointer was populated as best
as possible); only about a return of -1 (could not read metadata
or out of memory). Changing the return type, and normalizing
the variable names used, will make merging the functions easier
in the next commit.
* src/util/virstoragefile.c (virStorageFileGetMetadataFromBuf):
Change return value, and rename some variables.
(virStorageFileGetMetadataFromFD): Rename some variables.
No semantic change; done so the next patch doesn't need a forward
declaration of a static function.
* src/util/virstoragefile.c (virStorageFileProbeFormatFromBuf):
Hoist earlier.
This makes code easier to read, by avoiding lines longer than
80 columns and removing the repetition from the callers.
* src/util/virstoragefile.c (qedGetHeaderUL, qedGetHeaderULL):
Delete in favor of more generic macros.
(qcow2GetBackingStoreFormat, qcowXGetBackingStore)
(qedGetBackingStore, virStorageFileMatchesVersion)
(virStorageFileGetMetadataInternal): Use new macros.
* src/cpu/cpu_x86.c (x86VendorLoad): Likewise.
QEMU is fully capable of handling VDI images and we just refuse to
work with them. As qemu-img knows and supports this, there should be
no problem with this addition.
This is of course, just basic functionality, without searching for any
backing files, etc.
Some files have the magic shifted to some offset other than 0, so we
have to support that. I also cleaned up some lines to be more
readable and added missing magic for iso file format.
