On Thu, Oct 20, 2022 at 16:58:59 -0500, Jonathon Jongsma wrote:
An object for storing information about a nbdkit process that is serving a specific virStorageSource. At the moment, this information is just stored in the private data of virStorageSource and not used at all. Future commits will use this data to actually start a nbdkit process.
Signed-off-by: Jonathon Jongsma <jjongsma@redhat.com> --- src/qemu/qemu_conf.c | 23 ++++++++++++ src/qemu/qemu_conf.h | 3 ++ src/qemu/qemu_domain.c | 31 ++++++++++++++++ src/qemu/qemu_domain.h | 4 +++ src/qemu/qemu_nbdkit.c | 82 ++++++++++++++++++++++++++++++++++++++++++ src/qemu/qemu_nbdkit.h | 26 ++++++++++++++ 6 files changed, 169 insertions(+)
diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c index ae5bbcd138..0370429da0 100644 --- a/src/qemu/qemu_conf.c +++ b/src/qemu/qemu_conf.c @@ -1641,3 +1641,26 @@ qemuHugepageMakeBasedir(virQEMUDriver *driver,
return 0; } + + +/* + * qemuGetNbdkitCaps: + * @driver: the qemu driver + * + * Gets the capabilities for Nbdkit for the specified driver. These can be used + * to determine whether a particular disk source can be served by nbdkit or + * not. + * + * Returns: a reference to qemuNbdkitCaps or NULL + */ +qemuNbdkitCaps* +qemuGetNbdkitCaps(virQEMUDriver *driver) +{ + if (!driver->nbdkitBinary) + driver->nbdkitBinary = virFindFileInPath("nbdkit"); + + if (driver->nbdkitBinary) + return virFileCacheLookup(driver->nbdkitCapsCache, driver->nbdkitBinary); + + return NULL; +} diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h index 95c05e6888..8b4f6ce669 100644 --- a/src/qemu/qemu_conf.h +++ b/src/qemu/qemu_conf.h @@ -323,6 +323,7 @@ struct _virQEMUDriver {
/* Immutable pointer, self-locking APIs */ virFileCache *nbdkitCapsCache; + char *nbdkitBinary;
The above statement doesn't apply to 'nbdkitBinary'. It's not immutable because you update it in qemuGetNbdkitCaps and it also certainly doesn't have self-locking APIS. You can claim immutability if and only if it's assigned in qemuStateInitialize and never changed afterwards. I don't think we should cache the path though as it creates weird situations where a different version of nbdkit placed in $PATH preferentially will be picked up, but only after a restart. This brings another issue though I think that the path to modules/plugins should be detected from the actual NBDkit instance rather than hardcoded: $ nbdkit --dump-config binary=/usr/sbin/nbdkit bindir=/usr/bin exit_with_parent=yes filterdir=/usr/lib64/nbdkit/filters host_cpu=x86_64 host_os=linux-gnu libdir=/usr/lib64 mandir=/usr/share/man name=nbdkit plugindir=/usr/lib64/nbdkit/plugins root_tls_certificates_dir=/etc/pki/nbdkit sbindir=/usr/sbin selinux=yes sysconfdir=/etc tls=yes version=1.32.4 version_extra=nbdkit-1.32.4-1.fc37 version_major=1 version_minor=32 zstd=yes This way each cached version will properly see the corresponding plugin version. You also won't have a config-time option for it which can't be changed after the package is installed.