Re: [PATCH v2 7/12] storage: Refactor and fix virStorageBackendCreateExecCommand

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Yes, this should have read 8/12...

On 10/14/2015 02:01 PM, John Ferlan wrote:
> Refactor the code to handle the NETFS pool separately from other pool
> types. When the original code was developed (commit id 'e1f27784')
> the virCommandSetUmask did not exist (commit id '0e1a1a8c4'), so there
> was no way to set the permissions for the creation. Now that it exists,
> we can use it. The code currently fails to create a volume in a NETFS
> pool from some other volume within the pool because the chmod done after
> file creation fails.
> 
> So adjust the code to jump to cleanup once the file is successfully
> created in the NETFS pool. If it fails or for non NETFS files, just
> perform the create, chown, and chmod in order
> 
> Signed-off-by: John Ferlan <jferlan@xxxxxxxxxx>
> ---
>  src/storage/storage_backend.c | 30 ++++++++++++++++--------------
>  1 file changed, 16 insertions(+), 14 deletions(-)
> 
> diff --git a/src/storage/storage_backend.c b/src/storage/storage_backend.c
> index a375fe0..037d6d7 100644
> --- a/src/storage/storage_backend.c
> +++ b/src/storage/storage_backend.c
> @@ -678,7 +678,6 @@ virStorageBackendCreateExecCommand(virStoragePoolObjPtr pool,
>      gid_t gid;
>      uid_t uid;
>      mode_t mode;
> -    bool filecreated = false;
>      int ret = -1;
>  
>      if ((pool->def->type == VIR_STORAGE_POOL_NETFS)
> @@ -690,26 +689,29 @@ virStorageBackendCreateExecCommand(virStoragePoolObjPtr pool,
>  
>          virCommandSetUID(cmd, vol->target.perms->uid);
>          virCommandSetGID(cmd, vol->target.perms->gid);
> +        mode = (vol->target.perms->mode == (mode_t) -1 ?
> +            VIR_STORAGE_DEFAULT_VOL_PERM_MODE : vol->target.perms->mode);
> +        virCommandSetUmask(cmd, 0777 - mode);

^^^

Just to be clear - this fixes a bug in the existing code which cannot
create 'qcow2' file in an NFS pool that has root squash enabled.  The
failure "currently" is :

virsh vol-create-from bz1253609 qemu-img.xml test.img --inputpool bz1253609
error: Failed to create vol from qemu-img.xml
error: cannot set mode of '/tmp/netfs-pool/qemu-img-test.img' to 0644:
Operation not permitted


Assuming that 'test.img' was created using :

virsh vol-create bz1253609 vol.xml


The qemu-img.xml is:

<volume>
    <name>qemu-img-test.img</name>
    <source>
    </source>
    <capacity>4048576000</capacity>
    <allocation>0</allocation>
    <target>
        <format type='qcow2'/>
        <permissions>
            <mode>0644</mode>
            <owner>107</owner>
            <group>107</group>
            <label>system_u:object_r:nfs_t:s0</label>
        </permissions>
    </target>
</volume>

it fails it other ways if <mode> and/or <owner>/<group> are not supplied.

FWIW: The 'vol.xml' file differs from the above by only the "type='raw'"

John
>  
> -        if (virCommandRun(cmd, NULL) == 0) {
> -            /* command was successfully run, check if the file was created */
> -            if (stat(vol->target.path, &st) >= 0)
> -                filecreated = true;
> +        if ((ret = virCommandRun(cmd, NULL)) == 0) {
> +            /* command was successfully run, if the file was created
> +             * then we are done */
> +            if (virFileExists(vol->target.path))
> +                goto cleanup;
>          }
>      }
>  
> -    /* don't change uid/gid if we retry */
> +    /* don't change uid/gid/mode if we retry */
>      virCommandSetUID(cmd, -1);
>      virCommandSetGID(cmd, -1);
> +    virCommandSetUmask(cmd, 0);
>  
> -    if (!filecreated) {
> -        if (virCommandRun(cmd, NULL) < 0)
> -            goto cleanup;
> -        if (stat(vol->target.path, &st) < 0) {
> -            virReportSystemError(errno,
> -                                 _("failed to create %s"), vol->target.path);
> -            goto cleanup;
> -        }
> +    if (virCommandRun(cmd, NULL) < 0)
> +        goto cleanup;
> +    if (stat(vol->target.path, &st) < 0) {
> +        virReportSystemError(errno,
> +                             _("failed to create %s"), vol->target.path);
> +        goto cleanup;
>      }
>  
>      uid = (vol->target.perms->uid != st.st_uid) ? vol->target.perms->uid
> 

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