On Mon, Apr 09, 2012 at 21:52:22 -0600, Eric Blake wrote:
> This copies some of the checks from snapshots regarding testing
> when a file already exists. In the process, I noticed a missing
> sanity check in snapshots: REUSE_EXT should require the destination
> to already be present.
>
> * src/qemu/qemu_driver.c (qemuDomainBlockRebase): Allow REUSE_EXT
> flag.
> (qemuDomainBlockCopy): Wire up flag, and add some sanity checks.
> (qemuDomainSnapshotDiskPrepare): Require destination on REUSE_EXT.
> ---
> src/qemu/qemu_driver.c | 48 +++++++++++++++++++++++++++++++++++++++++++-----
> 1 files changed, 43 insertions(+), 5 deletions(-)
>
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 6d5a5da..661ccb4 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -9812,6 +9812,11 @@ qemuDomainSnapshotDiskPrepare(virDomainObjPtr vm, virDomainSnapshotDefPtr def,
> _("unable to stat for disk %s: %s"),
> disk->name, disk->file);
> goto cleanup;
> + } else if (allow_reuse) {
> + virReportSystemError(errno,
> + _("missing existing file for disk %s: %s"),
> + disk->name, disk->file);
> + goto cleanup;
> }
> } else if (!(S_ISBLK(st.st_mode) || !st.st_size || allow_reuse)) {
> qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> @@ -11889,9 +11894,11 @@ qemuDomainBlockCopy(virDomainPtr dom, const char *path,
> virDomainDiskDefPtr disk;
> int ret = -1;
> int idx;
> + struct stat st;
>
> /* Preliminaries: find the disk we are editing, sanity checks */
> - virCheckFlags(VIR_DOMAIN_BLOCK_REBASE_SHALLOW, -1);
> + virCheckFlags(VIR_DOMAIN_BLOCK_REBASE_SHALLOW |
> + VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT, -1);
>
> qemuDriverLock(driver);
> virUUIDFormat(dom->uuid, uuidstr);
> @@ -11936,12 +11943,42 @@ qemuDomainBlockCopy(virDomainPtr dom, const char *path,
> goto endjob;
> }
>
> + /* XXX this is pessimistic; we could use 'query-block' or even
> + * keep track of the backing chain ourselves, rather than assuming
> + * that all non-raw source files have a current backing image */
> + if ((flags & VIR_DOMAIN_BLOCK_REBASE_SHALLOW) &&
> + STREQ_NULLABLE(format, "raw") &&
> + STRNEQ_NULLABLE(disk->driverType, "raw")) {
> + qemuReportError(VIR_ERR_INVALID_ARG,
> + _("raw shallow copy of non-raw disk '%s' not possible"),
> + disk->dst);
> + goto endjob;
> + }
> +
> /* Prepare the destination file. */
> + if (stat(dest, &st) < 0) {
> + if (errno != ENOENT) {
> + virReportSystemError(errno, _("unable to stat for disk %s: %s"),
> + disk->dst, dest);
> + goto endjob;
> + } else if (flags & VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT) {
> + virReportSystemError(errno,
> + _("missing destination file for disk %s: %s"),
> + disk->dst, dest);
> + goto endjob;
> + }
> + } else if (!(S_ISBLK(st.st_mode) || !st.st_size ||
> + (flags & VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT))) {
Eh, this is quite hard to parse, I'd move the negation inside;
if (!S_ISBLK(st.st_mode) && st.st_size &&
!(flags & VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT))
> + qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> + _("external destination file for disk %s already "
> + "exists and is not a block device: %s"),
> + disk->dst, dest);
> + goto endjob;
> + }
> +
> /* XXX We also need to add security labeling, lock manager lease,
> - * and auditing of those events, as well as to support reuse of
> - * existing images, including probing the existing format of an
> - * existing image. */
> - if (!format)
> + * and auditing of those events. */
> + if (!format && !(flags & VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT))
> format = disk->driverType;
> if ((format && !(disk->mirrorFormat = strdup(format))) ||
> !(disk->mirror = strdup(dest))) {
> @@ -11980,6 +12017,7 @@ qemuDomainBlockRebase(virDomainPtr dom, const char *path, const char *base,
> unsigned long bandwidth, unsigned int flags)
> {
> virCheckFlags(VIR_DOMAIN_BLOCK_REBASE_SHALLOW |
> + VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT |
> VIR_DOMAIN_BLOCK_REBASE_COPY |
> VIR_DOMAIN_BLOCK_REBASE_COPY_RAW, -1);
>
OK
Jirka
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