On Wed, Apr 13, 2022 at 12:49 AM Claudio Fontana <cfontana@suse.de> wrote:
On 4/12/22 7:23 PM, Ani Sinha wrote:
On Tue, Apr 12, 2022 at 10:09 PM Ani Sinha <ani@anisinha.ca> wrote:
On Tue, Apr 12, 2022 at 2:48 PM Claudio Fontana <cfontana@suse.de> wrote:
align the "save" with the "restore" code, by only using the wrapper when using --bypass-cache.
This avoids a copy, resulting in better performance.
Signed-off-by: Claudio Fontana <cfontana@suse.de> --- src/qemu/qemu_saveimage.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/src/qemu/qemu_saveimage.c b/src/qemu/qemu_saveimage.c index 4fd4c5cfcd..5ea1b2fbcc 100644 --- a/src/qemu/qemu_saveimage.c +++ b/src/qemu/qemu_saveimage.c @@ -289,8 +289,10 @@ qemuSaveImageCreate(virQEMUDriver *driver, if (qemuSecuritySetImageFDLabel(driver->securityManager, vm->def,
fd) < 0)
goto cleanup;
- if (!(wrapperFd = virFileWrapperFdNew(&fd, path, wrapperFlags))) - goto cleanup; + if ((flags & VIR_DOMAIN_SAVE_BYPASS_CACHE)) { + if (!(wrapperFd = virFileWrapperFdNew(&fd, path, wrapperFlags))) + goto cleanup; + }
There is an obvious issue with this code. We are trying to close and free a file descriptor that we have not opened when VIR_DOMAIN_SAVE_BYPASS_CACHE is set in flags.
I meant *not* set in flags.
I don't think so. I don't think it is obvious, so can you be more specific?
See if (qemuDomainFileWrapperFDClose(vm, wrapperFd) < 0) goto cleanup; and under cleanup: if (qemuDomainFileWrapperFDClose(vm, wrapperFd) < 0) ret = -1; if VIR_DOMAIN_SAVE_BYPASS_CACHE not set in flags, both the above function calls use wrapperFd initialized to NULL. I think this patch would be incomplete if you do not handle all these scenarios.
From the function header comments it seems lecit and defined to call the function with NULL:
/** * virFileWrapperFdClose: * @wfd: fd wrapper, or NULL * * If @wfd is valid, then ensure that I/O has completed, which may * include reaping a child process. Return 0 if all data for the * wrapped fd is complete, or -1 on failure with an error emitted. * This function intentionally returns 0 when @wfd is NULL, so that * callers can conditionally create a virFileWrapperFd wrapper but * unconditionally call the cleanup code. To avoid deadlock, only * call this after closing the fd resulting from virFileWrapperFdNew(). * * This function can be safely called multiple times on the same @wfd. */
Seems it has been specifically designed to simplify situations like this.
Thanks,
Claudio
if (virQEMUSaveDataWrite(data, fd, path) < 0) goto cleanup; -- 2.34.1