From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49706) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZsBb3-0007sY-Dw for qemu-devel@nongnu.org; Fri, 30 Oct 2015 11:28:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZsBaz-0000rY-Ds for qemu-devel@nongnu.org; Fri, 30 Oct 2015 11:28:05 -0400 Received: from relay.parallels.com ([195.214.232.42]:60714) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZsBaz-0000r4-7N for qemu-devel@nongnu.org; Fri, 30 Oct 2015 11:28:01 -0400 Message-ID: <56338C66.2090609@virtuozzo.com> Date: Fri, 30 Oct 2015 18:27:34 +0300 From: Vladimir Sementsov-Ogievskiy MIME-Version: 1.0 References: <1446184587-142784-1-git-send-email-guangrong.xiao@linux.intel.com> <1446184587-142784-12-git-send-email-guangrong.xiao@linux.intel.com> In-Reply-To: <1446184587-142784-12-git-send-email-guangrong.xiao@linux.intel.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v6 11/33] hostmem-file: use whole file size if possible List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Xiao Guangrong , pbonzini@redhat.com, imammedo@redhat.com Cc: ehabkost@redhat.com, kvm@vger.kernel.org, mst@redhat.com, gleb@kernel.org, mtosatti@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com, dan.j.williams@intel.com, rth@twiddle.net On 30.10.2015 08:56, Xiao Guangrong wrote: > Use the whole file size if @size is not specified which is useful > if we want to directly pass a file to guest > > Signed-off-by: Xiao Guangrong > --- > backends/hostmem-file.c | 48 ++++++++++++++++++++++++++++++++++++++++++++---- > 1 file changed, 44 insertions(+), 4 deletions(-) > > diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c > index 9097a57..e1bc9ff 100644 > --- a/backends/hostmem-file.c > +++ b/backends/hostmem-file.c > @@ -9,6 +9,9 @@ > * This work is licensed under the terms of the GNU GPL, version 2 or later. > * See the COPYING file in the top-level directory. > */ > +#include > +#include > + > #include "qemu-common.h" > #include "sysemu/hostmem.h" > #include "sysemu/sysemu.h" > @@ -33,20 +36,57 @@ struct HostMemoryBackendFile { > char *mem_path; > }; > > +static uint64_t get_file_size(const char *file) > +{ > + struct stat stat_buf; > + uint64_t size = 0; > + int fd; > + > + fd = open(file, O_RDONLY); > + if (fd < 0) { > + return 0; > + } > + > + if (stat(file, &stat_buf) < 0) { > + goto exit; > + } > + > + if ((S_ISBLK(stat_buf.st_mode)) && !ioctl(fd, BLKGETSIZE64, &size)) { > + goto exit; > + } > + > + size = lseek(fd, 0, SEEK_END); > + if (size == -1) { > + size = 0; > + } > +exit: > + close(fd); > + return size; > +} > + > static void > file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) > { > HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend); > > - if (!backend->size) { > - error_setg(errp, "can't create backend with size 0"); > - return; > - } > if (!fb->mem_path) { > error_setg(errp, "mem-path property not set"); > return; > } > > + if (!backend->size) { > + /* > + * use the whole file size if @size is not specified. > + */ > + backend->size = get_file_size(fb->mem_path); > + } > + > + if (!backend->size) { > + error_setg(errp, "failed to get file size for %s, can't create " > + "backend on it", mem_path); > + return; > + } > + > backend->force_prealloc = mem_prealloc; > memory_region_init_ram_from_file(&backend->mr, OBJECT(backend), > object_get_canonical_path(OBJECT(backend)), You can use error_setg_errno to get an error descriptioin for free, as all possible errors from get_file_size comes with errno. Just zero size should be separated for this, for example by usiing int64_t as return type and -1 for an error. Sorry for this nit-picking) -- Best regards, Vladimir * now, @virtuozzo.com instead of @parallels.com. Sorry for this inconvenience.