From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41466) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZsRAf-0004Fe-5I for qemu-devel@nongnu.org; Sat, 31 Oct 2015 04:05:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZsRAb-0004zP-UZ for qemu-devel@nongnu.org; Sat, 31 Oct 2015 04:05:53 -0400 Received: from mga09.intel.com ([134.134.136.24]:38393) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZsRAb-0004zA-OI for qemu-devel@nongnu.org; Sat, 31 Oct 2015 04:05:49 -0400 References: <1446184587-142784-1-git-send-email-guangrong.xiao@linux.intel.com> <1446184587-142784-12-git-send-email-guangrong.xiao@linux.intel.com> <56338C66.2090609@virtuozzo.com> From: Xiao Guangrong Message-ID: <563474CC.9050701@linux.intel.com> Date: Sat, 31 Oct 2015 15:59:08 +0800 MIME-Version: 1.0 In-Reply-To: <56338C66.2090609@virtuozzo.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: Vladimir Sementsov-Ogievskiy , 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 10/30/2015 11:27 PM, Vladimir Sementsov-Ogievskiy wrote: > 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. > Okay. > Sorry for this nit-picking) Your comments/suggestion is valuable to me. :)