From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39910) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zu0lu-0003zw-Op for qemu-devel@nongnu.org; Wed, 04 Nov 2015 11:18:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Zu0lt-0002Ow-GV for qemu-devel@nongnu.org; Wed, 04 Nov 2015 11:18:50 -0500 Received: from mail-wi0-x22b.google.com ([2a00:1450:400c:c05::22b]:37097) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zu0lt-0002Oj-9t for qemu-devel@nongnu.org; Wed, 04 Nov 2015 11:18:49 -0500 Received: by wicfv8 with SMTP id fv8so35591220wic.0 for ; Wed, 04 Nov 2015 08:18:48 -0800 (PST) Sender: Paolo Bonzini From: Paolo Bonzini Date: Wed, 4 Nov 2015 17:18:30 +0100 Message-Id: <1446653912-116150-13-git-send-email-pbonzini@redhat.com> In-Reply-To: <1446653912-116150-1-git-send-email-pbonzini@redhat.com> References: <1446653912-116150-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PULL 12/14] backends/hostmem-file: Allow to specify full pathname for backing file List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Pavel Fedin From: Pavel Fedin This allows to explicitly specify file name to use with the backend. This is important when using it together with ivshmem in order to make it backed by hugetlbfs. By default filename is autogenerated using mkstemp(), and the file is unlink()ed after creation, effectively making it anonymous. This is not very useful with ivshmem because it ends up in a memory which cannot be accessed by something else. Distinction between directory and file name is done by stat() check. If an existing directory is given, the code keeps old behavior. Otherwise it creates or opens a file with the given pathname. Signed-off-by: Pavel Fedin Tested-by: Igor Skalkin Message-Id: <004301d11166$9672fe30$c358fa90$@samsung.com> Signed-off-by: Paolo Bonzini --- exec.c | 34 +++++++++++++++++++++------------- qemu-doc.texi | 2 +- 2 files changed, 22 insertions(+), 14 deletions(-) diff --git a/exec.c b/exec.c index 819ecc3..1e8b51b 100644 --- a/exec.c +++ b/exec.c @@ -1205,6 +1205,7 @@ static void *file_ram_alloc(RAMBlock *block, const char *path, Error **errp) { + struct stat st; char *filename; char *sanitized_name; char *c; @@ -1233,26 +1234,33 @@ static void *file_ram_alloc(RAMBlock *block, goto error; } - /* Make name safe to use with mkstemp by replacing '/' with '_'. */ - sanitized_name = g_strdup(memory_region_name(block->mr)); - for (c = sanitized_name; *c != '\0'; c++) { - if (*c == '/') - *c = '_'; - } + if (!stat(path, &st) && S_ISDIR(st.st_mode)) { + /* Make name safe to use with mkstemp by replacing '/' with '_'. */ + sanitized_name = g_strdup(memory_region_name(block->mr)); + for (c = sanitized_name; *c != '\0'; c++) { + if (*c == '/') { + *c = '_'; + } + } - filename = g_strdup_printf("%s/qemu_back_mem.%s.XXXXXX", path, - sanitized_name); - g_free(sanitized_name); + filename = g_strdup_printf("%s/qemu_back_mem.%s.XXXXXX", path, + sanitized_name); + g_free(sanitized_name); + + fd = mkstemp(filename); + if (fd >= 0) { + unlink(filename); + } + g_free(filename); + } else { + fd = open(path, O_RDWR | O_CREAT, 0644); + } - fd = mkstemp(filename); if (fd < 0) { error_setg_errno(errp, errno, "unable to create backing store for hugepages"); - g_free(filename); goto error; } - unlink(filename); - g_free(filename); memory = ROUND_UP(memory, hpagesize); diff --git a/qemu-doc.texi b/qemu-doc.texi index 3126abd..460ab71 100644 --- a/qemu-doc.texi +++ b/qemu-doc.texi @@ -1299,7 +1299,7 @@ Instead of specifying the using POSIX shm, you may specify a memory backend that has hugepage support: @example -qemu-system-i386 -object memory-backend-file,size=1G,mem-path=/mnt/hugepages,id=mb1 +qemu-system-i386 -object memory-backend-file,size=1G,mem-path=/mnt/hugepages/my-shmem-file,id=mb1 -device ivshmem,memdev=mb1 @end example -- 1.8.3.1