From patchwork Mon Jul 27 22:08:10 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Goldwyn Rodrigues X-Patchwork-Id: 11687731 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DDD21138A for ; Mon, 27 Jul 2020 22:08:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CEB562072E for ; Mon, 27 Jul 2020 22:08:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726590AbgG0WIf (ORCPT ); Mon, 27 Jul 2020 18:08:35 -0400 Received: from mx2.suse.de ([195.135.220.15]:58608 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726140AbgG0WIe (ORCPT ); Mon, 27 Jul 2020 18:08:34 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id B4F01B1B3; Mon, 27 Jul 2020 22:08:43 +0000 (UTC) From: Goldwyn Rodrigues To: linux-btrfs@vger.kernel.org Cc: Goldwyn Rodrigues Subject: [PATCH 2/4] btrfs-progs: add sysfs file reading functions Date: Mon, 27 Jul 2020 17:08:10 -0500 Message-Id: <20200727220812.2187-2-rgoldwyn@suse.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200727220812.2187-1-rgoldwyn@suse.de> References: <20200727220451.30680-1-rgoldwyn@suse.de> <20200727220812.2187-1-rgoldwyn@suse.de> MIME-Version: 1.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: Goldwyn Rodrigues Functions to read and and open sysfs files. Given a fd, find the fsid associated with the mount and convert into the sysfs directory to look. Read the exclusive_operation file to find the current exclusive operation running. Signed-off-by: Goldwyn Rodrigues --- Makefile | 4 ++-- common/sysfs.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++ common/utils.h | 3 +++ 3 files changed, 65 insertions(+), 2 deletions(-) create mode 100644 common/sysfs.c diff --git a/Makefile b/Makefile index ee57d9f8..8a267c45 100644 --- a/Makefile +++ b/Makefile @@ -168,8 +168,8 @@ libbtrfs_objects = send-stream.o send-utils.o kernel-lib/rbtree.o btrfs-list.o \ kernel-shared/free-space-tree.o repair.o kernel-shared/inode-item.o \ kernel-shared/file-item.o \ kernel-lib/raid56.o kernel-lib/tables.o \ - common/device-scan.o common/path-utils.o \ - common/utils.o libbtrfsutil/subvolume.o libbtrfsutil/stubs.o \ + common/device-scan.o common/path-utils.o common/utils.o \ + common/sysfs.o libbtrfsutil/subvolume.o libbtrfsutil/stubs.o \ crypto/hash.o crypto/xxhash.o $(CRYPTO_OBJECTS) libbtrfs_headers = send-stream.h send-utils.h send.h kernel-lib/rbtree.h btrfs-list.h \ crypto/crc32c.h kernel-lib/list.h kerncompat.h \ diff --git a/common/sysfs.c b/common/sysfs.c new file mode 100644 index 00000000..91ed270c --- /dev/null +++ b/common/sysfs.c @@ -0,0 +1,60 @@ + +#include +#include +#include + +#include +#include +#include + +#include "common/utils.h" + +static u8 fsid[BTRFS_UUID_SIZE] = {0}; + +int sysfs_open(int fd, const char *filename) +{ + char fsid_str[BTRFS_UUID_UNPARSED_SIZE]; + int ret; + char sysfs_file[128]; + + if (fsid[0] == 0) { + ret = get_fsid_fd(fd, fsid); + if (ret < 0) + return ret; + } + + uuid_unparse(fsid, fsid_str); + snprintf(sysfs_file, 128, "/sys/fs/btrfs/%s/%s", fsid_str, filename); + return open(sysfs_file, O_RDONLY); +} + +int sysfs_get_str_fd(int fd, char *val, int size) +{ + lseek(fd, 0, SEEK_SET); + memset(val, '\0', size); + return read(fd, val, size); +} + +int get_exclusive_operation(int mp_fd, char *val) +{ + char *s; + int fd; + int n; + + fd = sysfs_open(mp_fd, "exclusive_operation"); + if (fd < 0) + return fd; + + n = sysfs_get_str_fd(fd, val, BTRFS_SYSFS_EXOP_SIZE); + close(fd); + + if (n < 0) + return n; + + s = strchr(val, '\n'); + if (!s) + return n; + + *s = '\0'; + return strlen(val); +} diff --git a/common/utils.h b/common/utils.h index e34bb5a4..be8aab58 100644 --- a/common/utils.h +++ b/common/utils.h @@ -153,4 +153,7 @@ void init_rand_seed(u64 seed); char *btrfs_test_for_multiple_profiles(int fd); int btrfs_warn_multiple_profiles(int fd); +#define BTRFS_SYSFS_EXOP_SIZE 16 +int get_exclusive_operation(int fd, char *val); + #endif