From 7be4669a656a2de3cb658898255e5089429ccfd8 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=D0=BD=D0=B0=D0=B1?= Date: Sun, 11 Apr 2021 01:51:04 +0200 Subject: [PATCH] linux/libspl: gethostid: read from /proc/sys/kernel/spl/hostid, simplify MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Fixes get_system_hostid() if it was set via the aforementioned sysctl and simplifies the code a bit. The kernel and user-space must agree, after all. Reviewed-by: Brian Behlendorf Signed-off-by: Ahelenia Ziemiańska Closes #11879 --- lib/libspl/os/linux/gethostid.c | 41 ++++++++++++++------------------- 1 file changed, 17 insertions(+), 24 deletions(-) diff --git a/lib/libspl/os/linux/gethostid.c b/lib/libspl/os/linux/gethostid.c index 457d5bf6fa..c04b7fd3ee 100644 --- a/lib/libspl/os/linux/gethostid.c +++ b/lib/libspl/os/linux/gethostid.c @@ -40,47 +40,40 @@ get_spl_hostid(void) * Allow the hostid to be subverted for testing. */ env = getenv("ZFS_HOSTID"); - if (env) { - hostid = strtoull(env, NULL, 0); - return (hostid & HOSTID_MASK); - } + if (env) + return (strtoull(env, NULL, 0)); - f = fopen("/sys/module/spl/parameters/spl_hostid", "re"); + f = fopen("/proc/sys/kernel/spl/hostid", "re"); if (!f) return (0); - if (fscanf(f, "%lu", &hostid) != 1) + if (fscanf(f, "%lx", &hostid) != 1) hostid = 0; fclose(f); - return (hostid & HOSTID_MASK); + return (hostid); } unsigned long get_system_hostid(void) { - unsigned long system_hostid = get_spl_hostid(); + unsigned long hostid = get_spl_hostid(); + /* - * We do not use the library call gethostid() because - * it generates a hostid value that the kernel is - * unaware of, if the spl_hostid module parameter has not - * been set and there is no system hostid file (e.g. - * /etc/hostid). The kernel and userspace must agree. + * We do not use gethostid(3) because it can return a bogus ID, + * depending on the libc and /etc/hostid presence, + * and the kernel and userspace must agree. * See comments above hostid_read() in the SPL. */ - if (system_hostid == 0) { - int fd, rc; - unsigned long hostid; - int hostid_size = 4; /* 4 bytes regardless of arch */ - - fd = open("/etc/hostid", O_RDONLY | O_CLOEXEC); + if (hostid == 0) { + int fd = open("/etc/hostid", O_RDONLY | O_CLOEXEC); if (fd >= 0) { - rc = read(fd, &hostid, hostid_size); - if (rc > 0) - system_hostid = (hostid & HOSTID_MASK); - close(fd); + if (read(fd, &hostid, 4) < 0) + hostid = 0; + (void) close(fd); } } - return (system_hostid); + + return (hostid & HOSTID_MASK); }