From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 26877 invoked by alias); 25 Mar 2011 23:50:36 -0000 Received: (qmail 26860 invoked by uid 9447); 25 Mar 2011 23:50:36 -0000 Date: Fri, 25 Mar 2011 23:50:00 -0000 Message-ID: <20110325235036.26858.qmail@sourceware.org> From: agk@sourceware.org To: lvm-devel@redhat.com, lvm2-cvs@sourceware.org Subject: LVM2 ./WHATS_NEW_DM libdm/ioctl/libdm-iface.c Mailing-List: contact lvm2-cvs-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: lvm2-cvs-owner@sourceware.org X-SW-Source: 2011-03/txt/msg00076.txt.bz2 CVSROOT: /cvs/lvm2 Module name: LVM2 Changes by: agk@sourceware.org 2011-03-25 23:50:35 Modified files: . : WHATS_NEW_DM libdm/ioctl : libdm-iface.c Log message: Use hard-coded /dev/mapper/control details for 2.6.36+ kernels and simplify associated code. (Some obscure configurations that happened to work before are no longer supported.) Patches: http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/WHATS_NEW_DM.diff?cvsroot=lvm2&r1=1.457&r2=1.458 http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/libdm/ioctl/libdm-iface.c.diff?cvsroot=lvm2&r1=1.102&r2=1.103 --- LVM2/WHATS_NEW_DM 2011/03/18 13:21:03 1.457 +++ LVM2/WHATS_NEW_DM 2011/03/25 23:50:35 1.458 @@ -1,5 +1,7 @@ Version 1.02.64 - =================================== + Streamline /dev/mapper/control node code for common cases. + Use hard-coded dm control node device number for 2.6.36 kernels and above. Improve stack debug reporting in dm_task_create(). Fallback to control node creation only if node doesn't exist yet. Change dm_hash API for binary data to accept const void *key. --- LVM2/libdm/ioctl/libdm-iface.c 2011/03/20 02:00:52 1.102 +++ LVM2/libdm/ioctl/libdm-iface.c 2011/03/25 23:50:35 1.103 @@ -228,7 +228,7 @@ } /* - * Returns 1 if exists; 0 if it doesn't; -1 if it's wrong + * Returns 1 if it exists on returning; 0 if it doesn't; -1 if it's wrong. */ static int _control_exists(const char *control, uint32_t major, uint32_t minor) { @@ -267,8 +267,15 @@ int ret; mode_t old_umask; - if (!major) - return 0; + /* + * Return if the control already exists with intended major/minor + * or there's an error unlinking an apparently incorrect one. + */ + ret = _control_exists(control, major, minor); + if (ret == -1) + return 0; /* Failed to unlink existing incorrect node */ + if (ret) + return 1; /* Already exists and correct */ (void) dm_prepare_selinux_context(dm_dir(), S_IFDIR); old_umask = umask(DM_DEV_DIR_UMASK); @@ -359,14 +366,9 @@ } } -static int _open_and_assign_control_fd(const char *control, - int ignore_nodev) +static int _open_and_assign_control_fd(const char *control) { - _close_control_fd(); - if ((_control_fd = open(control, O_RDWR)) < 0) { - if (ignore_nodev && errno == ENODEV) - return 1; log_sys_error("open", control); return 0; } @@ -378,8 +380,8 @@ { #ifdef DM_IOCTLS char control[PATH_MAX]; - uint32_t major = 0, minor; - int dm_mod_autoload_support, needs_open; + uint32_t major = MISC_MAJOR; + uint32_t minor = MAPPER_CTRL_MINOR; if (_control_fd != -1) return 1; @@ -390,63 +392,27 @@ snprintf(control, sizeof(control), "%s/%s", dm_dir(), DM_CONTROL_NODE); /* - * dm-mod autoloading is supported since kernel 2.6.36. - * Udev daemon will try to read modules.devname file extracted - * by depmod and create any static nodes needed. - * The /dev/mapper/control node can be created and prepared this way. - * First access to such node should load dm-mod module automatically. - */ - dm_mod_autoload_support = KERNEL_VERSION(_kernel_major, _kernel_minor, - _kernel_release) >= KERNEL_VERSION(2, 6, 36); - - /* - * If dm-mod autoloading is supported and the control node exists - * already try to open it now. This should autoload dm-mod module. - */ - if (dm_mod_autoload_support) { - if (!_get_proc_number(PROC_DEVICES, MISC_NAME, &major)) - /* If major not found, just fallback to hardcoded value. */ - major = MISC_MAJOR; - - /* Recreate the node with correct major and minor if needed. */ - if (!_control_exists(control, major, MAPPER_CTRL_MINOR) && - !_create_control(control, major, MAPPER_CTRL_MINOR)) - goto error; - - /* Fallback to old code only if control node doesn't exist */ - if (!_open_and_assign_control_fd(control, 1)) - goto error; - } - - /* - * Get major and minor number assigned for the control node. - * In case we make use of the module autoload support, this - * information should be accessible now as well. + * Prior to 2.6.36 the minor number should be looked up in /proc. */ - if (!_control_device_number(&major, &minor)) - log_error("Is device-mapper driver missing from kernel?"); + if ((KERNEL_VERSION(_kernel_major, _kernel_minor, _kernel_release) < + KERNEL_VERSION(2, 6, 36)) && + !_control_device_number(&major, &minor)) + goto_bad; /* - * Check the control node and its major and minor number. - * If there's anything wrong, remove the old node and create - * a correct one. + * Create the node with correct major and minor if not already done. + * Udev may already have created /dev/mapper/control + * from the modules.devname file generated by depmod. */ - if ((needs_open = !_control_exists(control, major, minor)) && - !_create_control(control, major, minor)) { - _close_control_fd(); - goto error; - } + if (!_create_control(control, major, minor)) + goto_bad; /* - * For older kernels without dm-mod autoloading support, we always - * need to open the control node here - we still haven't done that! - * For newer kernels with dm-mod autoloading, we open it only if the - * node was recreated and corrected in previous step. + * As of 2.6.36 kernels, the open can trigger autoloading dm-mod. */ - if ((!dm_mod_autoload_support || needs_open) && - !_open_and_assign_control_fd(control, 0)) - goto error; - + if (!_open_and_assign_control_fd(control)) + goto_bad; + if (!_create_dm_bitset()) { log_error("Failed to set up list of device-mapper major numbers"); return 0; @@ -454,8 +420,10 @@ return 1; -error: +bad: log_error("Failure to communicate with kernel device-mapper driver."); + if (!geteuid()) + log_error("Check that device-mapper is available in the kernel."); return 0; #else return 1;