Gitweb: http://git.fedorahosted.org/git/?p=lvm2.git;a=commitdiff;h=44071331138a7ca3a... Commit: 44071331138a7ca3a7d775d8a091933404ee7509 Parent: 3d0cb0611e5e68fc4d865102f8339552a907ff4b Author: Peter Rajnoha prajnoha@redhat.com AuthorDate: Mon May 13 11:46:24 2013 +0200 Committer: Peter Rajnoha prajnoha@redhat.com CommitterDate: Mon May 13 11:53:53 2013 +0200

toolcontext: check dm version lazily for udev_fallback setting

Setting the cmd->default_settings.udev_fallback also requires DM driver version check. However, this caused useless mapper/control access with ioctl if not needed actually. For example if we're not using activation code, we don't need to know the udev_fallback as there's no node and symlink processing.

For example, this premature mapper/control access caused problems when using lvm2app even when no activation happens - there are situations in which we don't need to use mapper/control, but still need some of the lvm2app functionality. This is also the case for lvm2-activation systemd generator which just needs to look at the lvm2 configuration, but it shouldn't touch mapper/control. --- WHATS_NEW | 1 + lib/activate/dev_manager.c | 57 +++++++++++++++++++++++++++++++++++++++++-- lib/commands/toolcontext.c | 46 ++++++----------------------------- 3 files changed, 63 insertions(+), 41 deletions(-)

diff --git a/WHATS_NEW b/WHATS_NEW index bad183c..2cdd0cd 100644 --- a/WHATS_NEW +++ b/WHATS_NEW @@ -1,5 +1,6 @@ Version 2.02.99 - =================================== + Fix premature DM version checking which caused useless mapper/control access. Add "active" LV reporting field to show activation state. Add "monitor" segment reporting field to show dmevent monitoring status. Document lvextend --use-policies option in man. diff --git a/lib/activate/dev_manager.c b/lib/activate/dev_manager.c index 150bb35..8e3cbb7 100644 --- a/lib/activate/dev_manager.c +++ b/lib/activate/dev_manager.c @@ -1309,6 +1309,57 @@ int dev_manager_mknodes(const struct logical_volume *lv) return r; }

+#ifdef UDEV_SYNC_SUPPORT +/* + * Until the DM_UEVENT_GENERATED_FLAG was introduced in kernel patch + * 856a6f1dbd8940e72755af145ebcd806408ecedd + * some operations could not be performed by udev, requiring our fallback code. + */ +static int _dm_driver_has_stable_udev_support(void) +{ + char vsn[80]; + unsigned maj, min, patchlevel; + + return driver_version(vsn, sizeof(vsn)) && + (sscanf(vsn, "%u.%u.%u", &maj, &min, &patchlevel) == 3) && + (maj == 4 ? min >= 18 : maj > 4); +} + +static int _check_udev_fallback(struct cmd_context *cmd) +{ + struct config_info *settings = &cmd->current_settings; + + if (settings->udev_fallback != -1) + goto out; + + /* + * Use udev fallback automatically in case udev + * is disabled via DM_DISABLE_UDEV environment + * variable or udev rules are switched off. + */ + settings->udev_fallback = !settings->udev_rules ? 1 : + find_config_tree_bool(cmd, activation_verify_udev_operations_CFG); + + /* Do not rely fully on udev if the udev support is known to be incomplete. */ + if (!settings->udev_fallback && !_dm_driver_has_stable_udev_support()) { + log_very_verbose("Kernel driver has incomplete udev support so " + "LVM will check and perform some operations itself."); + settings->udev_fallback = 1; + } +out: + return settings->udev_fallback; +} + +#else /* UDEV_SYNC_SUPPORT */ + +static int _check_udev_fallback(struct cmd_context *cmd) +{ + /* We must use old node/symlink creation code if not compiled with udev support at all! */ + return cmd->current_settings.udev_fallback = 1; +} + +#endif /* UDEV_SYNC_SUPPORT */ + static uint16_t _get_udev_flags(struct dev_manager *dm, struct logical_volume *lv, const char *layer) { @@ -1318,7 +1369,7 @@ static uint16_t _get_udev_flags(struct dev_manager *dm, struct logical_volume *l * Instruct also libdevmapper to disable udev * fallback in accordance to LVM2 settings. */ - if (!dm->cmd->current_settings.udev_fallback) + if (!_check_udev_fallback(dm->cmd)) udev_flags |= DM_UDEV_DISABLE_LIBRARY_FALLBACK;

/* @@ -2399,7 +2450,7 @@ static int _create_lv_symlinks(struct dev_manager *dm, struct dm_tree_node *root int r = 1;

/* Nothing to do if udev fallback is disabled. */ - if (!dm->cmd->current_settings.udev_fallback) { + if (!_check_udev_fallback(dm->cmd)) { fs_set_create(); return 1; } @@ -2447,7 +2498,7 @@ static int _remove_lv_symlinks(struct dev_manager *dm, struct dm_tree_node *root int r = 1;

/* Nothing to do if udev fallback is disabled. */ - if (!dm->cmd->current_settings.udev_fallback) + if (!_check_udev_fallback(dm->cmd)) return 1;

while ((child = dm_tree_next_child(&handle, root, 0))) { diff --git a/lib/commands/toolcontext.c b/lib/commands/toolcontext.c index 8f06285..2ea877a 100644 --- a/lib/commands/toolcontext.c +++ b/lib/commands/toolcontext.c @@ -262,23 +262,6 @@ static int _check_disable_udev(const char *msg) { return 0; }

-#ifdef UDEV_SYNC_SUPPORT -/* - * Until the DM_UEVENT_GENERATED_FLAG was introduced in kernel patch - * 856a6f1dbd8940e72755af145ebcd806408ecedd - * some operations could not be performed by udev, requiring our fallback code. - */ -static int _dm_driver_has_stable_udev_support(void) -{ - char vsn[80]; - unsigned maj, min, patchlevel; - - return driver_version(vsn, sizeof(vsn)) && - (sscanf(vsn, "%u.%u.%u", &maj, &min, &patchlevel) == 3) && - (maj == 4 ? min >= 18 : maj > 4); -} -#endif - static int _process_config(struct cmd_context *cmd) { mode_t old_umask; @@ -372,30 +355,17 @@ static int _process_config(struct cmd_context *cmd) cmd->default_settings.udev_sync = udev_disabled ? 0 : find_config_tree_bool(cmd, activation_udev_sync_CFG);

- init_retry_deactivation(find_config_tree_bool(cmd, activation_retry_deactivation_CFG)); - - init_activation_checks(find_config_tree_bool(cmd, activation_checks_CFG)); - -#ifdef UDEV_SYNC_SUPPORT /* - * Use udev fallback automatically in case udev - * is disabled via DM_DISABLE_UDEV environment - * variable or udev rules are switched off. + * Set udev_fallback lazily on first use since it requires + * checking DM driver version which is an extra ioctl! + * This also prevents unnecessary use of mapper/control. + * If udev is disabled globally, set fallback mode immediately. */ - cmd->default_settings.udev_fallback = !cmd->default_settings.udev_rules || udev_disabled ? 1 : - find_config_tree_bool(cmd, activation_verify_udev_operations_CFG); + cmd->default_settings.udev_fallback = udev_disabled ? 1 : -1;

- /* Do not rely fully on udev if the udev support is known to be incomplete. */ - if (!cmd->default_settings.udev_fallback && !_dm_driver_has_stable_udev_support()) { - log_very_verbose("Kernel driver has incomplete udev support so " - "LVM will check and perform some operations itself."); - cmd->default_settings.udev_fallback = 1; - } + init_retry_deactivation(find_config_tree_bool(cmd, activation_retry_deactivation_CFG));

-#else - /* We must use old node/symlink creation code if not compiled with udev support at all! */ - cmd->default_settings.udev_fallback = 1; -#endif + init_activation_checks(find_config_tree_bool(cmd, activation_checks_CFG));

cmd->use_linear_target = find_config_tree_bool(cmd, activation_use_linear_target_CFG);