/* * Copyright (C) 2007-2015 Red Hat, Inc. All rights reserved. * * This file is part of LVM2. * * This copyrighted material is made available to anyone wishing to use, * modify, copy, or redistribute it subject to the terms and conditions * of the GNU Lesser General Public License v.2.1. * * You should have received a copy of the GNU Lesser General Public License * along with this program; if not, write to the Free Software Foundation, * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include "lib.h" #include "dmeventd_lvm.h" #include "libdevmapper-event.h" #include #include /* First warning when snapshot is 80% full. */ #define WARNING_THRESH 80 /* Run a check every 5%. */ #define CHECK_STEP 5 /* Do not bother checking snapshots less than 50% full. */ #define CHECK_MINIMUM 50 #define UMOUNT_COMMAND "/bin/umount" struct dso_state { struct dm_pool *mem; int percent_check; uint64_t known_size; char cmd_str[1024]; }; DM_EVENT_LOG_FN("snap") static int _run(const char *cmd, ...) { va_list ap; int argc = 1; /* for argv[0], i.e. cmd */ int i = 0; const char **argv; pid_t pid = fork(); int status; if (pid == 0) { /* child */ va_start(ap, cmd); while (va_arg(ap, const char *)) ++ argc; va_end(ap); /* + 1 for the terminating NULL */ argv = alloca(sizeof(const char *) * (argc + 1)); argv[0] = cmd; va_start(ap, cmd); while ((argv[++i] = va_arg(ap, const char *))); va_end(ap); execvp(cmd, (char **)argv); log_sys_error("exec", cmd); exit(127); } if (pid > 0) { /* parent */ if (waitpid(pid, &status, 0) != pid) return 0; /* waitpid failed */ if (!WIFEXITED(status) || WEXITSTATUS(status)) return 0; /* the child failed */ } if (pid < 0) return 0; /* fork failed */ return 1; /* all good */ } static int _extend(const char *cmd) { return dmeventd_lvm2_run(cmd); } static void _umount(const char *device, int major, int minor) { FILE *mounts; char buffer[4096]; char *words[3]; struct stat st; const char procmounts[] = "/proc/mounts"; if (!(mounts = fopen(procmounts, "r"))) { log_sys_error("fopen", procmounts); log_error("Not umounting %s.", device); return; } while (!feof(mounts)) { /* read a line of /proc/mounts */ if (!fgets(buffer, sizeof(buffer), mounts)) break; /* eof, likely */ /* words[0] is the mount point and words[1] is the device path */ if (dm_split_words(buffer, 3, 0, words) < 2) continue; /* find the major/minor of the device */ if (stat(words[0], &st)) continue; /* can't stat, skip this one */ if (S_ISBLK(st.st_mode) && major(st.st_rdev) == major && minor(st.st_rdev) == minor) { log_error("Unmounting invalid snapshot %s from %s.", device, words[1]); if (!_run(UMOUNT_COMMAND, "-fl", words[1], NULL)) log_error("Failed to umount snapshot %s from %s: %s.", device, words[1], strerror(errno)); } } if (fclose(mounts)) log_sys_error("close", procmounts); } void process_event(struct dm_task *dmt, enum dm_event_mask event __attribute__((unused)), void **user) { struct dso_state *state = *user; void *next = NULL; uint64_t start, length; char *target_type = NULL; char *params; struct dm_status_snapshot *status = NULL; const char *device = dm_task_get_name(dmt); int percent; /* No longer monitoring, waiting for remove */ if (!state->percent_check) return; dmeventd_lvm2_lock(); dm_get_next_target(dmt, next, &start, &length, &target_type, ¶ms); if (!target_type) goto out; if (!dm_get_status_snapshot(state->mem, params, &status)) goto out; if (status->invalid || status->overflow) { struct dm_info info; log_error("Snapshot %s is lost.", device); if (dm_task_get_info(dmt, &info)) { dmeventd_lvm2_unlock(); _umount(device, info.major, info.minor); return; } /* else; too bad, but this is best-effort thing... */ } /* Snapshot size had changed. Clear the threshold. */ if (state->known_size != status->total_sectors) { state->percent_check = CHECK_MINIMUM; state->known_size = status->total_sectors; } /* * If the snapshot has been invalidated or we failed to parse * the status string. Report the full status string to syslog. */ if (status->invalid || status->overflow || !status->total_sectors) { log_error("Snapshot %s changed state to: %s.", device, params); state->percent_check = 0; goto out; } percent = (int) (100 * status->used_sectors / status->total_sectors); if (percent >= state->percent_check) { /* Usage has raised more than CHECK_STEP since the last time. Run actions. */ state->percent_check = (percent / CHECK_STEP) * CHECK_STEP + CHECK_STEP; if (percent >= WARNING_THRESH) /* Print a warning to syslog. */ log_warn("WARNING: Snapshot %s is now %i%% full.", device, percent); /* Try to extend the snapshot, in accord with user-set policies */ if (!_extend(state->cmd_str)) log_error("Failed to extend snapshot %s.", device); } out: if (status) dm_pool_free(state->mem, status); dmeventd_lvm2_unlock(); } int register_device(const char *device, const char *uuid __attribute__((unused)), int major __attribute__((unused)), int minor __attribute__((unused)), void **user) { struct dm_pool *statemem = NULL; struct dso_state *state; if (!dmeventd_lvm2_init()) goto out; if (!(statemem = dm_pool_create("snapshot_state", 512)) || !(state = dm_pool_zalloc(statemem, sizeof(*state)))) goto bad; if (!dmeventd_lvm2_command(statemem, state->cmd_str, sizeof(state->cmd_str), "lvextend --use-policies", device)) goto bad; state->mem = statemem; state->percent_check = CHECK_MINIMUM; *user = state; log_info("Monitoring snapshot %s.", device); return 1; bad: if (statemem) dm_pool_destroy(statemem); dmeventd_lvm2_exit(); out: log_error("Failed to monitor snapshot %s.", device); return 0; } int unregister_device(const char *device, const char *uuid __attribute__((unused)), int major __attribute__((unused)), int minor __attribute__((unused)), void **user) { struct dso_state *state = *user; log_info("No longer monitoring snapshot %s.", device); dm_pool_destroy(state->mem); dmeventd_lvm2_exit(); return 1; }