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lvm2/lib/filters/filter-persistent.c

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/*
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* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
* Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
*
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* 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.
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*
* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
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#include "lib.h"
#include "filter.h"
#include "config.h"
#include "lvm-file.h"
#include "activate.h"
struct pfilter {
char *file;
struct dm_hash_table *devices;
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struct dev_filter *real;
time_t ctime;
struct dev_types *dt;
};
/*
* The hash table holds one of these two states
* against each entry.
*/
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#define PF_BAD_DEVICE ((void *) 1)
#define PF_GOOD_DEVICE ((void *) 2)
static int _init_hash(struct pfilter *pf)
{
if (pf->devices)
dm_hash_destroy(pf->devices);
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if (!(pf->devices = dm_hash_create(128)))
return_0;
return 1;
}
static void _persistent_filter_wipe(struct dev_filter *f)
{
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struct pfilter *pf = (struct pfilter *) f->private;
log_verbose("Wiping cache of LVM-capable devices");
dm_hash_wipe(pf->devices);
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/* Trigger complete device scan */
dev_cache_scan(1);
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}
static int _read_array(struct pfilter *pf, struct dm_config_tree *cft,
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const char *path, void *data)
{
const struct dm_config_node *cn;
const struct dm_config_value *cv;
if (!(cn = dm_config_find_node(cft->root, path))) {
log_very_verbose("Couldn't find %s array in '%s'",
path, pf->file);
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return 0;
}
/*
* iterate through the array, adding
* devices as we go.
*/
for (cv = cn->v; cv; cv = cv->next) {
if (cv->type != DM_CFG_STRING) {
log_verbose("Devices array contains a value "
"which is not a string ... ignoring");
continue;
}
if (!dm_hash_insert(pf->devices, cv->v.str, data))
log_verbose("Couldn't add '%s' to filter ... ignoring",
cv->v.str);
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/* Populate dev_cache ourselves */
dev_cache_get(cv->v.str, NULL);
}
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return 1;
}
int persistent_filter_load(struct dev_filter *f, struct dm_config_tree **cft_out)
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{
struct pfilter *pf = (struct pfilter *) f->private;
struct dm_config_tree *cft;
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struct stat info;
int r = 0;
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if (obtain_device_list_from_udev()) {
if (!stat(pf->file, &info)) {
log_very_verbose("Obtaining device list from udev. "
"Removing obsolete %s.",
pf->file);
if (unlink(pf->file) < 0 && errno != EROFS)
log_sys_error("unlink", pf->file);
}
return 1;
}
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if (!stat(pf->file, &info))
pf->ctime = info.st_ctime;
else {
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log_very_verbose("%s: stat failed: %s", pf->file,
strerror(errno));
return_0;
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}
if (!(cft = config_open(CONFIG_FILE, pf->file, 1)))
return_0;
if (!config_file_read(cft))
goto_out;
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_read_array(pf, cft, "persistent_filter_cache/valid_devices",
PF_GOOD_DEVICE);
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/* We don't gain anything by holding invalid devices */
/* _read_array(pf, cft, "persistent_filter_cache/invalid_devices",
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PF_BAD_DEVICE); */
/* Did we find anything? */
if (dm_hash_get_num_entries(pf->devices)) {
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/* We populated dev_cache ourselves */
dev_cache_scan(0);
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r = 1;
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}
log_very_verbose("Loaded persistent filter cache from %s", pf->file);
out:
if (r && cft_out)
*cft_out = cft;
else
config_destroy(cft);
return r;
}
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static void _write_array(struct pfilter *pf, FILE *fp, const char *path,
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void *data)
{
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void *d;
int first = 1;
char buf[2 * PATH_MAX];
struct dm_hash_node *n;
for (n = dm_hash_get_first(pf->devices); n;
n = dm_hash_get_next(pf->devices, n)) {
d = dm_hash_get_data(pf->devices, n);
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if (d != data)
continue;
if (!first)
fprintf(fp, ",\n");
else {
fprintf(fp, "\t%s=[\n", path);
first = 0;
}
dm_escape_double_quotes(buf, dm_hash_get_key(pf->devices, n));
fprintf(fp, "\t\t\"%s\"", buf);
}
if (!first)
fprintf(fp, "\n\t]\n");
}
static int _persistent_filter_dump(struct dev_filter *f, int merge_existing)
{
struct pfilter *pf;
char *tmp_file;
struct stat info, info2;
struct dm_config_tree *cft = NULL;
FILE *fp;
int lockfd;
int r = 0;
if (obtain_device_list_from_udev())
return 1;
if (!f)
return_0;
pf = (struct pfilter *) f->private;
if (!dm_hash_get_num_entries(pf->devices)) {
log_very_verbose("Internal persistent device cache empty "
"- not writing to %s", pf->file);
return 0;
}
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if (!dev_cache_has_scanned()) {
log_very_verbose("Device cache incomplete - not writing "
"to %s", pf->file);
return 0;
}
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log_very_verbose("Dumping persistent device cache to %s", pf->file);
while (1) {
if ((lockfd = fcntl_lock_file(pf->file, F_WRLCK, 0)) < 0)
return_0;
/*
* Ensure we locked the file we expected
*/
if (fstat(lockfd, &info)) {
log_sys_error("fstat", pf->file);
goto out;
}
if (stat(pf->file, &info2)) {
log_sys_error("stat", pf->file);
goto out;
}
if (is_same_inode(info, info2))
break;
fcntl_unlock_file(lockfd);
}
/*
* If file contents changed since we loaded it, merge new contents
*/
if (merge_existing && info.st_ctime != pf->ctime)
/* Keep cft open to avoid losing lock */
persistent_filter_load(f, &cft);
tmp_file = alloca(strlen(pf->file) + 5);
sprintf(tmp_file, "%s.tmp", pf->file);
if (!(fp = fopen(tmp_file, "w"))) {
/* EACCES has been reported over NFS */
if (errno != EROFS && errno != EACCES)
log_sys_error("fopen", tmp_file);
goto out;
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}
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fprintf(fp, "# This file is automatically maintained by lvm.\n\n");
fprintf(fp, "persistent_filter_cache {\n");
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_write_array(pf, fp, "valid_devices", PF_GOOD_DEVICE);
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/* We don't gain anything by remembering invalid devices */
/* _write_array(pf, fp, "invalid_devices", PF_BAD_DEVICE); */
fprintf(fp, "}\n");
if (lvm_fclose(fp, tmp_file))
goto_out;
if (rename(tmp_file, pf->file))
log_error("%s: rename to %s failed: %s", tmp_file, pf->file,
strerror(errno));
r = 1;
out:
fcntl_unlock_file(lockfd);
if (cft)
config_destroy(cft);
return r;
}
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static int _lookup_p(struct dev_filter *f, struct device *dev)
{
struct pfilter *pf = (struct pfilter *) f->private;
void *l = dm_hash_lookup(pf->devices, dev_name(dev));
struct str_list *sl;
/* Cached BAD? */
if (l == PF_BAD_DEVICE) {
log_debug_devs("%s: Skipping (cached)", dev_name(dev));
return 0;
}
/* Test dm devices every time, so cache them as GOOD. */
if (MAJOR(dev->dev) == pf->dt->device_mapper_major) {
if (!l)
dm_list_iterate_items(sl, &dev->aliases)
if (!dm_hash_insert(pf->devices, sl->str, PF_GOOD_DEVICE)) {
log_error("Failed to hash device to filter.");
return 0;
}
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if (!device_is_usable(dev)) {
log_debug_devs("%s: Skipping unusable device", dev_name(dev));
return 0;
}
return pf->real->passes_filter(pf->real, dev);
}
/* Uncached */
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if (!l) {
l = pf->real->passes_filter(pf->real, dev) ? PF_GOOD_DEVICE : PF_BAD_DEVICE;
dm_list_iterate_items(sl, &dev->aliases)
if (!dm_hash_insert(pf->devices, sl->str, l)) {
log_error("Failed to hash alias to filter.");
return 0;
}
}
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return (l == PF_BAD_DEVICE) ? 0 : 1;
}
static void _persistent_destroy(struct dev_filter *f)
{
struct pfilter *pf = (struct pfilter *) f->private;
if (f->use_count)
log_error(INTERNAL_ERROR "Destroying persistent filter while in use %u times.", f->use_count);
dm_hash_destroy(pf->devices);
dm_free(pf->file);
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pf->real->destroy(pf->real);
dm_free(pf);
dm_free(f);
}
struct dev_filter *persistent_filter_create(struct dev_types *dt,
struct dev_filter *real,
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const char *file)
{
struct pfilter *pf;
struct dev_filter *f = NULL;
struct stat info;
if (!(pf = dm_zalloc(sizeof(*pf)))) {
log_error("Allocation of persistent filter failed.");
return NULL;
}
pf->dt = dt;
if (!(pf->file = dm_strdup(file))) {
log_error("Filename duplication for persistent filter failed.");
goto bad;
}
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pf->real = real;
if (!(_init_hash(pf))) {
log_error("Couldn't create hash table for persistent filter.");
goto bad;
}
if (!(f = dm_zalloc(sizeof(*f)))) {
log_error("Allocation of device filter for persistent filter failed.");
goto bad;
}
/* Only merge cache file before dumping it if it changed externally. */
if (!stat(pf->file, &info))
pf->ctime = info.st_ctime;
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f->passes_filter = _lookup_p;
f->destroy = _persistent_destroy;
f->use_count = 0;
f->private = pf;
f->wipe = _persistent_filter_wipe;
f->dump = _persistent_filter_dump;
log_debug_devs("Persistent filter initialised.");
return f;
bad:
dm_free(pf->file);
if (pf->devices)
dm_hash_destroy(pf->devices);
dm_free(pf);
dm_free(f);
return NULL;
}