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fix multipath component detection for multiple holders

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sysfs-based multipath component detection quit if a
device had multiple holders, and in this case would
fail to detect a device was an mpath component.
This commit is contained in:
David Teigland 2021-07-09 15:05:11 -05:00
parent deaf43d6f0
commit f8b52f2763
1 changed files with 84 additions and 87 deletions
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171
lib/device/dev-mpath.c
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@ -240,38 +240,6 @@ static int _get_sysfs_dm_mpath(struct dev_types *dt, const char *sysfs_dir, cons
return 0;
}
static int _get_holder_name(const char *dir, char *name, int max_size)
{
struct dirent *d;
DIR *dr;
int r = 0;
if (!(dr = opendir(dir))) {
log_sys_error("opendir", dir);
return 0;
}
*name = '\0';
while ((d = readdir(dr))) {
if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
continue;
/* There should be only one holder if it is multipath */
if (*name) {
r = 0;
break;
}
strncpy(name, d->d_name, max_size);
r = 1;
}
if (closedir(dr))
log_sys_debug("closedir", dir);
return r;
}
#ifdef UDEV_SYNC_SUPPORT
static int _dev_is_mpath_component_udev(struct device *dev)
{
@ -310,15 +278,18 @@ static int _dev_is_mpath_component_sysfs(struct cmd_context *cmd, struct device
const char *name; /* e.g. "sda" for "/dev/sda" */
char link_path[PATH_MAX]; /* some obscure, unpredictable sysfs path */
char holders_path[PATH_MAX]; /* e.g. "/sys/block/sda/holders/" */
char dm_dev_path[PATH_MAX]; /* e.g. "/dev/dm-1" */
char holder_name[256]; /* e.g. "dm-1" */
char dm_dev_path[PATH_MAX]; /* e.g. "/dev/dm-1" */
char *holder_name; /* e.g. "dm-1" */
const char *sysfs_dir = dm_sysfs_dir();
DIR *dr;
struct dirent *de;
int dev_major = MAJOR(dev->dev);
int dev_minor = MINOR(dev->dev);
int dm_dev_major;
int dm_dev_minor;
struct stat info;
dev_t primary_dev;
int is_mpath_component = 0;
/* multipathing is only known to exist for SCSI or NVME devices */
if (!major_is_scsi_device(dt, dev_major) && !dev_is_nvme(dt, dev))
@ -365,70 +336,96 @@ static int _dev_is_mpath_component_sysfs(struct cmd_context *cmd, struct device
}
/*
* If holders dir contains an entry such as "dm-1", then this sets
* holder_name to "dm-1".
*
* If holders dir is empty, return 0 (this is generally where
* devs that are not mpath components return.)
* If any holder is a dm mpath device, then return 1;
*/
if (!_get_holder_name(holders_path, holder_name, sizeof(holder_name)))
return 0;
if (dm_snprintf(dm_dev_path, sizeof(dm_dev_path), "%s/%s", cmd->dev_dir, holder_name) < 0) {
log_warn("dm device path to check mpath is too long.");
if (!(dr = opendir(holders_path))) {
log_debug("Device %s has no holders dir", dev_name(dev));
return 0;
}
/*
* stat "/dev/dm-1" which is the holder of the dev we're checking
* dm_dev_major:dm_dev_minor come from stat("/dev/dm-1")
*/
if (stat(dm_dev_path, &info)) {
log_debug_devs("dev_is_mpath_component %s holder %s stat result %d",
dev_name(dev), dm_dev_path, errno);
return 0;
}
dm_dev_major = (int)MAJOR(info.st_rdev);
dm_dev_minor = (int)MINOR(info.st_rdev);
if (dm_dev_major != dt->device_mapper_major) {
log_debug_devs("dev_is_mpath_component %s holder %s %d:%d does not have dm major",
dev_name(dev), dm_dev_path, dm_dev_major, dm_dev_minor);
return 0;
}
while ((de = readdir(dr))) {
if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, ".."))
continue;
/*
* Save the result of checking that "/dev/dm-1" is an mpath device
* to avoid repeating it for each path component.
* The minor number of "/dev/dm-1" is added to the hash table with
* const value 2 meaning that dm minor 1 (for /dev/dm-1) is a multipath dev
* and const value 1 meaning that dm minor 1 is not a multipath dev.
*/
if (_minor_hash_tab) {
long look = (long) dm_hash_lookup_binary(_minor_hash_tab, &dm_dev_minor, sizeof(dm_dev_minor));
if (look > 0) {
log_debug_devs("dev_is_mpath_component %s holder %s %u:%u already checked as %sbeing mpath.",
dev_name(dev), holder_name, dm_dev_major, dm_dev_minor, (look > 1) ? "" : "not ");
return (look > 1) ? 1 : 0;
/*
* holder_name is e.g. "dm-1"
* dm_dev_path is then e.g. "/dev/dm-1"
*/
holder_name = de->d_name;
if (dm_snprintf(dm_dev_path, sizeof(dm_dev_path), "%s/%s", cmd->dev_dir, holder_name) < 0) {
log_warn("dm device path to check mpath is too long.");
continue;
}
}
/*
* Returns 1 if /sys/block/<holder_name>/dm/uuid indicates that
* <holder_name> is a dm device with dm uuid prefix mpath-.
* When true, <holder_name> will be something like "dm-1".
*/
if (_get_sysfs_dm_mpath(dt, sysfs_dir, holder_name)) {
log_debug_devs("dev_is_mpath_component %s holder %s %u:%u ignore mpath component",
dev_name(dev), holder_name, dm_dev_major, dm_dev_minor);
/*
* stat "/dev/dm-1" which is the holder of the dev we're checking
* dm_dev_major:dm_dev_minor come from stat("/dev/dm-1")
*/
if (stat(dm_dev_path, &info)) {
log_debug_devs("dev_is_mpath_component %s holder %s stat result %d",
dev_name(dev), dm_dev_path, errno);
continue;
}
dm_dev_major = (int)MAJOR(info.st_rdev);
dm_dev_minor = (int)MINOR(info.st_rdev);
if (dm_dev_major != dt->device_mapper_major) {
log_debug_devs("dev_is_mpath_component %s holder %s %d:%d does not have dm major",
dev_name(dev), dm_dev_path, dm_dev_major, dm_dev_minor);
continue;
}
/*
* A previous call may have checked if dm_dev_minor is mpath and saved
* the result in the hash table. If there's a saved result just use that.
*
* The minor number of "/dev/dm-1" is added to the hash table with
* const value 2 meaning that dm minor 1 (for /dev/dm-1) is a multipath dev
* and const value 1 meaning that dm minor 1 is not a multipath dev.
*/
if (_minor_hash_tab) {
long look = (long) dm_hash_lookup_binary(_minor_hash_tab, &dm_dev_minor, sizeof(dm_dev_minor));
if (look > 0) {
log_debug_devs("dev_is_mpath_component %s holder %s %u:%u already checked as %sbeing mpath.",
dev_name(dev), holder_name, dm_dev_major, dm_dev_minor, (look > 1) ? "" : "not ");
is_mpath_component = (look == 2);
goto out;
}
/* no saved result for dm_dev_minor, so check the uuid for it */
}
/*
* Returns 1 if /sys/block/<holder_name>/dm/uuid indicates that
* <holder_name> is a dm device with dm uuid prefix mpath-.
* When true, <holder_name> will be something like "dm-1".
*/
if (_get_sysfs_dm_mpath(dt, sysfs_dir, holder_name)) {
log_debug_devs("dev_is_mpath_component %s holder %s %u:%u ignore mpath component",
dev_name(dev), holder_name, dm_dev_major, dm_dev_minor);
/* For future checks, save that the dm minor refers to mpath ("2" == is mpath) */
if (_minor_hash_tab)
(void) dm_hash_insert_binary(_minor_hash_tab, &dm_dev_minor, sizeof(dm_dev_minor), (void*)2);
is_mpath_component = 1;
goto out;
}
/* For future checks, save that the dm minor does not refer to mpath ("1" == is not mpath) */
if (_minor_hash_tab)
(void) dm_hash_insert_binary(_minor_hash_tab, &dm_dev_minor, sizeof(dm_dev_minor), (void*)2);
return 1;
(void) dm_hash_insert_binary(_minor_hash_tab, &dm_dev_minor, sizeof(dm_dev_minor), (void*)1);
}
if (_minor_hash_tab)
(void) dm_hash_insert_binary(_minor_hash_tab, &dm_dev_minor, sizeof(dm_dev_minor), (void*)1);
return 0;
out:
if (closedir(dr))
stack;
return is_mpath_component;
}
static int _dev_in_wwid_file(struct cmd_context *cmd, struct device *dev)