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#ifndef CHECKERS_H_INCLUDED
#define CHECKERS_H_INCLUDED
#include <pthread.h>
#include <stdbool.h>
#include "list.h"
#include "defaults.h"
/*
*
* Userspace (multipath/multipathd) path states
*
* PATH_WILD:
* - Use: Any checker
* - Description: Corner case where "fd < 0" for path fd (see checker_check()),
* or where a checker detects an unsupported device
* (e.g. wrong checker configured for a given device).
*
* PATH_UNCHECKED:
* - Use: Only in directio checker
* - Description: set when fcntl(F_GETFL) fails to return flags or O_DIRECT
* not include in flags, or O_DIRECT read fails
* - Notes:
* - multipathd: uses it to skip over paths in sync_map_state()
* - multipath: used in update_paths(); if state==PATH_UNCHECKED, call
* pathinfo()
*
* PATH_DOWN:
* - Use: All checkers (directio, emc_clariion, hp_sw, readsector0, tur)
* - Description: Either a) SG_IO ioctl failed, or b) check condition on some
* SG_IO ioctls that succeed (tur, readsector0 checkers); path is down and
* you shouldn't try to send commands to it
*
* PATH_UP:
* - Use: All checkers (directio, emc_clariion, hp_sw, readsector0, tur)
* - Description: Path is up and I/O can be sent to it
*
* PATH_SHAKY:
* - Use: Only emc_clariion
* - Description: Indicates path not available for "normal" operations
*
* PATH_GHOST:
* - Use: Only hp_sw and rdac
* - Description: Indicates a "passive/standby" path on active/passive HP
* arrays. These paths will return valid answers to certain SCSI commands
* (tur, read_capacity, inquiry, start_stop), but will fail I/O commands.
* The path needs an initialization command to be sent to it in order for
* I/Os to succeed.
*
* PATH_PENDING:
* - Use: All async checkers
* - Description: Indicates a check IO is in flight.
*
* PATH_TIMEOUT:
* - Use: Only tur checker
* - Description: Command timed out
*
* PATH REMOVED:
* - Use: All checkers
* - Description: Device has been removed from the system
*
* PATH_DELAYED:
* - Use: None of the checkers (returned if the path is being delayed before
* reintegration.
* - Description: If a path fails after being up for less than
* delay_watch_checks checks, when it comes back up again, it will not
* be marked as up until it has been up for delay_wait_checks checks.
* During this time, it is marked as "delayed"
*
* PATH_DISCONNECTED is a special ephemeral state used to signal that a path
* has been disconnected at the storage target (e.g., LUN unmapped). When a
* checker returns PATH_DISCONNECTED:
* 1. The path's pp->disconnected field is set to track purge state
* 2. The state is immediately converted to PATH_DOWN for normal processing
* 3. If purge_disconnected is enabled, the path will be removed via sysfs
* This state should never be stored in pp->state or pp->chkrstate; it exists
* only as a transient return value from checkers to trigger special handling.
*/
enum path_check_state {
PATH_WILD = 0,
PATH_UNCHECKED,
PATH_DOWN,
PATH_UP,
PATH_SHAKY,
PATH_GHOST,
PATH_PENDING,
PATH_TIMEOUT,
PATH_REMOVED,
PATH_DELAYED,
PATH_DISCONNECTED, /* Ephemeral: mapped to PATH_DOWN */
PATH_MAX_STATE
};
#define DIRECTIO "directio"
#define TUR "tur"
#define HP_SW "hp_sw"
#define RDAC "rdac"
#define EMC_CLARIION "emc_clariion"
#define READSECTOR0 "readsector0"
#define CCISS_TUR "cciss_tur"
#define NONE "none"
#define INVALID "invalid"
#define ASYNC_TIMEOUT_SEC 30
/*
* strings lengths
*/
#define CHECKER_NAME_LEN 16
#define CHECKER_MSG_LEN 256
#define CHECKER_DEV_LEN 256
#define LIB_CHECKER_NAMELEN 256
/*
* Generic message IDs for use in checkers.
*/
enum {
CHECKER_MSGID_NONE = 0,
CHECKER_MSGID_DISABLED,
CHECKER_MSGID_NO_FD,
CHECKER_MSGID_INVALID,
CHECKER_MSGID_UP,
CHECKER_MSGID_DOWN,
CHECKER_MSGID_GHOST,
CHECKER_MSGID_UNSUPPORTED,
CHECKER_MSGID_DISCONNECTED,
CHECKER_GENERIC_MSGTABLE_SIZE,
CHECKER_FIRST_MSGID = 100, /* lowest msgid for checkers */
CHECKER_MSGTABLE_SIZE = 100, /* max msg table size for checkers */
};
struct checker_class;
struct checker {
struct checker_class *cls;
int fd;
unsigned int timeout;
int disable;
int path_state;
short msgid; /* checker-internal extra status */
void * context; /* store for persistent data */
void ** mpcontext; /* store for persistent data shared
multipath-wide. */
};
static inline int checker_selected(const struct checker *c)
{
return c != NULL && c->cls != NULL;
}
const char *checker_state_name(int);
int init_checkers(void);
void cleanup_checkers (void);
int checker_init (struct checker *, void **);
int checker_mp_init(struct checker *, void **);
void checker_clear (struct checker *);
void checker_put (struct checker *);
void checker_reset (struct checker *);
void checker_set_sync (struct checker *);
void checker_set_async (struct checker *);
void checker_set_fd (struct checker *, int);
void checker_enable (struct checker *);
void checker_disable (struct checker *);
/*
* start_checker_thread(): start async path checker thread
*
* This function provides a wrapper around pthread_create().
* The created thread will call the DSO's "libcheck_thread" function with the
* checker context as argument.
*
* Rationale:
* Path checkers that do I/O may hang forever. To avoid blocking, some
* checkers therefore use asynchronous, detached threads for checking
* the paths. These threads may continue hanging if multipathd is stopped.
* In this case, we can't unload the checker DSO at exit. In order to
* avoid race conditions and crashes, the entry point of the thread
* needs to be in libmultipath, not in the DSO itself.
*
* @param arg: pointer to struct checker_context.
*/
struct checker_context {
struct checker_class *cls;
};
int start_checker_thread (pthread_t *thread, const pthread_attr_t *attr,
struct checker_context *ctx);
int checker_get_state(struct checker *c);
bool checker_need_wait(struct checker *c);
void checker_check (struct checker *, int);
int checker_is_sync(const struct checker *);
const char *checker_name (const struct checker *);
void reset_checker_classes(void);
/*
* This returns a string that's best prepended with "$NAME checker",
* where $NAME is the return value of checker_name().
*/
const char *checker_message(const struct checker *);
void checker_clear_message (struct checker *c);
void checker_get(struct checker *, const char *);
/* Prototypes for symbols exported by path checker dynamic libraries (.so) */
int libcheck_check(struct checker *);
int libcheck_init(struct checker *);
void libcheck_free(struct checker *);
void *libcheck_thread(struct checker_context *ctx);
void libcheck_reset(void);
int libcheck_mp_init(struct checker *);
int libcheck_pending(struct checker *c);
bool libcheck_need_wait(struct checker *c);
/*
* msgid => message map.
*
* It only needs to be provided if the checker defines specific
* message IDs.
* Message IDs available to checkers start at CHECKER_FIRST_MSG.
* The msgtable array is 0-based, i.e. msgtable[0] is the message
* for msgid == CHECKER_FIRST_MSG.
* The table ends with a NULL element.
*/
extern const char *libcheck_msgtable[];
#endif /* CHECKERS_H_INCLUDED */
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