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freebsd-skq/sys/geom/sched/g_sched.c
pfg b63211eed5 Cleanup unnecessary semicolons from the kernel. 
Found with devel/coccinelle.
2016-04-10 23:07:00 +00:00

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/*-
* Copyright (c) 2009-2010 Fabio Checconi
* Copyright (c) 2009-2010 Luigi Rizzo, Universita` di Pisa
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* $Id$
* $FreeBSD$
*
* Main control module for geom-based disk schedulers ('sched').
*
* USER VIEW
* A 'sched' node is typically inserted transparently between
* an existing provider pp and its original geom gp
*
* [pp --> gp ..]
*
* using the command "geom sched insert <provider>" and
* resulting in the following topology
*
* [pp --> sched_gp --> cp] [new_pp --> gp ... ]
*
* Deletion "geom sched destroy <provider>.sched." restores the
* original chain. The normal "geom sched create <provide>"
* is also supported.
*
* INTERNALS
* Internally, the 'sched' uses the following data structures
*
* geom{} g_sched_softc{} g_gsched{}
* +----------+ +---------------+ +-------------+
* | softc *-|--->| sc_gsched *-|-->| gs_init |
* | ... | | | | gs_fini |
* | | | [ hash table] | | gs_start |
* +----------+ | | | ... |
* | | +-------------+
* | |
* | | g_*_softc{}
* | | +-------------+
* | sc_data *-|-->| |
* +---------------+ | algorithm- |
* | specific |
* +-------------+
*
* A g_sched_softc{} is created with a "geom sched insert" call.
* In turn this instantiates a specific scheduling algorithm,
* which sets sc_gsched to point to the algorithm callbacks,
* and calls gs_init() to create the g_*_softc{} .
* The other callbacks (gs_start, gs_next, ...) are invoked
* as needed
*
* g_sched_softc{} is defined in g_sched.h and mostly used here;
* g_gsched{}, and the gs_callbacks, are documented in gs_scheduler.h;
* g_*_softc{} is defined/implemented by each algorithm (gs_*.c)
*
* DATA MOVING
* When a bio is received on the provider, it goes to the
* g_sched_start() which calls gs_start() to initially queue it;
* then we call g_sched_dispatch() that loops around gs_next()
* to select zero or more bio's to be sent downstream.
*
* g_sched_dispatch() can also be called as a result of a timeout,
* e.g. when doing anticipation or pacing requests.
*
* When a bio comes back, it goes to g_sched_done() which in turn
* calls gs_done(). The latter does any necessary housekeeping in
* the scheduling algorithm, and may decide to call g_sched_dispatch()
* to send more bio's downstream.
*
* If an algorithm needs per-flow queues, these are created
* calling gs_init_class() and destroyed with gs_fini_class(),
* and they are also inserted in the hash table implemented in
* the g_sched_softc{}
*
* If an algorithm is replaced, or a transparently-inserted node is
* removed with "geom sched destroy", we need to remove all references
* to the g_*_softc{} and g_sched_softc from the bio's still in
* the scheduler. g_sched_forced_dispatch() helps doing this.
* XXX need to explain better.
*/
#include <sys/cdefs.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/bio.h>
#include <sys/limits.h>
#include <sys/hash.h>
#include <sys/sbuf.h>
#include <sys/sysctl.h>
#include <sys/malloc.h>
#include <sys/proc.h> /* we access curthread */
#include <geom/geom.h>
#include "gs_scheduler.h"
#include "g_sched.h" /* geom hooks */
/*
* Size of the per-geom hash table storing traffic classes.
* We may decide to change it at a later time, it has no ABI
* implications as it is only used for run-time allocations.
*/
#define G_SCHED_HASH_SIZE 32
static int g_sched_destroy(struct g_geom *gp, boolean_t force);
static int g_sched_destroy_geom(struct gctl_req *req,
struct g_class *mp, struct g_geom *gp);
static void g_sched_config(struct gctl_req *req, struct g_class *mp,
const char *verb);
static struct g_geom *g_sched_taste(struct g_class *mp,
struct g_provider *pp, int flags __unused);
static void g_sched_dumpconf(struct sbuf *sb, const char *indent,
struct g_geom *gp, struct g_consumer *cp, struct g_provider *pp);
static void g_sched_init(struct g_class *mp);
static void g_sched_fini(struct g_class *mp);
static int g_sched_ioctl(struct g_provider *pp, u_long cmd, void *data,
int fflag, struct thread *td);
struct g_class g_sched_class = {
.name = G_SCHED_CLASS_NAME,
.version = G_VERSION,
.ctlreq = g_sched_config,
.taste = g_sched_taste,
.destroy_geom = g_sched_destroy_geom,
.init = g_sched_init,
.ioctl = g_sched_ioctl,
.fini = g_sched_fini
};
MALLOC_DEFINE(M_GEOM_SCHED, "GEOM_SCHED", "Geom schedulers data structures");
/*
* Global variables describing the state of the geom_sched module.
* There is only one static instance of this structure.
*/
LIST_HEAD(gs_list, g_gsched); /* type, link field */
struct geom_sched_vars {
struct mtx gs_mtx;
struct gs_list gs_scheds; /* list of algorithms */
u_int gs_debug;
u_int gs_sched_count; /* how many algorithms ? */
u_int gs_patched; /* g_io_request was patched */
u_int gs_initialized;
u_int gs_expire_secs; /* expiration of hash entries */
struct bio_queue_head gs_pending;
u_int gs_npending;
/* The following are for stats, usually protected by gs_mtx. */
u_long gs_requests; /* total requests */
u_long gs_done; /* total done */
u_int gs_in_flight; /* requests in flight */
u_int gs_writes_in_flight;
u_int gs_bytes_in_flight;
u_int gs_write_bytes_in_flight;
char gs_names[256]; /* names of schedulers */
};
static struct geom_sched_vars me = {
.gs_expire_secs = 10,
};
SYSCTL_DECL(_kern_geom);
SYSCTL_NODE(_kern_geom, OID_AUTO, sched, CTLFLAG_RW, 0,
"GEOM_SCHED stuff");
SYSCTL_UINT(_kern_geom_sched, OID_AUTO, in_flight_wb, CTLFLAG_RD,
&me.gs_write_bytes_in_flight, 0, "Write bytes in flight");
SYSCTL_UINT(_kern_geom_sched, OID_AUTO, in_flight_b, CTLFLAG_RD,
&me.gs_bytes_in_flight, 0, "Bytes in flight");
SYSCTL_UINT(_kern_geom_sched, OID_AUTO, in_flight_w, CTLFLAG_RD,
&me.gs_writes_in_flight, 0, "Write Requests in flight");
SYSCTL_UINT(_kern_geom_sched, OID_AUTO, in_flight, CTLFLAG_RD,
&me.gs_in_flight, 0, "Requests in flight");
SYSCTL_ULONG(_kern_geom_sched, OID_AUTO, done, CTLFLAG_RD,
&me.gs_done, 0, "Total done");
SYSCTL_ULONG(_kern_geom_sched, OID_AUTO, requests, CTLFLAG_RD,
&me.gs_requests, 0, "Total requests");
SYSCTL_STRING(_kern_geom_sched, OID_AUTO, algorithms, CTLFLAG_RD,
&me.gs_names, 0, "Algorithm names");
SYSCTL_UINT(_kern_geom_sched, OID_AUTO, alg_count, CTLFLAG_RD,
&me.gs_sched_count, 0, "Number of algorithms");
SYSCTL_UINT(_kern_geom_sched, OID_AUTO, debug, CTLFLAG_RW,
&me.gs_debug, 0, "Debug level");
SYSCTL_UINT(_kern_geom_sched, OID_AUTO, expire_secs, CTLFLAG_RW,
&me.gs_expire_secs, 0, "Expire time in seconds");
/*
* g_sched calls the scheduler algorithms with this lock held.
* The locking functions are exposed so the scheduler algorithms can also
* protect themselves e.g. when running a callout handler.
*/
void
g_sched_lock(struct g_geom *gp)
{
struct g_sched_softc *sc = gp->softc;
mtx_lock(&sc->sc_mtx);
}
void
g_sched_unlock(struct g_geom *gp)
{
struct g_sched_softc *sc = gp->softc;
mtx_unlock(&sc->sc_mtx);
}
/*
* Support functions to handle references to the module,
* which are coming from devices using this scheduler.
*/
static inline void
g_gsched_ref(struct g_gsched *gsp)
{
atomic_add_int(&gsp->gs_refs, 1);
}
static inline void
g_gsched_unref(struct g_gsched *gsp)
{
atomic_add_int(&gsp->gs_refs, -1);
}
/*
* Update the stats when this request is done.
*/
static void
g_sched_update_stats(struct bio *bio)
{
me.gs_done++;
me.gs_in_flight--;
me.gs_bytes_in_flight -= bio->bio_length;
if (bio->bio_cmd == BIO_WRITE) {
me.gs_writes_in_flight--;
me.gs_write_bytes_in_flight -= bio->bio_length;
}
}
/*
* Dispatch any pending request.
*/
static void
g_sched_forced_dispatch(struct g_geom *gp)
{
struct g_sched_softc *sc = gp->softc;
struct g_gsched *gsp = sc->sc_gsched;
struct bio *bp;
KASSERT(mtx_owned(&sc->sc_mtx),
("sc_mtx not owned during forced dispatch"));
while ((bp = gsp->gs_next(sc->sc_data, 1)) != NULL)
g_io_request(bp, LIST_FIRST(&gp->consumer));
}
/*
* The main dispatch loop, called either here after the start
* routine, or by scheduling algorithms when they receive a timeout
* or a 'done' notification. Does not share code with the forced
* dispatch path, since the gs_done() callback can call us.
*/
void
g_sched_dispatch(struct g_geom *gp)
{
struct g_sched_softc *sc = gp->softc;
struct g_gsched *gsp = sc->sc_gsched;
struct bio *bp;
KASSERT(mtx_owned(&sc->sc_mtx), ("sc_mtx not owned during dispatch"));
if ((sc->sc_flags & G_SCHED_FLUSHING))
return;
while ((bp = gsp->gs_next(sc->sc_data, 0)) != NULL)
g_io_request(bp, LIST_FIRST(&gp->consumer));
}
/*
* Recent (8.0 and above) versions of FreeBSD have support to
* register classifiers of disk requests. The classifier is
* invoked by g_io_request(), and stores the information into
* bp->bio_classifier1.
*
* Support for older versions, which is left here only for
* documentation purposes, relies on two hacks:
* 1. classification info is written into the bio_caller1
* field of the topmost node in the bio chain. This field
* is rarely used, but this module is incompatible with
* those that use bio_caller1 for other purposes,
* such as ZFS and gjournal;
* 2. g_io_request() is patched in-memory when the module is
* loaded, so that the function calls a classifier as its
* first thing. g_io_request() is restored when the module
* is unloaded. This functionality is only supported for
* x86 and amd64, other architectures need source code changes.
*/
/*
* Lookup the identity of the issuer of the original request.
* In the current implementation we use the curthread of the
* issuer, but different mechanisms may be implemented later
* so we do not make assumptions on the return value which for
* us is just an opaque identifier.
*/
static inline u_long
g_sched_classify(struct bio *bp)
{
/* we have classifier fields in the struct bio */
return ((u_long)bp->bio_classifier1);
}
/* Return the hash chain for the given key. */
static inline struct g_hash *
g_sched_hash(struct g_sched_softc *sc, u_long key)
{
return (&sc->sc_hash[key & sc->sc_mask]);
}
/*
* Helper function for the children classes, which takes
* a geom and a bio and returns the private descriptor
* associated to the request. This involves fetching
* the classification field and [al]locating the
* corresponding entry in the hash table.
*/
void *
g_sched_get_class(struct g_geom *gp, struct bio *bp)
{
struct g_sched_softc *sc;
struct g_sched_class *gsc;
struct g_gsched *gsp;
struct g_hash *bucket;
u_long key;
sc = gp->softc;
key = g_sched_classify(bp);
bucket = g_sched_hash(sc, key);
LIST_FOREACH(gsc, bucket, gsc_clist) {
if (key == gsc->gsc_key) {
gsc->gsc_refs++;
return (gsc->gsc_priv);
}
}
gsp = sc->sc_gsched;
gsc = malloc(sizeof(*gsc) + gsp->gs_priv_size,
M_GEOM_SCHED, M_NOWAIT | M_ZERO);
if (!gsc)
return (NULL);
if (gsp->gs_init_class(sc->sc_data, gsc->gsc_priv)) {
free(gsc, M_GEOM_SCHED);
return (NULL);
}
gsc->gsc_refs = 2; /* 1 for the hash table, 1 for the caller. */
gsc->gsc_key = key;
LIST_INSERT_HEAD(bucket, gsc, gsc_clist);
gsc->gsc_expire = ticks + me.gs_expire_secs * hz;
return (gsc->gsc_priv);
}
/*
* Release a reference to the per-client descriptor,
*/
void
g_sched_put_class(struct g_geom *gp, void *priv)
{
struct g_sched_class *gsc;
struct g_sched_softc *sc;
gsc = g_sched_priv2class(priv);
gsc->gsc_expire = ticks + me.gs_expire_secs * hz;
if (--gsc->gsc_refs > 0)
return;
sc = gp->softc;
sc->sc_gsched->gs_fini_class(sc->sc_data, priv);
LIST_REMOVE(gsc, gsc_clist);
free(gsc, M_GEOM_SCHED);
}
static void
g_sched_hash_fini(struct g_geom *gp, struct g_hash *hp, u_long mask,
struct g_gsched *gsp, void *data)
{
struct g_sched_class *cp, *cp2;
int i;
if (!hp)
return;
if (data && gsp->gs_hash_unref)
gsp->gs_hash_unref(data);
for (i = 0; i < G_SCHED_HASH_SIZE; i++) {
LIST_FOREACH_SAFE(cp, &hp[i], gsc_clist, cp2)
g_sched_put_class(gp, cp->gsc_priv);
}
hashdestroy(hp, M_GEOM_SCHED, mask);
}
static struct g_hash *
g_sched_hash_init(struct g_gsched *gsp, u_long *mask, int flags)
{
struct g_hash *hash;
if (gsp->gs_priv_size == 0)
return (NULL);
hash = hashinit_flags(G_SCHED_HASH_SIZE, M_GEOM_SCHED, mask, flags);
return (hash);
}
static void
g_sched_flush_classes(struct g_geom *gp)
{
struct g_sched_softc *sc;
struct g_sched_class *cp, *cp2;
int i;
sc = gp->softc;
if (!sc->sc_hash || ticks - sc->sc_flush_ticks <= 0)
return;
for (i = 0; i < G_SCHED_HASH_SIZE; i++) {
LIST_FOREACH_SAFE(cp, &sc->sc_hash[i], gsc_clist, cp2) {
if (cp->gsc_refs == 1 && ticks - cp->gsc_expire > 0)
g_sched_put_class(gp, cp->gsc_priv);
}
}
sc->sc_flush_ticks = ticks + me.gs_expire_secs * hz;
}
/*
* Wait for the completion of any outstanding request. To ensure
* that this does not take forever the caller has to make sure that
* no new request enter the scehduler before calling us.
*
* Must be called with the gp mutex held and topology locked.
*/
static int
g_sched_wait_pending(struct g_geom *gp)
{
struct g_sched_softc *sc = gp->softc;
int endticks = ticks + hz;
g_topology_assert();
while (sc->sc_pending && endticks - ticks >= 0)
msleep(gp, &sc->sc_mtx, 0, "sched_wait_pending", hz / 4);
return (sc->sc_pending ? ETIMEDOUT : 0);
}
static int
g_sched_remove_locked(struct g_geom *gp, struct g_gsched *gsp)
{
struct g_sched_softc *sc = gp->softc;
int error;
/* Set the flushing flag: new bios will not enter the scheduler. */
sc->sc_flags |= G_SCHED_FLUSHING;
g_sched_forced_dispatch(gp);
error = g_sched_wait_pending(gp);
if (error)
goto failed;
/* No more requests pending or in flight from the old gsp. */
g_sched_hash_fini(gp, sc->sc_hash, sc->sc_mask, gsp, sc->sc_data);
sc->sc_hash = NULL;
/*
* Avoid deadlock here by releasing the gp mutex and reacquiring
* it once done. It should be safe, since no reconfiguration or
* destruction can take place due to the geom topology lock; no
* new request can use the current sc_data since we flagged the
* geom as being flushed.
*/
g_sched_unlock(gp);
gsp->gs_fini(sc->sc_data);
g_sched_lock(gp);
sc->sc_gsched = NULL;
sc->sc_data = NULL;
g_gsched_unref(gsp);
failed:
sc->sc_flags &= ~G_SCHED_FLUSHING;
return (error);
}
static int
g_sched_remove(struct g_geom *gp, struct g_gsched *gsp)
{
int error;
g_sched_lock(gp);
error = g_sched_remove_locked(gp, gsp); /* gsp is surely non-null */
g_sched_unlock(gp);
return (error);
}
/*
* Support function for create/taste -- locate the desired
* algorithm and grab a reference to it.
*/
static struct g_gsched *
g_gsched_find(const char *name)
{
struct g_gsched *gsp = NULL;
mtx_lock(&me.gs_mtx);
LIST_FOREACH(gsp, &me.gs_scheds, glist) {
if (strcmp(name, gsp->gs_name) == 0) {
g_gsched_ref(gsp);
break;
}
}
mtx_unlock(&me.gs_mtx);
return (gsp);
}
/*
* Rebuild the list of scheduler names.
* To be called with me.gs_mtx lock held.
*/
static void
g_gsched_build_names(struct g_gsched *gsp)
{
int pos, l;
struct g_gsched *cur;
pos = 0;
LIST_FOREACH(cur, &me.gs_scheds, glist) {
l = strlen(cur->gs_name);
if (l + pos + 1 + 1 < sizeof(me.gs_names)) {
if (pos != 0)
me.gs_names[pos++] = ' ';
strcpy(me.gs_names + pos, cur->gs_name);
pos += l;
}
}
me.gs_names[pos] = '\0';
}
/*
* Register or unregister individual scheduling algorithms.
*/
static int
g_gsched_register(struct g_gsched *gsp)
{
struct g_gsched *cur;
int error = 0;
mtx_lock(&me.gs_mtx);
LIST_FOREACH(cur, &me.gs_scheds, glist) {
if (strcmp(gsp->gs_name, cur->gs_name) == 0)
break;
}
if (cur != NULL) {
G_SCHED_DEBUG(0, "A scheduler named %s already"
"exists.", gsp->gs_name);
error = EEXIST;
} else {
LIST_INSERT_HEAD(&me.gs_scheds, gsp, glist);
gsp->gs_refs = 1;
me.gs_sched_count++;
g_gsched_build_names(gsp);
}
mtx_unlock(&me.gs_mtx);
return (error);
}
struct g_gsched_unregparm {
struct g_gsched *gup_gsp;
int gup_error;
};
static void
g_gsched_unregister(void *arg, int flag)
{
struct g_gsched_unregparm *parm = arg;
struct g_gsched *gsp = parm->gup_gsp, *cur, *tmp;
struct g_sched_softc *sc;
struct g_geom *gp, *gp_tmp;
int error;
parm->gup_error = 0;
g_topology_assert();
if (flag == EV_CANCEL)
return;
mtx_lock(&me.gs_mtx);
LIST_FOREACH_SAFE(gp, &g_sched_class.geom, geom, gp_tmp) {
if (gp->class != &g_sched_class)
continue; /* Should not happen. */
sc = gp->softc;
if (sc->sc_gsched == gsp) {
error = g_sched_remove(gp, gsp);
if (error)
goto failed;
}
}
LIST_FOREACH_SAFE(cur, &me.gs_scheds, glist, tmp) {
if (cur != gsp)
continue;
if (gsp->gs_refs != 1) {
G_SCHED_DEBUG(0, "%s still in use.",
gsp->gs_name);
parm->gup_error = EBUSY;
} else {
LIST_REMOVE(gsp, glist);
me.gs_sched_count--;
g_gsched_build_names(gsp);
}
break;
}
if (cur == NULL) {
G_SCHED_DEBUG(0, "%s not registered.", gsp->gs_name);
parm->gup_error = ENOENT;
}
failed:
mtx_unlock(&me.gs_mtx);
}
static inline void
g_gsched_global_init(void)
{
if (!me.gs_initialized) {
G_SCHED_DEBUG(0, "Initializing global data.");
mtx_init(&me.gs_mtx, "gsched", NULL, MTX_DEF);
LIST_INIT(&me.gs_scheds);
bioq_init(&me.gs_pending);
me.gs_initialized = 1;
}
}
/*
* Module event called when a scheduling algorithm module is loaded or
* unloaded.
*/
int
g_gsched_modevent(module_t mod, int cmd, void *arg)
{
struct g_gsched *gsp = arg;
struct g_gsched_unregparm parm;
int error;
G_SCHED_DEBUG(0, "Modevent %d.", cmd);
/*
* If the module is loaded at boot, the geom thread that calls
* g_sched_init() might actually run after g_gsched_modevent(),
* so make sure that the module is properly initialized.
*/
g_gsched_global_init();
error = EOPNOTSUPP;
switch (cmd) {
case MOD_LOAD:
error = g_gsched_register(gsp);
G_SCHED_DEBUG(0, "Loaded module %s error %d.",
gsp->gs_name, error);
if (error == 0)
g_retaste(&g_sched_class);
break;
case MOD_UNLOAD:
parm.gup_gsp = gsp;
parm.gup_error = 0;
error = g_waitfor_event(g_gsched_unregister,
&parm, M_WAITOK, NULL);
if (error == 0)
error = parm.gup_error;
G_SCHED_DEBUG(0, "Unloaded module %s error %d.",
gsp->gs_name, error);
break;
}
return (error);
}
#ifdef KTR
#define TRC_BIO_EVENT(e, bp) g_sched_trace_bio_ ## e (bp)
static inline char
g_sched_type(struct bio *bp)
{
if (bp->bio_cmd == BIO_READ)
return ('R');
else if (bp->bio_cmd == BIO_WRITE)
return ('W');
return ('U');
}
static inline void
g_sched_trace_bio_START(struct bio *bp)
{
CTR5(KTR_GSCHED, "S %lu %c %lu/%lu %lu", g_sched_classify(bp),
g_sched_type(bp), bp->bio_offset / ULONG_MAX,
bp->bio_offset, bp->bio_length);
}
static inline void
g_sched_trace_bio_DONE(struct bio *bp)
{
CTR5(KTR_GSCHED, "D %lu %c %lu/%lu %lu", g_sched_classify(bp),
g_sched_type(bp), bp->bio_offset / ULONG_MAX,
bp->bio_offset, bp->bio_length);
}
#else /* !KTR */
#define TRC_BIO_EVENT(e, bp)
#endif /* !KTR */
/*
* g_sched_done() and g_sched_start() dispatch the geom requests to
* the scheduling algorithm in use.
*/
static void
g_sched_done(struct bio *bio)
{
struct g_geom *gp = bio->bio_caller2;
struct g_sched_softc *sc = gp->softc;
TRC_BIO_EVENT(DONE, bio);
KASSERT(bio->bio_caller1, ("null bio_caller1 in g_sched_done"));
g_sched_lock(gp);
g_sched_update_stats(bio);
sc->sc_gsched->gs_done(sc->sc_data, bio);
if (!--sc->sc_pending)
wakeup(gp);
g_sched_flush_classes(gp);
g_sched_unlock(gp);
g_std_done(bio);
}
static void
g_sched_start(struct bio *bp)
{
struct g_geom *gp = bp->bio_to->geom;
struct g_sched_softc *sc = gp->softc;
struct bio *cbp;
TRC_BIO_EVENT(START, bp);
G_SCHED_LOGREQ(bp, "Request received.");
cbp = g_clone_bio(bp);
if (cbp == NULL) {
g_io_deliver(bp, ENOMEM);
return;
}
cbp->bio_done = g_sched_done;
cbp->bio_to = LIST_FIRST(&gp->provider);
KASSERT(cbp->bio_to != NULL, ("NULL provider"));
/* We only schedule reads and writes. */
if (bp->bio_cmd != BIO_READ && bp->bio_cmd != BIO_WRITE)
goto bypass;
G_SCHED_LOGREQ(cbp, "Sending request.");
g_sched_lock(gp);
/*
* Call the algorithm's gs_start to queue the request in the
* scheduler. If gs_start fails then pass the request down,
* otherwise call g_sched_dispatch() which tries to push
* one or more requests down.
*/
if (!sc->sc_gsched || (sc->sc_flags & G_SCHED_FLUSHING) ||
sc->sc_gsched->gs_start(sc->sc_data, cbp)) {
g_sched_unlock(gp);
goto bypass;
}
/*
* We use bio_caller1 to mark requests that are scheduled
* so make sure it is not NULL.
*/
if (cbp->bio_caller1 == NULL)
cbp->bio_caller1 = &me; /* anything not NULL */
cbp->bio_caller2 = gp;
sc->sc_pending++;
/* Update general stats. */
me.gs_in_flight++;
me.gs_requests++;
me.gs_bytes_in_flight += bp->bio_length;
if (bp->bio_cmd == BIO_WRITE) {
me.gs_writes_in_flight++;
me.gs_write_bytes_in_flight += bp->bio_length;
}
g_sched_dispatch(gp);
g_sched_unlock(gp);
return;
bypass:
cbp->bio_done = g_std_done;
cbp->bio_caller1 = NULL; /* not scheduled */
g_io_request(cbp, LIST_FIRST(&gp->consumer));
}
/*
* The next few functions are the geom glue.
*/
static void
g_sched_orphan(struct g_consumer *cp)
{
g_topology_assert();
g_sched_destroy(cp->geom, 1);
}
static int
g_sched_access(struct g_provider *pp, int dr, int dw, int de)
{
struct g_geom *gp;
struct g_consumer *cp;
int error;
gp = pp->geom;
cp = LIST_FIRST(&gp->consumer);
error = g_access(cp, dr, dw, de);
return (error);
}
static void
g_sched_temporary_start(struct bio *bio)
{
mtx_lock(&me.gs_mtx);
me.gs_npending++;
bioq_disksort(&me.gs_pending, bio);
mtx_unlock(&me.gs_mtx);
}
static void
g_sched_flush_pending(g_start_t *start)
{
struct bio *bp;
while ((bp = bioq_takefirst(&me.gs_pending)))
start(bp);
}
static int
g_insert_proxy(struct g_geom *gp, struct g_provider *newpp,
struct g_geom *dstgp, struct g_provider *pp, struct g_consumer *cp)
{
struct g_sched_softc *sc = gp->softc;
g_start_t *saved_start, *flush = g_sched_start;
int error = 0, endticks = ticks + hz;
g_cancel_event(newpp); /* prevent taste() */
/* copy private fields */
newpp->private = pp->private;
newpp->index = pp->index;
/* Queue all the early requests coming for us. */
me.gs_npending = 0;
saved_start = pp->geom->start;
dstgp->start = g_sched_temporary_start;
while (pp->nstart - pp->nend != me.gs_npending &&
endticks - ticks >= 0)
tsleep(pp, PRIBIO, "-", hz/10);
if (pp->nstart - pp->nend != me.gs_npending) {
flush = saved_start;
error = ETIMEDOUT;
goto fail;
}
/* link pp to this geom */
LIST_REMOVE(pp, provider);
pp->geom = gp;
LIST_INSERT_HEAD(&gp->provider, pp, provider);
/*
* replicate the counts from the parent in the
* new provider and consumer nodes
*/
cp->acr = newpp->acr = pp->acr;
cp->acw = newpp->acw = pp->acw;
cp->ace = newpp->ace = pp->ace;
sc->sc_flags |= G_SCHED_PROXYING;
fail:
dstgp->start = saved_start;
g_sched_flush_pending(flush);
return (error);
}
/*
* Create a geom node for the device passed as *pp.
* If successful, add a reference to this gsp.
*/
static int
g_sched_create(struct gctl_req *req, struct g_class *mp,
struct g_provider *pp, struct g_gsched *gsp, int proxy)
{
struct g_sched_softc *sc = NULL;
struct g_geom *gp, *dstgp;
struct g_provider *newpp = NULL;
struct g_consumer *cp = NULL;
char name[64];
int error;
g_topology_assert();
snprintf(name, sizeof(name), "%s%s", pp->name, G_SCHED_SUFFIX);
LIST_FOREACH(gp, &mp->geom, geom) {
if (strcmp(gp->name, name) == 0) {
gctl_error(req, "Geom %s already exists.",
name);
return (EEXIST);
}
}
gp = g_new_geomf(mp, "%s", name);
dstgp = proxy ? pp->geom : gp; /* where do we link the provider */
sc = g_malloc(sizeof(*sc), M_WAITOK | M_ZERO);
sc->sc_gsched = gsp;
sc->sc_data = gsp->gs_init(gp);
if (sc->sc_data == NULL) {
error = ENOMEM;
goto fail;
}
sc->sc_hash = g_sched_hash_init(gsp, &sc->sc_mask, HASH_WAITOK);
/*
* Do not initialize the flush mechanism, will be initialized
* on the first insertion on the hash table.
*/
mtx_init(&sc->sc_mtx, "g_sched_mtx", NULL, MTX_DEF);
gp->softc = sc;
gp->start = g_sched_start;
gp->orphan = g_sched_orphan;
gp->access = g_sched_access;
gp->dumpconf = g_sched_dumpconf;
newpp = g_new_providerf(dstgp, "%s", gp->name);
newpp->mediasize = pp->mediasize;
newpp->sectorsize = pp->sectorsize;
cp = g_new_consumer(gp);
error = g_attach(cp, proxy ? newpp : pp);
if (error != 0) {
gctl_error(req, "Cannot attach to provider %s.",
pp->name);
goto fail;
}
g_error_provider(newpp, 0);
if (proxy) {
error = g_insert_proxy(gp, newpp, dstgp, pp, cp);
if (error)
goto fail;
}
G_SCHED_DEBUG(0, "Device %s created.", gp->name);
g_gsched_ref(gsp);
return (0);
fail:
if (cp != NULL) {
if (cp->provider != NULL)
g_detach(cp);
g_destroy_consumer(cp);
}
if (newpp != NULL)
g_destroy_provider(newpp);
if (sc->sc_hash)
g_sched_hash_fini(gp, sc->sc_hash, sc->sc_mask,
gsp, sc->sc_data);
if (sc->sc_data)
gsp->gs_fini(sc->sc_data);
g_free(gp->softc);
g_destroy_geom(gp);
return (error);
}
/*
* Support for dynamic switching of scheduling algorithms.
* First initialize the data structures for the new algorithm,
* then call g_sched_remove_locked() to flush all references
* to the old one, finally link the new algorithm.
*/
static int
g_sched_change_algo(struct gctl_req *req, struct g_class *mp,
struct g_provider *pp, struct g_gsched *gsp)
{
struct g_sched_softc *sc;
struct g_geom *gp;
struct g_hash *newh;
void *data;
u_long mask;
int error = 0;
gp = pp->geom;
sc = gp->softc;
data = gsp->gs_init(gp);
if (data == NULL)
return (ENOMEM);
newh = g_sched_hash_init(gsp, &mask, HASH_WAITOK);
if (gsp->gs_priv_size && !newh) {
error = ENOMEM;
goto fail;
}
g_sched_lock(gp);
if (sc->sc_gsched) { /* can be NULL in some cases */
error = g_sched_remove_locked(gp, sc->sc_gsched);
if (error)
goto fail;
}
g_gsched_ref(gsp);
sc->sc_gsched = gsp;
sc->sc_data = data;
sc->sc_hash = newh;
sc->sc_mask = mask;
g_sched_unlock(gp);
return (0);
fail:
if (newh)
g_sched_hash_fini(gp, newh, mask, gsp, data);
if (data)
gsp->gs_fini(data);
g_sched_unlock(gp);
return (error);
}
/*
* Stop the request flow directed to the proxy, redirecting the new
* requests to the me.gs_pending queue.
*/
static struct g_provider *
g_detach_proxy(struct g_geom *gp)
{
struct g_consumer *cp;
struct g_provider *pp, *newpp;
do {
pp = LIST_FIRST(&gp->provider);
if (pp == NULL)
break;
cp = LIST_FIRST(&gp->consumer);
if (cp == NULL)
break;
newpp = cp->provider;
if (newpp == NULL)
break;
me.gs_npending = 0;
pp->geom->start = g_sched_temporary_start;
return (pp);
} while (0);
printf("%s error detaching proxy %s\n", __FUNCTION__, gp->name);
return (NULL);
}
static void
g_sched_blackhole(struct bio *bp)
{
g_io_deliver(bp, ENXIO);
}
static inline void
g_reparent_provider(struct g_provider *pp, struct g_geom *gp,
struct g_provider *newpp)
{
LIST_REMOVE(pp, provider);
if (newpp) {
pp->private = newpp->private;
pp->index = newpp->index;
}
pp->geom = gp;
LIST_INSERT_HEAD(&gp->provider, pp, provider);
}
static inline void
g_unproxy_provider(struct g_provider *oldpp, struct g_provider *newpp)
{
struct g_geom *gp = oldpp->geom;
g_reparent_provider(oldpp, newpp->geom, newpp);
/*
* Hackish: let the system destroy the old provider for us, just
* in case someone attached a consumer to it, in which case a
* direct call to g_destroy_provider() would not work.
*/
g_reparent_provider(newpp, gp, NULL);
}
/*
* Complete the proxy destruction, linking the old provider to its
* original geom, and destroying the proxy provider. Also take care
* of issuing the pending requests collected in me.gs_pending (if any).
*/
static int
g_destroy_proxy(struct g_geom *gp, struct g_provider *oldpp)
{
struct g_consumer *cp;
struct g_provider *newpp;
do {
cp = LIST_FIRST(&gp->consumer);
if (cp == NULL)
break;
newpp = cp->provider;
if (newpp == NULL)
break;
/* Relink the provider to its original geom. */
g_unproxy_provider(oldpp, newpp);
/* Detach consumer from provider, and destroy provider. */
cp->acr = newpp->acr = 0;
cp->acw = newpp->acw = 0;
cp->ace = newpp->ace = 0;
g_detach(cp);
/* Send the pending bios through the right start function. */
g_sched_flush_pending(oldpp->geom->start);
return (0);
} while (0);
printf("%s error destroying proxy %s\n", __FUNCTION__, gp->name);
/* We cannot send the pending bios anywhere... */
g_sched_flush_pending(g_sched_blackhole);
return (EINVAL);
}
static int
g_sched_destroy(struct g_geom *gp, boolean_t force)
{
struct g_provider *pp, *oldpp = NULL;
struct g_sched_softc *sc;
struct g_gsched *gsp;
int error;
g_topology_assert();
sc = gp->softc;
if (sc == NULL)
return (ENXIO);
if (!(sc->sc_flags & G_SCHED_PROXYING)) {
pp = LIST_FIRST(&gp->provider);
if (pp && (pp->acr != 0 || pp->acw != 0 || pp->ace != 0)) {
const char *msg = force ?
"but we force removal" : "cannot remove";
G_SCHED_DEBUG(!force,
"Device %s is still open (r%dw%de%d), %s.",
pp->name, pp->acr, pp->acw, pp->ace, msg);
if (!force)
return (EBUSY);
} else {
G_SCHED_DEBUG(0, "Device %s removed.", gp->name);
}
} else
oldpp = g_detach_proxy(gp);
gsp = sc->sc_gsched;
if (gsp) {
/*
* XXX bad hack here: force a dispatch to release
* any reference to the hash table still held by
* the scheduler.
*/
g_sched_lock(gp);
/*
* We are dying here, no new requests should enter
* the scheduler. This is granted by the topolgy,
* either in case we were proxying (new bios are
* being redirected) or not (see the access check
* above).
*/
g_sched_forced_dispatch(gp);
error = g_sched_wait_pending(gp);
if (error) {
/*
* Not all the requests came home: this might happen
* under heavy load, or if we were waiting for any
* bio which is served in the event path (see
* geom_slice.c for an example of how this can
* happen). Try to restore a working configuration
* if we can fail.
*/
if ((sc->sc_flags & G_SCHED_PROXYING) && oldpp) {
g_sched_flush_pending(force ?
g_sched_blackhole : g_sched_start);
}
/*
* In the forced destroy case there is not so much
* we can do, we have pending bios that will call
* g_sched_done() somehow, and we don't want them
* to crash the system using freed memory. We tell
* the user that something went wrong, and leak some
* memory here.
* Note: the callers using force = 1 ignore the
* return value.
*/
if (force) {
G_SCHED_DEBUG(0, "Pending requests while "
" destroying geom, some memory leaked.");
}
return (error);
}
g_sched_unlock(gp);
g_sched_hash_fini(gp, sc->sc_hash, sc->sc_mask,
gsp, sc->sc_data);
sc->sc_hash = NULL;
gsp->gs_fini(sc->sc_data);
g_gsched_unref(gsp);
sc->sc_gsched = NULL;
} else
error = 0;
if ((sc->sc_flags & G_SCHED_PROXYING) && oldpp) {
error = g_destroy_proxy(gp, oldpp);
if (error) {
if (force) {
G_SCHED_DEBUG(0, "Unrecoverable error while "
"destroying a proxy geom, leaking some "
" memory.");
}
return (error);
}
}
mtx_destroy(&sc->sc_mtx);
g_free(gp->softc);
gp->softc = NULL;
g_wither_geom(gp, ENXIO);
return (error);
}
static int
g_sched_destroy_geom(struct gctl_req *req, struct g_class *mp,
struct g_geom *gp)
{
return (g_sched_destroy(gp, 0));
}
/*
* Functions related to the classification of requests.
*
* On recent FreeBSD versions (8.0 and above), we store a reference
* to the issuer of a request in bp->bio_classifier1 as soon
* as the bio is posted to the geom queue (and not later, because
* requests are managed by the g_down thread afterwards).
*/
/*
* Classifier support for recent FreeBSD versions: we use
* a very simple classifier, only use curthread to tag a request.
* The classifier is registered at module load, and unregistered
* at module unload.
*/
static int
g_sched_tag(void *arg, struct bio *bp)
{
bp->bio_classifier1 = curthread;
return (1);
}
static struct g_classifier_hook g_sched_classifier = {
.func = g_sched_tag,
};
static inline void
g_classifier_ini(void)
{
g_register_classifier(&g_sched_classifier);
}
static inline void
g_classifier_fini(void)
{
g_unregister_classifier(&g_sched_classifier);
}
static void
g_sched_init(struct g_class *mp)
{
g_gsched_global_init();
G_SCHED_DEBUG(0, "Loading: mp = %p, g_sched_class = %p.",
mp, &g_sched_class);
/* Patch g_io_request to store classification info in the bio. */
g_classifier_ini();
}
static void
g_sched_fini(struct g_class *mp)
{
g_classifier_fini();
G_SCHED_DEBUG(0, "Unloading...");
KASSERT(LIST_EMPTY(&me.gs_scheds), ("still registered schedulers"));
mtx_destroy(&me.gs_mtx);
}
static int
g_sched_ioctl(struct g_provider *pp, u_long cmd, void *data, int fflag,
struct thread *td)
{
struct g_consumer *cp;
struct g_geom *gp;
cp = LIST_FIRST(&pp->geom->consumer);
if (cp == NULL)
return (ENOIOCTL);
gp = cp->provider->geom;
if (gp->ioctl == NULL)
return (ENOIOCTL);
return (gp->ioctl(cp->provider, cmd, data, fflag, td));
}
/*
* Read the i-th argument for a request, skipping the /dev/
* prefix if present.
*/
static const char *
g_sched_argi(struct gctl_req *req, int i)
{
static const char *dev_prefix = "/dev/";
const char *name;
char param[16];
int l = strlen(dev_prefix);
snprintf(param, sizeof(param), "arg%d", i);
name = gctl_get_asciiparam(req, param);
if (name == NULL)
gctl_error(req, "No 'arg%d' argument", i);
else if (strncmp(name, dev_prefix, l) == 0)
name += l;
return (name);
}
/*
* Fetch nargs and do appropriate checks.
*/
static int
g_sched_get_nargs(struct gctl_req *req)
{
int *nargs;
nargs = gctl_get_paraml(req, "nargs", sizeof(*nargs));
if (nargs == NULL) {
gctl_error(req, "No 'nargs' argument");
return (0);
}
if (*nargs <= 0)
gctl_error(req, "Missing device(s).");
return (*nargs);
}
/*
* Check whether we should add the class on certain volumes when
* this geom is created. Right now this is under control of a kenv
* variable containing the names of all devices that we care about.
* Probably we should only support transparent insertion as the
* preferred mode of operation.
*/
static struct g_geom *
g_sched_taste(struct g_class *mp, struct g_provider *pp,
int flags __unused)
{
struct g_gsched *gsp = NULL; /* the . algorithm we want */
const char *s; /* generic string pointer */
const char *taste_names; /* devices we like */
int l;
g_trace(G_T_TOPOLOGY, "%s(%s, %s)", __func__,
mp->name, pp->name);
g_topology_assert();
G_SCHED_DEBUG(2, "Tasting %s.", pp->name);
do {
/* do not taste on ourselves */
if (pp->geom->class == mp)
break;
taste_names = kern_getenv("geom.sched.taste");
if (taste_names == NULL)
break;
l = strlen(pp->name);
for (s = taste_names; *s &&
(s = strstr(s, pp->name)); s++) {
/* further checks for an exact match */
if ( (s == taste_names || s[-1] == ' ') &&
(s[l] == '\0' || s[l] == ' ') )
break;
}
if (s == NULL)
break;
G_SCHED_DEBUG(0, "Attach device %s match [%s]\n",
pp->name, s);
/* look up the provider name in the list */
s = kern_getenv("geom.sched.algo");
if (s == NULL)
s = "rr";
gsp = g_gsched_find(s); /* also get a reference */
if (gsp == NULL) {
G_SCHED_DEBUG(0, "Bad '%s' algorithm.", s);
break;
}
/* XXX create with 1 as last argument ? */
g_sched_create(NULL, mp, pp, gsp, 0);
g_gsched_unref(gsp);
} while (0);
return NULL;
}
static void
g_sched_ctl_create(struct gctl_req *req, struct g_class *mp, int proxy)
{
struct g_provider *pp;
struct g_gsched *gsp;
const char *name;
int i, nargs;
g_topology_assert();
name = gctl_get_asciiparam(req, "algo");
if (name == NULL) {
gctl_error(req, "No '%s' argument", "algo");
return;
}
gsp = g_gsched_find(name); /* also get a reference */
if (gsp == NULL) {
gctl_error(req, "Bad algorithm '%s'", name);
return;
}
nargs = g_sched_get_nargs(req);
/*
* Run on the arguments, and break on any error.
* We look for a device name, but skip the /dev/ prefix if any.
*/
for (i = 0; i < nargs; i++) {
name = g_sched_argi(req, i);
if (name == NULL)
break;
pp = g_provider_by_name(name);
if (pp == NULL) {
G_SCHED_DEBUG(1, "Provider %s is invalid.", name);
gctl_error(req, "Provider %s is invalid.", name);
break;
}
if (g_sched_create(req, mp, pp, gsp, proxy) != 0)
break;
}
g_gsched_unref(gsp);
}
static void
g_sched_ctl_configure(struct gctl_req *req, struct g_class *mp)
{
struct g_provider *pp;
struct g_gsched *gsp;
const char *name;
int i, nargs;
g_topology_assert();
name = gctl_get_asciiparam(req, "algo");
if (name == NULL) {
gctl_error(req, "No '%s' argument", "algo");
return;
}
gsp = g_gsched_find(name); /* also get a reference */
if (gsp == NULL) {
gctl_error(req, "Bad algorithm '%s'", name);
return;
}
nargs = g_sched_get_nargs(req);
/*
* Run on the arguments, and break on any error.
* We look for a device name, but skip the /dev/ prefix if any.
*/
for (i = 0; i < nargs; i++) {
name = g_sched_argi(req, i);
if (name == NULL)
break;
pp = g_provider_by_name(name);
if (pp == NULL || pp->geom->class != mp) {
G_SCHED_DEBUG(1, "Provider %s is invalid.", name);
gctl_error(req, "Provider %s is invalid.", name);
break;
}
if (g_sched_change_algo(req, mp, pp, gsp) != 0)
break;
}
g_gsched_unref(gsp);
}
static struct g_geom *
g_sched_find_geom(struct g_class *mp, const char *name)
{
struct g_geom *gp;
LIST_FOREACH(gp, &mp->geom, geom) {
if (strcmp(gp->name, name) == 0)
return (gp);
}
return (NULL);
}
static void
g_sched_ctl_destroy(struct gctl_req *req, struct g_class *mp)
{
int nargs, *force, error, i;
struct g_geom *gp;
const char *name;
g_topology_assert();
nargs = g_sched_get_nargs(req);
force = gctl_get_paraml(req, "force", sizeof(*force));
if (force == NULL) {
gctl_error(req, "No 'force' argument");
return;
}
for (i = 0; i < nargs; i++) {
name = g_sched_argi(req, i);
if (name == NULL)
break;
gp = g_sched_find_geom(mp, name);
if (gp == NULL) {
G_SCHED_DEBUG(1, "Device %s is invalid.", name);
gctl_error(req, "Device %s is invalid.", name);
break;
}
error = g_sched_destroy(gp, *force);
if (error != 0) {
gctl_error(req, "Cannot destroy device %s (error=%d).",
gp->name, error);
break;
}
}
}
static void
g_sched_config(struct gctl_req *req, struct g_class *mp, const char *verb)
{
uint32_t *version;
g_topology_assert();
version = gctl_get_paraml(req, "version", sizeof(*version));
if (version == NULL) {
gctl_error(req, "No '%s' argument.", "version");
return;
}
if (*version != G_SCHED_VERSION) {
gctl_error(req, "Userland and kernel parts are "
"out of sync.");
return;
}
if (strcmp(verb, "create") == 0) {
g_sched_ctl_create(req, mp, 0);
return;
} else if (strcmp(verb, "insert") == 0) {
g_sched_ctl_create(req, mp, 1);
return;
} else if (strcmp(verb, "configure") == 0) {
g_sched_ctl_configure(req, mp);
return;
} else if (strcmp(verb, "destroy") == 0) {
g_sched_ctl_destroy(req, mp);
return;
}
gctl_error(req, "Unknown verb.");
}
static void
g_sched_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp,
struct g_consumer *cp, struct g_provider *pp)
{
struct g_sched_softc *sc = gp->softc;
struct g_gsched *gsp = sc->sc_gsched;
if (indent == NULL) { /* plaintext */
sbuf_printf(sb, " algo %s", gsp ? gsp->gs_name : "--");
}
if (gsp != NULL && gsp->gs_dumpconf)
gsp->gs_dumpconf(sb, indent, gp, cp, pp);
}
DECLARE_GEOM_CLASS(g_sched_class, g_sched);
MODULE_VERSION(geom_sched, 0);
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