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Member "aoe6-83/linux/drivers/block/aoe/aoedev.c" of archive aoe6-83.tar.gz:

/* Copyright (c) 2013 Coraid, Inc.  See COPYING for GPL terms. */
/*
 * aoedev.c
 * AoE device utility functions; maintains device list.
 */

#include <linux/hdreg.h>
#include <linux/blkdev.h>
#include <linux/netdevice.h>
#include <linux/delay.h>
#include <linux/moduleparam.h>
#include <linux/bitmap.h>
#include <linux/kdev_t.h>
#include "aoe.h"

static void dummy_timer(ulong);
static void freetgt(struct aoedev *d, struct aoetgt *t);
static void skbpoolfree(struct aoedev *d);

static int aoe_dyndevs = AOE_DYNDEVS;	/* AOE_DYNDEVS set in Makefile */
module_param(aoe_dyndevs, int, 0644);
MODULE_PARM_DESC(aoe_dyndevs, "Use dynamic minor numbers for devices.");

static struct aoedev *devlist;
static DEFINE_SPINLOCK(devlist_lock);

/* Because some systems will have one, many, or no
 *   - partitions,
 *   - slots per shelf,
 *   - or shelves,
 * we need some flexibility in the way the minor numbers
 * are allocated.  So they are dynamic.
 */
#define N_DEVS ((1U<<MINORBITS)/AOE_PARTITIONS)

static DEFINE_SPINLOCK(used_minors_lock);
static DECLARE_BITMAP(used_minors, N_DEVS);

static int
minor_get_dyn(ulong *sysminor)
{
	ulong flags;
	ulong n;
	int error = 0;

	spin_lock_irqsave(&used_minors_lock, flags);
	n = find_first_zero_bit(used_minors, N_DEVS);
	if (n < N_DEVS)
		set_bit(n, used_minors);
	else
		error = -1;
	spin_unlock_irqrestore(&used_minors_lock, flags);

	*sysminor = n * AOE_PARTITIONS;
	return error;
}

static int
minor_get_static(ulong *sysminor, ulong aoemaj, int aoemin)
{
	ulong flags;
	ulong n;
	int error = 0;
	enum {
		/* for backwards compatibility when !aoe_dyndevs,
		 * a static number of supported slots per shelf */
		NPERSHELF = 16,
	};

	if (aoemin >= NPERSHELF) {
		printk(KERN_ERR
			"aoe: e%ld.%d: %s %d slots per shelf\n",
			aoemaj, aoemin,
			"static minor device numbers support only",
			NPERSHELF);
		error = -1;
		goto out;
	}

	n = aoemaj * NPERSHELF + aoemin;
	if (n >= N_DEVS) {
		printk(KERN_ERR
			"aoe: %s with e%ld.%d\n",
			"cannot use static minor device numbers",
			aoemaj, aoemin);
		error = -1;
		goto out;
	}

	spin_lock_irqsave(&used_minors_lock, flags);
	if (test_bit(n, used_minors)) {
		printk(KERN_ERR
			"aoe: %s %lu\n",
			"existing device already has static minor number",
			n);
		error = -1;
	} else
		set_bit(n, used_minors);
	spin_unlock_irqrestore(&used_minors_lock, flags);
	*sysminor = n * AOE_PARTITIONS;
 out:
	return error;
}

static int
minor_get(ulong *sysminor, ulong aoemaj, int aoemin)
{
	if (aoe_dyndevs)
		return minor_get_dyn(sysminor);
	else
		return minor_get_static(sysminor, aoemaj, aoemin);
}

static void
minor_free(ulong minor)
{
	ulong flags;

	minor /= AOE_PARTITIONS;
	BUG_ON(minor >= N_DEVS);

	spin_lock_irqsave(&used_minors_lock, flags);
	clear_bit(minor, used_minors);
	spin_unlock_irqrestore(&used_minors_lock, flags);
}

/*
	Users who grab a pointer to the device with aoedev_by_aoeaddr
	automatically get a reference count and must be responsible
	for performing a aoedev_put.  With the addition of async
	kthread processing I'm no longer confident that we can
	guarantee consistency in the face of device flushes.

	For the time being, we only bother to add extra references for
	frames sitting on the iocq.  When the kthreads finish processing
	these frames, they will aoedev_put the device.
*/

void
aoedev_put(struct aoedev *d)
{
	ulong flags;

	spin_lock_irqsave(&devlist_lock, flags);
	d->ref--;
	spin_unlock_irqrestore(&devlist_lock, flags);
}

static void
dummy_timer(ulong vp)
{
	struct aoedev *d;

	d = (struct aoedev *)vp;
	if (d->flags & DEVFL_TKILL)
		return;
	d->timer.expires = jiffies + HZ;
	add_timer(&d->timer);
}

static void
aoe_failip(struct aoedev *d)
{
	struct request *rq;
	struct bio *bio;
	unsigned long n;

	aoe_failbuf(d, d->ip.buf);

	rq = d->ip.rq;
	if (rq == NULL)
		return;
	while ((bio = d->ip.nxbio)) {
		clear_bit(BIO_UPTODATE, &bio->bi_flags);
		d->ip.nxbio = bio->bi_next;
		n = (unsigned long) rq->special;
		rq->special = (void *) --n;
	}
	if ((unsigned long) rq->special == 0)
		aoe_end_request(d, rq, 0);
}

static void
downdev_frame(struct list_head *pos)
{
	struct frame *f;

	f = list_entry(pos, struct frame, head);
	list_del(pos);
	if (f->buf) {
		f->buf->nframesout--;
		aoe_failbuf(f->t->d, f->buf);
	}
	aoe_freetframe(f);	
}

void
aoedev_downdev(struct aoedev *d)
{
	struct aoetgt *t, **tt, **te;
	struct list_head *head, *pos, *nx;
	struct request *rq;
	int i;

	d->flags &= ~DEVFL_UP;

	/* clean out active and to-be-retransmitted buffers */
	for (i=0; i<NFACTIVE; i++) {
		head = &d->factive[i];
		list_for_each_safe(pos, nx, head)
			downdev_frame(pos);
	}
	head = &d->rexmitq;
	list_for_each_safe(pos, nx, head)
		downdev_frame(pos);
		
	/* reset window dressings */
	tt = d->targets;
	te = tt + d->ntargets;
	for (; tt<te && (t=*tt); tt++) {
		aoecmd_wreset(t);
		t->nout = 0;
	}

	/* clean out the in-process request (if any) */
	aoe_failip(d);

	/* fast fail all pending I/O */
	if (d->blkq) {
		while ((rq = blk_peek_request(d->blkq))) {
			blk_start_request(rq);
			aoe_end_request(d, rq, 1);
		}
	}

	if (d->gd)
		set_capacity(d->gd, 0);
}

/* return whether the user asked for this particular
 * device to be flushed
 */
static int
user_req(char *s, size_t slen, struct aoedev *d)
{
	char *p;
	size_t lim;

	if (!d->gd)
		return 0;
	p = strrchr(d->gd->disk_name, '/');
	if (!p)
		p = d->gd->disk_name;
	else
		p += 1;
	lim = sizeof d->gd->disk_name;
	lim -= p - d->gd->disk_name;
	if (slen < lim)
		lim = slen;
	
	return !strncmp(s, p, lim);
}

static void
freedev(struct aoedev *d)
{
	struct aoetgt **t, **e;
	int freeing = 0;
	unsigned long flags;

	spin_lock_irqsave(&d->lock, flags);
	if (d->flags & DEVFL_TKILL
	&& !(d->flags & DEVFL_FREEING)) {
		d->flags |= DEVFL_FREEING;
		freeing = 1;
	}
	spin_unlock_irqrestore(&d->lock, flags);
	if (!freeing)
		return;

	del_timer_sync(&d->timer);
	aoedbg_undbg(d);
	if (d->gd) {
		aoedisk_rm_sysfs(d);
		del_gendisk(d->gd);
		put_disk(d->gd);
		blk_cleanup_queue(d->blkq);
	}
	t = d->targets;
	e = t + d->ntargets;
	for (; t<e && *t; t++)
		freetgt(d, *t);
	if (d->bufpool)
		mempool_destroy(d->bufpool);
	skbpoolfree(d);
	minor_free(d->sysminor);

	spin_lock_irqsave(&d->lock, flags);
	d->flags |= DEVFL_FREED;
	spin_unlock_irqrestore(&d->lock, flags);	
}

enum flush_parms {
	NOT_EXITING = 0,
	EXITING = 1,
};

static int
flush(const char __user *str, size_t cnt, int exiting)
{
	ulong flags;
	struct aoedev *d, **dd;
	char buf[16];
	int all = 0;
	int specified = 0;	/* flush a specific device */
	unsigned int skipflags;

	skipflags = DEVFL_GDALLOC | DEVFL_NEWSIZE | DEVFL_TKILL;

	if (!exiting && cnt >= 3) {
		if (cnt > sizeof buf)
			cnt = sizeof buf;
		if (copy_from_user(buf, str, cnt))
			return -EFAULT;
		all = !strncmp(buf, "all", 3);
		if (!all)
			specified = 1;
	}

	flush_scheduled_work();
	/* pass one: without sleeping, do aoedev_downdev */
	spin_lock_irqsave(&devlist_lock, flags);
	for (d = devlist; d; d = d->next) {
		spin_lock(&d->lock);
		if (exiting) {
			/* unconditionally take each device down */
		} else if (specified) {
			if (!user_req(buf, cnt, d))
				goto cont;
		} else if ((!all && (d->flags & DEVFL_UP))
		|| d->flags & skipflags
		|| d->nopen
		|| d->ref)
			goto cont;

		aoedev_downdev(d);
		d->flags |= DEVFL_TKILL;
	cont:
		spin_unlock(&d->lock);
	}
	spin_unlock_irqrestore(&devlist_lock, flags);

	/* pass two: call freedev, which might sleep,
	 * for aoedevs marked with DEVFL_TKILL
	 */
 restart:
	spin_lock_irqsave(&devlist_lock, flags);
	for (d = devlist; d; d = d->next) {
		spin_lock(&d->lock);
		if (d->flags & DEVFL_TKILL
		&& !(d->flags & DEVFL_FREEING)) {
			spin_unlock(&d->lock);
			spin_unlock_irqrestore(&devlist_lock, flags);
			freedev(d);
			goto restart;
		}
		spin_unlock(&d->lock);
	}

	/* pass three: remove aoedevs marked with DEVFL_FREED */
	for (dd = &devlist, d = *dd; d; d = *dd) {
		struct aoedev *doomed = NULL;

		spin_lock(&d->lock);
		if (d->flags & DEVFL_FREED) {
			*dd = d->next;
			doomed = d;
		} else {
			dd = &d->next;
		}
		spin_unlock(&d->lock);
		if (doomed)
			kfree(doomed->targets);
		kfree(doomed);
	}
	spin_unlock_irqrestore(&devlist_lock, flags);
	
	return 0;
}

int
aoedev_flush(const char __user *str, size_t cnt)
{
	return flush(str, cnt, NOT_EXITING);
}

/*
	This has been confirmed to occur once with Tms=3*1000 due to
	the driver changing link and not processing its transmit ring.
	The problem is hard enough to solve by returning an error that
	I'm still punting on "solving" this.
*/
static void
skbfree(struct sk_buff *skb)
{
	enum { Sms= 250, Tms= 30*1000};
	int i = Tms / Sms;

	if (skb == NULL)
		return;
	while (atomic_read(&skb_shinfo(skb)->dataref) != 1 && i-- > 0)
		msleep_interruptible(Sms);
	if (i < 0) {
		printk(KERN_ERR
			"aoe: %s holds ref: cannot free skb -- memory leaked.\n",
			skb->dev ? skb->dev->name : "netif");
		return;
	}
	skb->truesize -= skb->data_len;
	skb_shinfo(skb)->nr_frags = skb->data_len = 0;
	skb_trim(skb, 0);
	dev_kfree_skb(skb);
}

static void
skbpoolfree(struct aoedev *d)
{
	struct sk_buff *skb;

	while ((skb = d->skbpool_hd)) {
		d->skbpool_hd = skb->next;
		skb->next = NULL;
		skbfree(skb);
	}
	d->skbpool_tl = NULL;
}

/* find it or malloc it */
struct aoedev *
aoedev_by_aoeaddr(ulong maj, int min, int malloc)
{
	struct aoedev *d;
	int i;
	ulong flags;
	ulong sysminor = 0;

	spin_lock_irqsave(&devlist_lock, flags);

	for (d=devlist; d; d=d->next)
		if (d->aoemajor == maj && d->aoeminor == min) {
			spin_lock(&d->lock);
			if (d->flags & DEVFL_TKILL) {
				spin_unlock(&d->lock);
				d = NULL;
				goto out;
			}
			d->ref++;
			spin_unlock(&d->lock);
			break;
		}
	if (d
	|| !malloc
	|| minor_get(&sysminor, maj, min) < 0
	|| !(d = aoe_kcalloc(1, sizeof *d, GFP_ATOMIC)))
		goto out;

	d->targets = aoe_kcalloc(NTARGETS, sizeof *d->targets, GFP_ATOMIC);
	if (!d->targets) {
		kfree(d);
		d = NULL;
		goto out;
	}
	d->ntargets = NTARGETS;
	INIT_WORK(&d->work, aoecmd_sleepwork);
	spin_lock_init(&d->lock);
	init_timer(&d->timer);
	d->timer.data = (ulong) d;
	d->timer.function = dummy_timer;
	d->timer.expires = jiffies + HZ;
	add_timer(&d->timer);
	d->bufpool = NULL;	/* defer to aoeblk_gdalloc */
	d->tgt = d->targets;
	d->ref = 1;
	for (i=0; i<NFACTIVE; i++)
		INIT_LIST_HEAD(&d->factive[i]);
	INIT_LIST_HEAD(&d->rexmitq);
	d->sysminor = sysminor;
	d->aoemajor = maj;
	d->aoeminor = min;
	d->rttavg = RTTAVG_INIT;
	d->rttdev = RTTDEV_INIT;
	d->next = devlist;
	devlist = d;

 out:
	spin_unlock_irqrestore(&devlist_lock, flags);
	return d;
}

static void
freetgt(struct aoedev *d, struct aoetgt *t)
{
	struct frame *f;
	struct list_head *pos, *nx, *head;
	struct aoeif *ifp;

	for (ifp = t->ifs; ifp < &t->ifs[NAOEIFS]; ++ifp) {
		if (!ifp->nd)
			break;
		dev_put(ifp->nd);
	}

	head = &t->ffree;
	list_for_each_safe(pos, nx, head) {
		list_del(pos);
		f = list_entry(pos, struct frame, head);
		skbfree(f->skb);
		kfree(f);
	}
	kfree(t);
}

void
aoedev_exit(void)
{
	flush_scheduled_work();
	flush(NULL, 0, EXITING);
}

int __init
aoedev_init(void)
{
	return 0;
}