linux/drivers/mtd/mtd_blkdevs.c

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/*
* Interface to Linux block layer for MTD 'translation layers'.
*
* Copyright © 2003-2010 David Woodhouse <dwmw2@infradead.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/fs.h>
#include <linux/mtd/blktrans.h>
#include <linux/mtd/mtd.h>
#include <linux/blkdev.h>
#include <linux/blkpg.h>
#include <linux/spinlock.h>
#include <linux/hdreg.h>
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/kthread.h>
#include <asm/uaccess.h>
#include "mtdcore.h"
static LIST_HEAD(blktrans_majors);
static DEFINE_MUTEX(blktrans_ref_mutex);
static void blktrans_dev_release(struct kref *kref)
{
struct mtd_blktrans_dev *dev =
container_of(kref, struct mtd_blktrans_dev, ref);
dev->disk->private_data = NULL;
blk_cleanup_queue(dev->rq);
put_disk(dev->disk);
list_del(&dev->list);
kfree(dev);
}
static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
{
struct mtd_blktrans_dev *dev;
mutex_lock(&blktrans_ref_mutex);
dev = disk->private_data;
if (!dev)
goto unlock;
kref_get(&dev->ref);
unlock:
mutex_unlock(&blktrans_ref_mutex);
return dev;
}
static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
{
mutex_lock(&blktrans_ref_mutex);
kref_put(&dev->ref, blktrans_dev_release);
mutex_unlock(&blktrans_ref_mutex);
}
static int do_blktrans_request(struct mtd_blktrans_ops *tr,
struct mtd_blktrans_dev *dev,
struct request *req)
{
unsigned long block, nsect;
char *buf;
block: convert to pos and nr_sectors accessors With recent cleanups, there is no place where low level driver directly manipulates request fields. This means that the 'hard' request fields always equal the !hard fields. Convert all rq->sectors, nr_sectors and current_nr_sectors references to accessors. While at it, drop superflous blk_rq_pos() < 0 test in swim.c. [ Impact: use pos and nr_sectors accessors ] Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> Tested-by: Grant Likely <grant.likely@secretlab.ca> Acked-by: Grant Likely <grant.likely@secretlab.ca> Tested-by: Adrian McMenamin <adrian@mcmen.demon.co.uk> Acked-by: Adrian McMenamin <adrian@mcmen.demon.co.uk> Acked-by: Mike Miller <mike.miller@hp.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> Cc: Borislav Petkov <petkovbb@googlemail.com> Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com> Cc: Eric Moore <Eric.Moore@lsi.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Pete Zaitcev <zaitcev@redhat.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Paul Clements <paul.clements@steeleye.com> Cc: Tim Waugh <tim@cyberelk.net> Cc: Jeff Garzik <jgarzik@pobox.com> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Alex Dubov <oakad@yahoo.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Dario Ballabio <ballabio_dario@emc.com> Cc: David S. Miller <davem@davemloft.net> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: unsik Kim <donari75@gmail.com> Cc: Laurent Vivier <Laurent@lvivier.info> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-05-07 13:24:39 +00:00
block = blk_rq_pos(req) << 9 >> tr->blkshift;
nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
buf = req->buffer;
if (req->cmd_type != REQ_TYPE_FS)
2009-04-23 02:05:19 +00:00
return -EIO;
block: convert to pos and nr_sectors accessors With recent cleanups, there is no place where low level driver directly manipulates request fields. This means that the 'hard' request fields always equal the !hard fields. Convert all rq->sectors, nr_sectors and current_nr_sectors references to accessors. While at it, drop superflous blk_rq_pos() < 0 test in swim.c. [ Impact: use pos and nr_sectors accessors ] Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> Tested-by: Grant Likely <grant.likely@secretlab.ca> Acked-by: Grant Likely <grant.likely@secretlab.ca> Tested-by: Adrian McMenamin <adrian@mcmen.demon.co.uk> Acked-by: Adrian McMenamin <adrian@mcmen.demon.co.uk> Acked-by: Mike Miller <mike.miller@hp.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> Cc: Borislav Petkov <petkovbb@googlemail.com> Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com> Cc: Eric Moore <Eric.Moore@lsi.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Pete Zaitcev <zaitcev@redhat.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Paul Clements <paul.clements@steeleye.com> Cc: Tim Waugh <tim@cyberelk.net> Cc: Jeff Garzik <jgarzik@pobox.com> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Alex Dubov <oakad@yahoo.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Dario Ballabio <ballabio_dario@emc.com> Cc: David S. Miller <davem@davemloft.net> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: unsik Kim <donari75@gmail.com> Cc: Laurent Vivier <Laurent@lvivier.info> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-05-07 13:24:39 +00:00
if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
get_capacity(req->rq_disk))
2009-04-23 02:05:19 +00:00
return -EIO;
if (req->cmd_flags & REQ_DISCARD)
return tr->discard(dev, block, nsect);
switch(rq_data_dir(req)) {
case READ:
for (; nsect > 0; nsect--, block++, buf += tr->blksize)
if (tr->readsect(dev, block, buf))
2009-04-23 02:05:19 +00:00
return -EIO;
rq_flush_dcache_pages(req);
2009-04-23 02:05:19 +00:00
return 0;
case WRITE:
if (!tr->writesect)
2009-04-23 02:05:19 +00:00
return -EIO;
rq_flush_dcache_pages(req);
for (; nsect > 0; nsect--, block++, buf += tr->blksize)
if (tr->writesect(dev, block, buf))
2009-04-23 02:05:19 +00:00
return -EIO;
return 0;
default:
printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
2009-04-23 02:05:19 +00:00
return -EIO;
}
}
int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
{
if (kthread_should_stop())
return 1;
return !elv_queue_empty(dev->rq);
}
EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
static int mtd_blktrans_thread(void *arg)
{
struct mtd_blktrans_dev *dev = arg;
struct mtd_blktrans_ops *tr = dev->tr;
struct request_queue *rq = dev->rq;
struct request *req = NULL;
int background_done = 0;
spin_lock_irq(rq->queue_lock);
while (!kthread_should_stop()) {
2009-04-23 02:05:19 +00:00
int res;
block: implement and enforce request peek/start/fetch Till now block layer allowed two separate modes of request execution. A request is always acquired from the request queue via elv_next_request(). After that, drivers are free to either dequeue it or process it without dequeueing. Dequeue allows elv_next_request() to return the next request so that multiple requests can be in flight. Executing requests without dequeueing has its merits mostly in allowing drivers for simpler devices which can't do sg to deal with segments only without considering request boundary. However, the benefit this brings is dubious and declining while the cost of the API ambiguity is increasing. Segment based drivers are usually for very old or limited devices and as converting to dequeueing model isn't difficult, it doesn't justify the API overhead it puts on block layer and its more modern users. Previous patches converted all block low level drivers to dequeueing model. This patch completes the API transition by... * renaming elv_next_request() to blk_peek_request() * renaming blkdev_dequeue_request() to blk_start_request() * adding blk_fetch_request() which is combination of peek and start * disallowing completion of queued (not started) requests * applying new API to all LLDs Renamings are for consistency and to break out of tree code so that it's apparent that out of tree drivers need updating. [ Impact: block request issue API cleanup, no functional change ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Mike Miller <mike.miller@hp.com> Cc: unsik Kim <donari75@gmail.com> Cc: Paul Clements <paul.clements@steeleye.com> Cc: Tim Waugh <tim@cyberelk.net> Cc: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> Cc: David S. Miller <davem@davemloft.net> Cc: Laurent Vivier <Laurent@lvivier.info> Cc: Jeff Garzik <jgarzik@pobox.com> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Grant Likely <grant.likely@secretlab.ca> Cc: Adrian McMenamin <adrian@mcmen.demon.co.uk> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> Cc: Borislav Petkov <petkovbb@googlemail.com> Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com> Cc: Alex Dubov <oakad@yahoo.com> Cc: Pierre Ossman <drzeus@drzeus.cx> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Markus Lidel <Markus.Lidel@shadowconnect.com> Cc: Stefan Weinhuber <wein@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Pete Zaitcev <zaitcev@redhat.com> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-05-08 02:54:16 +00:00
if (!req && !(req = blk_fetch_request(rq))) {
if (tr->background && !background_done) {
spin_unlock_irq(rq->queue_lock);
mutex_lock(&dev->lock);
tr->background(dev);
mutex_unlock(&dev->lock);
spin_lock_irq(rq->queue_lock);
/*
* Do background processing just once per idle
* period.
*/
background_done = 1;
continue;
}
set_current_state(TASK_INTERRUPTIBLE);
if (kthread_should_stop())
set_current_state(TASK_RUNNING);
spin_unlock_irq(rq->queue_lock);
schedule();
spin_lock_irq(rq->queue_lock);
continue;
}
spin_unlock_irq(rq->queue_lock);
mutex_lock(&dev->lock);
res = do_blktrans_request(dev->tr, dev, req);
mutex_unlock(&dev->lock);
spin_lock_irq(rq->queue_lock);
if (!__blk_end_request_cur(req, res))
req = NULL;
background_done = 0;
}
if (req)
__blk_end_request_all(req, -EIO);
spin_unlock_irq(rq->queue_lock);
return 0;
}
static void mtd_blktrans_request(struct request_queue *rq)
{
struct mtd_blktrans_dev *dev;
struct request *req = NULL;
dev = rq->queuedata;
if (!dev)
while ((req = blk_fetch_request(rq)) != NULL)
__blk_end_request_all(req, -ENODEV);
else
wake_up_process(dev->thread);
}
static int blktrans_open(struct block_device *bdev, fmode_t mode)
{
struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
mtd: allow to unload the mtdtrans module if its block devices aren't open Now it once again possible to remove mtdtrans module. You still need to ensure that block devices of that module aren't mounted. This is due to the fact that as long as a block device is open, it still exists, therefore if we were to allow module removal, this block device might became used again. This time in addition to code review, I also made the code pass some torture tests like module reload in a loop + read in a loop + card insert/removal all at same time. The blktrans_open/blktrans_release don't take the mtd table lock because: While device is added (that includes execution of add_mtd_blktrans_dev) the lock is already taken Now suppose the device will never be removed. In this case even if we have changes in mtd table, the entry that we need will stay exactly the same. (Note that we don't look at table at all, just following private pointer of block device). Now suppose that someone tries to remove the mtd device. This will be propagated to trans driver which _ought_ to call del_mtd_blktrans_dev which will take the per device lock, release the mtd device and set trans->mtd = NULL. >From this point on, following opens won't even be able to know anything about that mtd device (which at that point is likely not to exist) Also the same care is taken not to trip over NULL mtd pointer in blktrans_dev_release. Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com> Tested-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2010-10-15 15:20:43 +00:00
int ret = 0;
if (!dev)
return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
mutex_lock(&dev->lock);
mtd: allow to unload the mtdtrans module if its block devices aren't open Now it once again possible to remove mtdtrans module. You still need to ensure that block devices of that module aren't mounted. This is due to the fact that as long as a block device is open, it still exists, therefore if we were to allow module removal, this block device might became used again. This time in addition to code review, I also made the code pass some torture tests like module reload in a loop + read in a loop + card insert/removal all at same time. The blktrans_open/blktrans_release don't take the mtd table lock because: While device is added (that includes execution of add_mtd_blktrans_dev) the lock is already taken Now suppose the device will never be removed. In this case even if we have changes in mtd table, the entry that we need will stay exactly the same. (Note that we don't look at table at all, just following private pointer of block device). Now suppose that someone tries to remove the mtd device. This will be propagated to trans driver which _ought_ to call del_mtd_blktrans_dev which will take the per device lock, release the mtd device and set trans->mtd = NULL. >From this point on, following opens won't even be able to know anything about that mtd device (which at that point is likely not to exist) Also the same care is taken not to trip over NULL mtd pointer in blktrans_dev_release. Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com> Tested-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2010-10-15 15:20:43 +00:00
if (dev->open++)
goto unlock;
mtd: allow to unload the mtdtrans module if its block devices aren't open Now it once again possible to remove mtdtrans module. You still need to ensure that block devices of that module aren't mounted. This is due to the fact that as long as a block device is open, it still exists, therefore if we were to allow module removal, this block device might became used again. This time in addition to code review, I also made the code pass some torture tests like module reload in a loop + read in a loop + card insert/removal all at same time. The blktrans_open/blktrans_release don't take the mtd table lock because: While device is added (that includes execution of add_mtd_blktrans_dev) the lock is already taken Now suppose the device will never be removed. In this case even if we have changes in mtd table, the entry that we need will stay exactly the same. (Note that we don't look at table at all, just following private pointer of block device). Now suppose that someone tries to remove the mtd device. This will be propagated to trans driver which _ought_ to call del_mtd_blktrans_dev which will take the per device lock, release the mtd device and set trans->mtd = NULL. >From this point on, following opens won't even be able to know anything about that mtd device (which at that point is likely not to exist) Also the same care is taken not to trip over NULL mtd pointer in blktrans_dev_release. Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com> Tested-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2010-10-15 15:20:43 +00:00
kref_get(&dev->ref);
__module_get(dev->tr->owner);
if (dev->mtd) {
ret = dev->tr->open ? dev->tr->open(dev) : 0;
__get_mtd_device(dev->mtd);
}
unlock:
mutex_unlock(&dev->lock);
blktrans_dev_put(dev);
return ret;
}
static int blktrans_release(struct gendisk *disk, fmode_t mode)
{
struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
mtd: allow to unload the mtdtrans module if its block devices aren't open Now it once again possible to remove mtdtrans module. You still need to ensure that block devices of that module aren't mounted. This is due to the fact that as long as a block device is open, it still exists, therefore if we were to allow module removal, this block device might became used again. This time in addition to code review, I also made the code pass some torture tests like module reload in a loop + read in a loop + card insert/removal all at same time. The blktrans_open/blktrans_release don't take the mtd table lock because: While device is added (that includes execution of add_mtd_blktrans_dev) the lock is already taken Now suppose the device will never be removed. In this case even if we have changes in mtd table, the entry that we need will stay exactly the same. (Note that we don't look at table at all, just following private pointer of block device). Now suppose that someone tries to remove the mtd device. This will be propagated to trans driver which _ought_ to call del_mtd_blktrans_dev which will take the per device lock, release the mtd device and set trans->mtd = NULL. >From this point on, following opens won't even be able to know anything about that mtd device (which at that point is likely not to exist) Also the same care is taken not to trip over NULL mtd pointer in blktrans_dev_release. Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com> Tested-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2010-10-15 15:20:43 +00:00
int ret = 0;
if (!dev)
return ret;
mutex_lock(&dev->lock);
mtd: allow to unload the mtdtrans module if its block devices aren't open Now it once again possible to remove mtdtrans module. You still need to ensure that block devices of that module aren't mounted. This is due to the fact that as long as a block device is open, it still exists, therefore if we were to allow module removal, this block device might became used again. This time in addition to code review, I also made the code pass some torture tests like module reload in a loop + read in a loop + card insert/removal all at same time. The blktrans_open/blktrans_release don't take the mtd table lock because: While device is added (that includes execution of add_mtd_blktrans_dev) the lock is already taken Now suppose the device will never be removed. In this case even if we have changes in mtd table, the entry that we need will stay exactly the same. (Note that we don't look at table at all, just following private pointer of block device). Now suppose that someone tries to remove the mtd device. This will be propagated to trans driver which _ought_ to call del_mtd_blktrans_dev which will take the per device lock, release the mtd device and set trans->mtd = NULL. >From this point on, following opens won't even be able to know anything about that mtd device (which at that point is likely not to exist) Also the same care is taken not to trip over NULL mtd pointer in blktrans_dev_release. Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com> Tested-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2010-10-15 15:20:43 +00:00
if (--dev->open)
goto unlock;
mtd: allow to unload the mtdtrans module if its block devices aren't open Now it once again possible to remove mtdtrans module. You still need to ensure that block devices of that module aren't mounted. This is due to the fact that as long as a block device is open, it still exists, therefore if we were to allow module removal, this block device might became used again. This time in addition to code review, I also made the code pass some torture tests like module reload in a loop + read in a loop + card insert/removal all at same time. The blktrans_open/blktrans_release don't take the mtd table lock because: While device is added (that includes execution of add_mtd_blktrans_dev) the lock is already taken Now suppose the device will never be removed. In this case even if we have changes in mtd table, the entry that we need will stay exactly the same. (Note that we don't look at table at all, just following private pointer of block device). Now suppose that someone tries to remove the mtd device. This will be propagated to trans driver which _ought_ to call del_mtd_blktrans_dev which will take the per device lock, release the mtd device and set trans->mtd = NULL. >From this point on, following opens won't even be able to know anything about that mtd device (which at that point is likely not to exist) Also the same care is taken not to trip over NULL mtd pointer in blktrans_dev_release. Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com> Tested-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2010-10-15 15:20:43 +00:00
kref_put(&dev->ref, blktrans_dev_release);
module_put(dev->tr->owner);
if (dev->mtd) {
ret = dev->tr->release ? dev->tr->release(dev) : 0;
__put_mtd_device(dev->mtd);
}
unlock:
mutex_unlock(&dev->lock);
blktrans_dev_put(dev);
return ret;
}
static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
int ret = -ENXIO;
if (!dev)
return ret;
mutex_lock(&dev->lock);
if (!dev->mtd)
goto unlock;
ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
unlock:
mutex_unlock(&dev->lock);
blktrans_dev_put(dev);
return ret;
}
static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
unsigned int cmd, unsigned long arg)
{
struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
int ret = -ENXIO;
if (!dev)
return ret;
mutex_lock(&dev->lock);
if (!dev->mtd)
goto unlock;
switch (cmd) {
case BLKFLSBUF:
ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
break;
default:
ret = -ENOTTY;
}
unlock:
mutex_unlock(&dev->lock);
blktrans_dev_put(dev);
return ret;
}
static const struct block_device_operations mtd_blktrans_ops = {
.owner = THIS_MODULE,
.open = blktrans_open,
.release = blktrans_release,
.ioctl = blktrans_ioctl,
.getgeo = blktrans_getgeo,
};
int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
{
struct mtd_blktrans_ops *tr = new->tr;
struct mtd_blktrans_dev *d;
int last_devnum = -1;
struct gendisk *gd;
int ret;
if (mutex_trylock(&mtd_table_mutex)) {
mutex_unlock(&mtd_table_mutex);
BUG();
}
mutex_lock(&blktrans_ref_mutex);
list_for_each_entry(d, &tr->devs, list) {
if (new->devnum == -1) {
/* Use first free number */
if (d->devnum != last_devnum+1) {
/* Found a free devnum. Plug it in here */
new->devnum = last_devnum+1;
list_add_tail(&new->list, &d->list);
goto added;
}
} else if (d->devnum == new->devnum) {
/* Required number taken */
mutex_unlock(&blktrans_ref_mutex);
return -EBUSY;
} else if (d->devnum > new->devnum) {
/* Required number was free */
list_add_tail(&new->list, &d->list);
goto added;
}
last_devnum = d->devnum;
}
ret = -EBUSY;
if (new->devnum == -1)
new->devnum = last_devnum+1;
/* Check that the device and any partitions will get valid
* minor numbers and that the disk naming code below can cope
* with this number. */
if (new->devnum > (MINORMASK >> tr->part_bits) ||
(tr->part_bits && new->devnum >= 27 * 26)) {
mutex_unlock(&blktrans_ref_mutex);
goto error1;
}
list_add_tail(&new->list, &tr->devs);
added:
mutex_unlock(&blktrans_ref_mutex);
mutex_init(&new->lock);
kref_init(&new->ref);
if (!tr->writesect)
new->readonly = 1;
/* Create gendisk */
ret = -ENOMEM;
gd = alloc_disk(1 << tr->part_bits);
if (!gd)
goto error2;
new->disk = gd;
gd->private_data = new;
gd->major = tr->major;
gd->first_minor = (new->devnum) << tr->part_bits;
gd->fops = &mtd_blktrans_ops;
if (tr->part_bits)
if (new->devnum < 26)
snprintf(gd->disk_name, sizeof(gd->disk_name),
"%s%c", tr->name, 'a' + new->devnum);
else
snprintf(gd->disk_name, sizeof(gd->disk_name),
"%s%c%c", tr->name,
'a' - 1 + new->devnum / 26,
'a' + new->devnum % 26);
else
snprintf(gd->disk_name, sizeof(gd->disk_name),
"%s%d", tr->name, new->devnum);
set_capacity(gd, (new->size * tr->blksize) >> 9);
/* Create the request queue */
spin_lock_init(&new->queue_lock);
new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
if (!new->rq)
goto error3;
new->rq->queuedata = new;
blk_queue_logical_block_size(new->rq, tr->blksize);
if (tr->discard) {
queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, new->rq);
new->rq->limits.max_discard_sectors = UINT_MAX;
}
gd->queue = new->rq;
/* Create processing thread */
/* TODO: workqueue ? */
new->thread = kthread_run(mtd_blktrans_thread, new,
"%s%d", tr->name, new->mtd->index);
if (IS_ERR(new->thread)) {
ret = PTR_ERR(new->thread);
goto error4;
}
gd->driverfs_dev = &new->mtd->dev;
if (new->readonly)
set_disk_ro(gd, 1);
add_disk(gd);
if (new->disk_attributes) {
ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
new->disk_attributes);
WARN_ON(ret);
}
return 0;
error4:
blk_cleanup_queue(new->rq);
error3:
put_disk(new->disk);
error2:
list_del(&new->list);
error1:
return ret;
}
int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
{
unsigned long flags;
if (mutex_trylock(&mtd_table_mutex)) {
mutex_unlock(&mtd_table_mutex);
BUG();
}
if (old->disk_attributes)
sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
old->disk_attributes);
/* Stop new requests to arrive */
del_gendisk(old->disk);
/* Stop the thread */
kthread_stop(old->thread);
/* Kill current requests */
spin_lock_irqsave(&old->queue_lock, flags);
old->rq->queuedata = NULL;
blk_start_queue(old->rq);
spin_unlock_irqrestore(&old->queue_lock, flags);
mtd: allow to unload the mtdtrans module if its block devices aren't open Now it once again possible to remove mtdtrans module. You still need to ensure that block devices of that module aren't mounted. This is due to the fact that as long as a block device is open, it still exists, therefore if we were to allow module removal, this block device might became used again. This time in addition to code review, I also made the code pass some torture tests like module reload in a loop + read in a loop + card insert/removal all at same time. The blktrans_open/blktrans_release don't take the mtd table lock because: While device is added (that includes execution of add_mtd_blktrans_dev) the lock is already taken Now suppose the device will never be removed. In this case even if we have changes in mtd table, the entry that we need will stay exactly the same. (Note that we don't look at table at all, just following private pointer of block device). Now suppose that someone tries to remove the mtd device. This will be propagated to trans driver which _ought_ to call del_mtd_blktrans_dev which will take the per device lock, release the mtd device and set trans->mtd = NULL. >From this point on, following opens won't even be able to know anything about that mtd device (which at that point is likely not to exist) Also the same care is taken not to trip over NULL mtd pointer in blktrans_dev_release. Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com> Tested-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2010-10-15 15:20:43 +00:00
/* If the device is currently open, tell trans driver to close it,
then put mtd device, and don't touch it again */
mutex_lock(&old->lock);
mtd: allow to unload the mtdtrans module if its block devices aren't open Now it once again possible to remove mtdtrans module. You still need to ensure that block devices of that module aren't mounted. This is due to the fact that as long as a block device is open, it still exists, therefore if we were to allow module removal, this block device might became used again. This time in addition to code review, I also made the code pass some torture tests like module reload in a loop + read in a loop + card insert/removal all at same time. The blktrans_open/blktrans_release don't take the mtd table lock because: While device is added (that includes execution of add_mtd_blktrans_dev) the lock is already taken Now suppose the device will never be removed. In this case even if we have changes in mtd table, the entry that we need will stay exactly the same. (Note that we don't look at table at all, just following private pointer of block device). Now suppose that someone tries to remove the mtd device. This will be propagated to trans driver which _ought_ to call del_mtd_blktrans_dev which will take the per device lock, release the mtd device and set trans->mtd = NULL. >From this point on, following opens won't even be able to know anything about that mtd device (which at that point is likely not to exist) Also the same care is taken not to trip over NULL mtd pointer in blktrans_dev_release. Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com> Tested-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2010-10-15 15:20:43 +00:00
if (old->open) {
if (old->tr->release)
old->tr->release(old);
__put_mtd_device(old->mtd);
}
old->mtd = NULL;
mutex_unlock(&old->lock);
blktrans_dev_put(old);
return 0;
}
static void blktrans_notify_remove(struct mtd_info *mtd)
{
struct mtd_blktrans_ops *tr;
struct mtd_blktrans_dev *dev, *next;
list_for_each_entry(tr, &blktrans_majors, list)
list_for_each_entry_safe(dev, next, &tr->devs, list)
if (dev->mtd == mtd)
tr->remove_dev(dev);
}
static void blktrans_notify_add(struct mtd_info *mtd)
{
struct mtd_blktrans_ops *tr;
if (mtd->type == MTD_ABSENT)
return;
list_for_each_entry(tr, &blktrans_majors, list)
tr->add_mtd(tr, mtd);
}
static struct mtd_notifier blktrans_notifier = {
.add = blktrans_notify_add,
.remove = blktrans_notify_remove,
};
int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
{
struct mtd_info *mtd;
int ret;
/* Register the notifier if/when the first device type is
registered, to prevent the link/init ordering from fucking
us over. */
if (!blktrans_notifier.list.next)
register_mtd_user(&blktrans_notifier);
mutex_lock(&mtd_table_mutex);
ret = register_blkdev(tr->major, tr->name);
if (ret < 0) {
printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
tr->name, tr->major, ret);
mutex_unlock(&mtd_table_mutex);
return ret;
}
if (ret)
tr->major = ret;
tr->blkshift = ffs(tr->blksize) - 1;
INIT_LIST_HEAD(&tr->devs);
list_add(&tr->list, &blktrans_majors);
mtd_for_each_device(mtd)
if (mtd->type != MTD_ABSENT)
tr->add_mtd(tr, mtd);
mutex_unlock(&mtd_table_mutex);
return 0;
}
int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
{
struct mtd_blktrans_dev *dev, *next;
mutex_lock(&mtd_table_mutex);
/* Remove it from the list of active majors */
list_del(&tr->list);
list_for_each_entry_safe(dev, next, &tr->devs, list)
tr->remove_dev(dev);
unregister_blkdev(tr->major, tr->name);
mutex_unlock(&mtd_table_mutex);
BUG_ON(!list_empty(&tr->devs));
return 0;
}
static void __exit mtd_blktrans_exit(void)
{
/* No race here -- if someone's currently in register_mtd_blktrans
we're screwed anyway. */
if (blktrans_notifier.list.next)
unregister_mtd_user(&blktrans_notifier);
}
module_exit(mtd_blktrans_exit);
EXPORT_SYMBOL_GPL(register_mtd_blktrans);
EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");