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0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * Interface to Linux block layer for MTD 'translation layers'.
0004  *
0005  * Copyright © 2003-2010 David Woodhouse <dwmw2@infradead.org>
0006  */
0007 
0008 #include <linux/kernel.h>
0009 #include <linux/slab.h>
0010 #include <linux/module.h>
0011 #include <linux/list.h>
0012 #include <linux/fs.h>
0013 #include <linux/mtd/blktrans.h>
0014 #include <linux/mtd/mtd.h>
0015 #include <linux/blkdev.h>
0016 #include <linux/blk-mq.h>
0017 #include <linux/blkpg.h>
0018 #include <linux/spinlock.h>
0019 #include <linux/hdreg.h>
0020 #include <linux/mutex.h>
0021 #include <linux/uaccess.h>
0022 
0023 #include "mtdcore.h"
0024 
0025 static LIST_HEAD(blktrans_majors);
0026 
0027 static void blktrans_dev_release(struct kref *kref)
0028 {
0029     struct mtd_blktrans_dev *dev =
0030         container_of(kref, struct mtd_blktrans_dev, ref);
0031 
0032     put_disk(dev->disk);
0033     blk_mq_free_tag_set(dev->tag_set);
0034     kfree(dev->tag_set);
0035     list_del(&dev->list);
0036     kfree(dev);
0037 }
0038 
0039 static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
0040 {
0041     kref_put(&dev->ref, blktrans_dev_release);
0042 }
0043 
0044 
0045 static blk_status_t do_blktrans_request(struct mtd_blktrans_ops *tr,
0046                    struct mtd_blktrans_dev *dev,
0047                    struct request *req)
0048 {
0049     struct req_iterator iter;
0050     struct bio_vec bvec;
0051     unsigned long block, nsect;
0052     char *buf;
0053 
0054     block = blk_rq_pos(req) << 9 >> tr->blkshift;
0055     nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
0056 
0057     switch (req_op(req)) {
0058     case REQ_OP_FLUSH:
0059         if (tr->flush(dev))
0060             return BLK_STS_IOERR;
0061         return BLK_STS_OK;
0062     case REQ_OP_DISCARD:
0063         if (tr->discard(dev, block, nsect))
0064             return BLK_STS_IOERR;
0065         return BLK_STS_OK;
0066     case REQ_OP_READ:
0067         buf = kmap(bio_page(req->bio)) + bio_offset(req->bio);
0068         for (; nsect > 0; nsect--, block++, buf += tr->blksize) {
0069             if (tr->readsect(dev, block, buf)) {
0070                 kunmap(bio_page(req->bio));
0071                 return BLK_STS_IOERR;
0072             }
0073         }
0074         kunmap(bio_page(req->bio));
0075 
0076         rq_for_each_segment(bvec, req, iter)
0077             flush_dcache_page(bvec.bv_page);
0078         return BLK_STS_OK;
0079     case REQ_OP_WRITE:
0080         if (!tr->writesect)
0081             return BLK_STS_IOERR;
0082 
0083         rq_for_each_segment(bvec, req, iter)
0084             flush_dcache_page(bvec.bv_page);
0085 
0086         buf = kmap(bio_page(req->bio)) + bio_offset(req->bio);
0087         for (; nsect > 0; nsect--, block++, buf += tr->blksize) {
0088             if (tr->writesect(dev, block, buf)) {
0089                 kunmap(bio_page(req->bio));
0090                 return BLK_STS_IOERR;
0091             }
0092         }
0093         kunmap(bio_page(req->bio));
0094         return BLK_STS_OK;
0095     default:
0096         return BLK_STS_IOERR;
0097     }
0098 }
0099 
0100 int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
0101 {
0102     return dev->bg_stop;
0103 }
0104 EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
0105 
0106 static struct request *mtd_next_request(struct mtd_blktrans_dev *dev)
0107 {
0108     struct request *rq;
0109 
0110     rq = list_first_entry_or_null(&dev->rq_list, struct request, queuelist);
0111     if (rq) {
0112         list_del_init(&rq->queuelist);
0113         blk_mq_start_request(rq);
0114         return rq;
0115     }
0116 
0117     return NULL;
0118 }
0119 
0120 static void mtd_blktrans_work(struct mtd_blktrans_dev *dev)
0121     __releases(&dev->queue_lock)
0122     __acquires(&dev->queue_lock)
0123 {
0124     struct mtd_blktrans_ops *tr = dev->tr;
0125     struct request *req = NULL;
0126     int background_done = 0;
0127 
0128     while (1) {
0129         blk_status_t res;
0130 
0131         dev->bg_stop = false;
0132         if (!req && !(req = mtd_next_request(dev))) {
0133             if (tr->background && !background_done) {
0134                 spin_unlock_irq(&dev->queue_lock);
0135                 mutex_lock(&dev->lock);
0136                 tr->background(dev);
0137                 mutex_unlock(&dev->lock);
0138                 spin_lock_irq(&dev->queue_lock);
0139                 /*
0140                  * Do background processing just once per idle
0141                  * period.
0142                  */
0143                 background_done = !dev->bg_stop;
0144                 continue;
0145             }
0146             break;
0147         }
0148 
0149         spin_unlock_irq(&dev->queue_lock);
0150 
0151         mutex_lock(&dev->lock);
0152         res = do_blktrans_request(dev->tr, dev, req);
0153         mutex_unlock(&dev->lock);
0154 
0155         if (!blk_update_request(req, res, blk_rq_cur_bytes(req))) {
0156             __blk_mq_end_request(req, res);
0157             req = NULL;
0158         }
0159 
0160         background_done = 0;
0161         cond_resched();
0162         spin_lock_irq(&dev->queue_lock);
0163     }
0164 }
0165 
0166 static blk_status_t mtd_queue_rq(struct blk_mq_hw_ctx *hctx,
0167                  const struct blk_mq_queue_data *bd)
0168 {
0169     struct mtd_blktrans_dev *dev;
0170 
0171     dev = hctx->queue->queuedata;
0172     if (!dev) {
0173         blk_mq_start_request(bd->rq);
0174         return BLK_STS_IOERR;
0175     }
0176 
0177     spin_lock_irq(&dev->queue_lock);
0178     list_add_tail(&bd->rq->queuelist, &dev->rq_list);
0179     mtd_blktrans_work(dev);
0180     spin_unlock_irq(&dev->queue_lock);
0181 
0182     return BLK_STS_OK;
0183 }
0184 
0185 static int blktrans_open(struct block_device *bdev, fmode_t mode)
0186 {
0187     struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
0188     int ret = 0;
0189 
0190     kref_get(&dev->ref);
0191 
0192     mutex_lock(&dev->lock);
0193 
0194     if (dev->open)
0195         goto unlock;
0196 
0197     __module_get(dev->tr->owner);
0198 
0199     if (!dev->mtd)
0200         goto unlock;
0201 
0202     if (dev->tr->open) {
0203         ret = dev->tr->open(dev);
0204         if (ret)
0205             goto error_put;
0206     }
0207 
0208     ret = __get_mtd_device(dev->mtd);
0209     if (ret)
0210         goto error_release;
0211     dev->file_mode = mode;
0212 
0213 unlock:
0214     dev->open++;
0215     mutex_unlock(&dev->lock);
0216     return ret;
0217 
0218 error_release:
0219     if (dev->tr->release)
0220         dev->tr->release(dev);
0221 error_put:
0222     module_put(dev->tr->owner);
0223     mutex_unlock(&dev->lock);
0224     blktrans_dev_put(dev);
0225     return ret;
0226 }
0227 
0228 static void blktrans_release(struct gendisk *disk, fmode_t mode)
0229 {
0230     struct mtd_blktrans_dev *dev = disk->private_data;
0231 
0232     mutex_lock(&dev->lock);
0233 
0234     if (--dev->open)
0235         goto unlock;
0236 
0237     module_put(dev->tr->owner);
0238 
0239     if (dev->mtd) {
0240         if (dev->tr->release)
0241             dev->tr->release(dev);
0242         __put_mtd_device(dev->mtd);
0243     }
0244 unlock:
0245     mutex_unlock(&dev->lock);
0246     blktrans_dev_put(dev);
0247 }
0248 
0249 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
0250 {
0251     struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
0252     int ret = -ENXIO;
0253 
0254     mutex_lock(&dev->lock);
0255 
0256     if (!dev->mtd)
0257         goto unlock;
0258 
0259     ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : -ENOTTY;
0260 unlock:
0261     mutex_unlock(&dev->lock);
0262     return ret;
0263 }
0264 
0265 static const struct block_device_operations mtd_block_ops = {
0266     .owner      = THIS_MODULE,
0267     .open       = blktrans_open,
0268     .release    = blktrans_release,
0269     .getgeo     = blktrans_getgeo,
0270 };
0271 
0272 static const struct blk_mq_ops mtd_mq_ops = {
0273     .queue_rq   = mtd_queue_rq,
0274 };
0275 
0276 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
0277 {
0278     struct mtd_blktrans_ops *tr = new->tr;
0279     struct mtd_blktrans_dev *d;
0280     int last_devnum = -1;
0281     struct gendisk *gd;
0282     int ret;
0283 
0284     lockdep_assert_held(&mtd_table_mutex);
0285 
0286     list_for_each_entry(d, &tr->devs, list) {
0287         if (new->devnum == -1) {
0288             /* Use first free number */
0289             if (d->devnum != last_devnum+1) {
0290                 /* Found a free devnum. Plug it in here */
0291                 new->devnum = last_devnum+1;
0292                 list_add_tail(&new->list, &d->list);
0293                 goto added;
0294             }
0295         } else if (d->devnum == new->devnum) {
0296             /* Required number taken */
0297             return -EBUSY;
0298         } else if (d->devnum > new->devnum) {
0299             /* Required number was free */
0300             list_add_tail(&new->list, &d->list);
0301             goto added;
0302         }
0303         last_devnum = d->devnum;
0304     }
0305 
0306     ret = -EBUSY;
0307     if (new->devnum == -1)
0308         new->devnum = last_devnum+1;
0309 
0310     /* Check that the device and any partitions will get valid
0311      * minor numbers and that the disk naming code below can cope
0312      * with this number. */
0313     if (new->devnum > (MINORMASK >> tr->part_bits) ||
0314         (tr->part_bits && new->devnum >= 27 * 26))
0315         return ret;
0316 
0317     list_add_tail(&new->list, &tr->devs);
0318  added:
0319 
0320     mutex_init(&new->lock);
0321     kref_init(&new->ref);
0322     if (!tr->writesect)
0323         new->readonly = 1;
0324 
0325     ret = -ENOMEM;
0326     new->tag_set = kzalloc(sizeof(*new->tag_set), GFP_KERNEL);
0327     if (!new->tag_set)
0328         goto out_list_del;
0329 
0330     ret = blk_mq_alloc_sq_tag_set(new->tag_set, &mtd_mq_ops, 2,
0331             BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING);
0332     if (ret)
0333         goto out_kfree_tag_set;
0334 
0335     /* Create gendisk */
0336     gd = blk_mq_alloc_disk(new->tag_set, new);
0337     if (IS_ERR(gd)) {
0338         ret = PTR_ERR(gd);
0339         goto out_free_tag_set;
0340     }
0341 
0342     new->disk = gd;
0343     new->rq = new->disk->queue;
0344     gd->private_data = new;
0345     gd->major = tr->major;
0346     gd->first_minor = (new->devnum) << tr->part_bits;
0347     gd->minors = 1 << tr->part_bits;
0348     gd->fops = &mtd_block_ops;
0349 
0350     if (tr->part_bits) {
0351         if (new->devnum < 26)
0352             snprintf(gd->disk_name, sizeof(gd->disk_name),
0353                  "%s%c", tr->name, 'a' + new->devnum);
0354         else
0355             snprintf(gd->disk_name, sizeof(gd->disk_name),
0356                  "%s%c%c", tr->name,
0357                  'a' - 1 + new->devnum / 26,
0358                  'a' + new->devnum % 26);
0359     } else {
0360         snprintf(gd->disk_name, sizeof(gd->disk_name),
0361              "%s%d", tr->name, new->devnum);
0362         gd->flags |= GENHD_FL_NO_PART;
0363     }
0364 
0365     set_capacity(gd, ((u64)new->size * tr->blksize) >> 9);
0366 
0367     /* Create the request queue */
0368     spin_lock_init(&new->queue_lock);
0369     INIT_LIST_HEAD(&new->rq_list);
0370 
0371     if (tr->flush)
0372         blk_queue_write_cache(new->rq, true, false);
0373 
0374     blk_queue_logical_block_size(new->rq, tr->blksize);
0375 
0376     blk_queue_flag_set(QUEUE_FLAG_NONROT, new->rq);
0377     blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, new->rq);
0378 
0379     if (tr->discard) {
0380         blk_queue_max_discard_sectors(new->rq, UINT_MAX);
0381         new->rq->limits.discard_granularity = tr->blksize;
0382     }
0383 
0384     gd->queue = new->rq;
0385 
0386     if (new->readonly)
0387         set_disk_ro(gd, 1);
0388 
0389     ret = device_add_disk(&new->mtd->dev, gd, NULL);
0390     if (ret)
0391         goto out_cleanup_disk;
0392 
0393     if (new->disk_attributes) {
0394         ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
0395                     new->disk_attributes);
0396         WARN_ON(ret);
0397     }
0398     return 0;
0399 
0400 out_cleanup_disk:
0401     put_disk(new->disk);
0402 out_free_tag_set:
0403     blk_mq_free_tag_set(new->tag_set);
0404 out_kfree_tag_set:
0405     kfree(new->tag_set);
0406 out_list_del:
0407     list_del(&new->list);
0408     return ret;
0409 }
0410 
0411 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
0412 {
0413     unsigned long flags;
0414 
0415     lockdep_assert_held(&mtd_table_mutex);
0416 
0417     if (old->disk_attributes)
0418         sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
0419                         old->disk_attributes);
0420 
0421     /* Stop new requests to arrive */
0422     del_gendisk(old->disk);
0423 
0424     /* Kill current requests */
0425     spin_lock_irqsave(&old->queue_lock, flags);
0426     old->rq->queuedata = NULL;
0427     spin_unlock_irqrestore(&old->queue_lock, flags);
0428 
0429     /* freeze+quiesce queue to ensure all requests are flushed */
0430     blk_mq_freeze_queue(old->rq);
0431     blk_mq_quiesce_queue(old->rq);
0432     blk_mq_unquiesce_queue(old->rq);
0433     blk_mq_unfreeze_queue(old->rq);
0434 
0435     /* If the device is currently open, tell trans driver to close it,
0436         then put mtd device, and don't touch it again */
0437     mutex_lock(&old->lock);
0438     if (old->open) {
0439         if (old->tr->release)
0440             old->tr->release(old);
0441         __put_mtd_device(old->mtd);
0442     }
0443 
0444     old->mtd = NULL;
0445 
0446     mutex_unlock(&old->lock);
0447     blktrans_dev_put(old);
0448     return 0;
0449 }
0450 
0451 static void blktrans_notify_remove(struct mtd_info *mtd)
0452 {
0453     struct mtd_blktrans_ops *tr;
0454     struct mtd_blktrans_dev *dev, *next;
0455 
0456     list_for_each_entry(tr, &blktrans_majors, list)
0457         list_for_each_entry_safe(dev, next, &tr->devs, list)
0458             if (dev->mtd == mtd)
0459                 tr->remove_dev(dev);
0460 }
0461 
0462 static void blktrans_notify_add(struct mtd_info *mtd)
0463 {
0464     struct mtd_blktrans_ops *tr;
0465 
0466     if (mtd->type == MTD_ABSENT)
0467         return;
0468 
0469     list_for_each_entry(tr, &blktrans_majors, list)
0470         tr->add_mtd(tr, mtd);
0471 }
0472 
0473 static struct mtd_notifier blktrans_notifier = {
0474     .add = blktrans_notify_add,
0475     .remove = blktrans_notify_remove,
0476 };
0477 
0478 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
0479 {
0480     struct mtd_info *mtd;
0481     int ret;
0482 
0483     /* Register the notifier if/when the first device type is
0484        registered, to prevent the link/init ordering from fucking
0485        us over. */
0486     if (!blktrans_notifier.list.next)
0487         register_mtd_user(&blktrans_notifier);
0488 
0489     ret = register_blkdev(tr->major, tr->name);
0490     if (ret < 0) {
0491         printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
0492                tr->name, tr->major, ret);
0493         return ret;
0494     }
0495 
0496     if (ret)
0497         tr->major = ret;
0498 
0499     tr->blkshift = ffs(tr->blksize) - 1;
0500 
0501     INIT_LIST_HEAD(&tr->devs);
0502 
0503     mutex_lock(&mtd_table_mutex);
0504     list_add(&tr->list, &blktrans_majors);
0505     mtd_for_each_device(mtd)
0506         if (mtd->type != MTD_ABSENT)
0507             tr->add_mtd(tr, mtd);
0508     mutex_unlock(&mtd_table_mutex);
0509     return 0;
0510 }
0511 
0512 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
0513 {
0514     struct mtd_blktrans_dev *dev, *next;
0515 
0516     mutex_lock(&mtd_table_mutex);
0517 
0518     /* Remove it from the list of active majors */
0519     list_del(&tr->list);
0520 
0521     list_for_each_entry_safe(dev, next, &tr->devs, list)
0522         tr->remove_dev(dev);
0523 
0524     mutex_unlock(&mtd_table_mutex);
0525     unregister_blkdev(tr->major, tr->name);
0526 
0527     BUG_ON(!list_empty(&tr->devs));
0528     return 0;
0529 }
0530 
0531 static void __exit mtd_blktrans_exit(void)
0532 {
0533     /* No race here -- if someone's currently in register_mtd_blktrans
0534        we're screwed anyway. */
0535     if (blktrans_notifier.list.next)
0536         unregister_mtd_user(&blktrans_notifier);
0537 }
0538 
0539 module_exit(mtd_blktrans_exit);
0540 
0541 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
0542 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
0543 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
0544 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
0545 
0546 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
0547 MODULE_LICENSE("GPL");
0548 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");
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