block: switch gendisk lookup to a simple xarray
Now that bdev_map is only used for finding gendisks, we can use a simple xarray instead of the regions tracking structure for it. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig
Jens Axboe
parent
76487f0241
commit
e418de3abc
206
block/genhd.c
206
block/genhd.c
@ -27,15 +27,7 @@
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static struct kobject *block_depr;
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struct bdev_map {
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struct bdev_map *next;
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dev_t dev;
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unsigned long range;
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struct module *owner;
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struct kobject *(*probe)(dev_t, int *, void *);
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int (*lock)(dev_t, void *);
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void *data;
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} *bdev_map[255];
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static DEFINE_XARRAY(bdev_map);
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static DEFINE_MUTEX(bdev_map_lock);
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/* for extended dynamic devt allocation, currently only one major is used */
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@ -649,85 +641,26 @@ static char *bdevt_str(dev_t devt, char *buf)
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return buf;
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}
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/*
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* Register device numbers dev..(dev+range-1)
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* range must be nonzero
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* The hash chain is sorted on range, so that subranges can override.
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*/
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void blk_register_region(dev_t devt, unsigned long range, struct module *module,
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struct kobject *(*probe)(dev_t, int *, void *),
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int (*lock)(dev_t, void *), void *data)
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static void blk_register_region(struct gendisk *disk)
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{
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unsigned n = MAJOR(devt + range - 1) - MAJOR(devt) + 1;
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unsigned index = MAJOR(devt);
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unsigned i;
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struct bdev_map *p;
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n = min(n, 255u);
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p = kmalloc_array(n, sizeof(struct bdev_map), GFP_KERNEL);
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if (p == NULL)
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return;
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for (i = 0; i < n; i++, p++) {
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p->owner = module;
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p->probe = probe;
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p->lock = lock;
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p->dev = devt;
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p->range = range;
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p->data = data;
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}
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int i;
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mutex_lock(&bdev_map_lock);
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for (i = 0, p -= n; i < n; i++, p++, index++) {
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struct bdev_map **s = &bdev_map[index % 255];
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while (*s && (*s)->range < range)
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s = &(*s)->next;
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p->next = *s;
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*s = p;
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for (i = 0; i < disk->minors; i++) {
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if (xa_insert(&bdev_map, disk_devt(disk) + i, disk, GFP_KERNEL))
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WARN_ON_ONCE(1);
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}
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mutex_unlock(&bdev_map_lock);
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}
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EXPORT_SYMBOL(blk_register_region);
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void blk_unregister_region(dev_t devt, unsigned long range)
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static void blk_unregister_region(struct gendisk *disk)
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{
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unsigned n = MAJOR(devt + range - 1) - MAJOR(devt) + 1;
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unsigned index = MAJOR(devt);
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unsigned i;
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struct bdev_map *found = NULL;
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int i;
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mutex_lock(&bdev_map_lock);
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for (i = 0; i < min(n, 255u); i++, index++) {
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struct bdev_map **s;
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for (s = &bdev_map[index % 255]; *s; s = &(*s)->next) {
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struct bdev_map *p = *s;
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if (p->dev == devt && p->range == range) {
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*s = p->next;
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if (!found)
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found = p;
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break;
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}
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}
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}
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for (i = 0; i < disk->minors; i++)
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xa_erase(&bdev_map, disk_devt(disk) + i);
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mutex_unlock(&bdev_map_lock);
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kfree(found);
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}
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EXPORT_SYMBOL(blk_unregister_region);
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static struct kobject *exact_match(dev_t devt, int *partno, void *data)
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{
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struct gendisk *p = data;
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return &disk_to_dev(p)->kobj;
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}
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static int exact_lock(dev_t devt, void *data)
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{
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struct gendisk *p = data;
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if (!get_disk_and_module(p))
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return -1;
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return 0;
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}
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static void disk_scan_partitions(struct gendisk *disk)
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@ -873,8 +806,7 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk,
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ret = bdi_register(bdi, "%u:%u", MAJOR(devt), MINOR(devt));
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WARN_ON(ret);
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bdi_set_owner(bdi, dev);
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blk_register_region(disk_devt(disk), disk->minors, NULL,
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exact_match, exact_lock, disk);
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blk_register_region(disk);
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}
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register_disk(parent, disk, groups);
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if (register_queue)
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@ -987,7 +919,7 @@ void del_gendisk(struct gendisk *disk)
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blk_unregister_queue(disk);
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if (!(disk->flags & GENHD_FL_HIDDEN))
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blk_unregister_region(disk_devt(disk), disk->minors);
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blk_unregister_region(disk);
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/*
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* Remove gendisk pointer from idr so that it cannot be looked up
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* while RCU period before freeing gendisk is running to prevent
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@ -1053,54 +985,22 @@ static void request_gendisk_module(dev_t devt)
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request_module("block-major-%d", MAJOR(devt));
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}
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static struct gendisk *lookup_gendisk(dev_t dev, int *partno)
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static bool get_disk_and_module(struct gendisk *disk)
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{
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struct kobject *kobj;
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struct bdev_map *p;
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unsigned long best = ~0UL;
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struct module *owner;
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retry:
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mutex_lock(&bdev_map_lock);
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for (p = bdev_map[MAJOR(dev) % 255]; p; p = p->next) {
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struct kobject *(*probe)(dev_t, int *, void *);
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struct module *owner;
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void *data;
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if (p->dev > dev || p->dev + p->range - 1 < dev)
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continue;
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if (p->range - 1 >= best)
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break;
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if (!try_module_get(p->owner))
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continue;
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owner = p->owner;
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data = p->data;
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probe = p->probe;
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best = p->range - 1;
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*partno = dev - p->dev;
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if (!probe) {
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mutex_unlock(&bdev_map_lock);
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module_put(owner);
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request_gendisk_module(dev);
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goto retry;
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}
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if (p->lock && p->lock(dev, data) < 0) {
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module_put(owner);
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continue;
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}
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mutex_unlock(&bdev_map_lock);
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kobj = probe(dev, partno, data);
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/* Currently ->owner protects _only_ ->probe() itself. */
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if (!disk->fops)
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return false;
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owner = disk->fops->owner;
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if (owner && !try_module_get(owner))
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return false;
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if (!kobject_get_unless_zero(&disk_to_dev(disk)->kobj)) {
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module_put(owner);
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if (kobj)
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return dev_to_disk(kobj_to_dev(kobj));
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goto retry;
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return false;
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}
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mutex_unlock(&bdev_map_lock);
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return NULL;
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}
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return true;
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}
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/**
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* get_gendisk - get partitioning information for a given device
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@ -1119,7 +1019,19 @@ struct gendisk *get_gendisk(dev_t devt, int *partno)
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might_sleep();
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if (MAJOR(devt) != BLOCK_EXT_MAJOR) {
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disk = lookup_gendisk(devt, partno);
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mutex_lock(&bdev_map_lock);
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disk = xa_load(&bdev_map, devt);
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if (!disk) {
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mutex_unlock(&bdev_map_lock);
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request_gendisk_module(devt);
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mutex_lock(&bdev_map_lock);
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disk = xa_load(&bdev_map, devt);
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}
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if (disk && !get_disk_and_module(disk))
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disk = NULL;
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if (disk)
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*partno = devt - disk_devt(disk);
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mutex_unlock(&bdev_map_lock);
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} else {
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struct hd_struct *part;
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@ -1323,21 +1235,6 @@ static const struct seq_operations partitions_op = {
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};
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#endif
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static void bdev_map_init(void)
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{
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struct bdev_map *base;
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int i;
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base = kzalloc(sizeof(*base), GFP_KERNEL);
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if (!base)
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panic("cannot allocate bdev_map");
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base->dev = 1;
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base->range = ~0 ;
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for (i = 0; i < 255; i++)
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bdev_map[i] = base;
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}
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static int __init genhd_device_init(void)
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{
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int error;
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@ -1346,7 +1243,6 @@ static int __init genhd_device_init(void)
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error = class_register(&block_class);
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if (unlikely(error))
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return error;
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bdev_map_init();
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blk_dev_init();
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register_blkdev(BLOCK_EXT_MAJOR, "blkext");
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@ -1895,35 +1791,6 @@ out_free_disk:
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}
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EXPORT_SYMBOL(__alloc_disk_node);
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/**
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* get_disk_and_module - increments the gendisk and gendisk fops module refcount
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* @disk: the struct gendisk to increment the refcount for
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*
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* This increments the refcount for the struct gendisk, and the gendisk's
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* fops module owner.
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*
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* Context: Any context.
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*/
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struct kobject *get_disk_and_module(struct gendisk *disk)
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{
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struct module *owner;
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struct kobject *kobj;
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if (!disk->fops)
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return NULL;
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owner = disk->fops->owner;
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if (owner && !try_module_get(owner))
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return NULL;
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kobj = kobject_get_unless_zero(&disk_to_dev(disk)->kobj);
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if (kobj == NULL) {
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module_put(owner);
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return NULL;
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}
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return kobj;
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}
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EXPORT_SYMBOL(get_disk_and_module);
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/**
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* put_disk - decrements the gendisk refcount
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* @disk: the struct gendisk to decrement the refcount for
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@ -1960,7 +1827,6 @@ void put_disk_and_module(struct gendisk *disk)
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module_put(owner);
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}
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}
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EXPORT_SYMBOL(put_disk_and_module);
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static void set_disk_ro_uevent(struct gendisk *gd, int ro)
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{
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@ -339,15 +339,8 @@ int blk_add_partitions(struct gendisk *disk, struct block_device *bdev);
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int blk_drop_partitions(struct block_device *bdev);
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extern struct gendisk *__alloc_disk_node(int minors, int node_id);
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extern struct kobject *get_disk_and_module(struct gendisk *disk);
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extern void put_disk(struct gendisk *disk);
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extern void put_disk_and_module(struct gendisk *disk);
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extern void blk_register_region(dev_t devt, unsigned long range,
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struct module *module,
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struct kobject *(*probe)(dev_t, int *, void *),
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int (*lock)(dev_t, void *),
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void *data);
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extern void blk_unregister_region(dev_t devt, unsigned long range);
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#define alloc_disk_node(minors, node_id) \
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({ \
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