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path: root/drivers/block/brd.c
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Diffstat (limited to 'drivers/block/brd.c')
-rw-r--r--drivers/block/brd.c141
1 files changed, 86 insertions, 55 deletions
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index e322cef6596b..292f127cae0a 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -29,10 +29,7 @@
/*
* Each block ramdisk device has a xarray brd_pages of pages that stores
- * the pages containing the block device's contents. A brd page's ->index is
- * its offset in PAGE_SIZE units. This is similar to, but in no way connected
- * with, the kernel's pagecache or buffer cache (which sit above our block
- * device).
+ * the pages containing the block device's contents.
*/
struct brd_device {
int brd_number;
@@ -51,15 +48,7 @@ struct brd_device {
*/
static struct page *brd_lookup_page(struct brd_device *brd, sector_t sector)
{
- pgoff_t idx;
- struct page *page;
-
- idx = sector >> PAGE_SECTORS_SHIFT; /* sector to page index */
- page = xa_load(&brd->brd_pages, idx);
-
- BUG_ON(page && page->index != idx);
-
- return page;
+ return xa_load(&brd->brd_pages, sector >> PAGE_SECTORS_SHIFT);
}
/*
@@ -67,8 +56,8 @@ static struct page *brd_lookup_page(struct brd_device *brd, sector_t sector)
*/
static int brd_insert_page(struct brd_device *brd, sector_t sector, gfp_t gfp)
{
- pgoff_t idx;
- struct page *page, *cur;
+ pgoff_t idx = sector >> PAGE_SECTORS_SHIFT;
+ struct page *page;
int ret = 0;
page = brd_lookup_page(brd, sector);
@@ -80,23 +69,16 @@ static int brd_insert_page(struct brd_device *brd, sector_t sector, gfp_t gfp)
return -ENOMEM;
xa_lock(&brd->brd_pages);
-
- idx = sector >> PAGE_SECTORS_SHIFT;
- page->index = idx;
-
- cur = __xa_cmpxchg(&brd->brd_pages, idx, NULL, page, gfp);
-
- if (unlikely(cur)) {
- __free_page(page);
- ret = xa_err(cur);
- if (!ret && (cur->index != idx))
- ret = -EIO;
- } else {
+ ret = __xa_insert(&brd->brd_pages, idx, page, gfp);
+ if (!ret)
brd->brd_nr_pages++;
- }
-
xa_unlock(&brd->brd_pages);
+ if (ret < 0) {
+ __free_page(page);
+ if (ret == -EBUSY)
+ ret = 0;
+ }
return ret;
}
@@ -240,6 +222,25 @@ out:
return err;
}
+static void brd_do_discard(struct brd_device *brd, sector_t sector, u32 size)
+{
+ sector_t aligned_sector = (sector + PAGE_SECTORS) & ~PAGE_SECTORS;
+ struct page *page;
+
+ size -= (aligned_sector - sector) * SECTOR_SIZE;
+ xa_lock(&brd->brd_pages);
+ while (size >= PAGE_SIZE && aligned_sector < rd_size * 2) {
+ page = __xa_erase(&brd->brd_pages, aligned_sector >> PAGE_SECTORS_SHIFT);
+ if (page) {
+ __free_page(page);
+ brd->brd_nr_pages--;
+ }
+ aligned_sector += PAGE_SECTORS;
+ size -= PAGE_SIZE;
+ }
+ xa_unlock(&brd->brd_pages);
+}
+
static void brd_submit_bio(struct bio *bio)
{
struct brd_device *brd = bio->bi_bdev->bd_disk->private_data;
@@ -247,6 +248,12 @@ static void brd_submit_bio(struct bio *bio)
struct bio_vec bvec;
struct bvec_iter iter;
+ if (unlikely(op_is_discard(bio->bi_opf))) {
+ brd_do_discard(brd, sector, bio->bi_iter.bi_size);
+ bio_endio(bio);
+ return;
+ }
+
bio_for_each_segment(bvec, bio, iter) {
unsigned int len = bvec.bv_len;
int err;
@@ -291,6 +298,7 @@ static int max_part = 1;
module_param(max_part, int, 0444);
MODULE_PARM_DESC(max_part, "Num Minors to reserve between devices");
+MODULE_DESCRIPTION("Ram backed block device driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR);
MODULE_ALIAS("rd");
@@ -310,8 +318,40 @@ __setup("ramdisk_size=", ramdisk_size);
* (should share code eventually).
*/
static LIST_HEAD(brd_devices);
+static DEFINE_MUTEX(brd_devices_mutex);
static struct dentry *brd_debugfs_dir;
+static struct brd_device *brd_find_or_alloc_device(int i)
+{
+ struct brd_device *brd;
+
+ mutex_lock(&brd_devices_mutex);
+ list_for_each_entry(brd, &brd_devices, brd_list) {
+ if (brd->brd_number == i) {
+ mutex_unlock(&brd_devices_mutex);
+ return ERR_PTR(-EEXIST);
+ }
+ }
+
+ brd = kzalloc(sizeof(*brd), GFP_KERNEL);
+ if (!brd) {
+ mutex_unlock(&brd_devices_mutex);
+ return ERR_PTR(-ENOMEM);
+ }
+ brd->brd_number = i;
+ list_add_tail(&brd->brd_list, &brd_devices);
+ mutex_unlock(&brd_devices_mutex);
+ return brd;
+}
+
+static void brd_free_device(struct brd_device *brd)
+{
+ mutex_lock(&brd_devices_mutex);
+ list_del(&brd->brd_list);
+ mutex_unlock(&brd_devices_mutex);
+ kfree(brd);
+}
+
static int brd_alloc(int i)
{
struct brd_device *brd;
@@ -327,16 +367,16 @@ static int brd_alloc(int i)
* is harmless)
*/
.physical_block_size = PAGE_SIZE,
+ .max_hw_discard_sectors = UINT_MAX,
+ .max_discard_segments = 1,
+ .discard_granularity = PAGE_SIZE,
+ .features = BLK_FEAT_SYNCHRONOUS |
+ BLK_FEAT_NOWAIT,
};
- list_for_each_entry(brd, &brd_devices, brd_list)
- if (brd->brd_number == i)
- return -EEXIST;
- brd = kzalloc(sizeof(*brd), GFP_KERNEL);
- if (!brd)
- return -ENOMEM;
- brd->brd_number = i;
- list_add_tail(&brd->brd_list, &brd_devices);
+ brd = brd_find_or_alloc_device(i);
+ if (IS_ERR(brd))
+ return PTR_ERR(brd);
xa_init(&brd->brd_pages);
@@ -358,10 +398,6 @@ static int brd_alloc(int i)
strscpy(disk->disk_name, buf, DISK_NAME_LEN);
set_capacity(disk, rd_size * 2);
- /* Tell the block layer that this is not a rotational device */
- blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);
- blk_queue_flag_set(QUEUE_FLAG_SYNCHRONOUS, disk->queue);
- blk_queue_flag_set(QUEUE_FLAG_NOWAIT, disk->queue);
err = add_disk(disk);
if (err)
goto out_cleanup_disk;
@@ -371,8 +407,7 @@ static int brd_alloc(int i)
out_cleanup_disk:
put_disk(disk);
out_free_dev:
- list_del(&brd->brd_list);
- kfree(brd);
+ brd_free_device(brd);
return err;
}
@@ -391,8 +426,7 @@ static void brd_cleanup(void)
del_gendisk(brd->brd_disk);
put_disk(brd->brd_disk);
brd_free_pages(brd);
- list_del(&brd->brd_list);
- kfree(brd);
+ brd_free_device(brd);
}
}
@@ -419,16 +453,6 @@ static int __init brd_init(void)
{
int err, i;
- brd_check_and_reset_par();
-
- brd_debugfs_dir = debugfs_create_dir("ramdisk_pages", NULL);
-
- for (i = 0; i < rd_nr; i++) {
- err = brd_alloc(i);
- if (err)
- goto out_free;
- }
-
/*
* brd module now has a feature to instantiate underlying device
* structure on-demand, provided that there is an access dev node.
@@ -444,11 +468,18 @@ static int __init brd_init(void)
* dynamically.
*/
+ brd_check_and_reset_par();
+
+ brd_debugfs_dir = debugfs_create_dir("ramdisk_pages", NULL);
+
if (__register_blkdev(RAMDISK_MAJOR, "ramdisk", brd_probe)) {
err = -EIO;
goto out_free;
}
+ for (i = 0; i < rd_nr; i++)
+ brd_alloc(i);
+
pr_info("brd: module loaded\n");
return 0;
generated by cgit (git 2.34.1) at 2025-03-22 09:03:59 +0000