From: Shaohua Li <shli@fb.com>
Date: Mon, 14 Aug 2017 15:04:56 -0700
Subject: [PATCH] nullb: support memory backed store
Git-commit: 5bcd0e0c79b513261172d1348f93d1bf00dffbdf
Patch-mainline: v4.14-rc1
References: bsc#1104967,FATE#325924
This adds memory backed store in nullb.
User configure 'memory_backed' attribute for this. By default, nullb
disk doesn't use memory backed store.
Based on original patch from Kyungchan Koh
Signed-off-by: Kyungchan Koh <kkc6196@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
drivers/block/null_blk.c | 339 +++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 330 insertions(+), 9 deletions(-)
diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index 2f66627d8c4b..45e0b565f448 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -15,6 +15,14 @@
#include <linux/lightnvm.h>
#include <linux/configfs.h>
+#define SECTOR_SHIFT 9
+#define PAGE_SECTORS_SHIFT (PAGE_SHIFT - SECTOR_SHIFT)
+#define PAGE_SECTORS (1 << PAGE_SECTORS_SHIFT)
+#define SECTOR_SIZE (1 << SECTOR_SHIFT)
+#define SECTOR_MASK (PAGE_SECTORS - 1)
+
+#define FREE_BATCH 16
+
struct nullb_cmd {
struct list_head list;
struct llist_node ll_list;
@@ -24,6 +32,7 @@ struct nullb_cmd {
unsigned int tag;
struct nullb_queue *nq;
struct hrtimer timer;
+ blk_status_t error;
};
struct nullb_queue {
@@ -46,9 +55,23 @@ enum nullb_device_flags {
NULLB_DEV_FL_UP = 1,
};
+/*
+ * nullb_page is a page in memory for nullb devices.
+ *
+ * @page: The page holding the data.
+ * @bitmap: The bitmap represents which sector in the page has data.
+ * Each bit represents one block size. For example, sector 8
+ * will use the 7th bit
+ */
+struct nullb_page {
+ struct page *page;
+ unsigned long bitmap;
+};
+
struct nullb_device {
struct nullb *nullb;
struct config_item item;
+ struct radix_tree_root data; /* data stored in the disk */
unsigned long flags; /* device flags */
unsigned long size; /* device size in MB */
@@ -64,6 +87,7 @@ struct nullb_device {
bool blocking; /* blocking blk-mq device */
bool use_per_node_hctx; /* use per-node allocation for hardware context */
bool power; /* power on/off the device */
+ bool memory_backed; /* if data is stored in memory */
};
struct nullb {
@@ -197,6 +221,7 @@ static struct nullb_device *null_alloc_dev(void);
static void null_free_dev(struct nullb_device *dev);
static void null_del_dev(struct nullb *nullb);
static int null_add_dev(struct nullb_device *dev);
+static void null_free_device_storage(struct nullb_device *dev);
static inline struct nullb_device *to_nullb_device(struct config_item *item)
{
@@ -292,6 +317,7 @@ NULLB_DEVICE_ATTR(index, uint);
NULLB_DEVICE_ATTR(use_lightnvm, bool);
NULLB_DEVICE_ATTR(blocking, bool);
NULLB_DEVICE_ATTR(use_per_node_hctx, bool);
+NULLB_DEVICE_ATTR(memory_backed, bool);
static ssize_t nullb_device_power_show(struct config_item *item, char *page)
{
@@ -346,12 +372,16 @@ static struct configfs_attribute *nullb_device_attrs[] = {
&nullb_device_attr_blocking,
&nullb_device_attr_use_per_node_hctx,
&nullb_device_attr_power,
+ &nullb_device_attr_memory_backed,
NULL,
};
static void nullb_device_release(struct config_item *item)
{
- null_free_dev(to_nullb_device(item));
+ struct nullb_device *dev = to_nullb_device(item);
+
+ null_free_device_storage(dev);
+ null_free_dev(dev);
}
static struct configfs_item_operations nullb_device_ops = {
@@ -395,7 +425,7 @@ nullb_group_drop_item(struct config_group *group, struct config_item *item)
static ssize_t memb_group_features_show(struct config_item *item, char *page)
{
- return snprintf(page, PAGE_SIZE, "\n");
+ return snprintf(page, PAGE_SIZE, "memory_backed\n");
}
CONFIGFS_ATTR_RO(memb_group_, features);
@@ -432,6 +462,7 @@ static struct nullb_device *null_alloc_dev(void)
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (!dev)
return NULL;
+ INIT_RADIX_TREE(&dev->data, GFP_ATOMIC);
dev->size = g_gb * 1024;
dev->completion_nsec = g_completion_nsec;
dev->submit_queues = g_submit_queues;
@@ -532,13 +563,14 @@ static void end_cmd(struct nullb_cmd *cmd)
switch (queue_mode) {
case NULL_Q_MQ:
- blk_mq_end_request(cmd->rq, BLK_STS_OK);
+ blk_mq_end_request(cmd->rq, cmd->error);
return;
case NULL_Q_RQ:
INIT_LIST_HEAD(&cmd->rq->queuelist);
- blk_end_request_all(cmd->rq, BLK_STS_OK);
+ blk_end_request_all(cmd->rq, cmd->error);
break;
case NULL_Q_BIO:
+ cmd->bio->bi_status = cmd->error;
bio_endio(cmd->bio);
break;
}
@@ -579,12 +611,297 @@ static void null_softirq_done_fn(struct request *rq)
end_cmd(rq->special);
}
-static inline void null_handle_cmd(struct nullb_cmd *cmd)
+static struct nullb_page *null_alloc_page(gfp_t gfp_flags)
+{
+ struct nullb_page *t_page;
+
+ t_page = kmalloc(sizeof(struct nullb_page), gfp_flags);
+ if (!t_page)
+ goto out;
+
+ t_page->page = alloc_pages(gfp_flags, 0);
+ if (!t_page->page)
+ goto out_freepage;
+
+ t_page->bitmap = 0;
+ return t_page;
+out_freepage:
+ kfree(t_page);
+out:
+ return NULL;
+}
+
+static void null_free_page(struct nullb_page *t_page)
+{
+ __free_page(t_page->page);
+ kfree(t_page);
+}
+
+static void null_free_sector(struct nullb *nullb, sector_t sector)
+{
+ unsigned int sector_bit;
+ u64 idx;
+ struct nullb_page *t_page, *ret;
+ struct radix_tree_root *root;
+
+ root = &nullb->dev->data;
+ idx = sector >> PAGE_SECTORS_SHIFT;
+ sector_bit = (sector & SECTOR_MASK);
+
+ t_page = radix_tree_lookup(root, idx);
+ if (t_page) {
+ __clear_bit(sector_bit, &t_page->bitmap);
+
+ if (!t_page->bitmap) {
+ ret = radix_tree_delete_item(root, idx, t_page);
+ WARN_ON(ret != t_page);
+ null_free_page(ret);
+ }
+ }
+}
+
+static struct nullb_page *null_radix_tree_insert(struct nullb *nullb, u64 idx,
+ struct nullb_page *t_page)
{
+ struct radix_tree_root *root;
+
+ root = &nullb->dev->data;
+
+ if (radix_tree_insert(root, idx, t_page)) {
+ null_free_page(t_page);
+ t_page = radix_tree_lookup(root, idx);
+ WARN_ON(!t_page || t_page->page->index != idx);
+ }
+
+ return t_page;
+}
+
+static void null_free_device_storage(struct nullb_device *dev)
+{
+ unsigned long pos = 0;
+ int nr_pages;
+ struct nullb_page *ret, *t_pages[FREE_BATCH];
+ struct radix_tree_root *root;
+
+ root = &dev->data;
+
+ do {
+ int i;
+
+ nr_pages = radix_tree_gang_lookup(root,
+ (void **)t_pages, pos, FREE_BATCH);
+
+ for (i = 0; i < nr_pages; i++) {
+ pos = t_pages[i]->page->index;
+ ret = radix_tree_delete_item(root, pos, t_pages[i]);
+ WARN_ON(ret != t_pages[i]);
+ null_free_page(ret);
+ }
+
+ pos++;
+ } while (nr_pages == FREE_BATCH);
+}
+
+static struct nullb_page *null_lookup_page(struct nullb *nullb,
+ sector_t sector, bool for_write)
+{
+ unsigned int sector_bit;
+ u64 idx;
+ struct nullb_page *t_page;
+
+ idx = sector >> PAGE_SECTORS_SHIFT;
+ sector_bit = (sector & SECTOR_MASK);
+
+ t_page = radix_tree_lookup(&nullb->dev->data, idx);
+ WARN_ON(t_page && t_page->page->index != idx);
+
+ if (t_page && (for_write || test_bit(sector_bit, &t_page->bitmap)))
+ return t_page;
+
+ return NULL;
+}
+
+static struct nullb_page *null_insert_page(struct nullb *nullb,
+ sector_t sector)
+{
+ u64 idx;
+ struct nullb_page *t_page;
+
+ t_page = null_lookup_page(nullb, sector, true);
+ if (t_page)
+ return t_page;
+
+ spin_unlock_irq(&nullb->lock);
+
+ t_page = null_alloc_page(GFP_NOIO);
+ if (!t_page)
+ goto out_lock;
+
+ if (radix_tree_preload(GFP_NOIO))
+ goto out_freepage;
+
+ spin_lock_irq(&nullb->lock);
+ idx = sector >> PAGE_SECTORS_SHIFT;
+ t_page->page->index = idx;
+ t_page = null_radix_tree_insert(nullb, idx, t_page);
+ radix_tree_preload_end();
+
+ return t_page;
+out_freepage:
+ null_free_page(t_page);
+out_lock:
+ spin_lock_irq(&nullb->lock);
+ return null_lookup_page(nullb, sector, true);
+}
+
+static int copy_to_nullb(struct nullb *nullb, struct page *source,
+ unsigned int off, sector_t sector, size_t n)
+{
+ size_t temp, count = 0;
+ unsigned int offset;
+ struct nullb_page *t_page;
+ void *dst, *src;
+
+ while (count < n) {
+ temp = min_t(size_t, nullb->dev->blocksize, n - count);
+
+ offset = (sector & SECTOR_MASK) << SECTOR_SHIFT;
+ t_page = null_insert_page(nullb, sector);
+ if (!t_page)
+ return -ENOSPC;
+
+ src = kmap_atomic(source);
+ dst = kmap_atomic(t_page->page);
+ memcpy(dst + offset, src + off + count, temp);
+ kunmap_atomic(dst);
+ kunmap_atomic(src);
+
+ __set_bit(sector & SECTOR_MASK, &t_page->bitmap);
+
+ count += temp;
+ sector += temp >> SECTOR_SHIFT;
+ }
+ return 0;
+}
+
+static int copy_from_nullb(struct nullb *nullb, struct page *dest,
+ unsigned int off, sector_t sector, size_t n)
+{
+ size_t temp, count = 0;
+ unsigned int offset;
+ struct nullb_page *t_page;
+ void *dst, *src;
+
+ while (count < n) {
+ temp = min_t(size_t, nullb->dev->blocksize, n - count);
+
+ offset = (sector & SECTOR_MASK) << SECTOR_SHIFT;
+ t_page = null_lookup_page(nullb, sector, false);
+
+ dst = kmap_atomic(dest);
+ if (!t_page) {
+ memset(dst + off + count, 0, temp);
+ goto next;
+ }
+ src = kmap_atomic(t_page->page);
+ memcpy(dst + off + count, src + offset, temp);
+ kunmap_atomic(src);
+next:
+ kunmap_atomic(dst);
+
+ count += temp;
+ sector += temp >> SECTOR_SHIFT;
+ }
+ return 0;
+}
+
+static int null_transfer(struct nullb *nullb, struct page *page,
+ unsigned int len, unsigned int off, bool is_write, sector_t sector)
+{
+ int err = 0;
+
+ if (!is_write) {
+ err = copy_from_nullb(nullb, page, off, sector, len);
+ flush_dcache_page(page);
+ } else {
+ flush_dcache_page(page);
+ err = copy_to_nullb(nullb, page, off, sector, len);
+ }
+
+ return err;
+}
+
+static int null_handle_rq(struct nullb_cmd *cmd)
+{
+ struct request *rq = cmd->rq;
+ struct nullb *nullb = cmd->nq->dev->nullb;
+ int err;
+ unsigned int len;
+ sector_t sector;
+ struct req_iterator iter;
+ struct bio_vec bvec;
+
+ sector = blk_rq_pos(rq);
+
+ spin_lock_irq(&nullb->lock);
+ rq_for_each_segment(bvec, rq, iter) {
+ len = bvec.bv_len;
+ err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
+ op_is_write(req_op(rq)), sector);
+ if (err) {
+ spin_unlock_irq(&nullb->lock);
+ return err;
+ }
+ sector += len >> SECTOR_SHIFT;
+ }
+ spin_unlock_irq(&nullb->lock);
+
+ return 0;
+}
+
+static int null_handle_bio(struct nullb_cmd *cmd)
+{
+ struct bio *bio = cmd->bio;
+ struct nullb *nullb = cmd->nq->dev->nullb;
+ int err;
+ unsigned int len;
+ sector_t sector;
+ struct bio_vec bvec;
+ struct bvec_iter iter;
+
+ sector = bio->bi_iter.bi_sector;
+
+ spin_lock_irq(&nullb->lock);
+ bio_for_each_segment(bvec, bio, iter) {
+ len = bvec.bv_len;
+ err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
+ op_is_write(bio_op(bio)), sector);
+ if (err) {
+ spin_unlock_irq(&nullb->lock);
+ return err;
+ }
+ sector += len >> SECTOR_SHIFT;
+ }
+ spin_unlock_irq(&nullb->lock);
+ return 0;
+}
+
+static blk_status_t null_handle_cmd(struct nullb_cmd *cmd)
+{
+ struct nullb_device *dev = cmd->nq->dev;
+ int err = 0;
+
+ if (dev->memory_backed) {
+ if (dev->queue_mode == NULL_Q_BIO)
+ err = null_handle_bio(cmd);
+ else
+ err = null_handle_rq(cmd);
+ }
+ cmd->error = errno_to_blk_status(err);
/* Complete IO by inline, softirq or timer */
- switch (cmd->nq->dev->irqmode) {
+ switch (dev->irqmode) {
case NULL_IRQ_SOFTIRQ:
- switch (cmd->nq->dev->queue_mode) {
+ switch (dev->queue_mode) {
case NULL_Q_MQ:
blk_mq_complete_request(cmd->rq);
break;
@@ -606,6 +923,7 @@ static inline void null_handle_cmd(struct nullb_cmd *cmd)
null_cmd_end_timer(cmd);
break;
}
+ return BLK_STS_OK;
}
static struct nullb_queue *nullb_to_queue(struct nullb *nullb)
@@ -678,8 +996,7 @@ static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx,
blk_mq_start_request(bd->rq);
- null_handle_cmd(cmd);
- return BLK_STS_OK;
+ return null_handle_cmd(cmd);
}
static const struct blk_mq_ops null_mq_ops = {
@@ -1050,6 +1367,10 @@ static void null_validate_conf(struct nullb_device *dev)
dev->queue_mode = min_t(unsigned int, dev->queue_mode, NULL_Q_MQ);
dev->irqmode = min_t(unsigned int, dev->irqmode, NULL_IRQ_TIMER);
+
+ /* Do memory allocation, so set blocking */
+ if (dev->memory_backed)
+ dev->blocking = true;
}
static int null_add_dev(struct nullb_device *dev)
--
2.16.4