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Date: Thu, 7 Jul 2016 09:54:20 +0200
From: Matias Bjørling <m@...rling.me>
To: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
axboe@...com
Cc: Matias Bjørling <m@...rling.me>
Subject: [PATCH 14/17] lightnvm: make rrpc_map_page call nvm_get_blk outside locks
The nvm_get_blk() function is called with rlun->lock held. This is ok
when the media manager implementation doesn't go out of its atomic
context. However, if a media manager persists its metadata, and
guarantees that the block is given to the target, this is no longer
a viable approach. Therefore, clean up the flow of rrpc_map_page,
and make sure that nvm_get_blk() is called without any locks acquired.
Signed-off-by: Matias Bjørling <m@...rling.me>
---
drivers/lightnvm/rrpc.c | 108 +++++++++++++++++++++++++++++-------------------
drivers/lightnvm/rrpc.h | 1 +
2 files changed, 66 insertions(+), 43 deletions(-)
diff --git a/drivers/lightnvm/rrpc.c b/drivers/lightnvm/rrpc.c
index fa8d5be..fa1ab04 100644
--- a/drivers/lightnvm/rrpc.c
+++ b/drivers/lightnvm/rrpc.c
@@ -175,18 +175,17 @@ static struct ppa_addr rrpc_ppa_to_gaddr(struct nvm_dev *dev, u64 addr)
}
/* requires lun->lock taken */
-static void rrpc_set_lun_cur(struct rrpc_lun *rlun, struct rrpc_block *rblk)
+static void rrpc_set_lun_cur(struct rrpc_lun *rlun, struct rrpc_block *new_rblk,
+ struct rrpc_block **cur_rblk)
{
struct rrpc *rrpc = rlun->rrpc;
- BUG_ON(!rblk);
-
- if (rlun->cur) {
- spin_lock(&rlun->cur->lock);
- WARN_ON(!block_is_full(rrpc, rlun->cur));
- spin_unlock(&rlun->cur->lock);
+ if (*cur_rblk) {
+ spin_lock(&(*cur_rblk)->lock);
+ WARN_ON(!block_is_full(rrpc, *cur_rblk));
+ spin_unlock(&(*cur_rblk)->lock);
}
- rlun->cur = rblk;
+ *cur_rblk = new_rblk;
}
static struct rrpc_block *rrpc_get_blk(struct rrpc *rrpc, struct rrpc_lun *rlun,
@@ -577,21 +576,20 @@ out:
return addr;
}
-/* Simple round-robin Logical to physical address translation.
+/* Map logical address to a physical page. The mapping implements a round robin
+ * approach and allocates a page from the next lun available.
*
- * Retrieve the mapping using the active append point. Then update the ap for
- * the next write to the disk.
- *
- * Returns rrpc_addr with the physical address and block. Remember to return to
- * rrpc->addr_cache when request is finished.
+ * Returns rrpc_addr with the physical address and block. Returns NULL if no
+ * blocks in the next rlun are available.
*/
static struct rrpc_addr *rrpc_map_page(struct rrpc *rrpc, sector_t laddr,
int is_gc)
{
struct rrpc_lun *rlun;
- struct rrpc_block *rblk;
+ struct rrpc_block *rblk, **cur_rblk;
struct nvm_lun *lun;
u64 paddr;
+ int gc_force = 0;
rlun = rrpc_get_lun_rr(rrpc, is_gc);
lun = rlun->parent;
@@ -599,41 +597,65 @@ static struct rrpc_addr *rrpc_map_page(struct rrpc *rrpc, sector_t laddr,
if (!is_gc && lun->nr_free_blocks < rrpc->nr_luns * 4)
return NULL;
- spin_lock(&rlun->lock);
+ /*
+ * page allocation steps:
+ * 1. Try to allocate new page from current rblk
+ * 2a. If succeed, proceed to map it in and return
+ * 2b. If fail, first try to allocate a new block from media manger,
+ * and then retry step 1. Retry until the normal block pool is
+ * exhausted.
+ * 3. If exhausted, and garbage collector is requesting the block,
+ * go to the reserved block and retry step 1.
+ * In the case that this fails as well, or it is not GC
+ * requesting, report not able to retrieve a block and let the
+ * caller handle further processing.
+ */
+ spin_lock(&rlun->lock);
+ cur_rblk = &rlun->cur;
rblk = rlun->cur;
retry:
paddr = rrpc_alloc_addr(rrpc, rblk);
- if (paddr == ADDR_EMPTY) {
- rblk = rrpc_get_blk(rrpc, rlun, 0);
- if (rblk) {
- rrpc_set_lun_cur(rlun, rblk);
- goto retry;
- }
+ if (paddr != ADDR_EMPTY)
+ goto done;
- if (is_gc) {
- /* retry from emergency gc block */
- paddr = rrpc_alloc_addr(rrpc, rlun->gc_cur);
- if (paddr == ADDR_EMPTY) {
- rblk = rrpc_get_blk(rrpc, rlun, 1);
- if (!rblk) {
- pr_err("rrpc: no more blocks");
- goto err;
- }
+ if (!list_empty(&rlun->wblk_list)) {
+new_blk:
+ rblk = list_first_entry(&rlun->wblk_list, struct rrpc_block,
+ prio);
+ rrpc_set_lun_cur(rlun, rblk, cur_rblk);
+ list_del(&rblk->prio);
+ goto retry;
+ }
+ spin_unlock(&rlun->lock);
- rlun->gc_cur = rblk;
- paddr = rrpc_alloc_addr(rrpc, rlun->gc_cur);
- }
- rblk = rlun->gc_cur;
- }
+ rblk = rrpc_get_blk(rrpc, rlun, gc_force);
+ if (rblk) {
+ spin_lock(&rlun->lock);
+ list_add_tail(&rblk->prio, &rlun->wblk_list);
+ /*
+ * another thread might already have added a new block,
+ * Therefore, make sure that one is used, instead of the
+ * one just added.
+ */
+ goto new_blk;
}
- spin_unlock(&rlun->lock);
- return rrpc_update_map(rrpc, laddr, rblk, paddr);
-err:
- spin_unlock(&rlun->lock);
+ if (unlikely(is_gc) && !gc_force) {
+ /* retry from emergency gc block */
+ cur_rblk = &rlun->gc_cur;
+ rblk = rlun->gc_cur;
+ gc_force = 1;
+ spin_lock(&rlun->lock);
+ goto retry;
+ }
+
+ pr_err("rrpc: failed to allocate new block\n");
return NULL;
+done:
+ spin_unlock(&rlun->lock);
+ return rrpc_update_map(rrpc, laddr, rblk, paddr);
}
static void rrpc_run_gc(struct rrpc *rrpc, struct rrpc_block *rblk)
@@ -1177,6 +1199,7 @@ static int rrpc_luns_init(struct rrpc *rrpc, int lun_begin, int lun_end)
rlun->rrpc = rrpc;
INIT_LIST_HEAD(&rlun->prio_list);
+ INIT_LIST_HEAD(&rlun->wblk_list);
INIT_WORK(&rlun->ws_gc, rrpc_lun_gc);
spin_lock_init(&rlun->lock);
@@ -1317,14 +1340,13 @@ static int rrpc_luns_configure(struct rrpc *rrpc)
rblk = rrpc_get_blk(rrpc, rlun, 0);
if (!rblk)
goto err;
-
- rrpc_set_lun_cur(rlun, rblk);
+ rrpc_set_lun_cur(rlun, rblk, &rlun->cur);
/* Emergency gc block */
rblk = rrpc_get_blk(rrpc, rlun, 1);
if (!rblk)
goto err;
- rlun->gc_cur = rblk;
+ rrpc_set_lun_cur(rlun, rblk, &rlun->gc_cur);
}
return 0;
diff --git a/drivers/lightnvm/rrpc.h b/drivers/lightnvm/rrpc.h
index 448e39a..5e87d52 100644
--- a/drivers/lightnvm/rrpc.h
+++ b/drivers/lightnvm/rrpc.h
@@ -76,6 +76,7 @@ struct rrpc_lun {
struct rrpc_block *blocks; /* Reference to block allocation */
struct list_head prio_list; /* Blocks that may be GC'ed */
+ struct list_head wblk_list; /* Queued blocks to be written to */
struct work_struct ws_gc;
--
2.1.4
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