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Message-Id: <20180117202203.19756-100-willy@infradead.org>
Date: Wed, 17 Jan 2018 12:22:03 -0800
From: Matthew Wilcox <willy@...radead.org>
To: linux-kernel@...r.kernel.org
Cc: Matthew Wilcox <mawilcox@...rosoft.com>, linux-mm@...ck.org,
linux-fsdevel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net,
linux-nilfs@...r.kernel.org, linux-btrfs@...r.kernel.org,
linux-xfs@...r.kernel.org, linux-usb@...r.kernel.org,
Bjorn Andersson <bjorn.andersson@...aro.org>,
Stefano Stabellini <sstabellini@...nel.org>,
iommu@...ts.linux-foundation.org, linux-remoteproc@...r.kernel.org,
linux-s390@...r.kernel.org, intel-gfx@...ts.freedesktop.org,
cgroups@...r.kernel.org, linux-sh@...r.kernel.org,
David Howells <dhowells@...hat.com>
Subject: [PATCH v6 99/99] null_blk: Convert to XArray
From: Matthew Wilcox <mawilcox@...rosoft.com>
We can probably avoid the call to xa_reserve() by changing the locking,
but I didn't feel confident enough to do that.
Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
---
drivers/block/null_blk.c | 87 +++++++++++++++++++++---------------------------
1 file changed, 38 insertions(+), 49 deletions(-)
diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index ad0477ae820f..d90d173b8885 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -15,6 +15,7 @@
#include <linux/lightnvm.h>
#include <linux/configfs.h>
#include <linux/badblocks.h>
+#include <linux/xarray.h>
#define SECTOR_SHIFT 9
#define PAGE_SECTORS_SHIFT (PAGE_SHIFT - SECTOR_SHIFT)
@@ -90,8 +91,8 @@ struct nullb_page {
struct nullb_device {
struct nullb *nullb;
struct config_item item;
- struct radix_tree_root data; /* data stored in the disk */
- struct radix_tree_root cache; /* disk cache data */
+ struct xarray data; /* data stored in the disk */
+ struct xarray cache; /* disk cache data */
unsigned long flags; /* device flags */
unsigned int curr_cache;
struct badblocks badblocks;
@@ -558,8 +559,8 @@ 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);
- INIT_RADIX_TREE(&dev->cache, GFP_ATOMIC);
+ xa_init_flags(&dev->data, XA_FLAGS_LOCK_IRQ);
+ xa_init_flags(&dev->cache, XA_FLAGS_LOCK_IRQ);
if (badblocks_init(&dev->badblocks, 0)) {
kfree(dev);
return NULL;
@@ -752,18 +753,18 @@ 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;
+ struct xarray *xa;
- root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
+ xa = is_cache ? &nullb->dev->cache : &nullb->dev->data;
idx = sector >> PAGE_SECTORS_SHIFT;
sector_bit = (sector & SECTOR_MASK);
- t_page = radix_tree_lookup(root, idx);
+ t_page = xa_load(xa, idx);
if (t_page) {
__clear_bit(sector_bit, &t_page->bitmap);
if (!t_page->bitmap) {
- ret = radix_tree_delete_item(root, idx, t_page);
+ ret = xa_cmpxchg(xa, idx, t_page, NULL, 0);
WARN_ON(ret != t_page);
null_free_page(ret);
if (is_cache)
@@ -772,47 +773,34 @@ static void null_free_sector(struct nullb *nullb, sector_t sector,
}
}
-static struct nullb_page *null_radix_tree_insert(struct nullb *nullb, u64 idx,
+static struct nullb_page *null_xa_insert(struct nullb *nullb, u64 idx,
struct nullb_page *t_page, bool is_cache)
{
- struct radix_tree_root *root;
+ struct xarray *xa = is_cache ? &nullb->dev->cache : &nullb->dev->data;
+ struct nullb_page *exist;
- root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
-
- if (radix_tree_insert(root, idx, t_page)) {
+ exist = xa_cmpxchg(xa, idx, NULL, t_page, GFP_ATOMIC);
+ if (exist) {
null_free_page(t_page);
- t_page = radix_tree_lookup(root, idx);
- WARN_ON(!t_page || t_page->page->index != idx);
+ t_page = exist;
} else if (is_cache)
nullb->dev->curr_cache += PAGE_SIZE;
+ WARN_ON(t_page->page->index != idx);
return t_page;
}
static void null_free_device_storage(struct nullb_device *dev, bool is_cache)
{
- unsigned long pos = 0;
- int nr_pages;
- struct nullb_page *ret, *t_pages[FREE_BATCH];
- struct radix_tree_root *root;
-
- root = is_cache ? &dev->cache : &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);
- }
+ struct nullb_page *t_page;
+ XA_STATE(xas, is_cache ? &dev->cache : &dev->data, 0);
- pos++;
- } while (nr_pages == FREE_BATCH);
+ xas_lock(&xas);
+ xas_for_each(&xas, t_page, ULONG_MAX) {
+ xas_store(&xas, NULL);
+ null_free_page(t_page);
+ }
+ xas_unlock(&xas);
if (is_cache)
dev->curr_cache = 0;
@@ -824,13 +812,13 @@ static struct nullb_page *__null_lookup_page(struct nullb *nullb,
unsigned int sector_bit;
u64 idx;
struct nullb_page *t_page;
- struct radix_tree_root *root;
+ struct xarray *xa;
idx = sector >> PAGE_SECTORS_SHIFT;
sector_bit = (sector & SECTOR_MASK);
- root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
- t_page = radix_tree_lookup(root, idx);
+ xa = is_cache ? &nullb->dev->cache : &nullb->dev->data;
+ t_page = xa_load(xa, idx);
WARN_ON(t_page && t_page->page->index != idx);
if (t_page && (for_write || test_bit(sector_bit, &t_page->bitmap)))
@@ -854,6 +842,7 @@ static struct nullb_page *null_lookup_page(struct nullb *nullb,
static struct nullb_page *null_insert_page(struct nullb *nullb,
sector_t sector, bool ignore_cache)
{
+ struct xarray *xa;
u64 idx;
struct nullb_page *t_page;
@@ -867,14 +856,14 @@ static struct nullb_page *null_insert_page(struct nullb *nullb,
if (!t_page)
goto out_lock;
- if (radix_tree_preload(GFP_NOIO))
+ idx = sector >> PAGE_SECTORS_SHIFT;
+ xa = ignore_cache ? &nullb->dev->data : &nullb->dev->cache;
+ if (xa_reserve(xa, idx, 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, !ignore_cache);
- radix_tree_preload_end();
+ t_page = null_xa_insert(nullb, idx, t_page, !ignore_cache);
return t_page;
out_freepage:
@@ -900,8 +889,7 @@ static int null_flush_cache_page(struct nullb *nullb, struct nullb_page *c_page)
if (test_bit(NULLB_PAGE_FREE, &c_page->bitmap)) {
null_free_page(c_page);
if (t_page && t_page->bitmap == 0) {
- ret = radix_tree_delete_item(&nullb->dev->data,
- idx, t_page);
+ xa_cmpxchg(&nullb->dev->data, idx, t_page, NULL, 0);
null_free_page(t_page);
}
return 0;
@@ -926,7 +914,7 @@ static int null_flush_cache_page(struct nullb *nullb, struct nullb_page *c_page)
kunmap_atomic(dst);
kunmap_atomic(src);
- ret = radix_tree_delete_item(&nullb->dev->cache, idx, c_page);
+ ret = xa_cmpxchg(&nullb->dev->cache, idx, c_page, NULL, 0);
null_free_page(ret);
nullb->dev->curr_cache -= PAGE_SIZE;
@@ -944,8 +932,9 @@ static int null_make_cache_space(struct nullb *nullb, unsigned long n)
nullb->dev->curr_cache + n || nullb->dev->curr_cache == 0)
return 0;
- nr_pages = radix_tree_gang_lookup(&nullb->dev->cache,
- (void **)c_pages, nullb->cache_flush_pos, FREE_BATCH);
+ nr_pages = xa_extract(&nullb->dev->cache, (void **)c_pages,
+ nullb->cache_flush_pos, ULONG_MAX,
+ FREE_BATCH, XA_PRESENT);
/*
* nullb_flush_cache_page could unlock before using the c_pages. To
* avoid race, we don't allow page free
@@ -1086,7 +1075,7 @@ static int null_handle_flush(struct nullb *nullb)
break;
}
- WARN_ON(!radix_tree_empty(&nullb->dev->cache));
+ WARN_ON(!xa_empty(&nullb->dev->cache));
spin_unlock_irq(&nullb->lock);
return err;
}
--
2.15.1
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