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Date: Thu, 16 Mar 2017 11:46:36 +0900
From: js1304@...il.com
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Minchan Kim <minchan@...nel.org>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
linux-kernel@...r.kernel.org, kernel-team@....com,
Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: [PATCH 2/4] zram: introduce zram_entry to prepare dedup functionality
From: Joonsoo Kim <iamjoonsoo.kim@....com>
Following patch will implement deduplication functionality
in the zram and it requires an indirection layer to manage
the life cycle of zsmalloc handle. To prepare that, this patch
introduces zram_entry which can be used to manage the life-cycle
of zsmalloc handle. Many lines are changed due to rename but
core change is just simple introduction about newly data structure.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
---
drivers/block/zram/zram_drv.c | 81 ++++++++++++++++++++++++++++---------------
drivers/block/zram/zram_drv.h | 6 +++-
2 files changed, 59 insertions(+), 28 deletions(-)
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index f65dcd1..a3d9cbca 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -419,6 +419,31 @@ static ssize_t debug_stat_show(struct device *dev,
static DEVICE_ATTR_RO(mm_stat);
static DEVICE_ATTR_RO(debug_stat);
+static struct zram_entry *zram_entry_alloc(struct zram_meta *meta,
+ unsigned int len, gfp_t flags)
+{
+ struct zram_entry *entry;
+
+ entry = kzalloc(sizeof(*entry), flags);
+ if (!entry)
+ return NULL;
+
+ entry->handle = zs_malloc(meta->mem_pool, len, flags);
+ if (!entry->handle) {
+ kfree(entry);
+ return NULL;
+ }
+
+ return entry;
+}
+
+static inline void zram_entry_free(struct zram_meta *meta,
+ struct zram_entry *entry)
+{
+ zs_free(meta->mem_pool, entry->handle);
+ kfree(entry);
+}
+
static void zram_meta_free(struct zram_meta *meta, u64 disksize)
{
size_t num_pages = disksize >> PAGE_SHIFT;
@@ -426,15 +451,15 @@ static void zram_meta_free(struct zram_meta *meta, u64 disksize)
/* Free all pages that are still in this zram device */
for (index = 0; index < num_pages; index++) {
- unsigned long handle = meta->table[index].handle;
+ struct zram_entry *entry = meta->table[index].entry;
/*
* No memory is allocated for same element filled pages.
* Simply clear same page flag.
*/
- if (!handle || zram_test_flag(meta, index, ZRAM_SAME))
+ if (!entry || zram_test_flag(meta, index, ZRAM_SAME))
continue;
- zs_free(meta->mem_pool, handle);
+ zram_entry_free(meta, entry);
}
zs_destroy_pool(meta->mem_pool);
@@ -479,7 +504,7 @@ static struct zram_meta *zram_meta_alloc(char *pool_name, u64 disksize)
static void zram_free_page(struct zram *zram, size_t index)
{
struct zram_meta *meta = zram->meta;
- unsigned long handle = meta->table[index].handle;
+ struct zram_entry *entry = meta->table[index].entry;
/*
* No memory is allocated for same element filled pages.
@@ -492,16 +517,16 @@ static void zram_free_page(struct zram *zram, size_t index)
return;
}
- if (!handle)
+ if (!entry)
return;
- zs_free(meta->mem_pool, handle);
+ zram_entry_free(meta, entry);
atomic64_sub(zram_get_obj_size(meta, index),
&zram->stats.compr_data_size);
atomic64_dec(&zram->stats.pages_stored);
- meta->table[index].handle = 0;
+ meta->table[index].entry = NULL;
zram_set_obj_size(meta, index, 0);
}
@@ -510,20 +535,20 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
int ret = 0;
unsigned char *cmem;
struct zram_meta *meta = zram->meta;
- unsigned long handle;
+ struct zram_entry *entry;
unsigned int size;
bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
- handle = meta->table[index].handle;
+ entry = meta->table[index].entry;
size = zram_get_obj_size(meta, index);
- if (!handle || zram_test_flag(meta, index, ZRAM_SAME)) {
+ if (!entry || zram_test_flag(meta, index, ZRAM_SAME)) {
bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
zram_fill_page(mem, PAGE_SIZE, meta->table[index].element);
return 0;
}
- cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);
+ cmem = zs_map_object(meta->mem_pool, entry->handle, ZS_MM_RO);
if (size == PAGE_SIZE) {
copy_page(mem, cmem);
} else {
@@ -532,7 +557,7 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
ret = zcomp_decompress(zstrm, cmem, size, mem);
zcomp_stream_put(zram->comp);
}
- zs_unmap_object(meta->mem_pool, handle);
+ zs_unmap_object(meta->mem_pool, entry->handle);
bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
/* Should NEVER happen. Return bio error if it does. */
@@ -554,7 +579,7 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
page = bvec->bv_page;
bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
- if (unlikely(!meta->table[index].handle) ||
+ if (unlikely(!meta->table[index].entry) ||
zram_test_flag(meta, index, ZRAM_SAME)) {
bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
handle_same_page(bvec, meta->table[index].element);
@@ -599,7 +624,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
{
int ret = 0;
unsigned int clen;
- unsigned long handle = 0;
+ struct zram_entry *entry = NULL;
struct page *page;
unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
struct zram_meta *meta = zram->meta;
@@ -670,29 +695,31 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
}
/*
- * handle allocation has 2 paths:
+ * entry allocation has 2 paths:
* a) fast path is executed with preemption disabled (for
* per-cpu streams) and has __GFP_DIRECT_RECLAIM bit clear,
* since we can't sleep;
* b) slow path enables preemption and attempts to allocate
* the page with __GFP_DIRECT_RECLAIM bit set. we have to
* put per-cpu compression stream and, thus, to re-do
- * the compression once handle is allocated.
+ * the compression once entry is allocated.
*
- * if we have a 'non-null' handle here then we are coming
- * from the slow path and handle has already been allocated.
+ * if we have a 'non-null' entry here then we are coming
+ * from the slow path and entry has already been allocated.
*/
- if (!handle)
- handle = zs_malloc(meta->mem_pool, clen,
+ if (!entry) {
+ entry = zram_entry_alloc(meta, clen,
__GFP_KSWAPD_RECLAIM | __GFP_NOWARN);
- if (!handle) {
+ }
+
+ if (!entry) {
zcomp_stream_put(zram->comp);
zstrm = NULL;
atomic64_inc(&zram->stats.writestall);
- handle = zs_malloc(meta->mem_pool, clen, GFP_NOIO);
- if (handle)
+ entry = zram_entry_alloc(meta, clen, GFP_NOIO);
+ if (entry)
goto compress_again;
pr_err("Error allocating memory for compressed page: %u, size=%u\n",
@@ -705,12 +732,12 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
update_used_max(zram, alloced_pages);
if (zram->limit_pages && alloced_pages > zram->limit_pages) {
- zs_free(meta->mem_pool, handle);
+ zram_entry_free(meta, entry);
ret = -ENOMEM;
goto out;
}
- cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
+ cmem = zs_map_object(meta->mem_pool, entry->handle, ZS_MM_WO);
if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
src = kmap_atomic(page);
@@ -722,7 +749,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
zcomp_stream_put(zram->comp);
zstrm = NULL;
- zs_unmap_object(meta->mem_pool, handle);
+ zs_unmap_object(meta->mem_pool, entry->handle);
/*
* Free memory associated with this sector
@@ -731,7 +758,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
zram_free_page(zram, index);
- meta->table[index].handle = handle;
+ meta->table[index].entry = entry;
zram_set_obj_size(meta, index, clen);
bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index caeff51..a7ae46c 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -69,10 +69,14 @@ enum zram_pageflags {
/*-- Data structures */
+struct zram_entry {
+ unsigned long handle;
+};
+
/* Allocated for each disk page */
struct zram_table_entry {
union {
- unsigned long handle;
+ struct zram_entry *entry;
unsigned long element;
};
unsigned long value;
--
1.9.1
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