jenna
/
kernel_samsung_sm7125
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

mm/zswap: refactor the get/put routines

Browse Source 
The refcount routine was not fit the kernel get/put semantic exactly,
There were too many judgement statements on refcount and it could be
minus.

This patch does the following:

 - move refcount judgement to zswap_entry_put() to hide resource free function.

 - add a new function zswap_entry_find_get(), so that callers can use
   easily in the following pattern:

     zswap_entry_find_get
     .../* do something */
     zswap_entry_put

 - to eliminate compile error, move some functions declaration

This patch is based on Minchan Kim <minchan@kernel.org> 's idea and suggestion.

Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
Cc: Seth Jennings <sjennings@variantweb.net>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
tirimbino
Weijie Yang 11 years ago committed by Linus Torvalds
parent 67d13fe846
commit 0ab0abcf51
1 changed files with 88 additions and 94 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Show Stats Download Patch File Download Diff File
  1. 182
      mm/zswap.c

182
mm/zswap.c
Unescape View File

@ -217,6 +217,7 @@ static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp)
if (!entry)
return NULL;
entry->refcount = 1;
RB_CLEAR_NODE(&entry->rbnode);
return entry;
}
@ -225,19 +226,6 @@ static void zswap_entry_cache_free(struct zswap_entry *entry)
kmem_cache_free(zswap_entry_cache, entry);
}
/* caller must hold the tree lock */
static void zswap_entry_get(struct zswap_entry *entry)
{
entry->refcount++;
}
/* caller must hold the tree lock */
static int zswap_entry_put(struct zswap_entry *entry)
{
entry->refcount--;
return entry->refcount;
}
/*********************************
* rbtree functions
**********************************/
@ -285,6 +273,61 @@ static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry,
return 0;
}
static void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry)
{
if (!RB_EMPTY_NODE(&entry->rbnode)) {
rb_erase(&entry->rbnode, root);
RB_CLEAR_NODE(&entry->rbnode);
}
}
/*
* Carries out the common pattern of freeing and entry's zsmalloc allocation,
* freeing the entry itself, and decrementing the number of stored pages.
*/
static void zswap_free_entry(struct zswap_tree *tree,
struct zswap_entry *entry)
{
zbud_free(tree->pool, entry->handle);
zswap_entry_cache_free(entry);
atomic_dec(&zswap_stored_pages);
zswap_pool_pages = zbud_get_pool_size(tree->pool);
}
/* caller must hold the tree lock */
static void zswap_entry_get(struct zswap_entry *entry)
{
entry->refcount++;
}
/* caller must hold the tree lock
* remove from the tree and free it, if nobody reference the entry
*/
static void zswap_entry_put(struct zswap_tree *tree,
struct zswap_entry *entry)
{
int refcount = --entry->refcount;
BUG_ON(refcount < 0);
if (refcount == 0) {
zswap_rb_erase(&tree->rbroot, entry);
zswap_free_entry(tree, entry);
}
}
/* caller must hold the tree lock */
static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
pgoff_t offset)
{
struct zswap_entry *entry = NULL;
entry = zswap_rb_search(root, offset);
if (entry)
zswap_entry_get(entry);
return entry;
}
/*********************************
* per-cpu code
**********************************/
@ -368,18 +411,6 @@ static bool zswap_is_full(void)
zswap_pool_pages);
}
/*
* Carries out the common pattern of freeing and entry's zsmalloc allocation,
* freeing the entry itself, and decrementing the number of stored pages.
*/
static void zswap_free_entry(struct zswap_tree *tree, struct zswap_entry *entry)
{
zbud_free(tree->pool, entry->handle);
zswap_entry_cache_free(entry);
atomic_dec(&zswap_stored_pages);
zswap_pool_pages = zbud_get_pool_size(tree->pool);
}
/*********************************
* writeback code
**********************************/
@ -503,7 +534,7 @@ static int zswap_writeback_entry(struct zbud_pool *pool, unsigned long handle)
struct page *page;
u8 *src, *dst;
unsigned int dlen;
int ret, refcount;
int ret;
struct writeback_control wbc = {
.sync_mode = WB_SYNC_NONE,
};
@ -518,13 +549,12 @@ static int zswap_writeback_entry(struct zbud_pool *pool, unsigned long handle)
/* find and ref zswap entry */
spin_lock(&tree->lock);
entry = zswap_rb_search(&tree->rbroot, offset);
entry = zswap_entry_find_get(&tree->rbroot, offset);
if (!entry) {
/* entry was invalidated */
spin_unlock(&tree->lock);
return 0;
}
zswap_entry_get(entry);
spin_unlock(&tree->lock);
BUG_ON(offset != entry->offset);
@ -566,42 +596,35 @@ static int zswap_writeback_entry(struct zbud_pool *pool, unsigned long handle)
zswap_written_back_pages++;
spin_lock(&tree->lock);
/* drop local reference */
zswap_entry_put(entry);
/* drop the initial reference from entry creation */
refcount = zswap_entry_put(entry);
zswap_entry_put(tree, entry);
/*
* There are three possible values for refcount here:
* (1) refcount is 1, load is in progress, unlink from rbtree,
* load will free
* (2) refcount is 0, (normal case) entry is valid,
* remove from rbtree and free entry
* (3) refcount is -1, invalidate happened during writeback,
* free entry
*/
if (refcount >= 0) {
/* no invalidate yet, remove from rbtree */
rb_erase(&entry->rbnode, &tree->rbroot);
}
* There are two possible situations for entry here:
* (1) refcount is 1(normal case), entry is valid and on the tree
* (2) refcount is 0, entry is freed and not on the tree
* because invalidate happened during writeback
* search the tree and free the entry if find entry
*/
if (entry == zswap_rb_search(&tree->rbroot, offset))
zswap_entry_put(tree, entry);
spin_unlock(&tree->lock);
if (refcount <= 0) {
/* free the entry */
zswap_free_entry(tree, entry);
return 0;
}
return -EAGAIN;
goto end;
/*
* if we get here due to ZSWAP_SWAPCACHE_EXIST
* a load may happening concurrently
* it is safe and okay to not free the entry
* if we free the entry in the following put
* it it either okay to return !0
*/
fail:
spin_lock(&tree->lock);
refcount = zswap_entry_put(entry);
if (refcount <= 0) {
/* invalidate happened, consider writeback as success */
zswap_free_entry(tree, entry);
ret = 0;
}
zswap_entry_put(tree, entry);
spin_unlock(&tree->lock);
end:
return ret;
}
@ -685,11 +708,8 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
if (ret == -EEXIST) {
zswap_duplicate_entry++;
/* remove from rbtree */
rb_erase(&dupentry->rbnode, &tree->rbroot);
if (!zswap_entry_put(dupentry)) {
/* free */
zswap_free_entry(tree, dupentry);
}
zswap_rb_erase(&tree->rbroot, dupentry);
zswap_entry_put(tree, dupentry);
}
} while (ret == -EEXIST);
spin_unlock(&tree->lock);
@ -718,17 +738,16 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
struct zswap_entry *entry;
u8 *src, *dst;
unsigned int dlen;
int refcount, ret;
int ret;
/* find */
spin_lock(&tree->lock);
entry = zswap_rb_search(&tree->rbroot, offset);
entry = zswap_entry_find_get(&tree->rbroot, offset);
if (!entry) {
/* entry was written back */
spin_unlock(&tree->lock);
return -1;
}
zswap_entry_get(entry);
spin_unlock(&tree->lock);
/* decompress */
@ -743,22 +762,9 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
BUG_ON(ret);
spin_lock(&tree->lock);
refcount = zswap_entry_put(entry);
if (likely(refcount)) {
spin_unlock(&tree->lock);
return 0;
}
zswap_entry_put(tree, entry);
spin_unlock(&tree->lock);
/*
* We don't have to unlink from the rbtree because
* zswap_writeback_entry() or zswap_frontswap_invalidate page()
* has already done this for us if we are the last reference.
*/
/* free */
zswap_free_entry(tree, entry);
return 0;
}
@ -767,7 +773,6 @@ static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset)
{
struct zswap_tree *tree = zswap_trees[type];
struct zswap_entry *entry;
int refcount;
/* find */
spin_lock(&tree->lock);
@ -779,20 +784,12 @@ static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset)
}
/* remove from rbtree */
rb_erase(&entry->rbnode, &tree->rbroot);
zswap_rb_erase(&tree->rbroot, entry);
/* drop the initial reference from entry creation */
refcount = zswap_entry_put(entry);
zswap_entry_put(tree, entry);
spin_unlock(&tree->lock);
if (refcount) {
/* writeback in progress, writeback will free */
return;
}
/* free */
zswap_free_entry(tree, entry);
}
/* frees all zswap entries for the given swap type */
@ -806,11 +803,8 @@ static void zswap_frontswap_invalidate_area(unsigned type)
/* walk the tree and free everything */
spin_lock(&tree->lock);
rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode) {
zbud_free(tree->pool, entry->handle);
zswap_entry_cache_free(entry);
atomic_dec(&zswap_stored_pages);
}
rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode)
zswap_free_entry(tree, entry);
tree->rbroot = RB_ROOT;
spin_unlock(&tree->lock);

Write Preview
Loading…
Cancel
Save