mm: clean up and kernelify shrinker registration
I can never remember what the function to register to receive VM pressure
is called. I have to trace down from __alloc_pages() to find it.
It's called "set_shrinker()", and it needs Your Help.
1) Don't hide struct shrinker. It contains no magic.
2) Don't allocate "struct shrinker". It's not helpful.
3) Call them "register_shrinker" and "unregister_shrinker".
4) Call the function "shrink" not "shrinker".
5) Reduce the 17 lines of waffly comments to 13, but document it properly.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: David Chinner <dgc@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/dcache.c b/fs/dcache.c
index 0e73aa0..cb9d050 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -883,6 +883,11 @@
return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
}
+static struct shrinker dcache_shrinker = {
+ .shrink = shrink_dcache_memory,
+ .seeks = DEFAULT_SEEKS,
+};
+
/**
* d_alloc - allocate a dcache entry
* @parent: parent of entry to allocate
@@ -2115,7 +2120,7 @@
dentry_cache = KMEM_CACHE(dentry,
SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);
- set_shrinker(DEFAULT_SEEKS, shrink_dcache_memory);
+ register_shrinker(&dcache_shrinker);
/* Hash may have been set up in dcache_init_early */
if (!hashdist)
diff --git a/fs/dquot.c b/fs/dquot.c
index 8819d28..7e27315 100644
--- a/fs/dquot.c
+++ b/fs/dquot.c
@@ -538,6 +538,11 @@
return (dqstats.free_dquots / 100) * sysctl_vfs_cache_pressure;
}
+static struct shrinker dqcache_shrinker = {
+ .shrink = shrink_dqcache_memory,
+ .seeks = DEFAULT_SEEKS,
+};
+
/*
* Put reference to dquot
* NOTE: If you change this function please check whether dqput_blocks() works right...
@@ -1870,7 +1875,7 @@
printk("Dquot-cache hash table entries: %ld (order %ld, %ld bytes)\n",
nr_hash, order, (PAGE_SIZE << order));
- set_shrinker(DEFAULT_SEEKS, shrink_dqcache_memory);
+ register_shrinker(&dqcache_shrinker);
return 0;
}
diff --git a/fs/inode.c b/fs/inode.c
index 47b87b07..320e088 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -462,6 +462,11 @@
return (inodes_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
}
+static struct shrinker icache_shrinker = {
+ .shrink = shrink_icache_memory,
+ .seeks = DEFAULT_SEEKS,
+};
+
static void __wait_on_freeing_inode(struct inode *inode);
/*
* Called with the inode lock held.
@@ -1385,7 +1390,7 @@
SLAB_MEM_SPREAD),
init_once,
NULL);
- set_shrinker(DEFAULT_SEEKS, shrink_icache_memory);
+ register_shrinker(&icache_shrinker);
/* Hash may have been set up in inode_init_early */
if (!hashdist)
diff --git a/fs/mbcache.c b/fs/mbcache.c
index deeb9dc..fbb1d02 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -100,7 +100,6 @@
static LIST_HEAD(mb_cache_list);
static LIST_HEAD(mb_cache_lru_list);
static DEFINE_SPINLOCK(mb_cache_spinlock);
-static struct shrinker *mb_shrinker;
static inline int
mb_cache_indexes(struct mb_cache *cache)
@@ -118,6 +117,10 @@
static int mb_cache_shrink_fn(int nr_to_scan, gfp_t gfp_mask);
+static struct shrinker mb_cache_shrinker = {
+ .shrink = mb_cache_shrink_fn,
+ .seeks = DEFAULT_SEEKS,
+};
static inline int
__mb_cache_entry_is_hashed(struct mb_cache_entry *ce)
@@ -662,13 +665,13 @@
static int __init init_mbcache(void)
{
- mb_shrinker = set_shrinker(DEFAULT_SEEKS, mb_cache_shrink_fn);
+ register_shrinker(&mb_cache_shrinker);
return 0;
}
static void __exit exit_mbcache(void)
{
- remove_shrinker(mb_shrinker);
+ unregister_shrinker(&mb_cache_shrinker);
}
module_init(init_mbcache)
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index a2b1af8..adffe16 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -300,7 +300,10 @@
};
#endif
-static struct shrinker *acl_shrinker;
+static struct shrinker acl_shrinker = {
+ .shrink = nfs_access_cache_shrinker,
+ .seeks = DEFAULT_SEEKS,
+};
/*
* Register the NFS filesystems
@@ -321,7 +324,7 @@
if (ret < 0)
goto error_2;
#endif
- acl_shrinker = set_shrinker(DEFAULT_SEEKS, nfs_access_cache_shrinker);
+ register_shrinker(&acl_shrinker);
return 0;
#ifdef CONFIG_NFS_V4
@@ -339,8 +342,7 @@
*/
void __exit unregister_nfs_fs(void)
{
- if (acl_shrinker != NULL)
- remove_shrinker(acl_shrinker);
+ unregister_shrinker(&acl_shrinker);
#ifdef CONFIG_NFS_V4
unregister_filesystem(&nfs4_fs_type);
nfs_unregister_sysctl();
diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index 2df6362..b0f0e58 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -35,10 +35,13 @@
#include <linux/freezer.h>
static kmem_zone_t *xfs_buf_zone;
-static struct shrinker *xfs_buf_shake;
STATIC int xfsbufd(void *);
STATIC int xfsbufd_wakeup(int, gfp_t);
STATIC void xfs_buf_delwri_queue(xfs_buf_t *, int);
+static struct shrinker xfs_buf_shake = {
+ .shrink = xfsbufd_wakeup,
+ .seeks = DEFAULT_SEEKS,
+};
static struct workqueue_struct *xfslogd_workqueue;
struct workqueue_struct *xfsdatad_workqueue;
@@ -1832,14 +1835,9 @@
if (!xfsdatad_workqueue)
goto out_destroy_xfslogd_workqueue;
- xfs_buf_shake = set_shrinker(DEFAULT_SEEKS, xfsbufd_wakeup);
- if (!xfs_buf_shake)
- goto out_destroy_xfsdatad_workqueue;
-
+ register_shrinker(&xfs_buf_shake);
return 0;
- out_destroy_xfsdatad_workqueue:
- destroy_workqueue(xfsdatad_workqueue);
out_destroy_xfslogd_workqueue:
destroy_workqueue(xfslogd_workqueue);
out_free_buf_zone:
@@ -1854,7 +1852,7 @@
void
xfs_buf_terminate(void)
{
- remove_shrinker(xfs_buf_shake);
+ unregister_shrinker(&xfs_buf_shake);
destroy_workqueue(xfsdatad_workqueue);
destroy_workqueue(xfslogd_workqueue);
kmem_zone_destroy(xfs_buf_zone);
diff --git a/fs/xfs/quota/xfs_qm.c b/fs/xfs/quota/xfs_qm.c
index 7def4c6..2d274b2 100644
--- a/fs/xfs/quota/xfs_qm.c
+++ b/fs/xfs/quota/xfs_qm.c
@@ -62,7 +62,6 @@
kmem_zone_t *qm_dqzone;
kmem_zone_t *qm_dqtrxzone;
-static struct shrinker *xfs_qm_shaker;
static cred_t xfs_zerocr;
@@ -78,6 +77,11 @@
STATIC int xfs_qm_init_quotainfo(xfs_mount_t *);
STATIC int xfs_qm_shake(int, gfp_t);
+static struct shrinker xfs_qm_shaker = {
+ .shrink = xfs_qm_shake,
+ .seeks = DEFAULT_SEEKS,
+};
+
#ifdef DEBUG
extern mutex_t qcheck_lock;
#endif
@@ -149,7 +153,7 @@
} else
xqm->qm_dqzone = qm_dqzone;
- xfs_qm_shaker = set_shrinker(DEFAULT_SEEKS, xfs_qm_shake);
+ register_shrinker(&xfs_qm_shaker);
/*
* The t_dqinfo portion of transactions.
@@ -181,7 +185,7 @@
ASSERT(xqm != NULL);
ASSERT(xqm->qm_nrefs == 0);
- remove_shrinker(xfs_qm_shaker);
+ unregister_shrinker(&xfs_qm_shaker);
hsize = xqm->qm_dqhashmask + 1;
for (i = 0; i < hsize; i++) {
xfs_qm_list_destroy(&(xqm->qm_usr_dqhtable[i]));
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 97d0cdd..4c482a3 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -810,27 +810,31 @@
unsigned long flags, unsigned long new_addr);
/*
- * Prototype to add a shrinker callback for ageable caches.
- *
- * These functions are passed a count `nr_to_scan' and a gfpmask. They should
- * scan `nr_to_scan' objects, attempting to free them.
+ * A callback you can register to apply pressure to ageable caches.
*
- * The callback must return the number of objects which remain in the cache.
+ * 'shrink' is passed a count 'nr_to_scan' and a 'gfpmask'. It should
+ * look through the least-recently-used 'nr_to_scan' entries and
+ * attempt to free them up. It should return the number of objects
+ * which remain in the cache. If it returns -1, it means it cannot do
+ * any scanning at this time (eg. there is a risk of deadlock).
*
- * The callback will be passed nr_to_scan == 0 when the VM is querying the
- * cache size, so a fastpath for that case is appropriate.
+ * The 'gfpmask' refers to the allocation we are currently trying to
+ * fulfil.
+ *
+ * Note that 'shrink' will be passed nr_to_scan == 0 when the VM is
+ * querying the cache size, so a fastpath for that case is appropriate.
*/
-typedef int (*shrinker_t)(int nr_to_scan, gfp_t gfp_mask);
+struct shrinker {
+ int (*shrink)(int nr_to_scan, gfp_t gfp_mask);
+ int seeks; /* seeks to recreate an obj */
-/*
- * Add an aging callback. The int is the number of 'seeks' it takes
- * to recreate one of the objects that these functions age.
- */
-
-#define DEFAULT_SEEKS 2
-struct shrinker;
-extern struct shrinker *set_shrinker(int, shrinker_t);
-extern void remove_shrinker(struct shrinker *shrinker);
+ /* These are for internal use */
+ struct list_head list;
+ long nr; /* objs pending delete */
+};
+#define DEFAULT_SEEKS 2 /* A good number if you don't know better. */
+extern void register_shrinker(struct shrinker *);
+extern void unregister_shrinker(struct shrinker *);
/*
* Some shared mappigns will want the pages marked read-only
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1d9971d..2225b7c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -70,17 +70,6 @@
int order;
};
-/*
- * The list of shrinker callbacks used by to apply pressure to
- * ageable caches.
- */
-struct shrinker {
- shrinker_t shrinker;
- struct list_head list;
- int seeks; /* seeks to recreate an obj */
- long nr; /* objs pending delete */
-};
-
#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
#ifdef ARCH_HAS_PREFETCH
@@ -123,34 +112,25 @@
/*
* Add a shrinker callback to be called from the vm
*/
-struct shrinker *set_shrinker(int seeks, shrinker_t theshrinker)
+void register_shrinker(struct shrinker *shrinker)
{
- struct shrinker *shrinker;
-
- shrinker = kmalloc(sizeof(*shrinker), GFP_KERNEL);
- if (shrinker) {
- shrinker->shrinker = theshrinker;
- shrinker->seeks = seeks;
- shrinker->nr = 0;
- down_write(&shrinker_rwsem);
- list_add_tail(&shrinker->list, &shrinker_list);
- up_write(&shrinker_rwsem);
- }
- return shrinker;
+ shrinker->nr = 0;
+ down_write(&shrinker_rwsem);
+ list_add_tail(&shrinker->list, &shrinker_list);
+ up_write(&shrinker_rwsem);
}
-EXPORT_SYMBOL(set_shrinker);
+EXPORT_SYMBOL(register_shrinker);
/*
* Remove one
*/
-void remove_shrinker(struct shrinker *shrinker)
+void unregister_shrinker(struct shrinker *shrinker)
{
down_write(&shrinker_rwsem);
list_del(&shrinker->list);
up_write(&shrinker_rwsem);
- kfree(shrinker);
}
-EXPORT_SYMBOL(remove_shrinker);
+EXPORT_SYMBOL(unregister_shrinker);
#define SHRINK_BATCH 128
/*
@@ -187,7 +167,7 @@
list_for_each_entry(shrinker, &shrinker_list, list) {
unsigned long long delta;
unsigned long total_scan;
- unsigned long max_pass = (*shrinker->shrinker)(0, gfp_mask);
+ unsigned long max_pass = (*shrinker->shrink)(0, gfp_mask);
delta = (4 * scanned) / shrinker->seeks;
delta *= max_pass;
@@ -215,8 +195,8 @@
int shrink_ret;
int nr_before;
- nr_before = (*shrinker->shrinker)(0, gfp_mask);
- shrink_ret = (*shrinker->shrinker)(this_scan, gfp_mask);
+ nr_before = (*shrinker->shrink)(0, gfp_mask);
+ shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask);
if (shrink_ret == -1)
break;
if (shrink_ret < nr_before)
diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
index aa55d0a..29a8ecc 100644
--- a/net/sunrpc/auth.c
+++ b/net/sunrpc/auth.c
@@ -543,17 +543,18 @@
test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
}
-
-static struct shrinker *rpc_cred_shrinker;
+static struct shrinker rpc_cred_shrinker = {
+ .shrink = rpcauth_cache_shrinker,
+ .seeks = DEFAULT_SEEKS,
+};
void __init rpcauth_init_module(void)
{
rpc_init_authunix();
- rpc_cred_shrinker = set_shrinker(DEFAULT_SEEKS, rpcauth_cache_shrinker);
+ register_shrinker(&rpc_cred_shrinker);
}
void __exit rpcauth_remove_module(void)
{
- if (rpc_cred_shrinker != NULL)
- remove_shrinker(rpc_cred_shrinker);
+ unregister_shrinker(&rpc_cred_shrinker);
}