From 8e1f936b73150f5095448a0fee6d4f30a1f9001d Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Tue, 17 Jul 2007 04:03:17 -0700 Subject: [PATCH] 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 Cc: David Chinner Cc: Trond Myklebust Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/dcache.c | 7 ++++++- fs/dquot.c | 7 ++++++- fs/inode.c | 7 ++++++- fs/mbcache.c | 9 +++++--- fs/nfs/super.c | 10 +++++---- fs/xfs/linux-2.6/xfs_buf.c | 14 ++++++------- fs/xfs/quota/xfs_qm.c | 10 ++++++--- include/linux/mm.h | 38 +++++++++++++++++++--------------- mm/vmscan.c | 42 ++++++++++---------------------------- net/sunrpc/auth.c | 11 +++++----- 10 files changed, 81 insertions(+), 74 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 0e73aa0a0e8..cb9d05056b5 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -883,6 +883,11 @@ static int shrink_dcache_memory(int nr, gfp_t gfp_mask) 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 @@ static void __init dcache_init(unsigned long mempages) 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 8819d281500..7e273151f58 100644 --- a/fs/dquot.c +++ b/fs/dquot.c @@ -538,6 +538,11 @@ static int shrink_dqcache_memory(int nr, gfp_t gfp_mask) 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 @@ static int __init dquot_init(void) 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 47b87b071de..320e088d0b2 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -462,6 +462,11 @@ static int shrink_icache_memory(int nr, gfp_t gfp_mask) 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 @@ void __init inode_init(unsigned long mempages) 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 deeb9dc062d..fbb1d02f879 100644 --- a/fs/mbcache.c +++ b/fs/mbcache.c @@ -100,7 +100,6 @@ struct mb_cache { 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 @@ mb_cache_indexes(struct mb_cache *cache) 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 @@ mb_cache_entry_find_next(struct mb_cache_entry *prev, int index, 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 a2b1af89ca1..adffe1615c5 100644 --- a/fs/nfs/super.c +++ b/fs/nfs/super.c @@ -300,7 +300,10 @@ static const struct super_operations nfs4_sops = { }; #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 @@ int __init register_nfs_fs(void) 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 @@ int __init register_nfs_fs(void) */ 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 2df63622354..b0f0e58866d 100644 --- a/fs/xfs/linux-2.6/xfs_buf.c +++ b/fs/xfs/linux-2.6/xfs_buf.c @@ -35,10 +35,13 @@ #include 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 @@ xfs_buf_init(void) 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 @@ xfs_buf_init(void) 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 7def4c69934..2d274b23ade 100644 --- a/fs/xfs/quota/xfs_qm.c +++ b/fs/xfs/quota/xfs_qm.c @@ -62,7 +62,6 @@ uint ndquot; 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_quotainos(xfs_mount_t *); 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 @@ xfs_Gqm_init(void) } 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 @@ xfs_qm_destroy( 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 97d0cddfd22..4c482a3ee87 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -810,27 +810,31 @@ extern unsigned long do_mremap(unsigned long addr, 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. - */ -typedef int (*shrinker_t)(int nr_to_scan, gfp_t gfp_mask); - -/* - * Add an aging callback. The int is the number of 'seeks' it takes - * to recreate one of the objects that these functions age. + * 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. */ +struct shrinker { + int (*shrink)(int nr_to_scan, gfp_t gfp_mask); + int seeks; /* seeks to recreate an obj */ -#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 1d9971d8924..2225b7c9df8 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -70,17 +70,6 @@ struct scan_control { 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 @@ static DECLARE_RWSEM(shrinker_rwsem); /* * 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 @@ unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, 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 @@ unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, 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 aa55d0a03e6..29a8ecc6092 100644 --- a/net/sunrpc/auth.c +++ b/net/sunrpc/auth.c @@ -543,17 +543,18 @@ rpcauth_uptodatecred(struct rpc_task *task) 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); }