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Message-ID: <20140305035219.GE26528@ZenIV.linux.org.uk>
Date: Wed, 5 Mar 2014 03:52:19 +0000
From: Al Viro <viro@...IV.linux.org.uk>
To: linux-fsdevel@...r.kernel.org
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
linux-kernel@...r.kernel.org, Stephen Tweedie <sct@...hat.com>,
Jeremy Eder <jeder@...hat.com>
Subject: [PATCH 5/5][RFC][CFT] resizable namespace.c hashes
* switch allocation to alloc_large_system_hash()
* make sizes overridable by boot parameters (mhash_entries=, mphash_entries=)
* switch mountpoint_hashtable from list_head to hlist_head
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
fs/mount.h | 2 +-
fs/namespace.c | 81 ++++++++++++++++++++++++++++++++++++++++----------------
2 files changed, 59 insertions(+), 24 deletions(-)
diff --git a/fs/mount.h b/fs/mount.h
index 61e1c05..46790ae1 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -19,7 +19,7 @@ struct mnt_pcp {
};
struct mountpoint {
- struct list_head m_hash;
+ struct hlist_node m_hash;
struct dentry *m_dentry;
int m_count;
};
diff --git a/fs/namespace.c b/fs/namespace.c
index 00f12af..6be899f 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -23,11 +23,34 @@
#include <linux/uaccess.h>
#include <linux/proc_ns.h>
#include <linux/magic.h>
+#include <linux/bootmem.h>
#include "pnode.h"
#include "internal.h"
-#define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head))
-#define HASH_SIZE (1UL << HASH_SHIFT)
+static unsigned int m_hash_mask __read_mostly;
+static unsigned int m_hash_shift __read_mostly;
+static unsigned int mp_hash_mask __read_mostly;
+static unsigned int mp_hash_shift __read_mostly;
+
+static __initdata unsigned long mhash_entries;
+static int __init set_mhash_entries(char *str)
+{
+ if (!str)
+ return 0;
+ mhash_entries = simple_strtoul(str, &str, 0);
+ return 1;
+}
+__setup("mhash_entries=", set_mhash_entries);
+
+static __initdata unsigned long mphash_entries;
+static int __init set_mphash_entries(char *str)
+{
+ if (!str)
+ return 0;
+ mphash_entries = simple_strtoul(str, &str, 0);
+ return 1;
+}
+__setup("mphash_entries=", set_mphash_entries);
static u64 event;
static DEFINE_IDA(mnt_id_ida);
@@ -37,7 +60,7 @@ static int mnt_id_start = 0;
static int mnt_group_start = 1;
static struct list_head *mount_hashtable __read_mostly;
-static struct list_head *mountpoint_hashtable __read_mostly;
+static struct hlist_head *mountpoint_hashtable __read_mostly;
static struct kmem_cache *mnt_cache __read_mostly;
static DECLARE_RWSEM(namespace_sem);
@@ -55,12 +78,19 @@ EXPORT_SYMBOL_GPL(fs_kobj);
*/
__cacheline_aligned_in_smp DEFINE_SEQLOCK(mount_lock);
-static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry)
+static inline struct list_head *m_hash(struct vfsmount *mnt, struct dentry *dentry)
{
unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES);
tmp += ((unsigned long)dentry / L1_CACHE_BYTES);
- tmp = tmp + (tmp >> HASH_SHIFT);
- return tmp & (HASH_SIZE - 1);
+ tmp = tmp + (tmp >> m_hash_shift);
+ return &mount_hashtable[tmp & m_hash_mask];
+}
+
+static inline struct hlist_head *mp_hash(struct dentry *dentry)
+{
+ unsigned long tmp = ((unsigned long)dentry / L1_CACHE_BYTES);
+ tmp = tmp + (tmp >> mp_hash_shift);
+ return &mountpoint_hashtable[tmp & mp_hash_mask];
}
/*
@@ -575,7 +605,7 @@ bool legitimize_mnt(struct vfsmount *bastard, unsigned seq)
*/
struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)
{
- struct list_head *head = mount_hashtable + hash(mnt, dentry);
+ struct list_head *head = m_hash(mnt, dentry);
struct mount *p;
list_for_each_entry_rcu(p, head, mnt_hash)
@@ -590,7 +620,7 @@ struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)
*/
struct mount *__lookup_mnt_last(struct vfsmount *mnt, struct dentry *dentry)
{
- struct list_head *head = mount_hashtable + hash(mnt, dentry);
+ struct list_head *head = m_hash(mnt, dentry);
struct mount *p;
list_for_each_entry_reverse(p, head, mnt_hash)
@@ -633,11 +663,11 @@ struct vfsmount *lookup_mnt(struct path *path)
static struct mountpoint *new_mountpoint(struct dentry *dentry)
{
- struct list_head *chain = mountpoint_hashtable + hash(NULL, dentry);
+ struct hlist_head *chain = mp_hash(dentry);
struct mountpoint *mp;
int ret;
- list_for_each_entry(mp, chain, m_hash) {
+ hlist_for_each_entry(mp, chain, m_hash) {
if (mp->m_dentry == dentry) {
/* might be worth a WARN_ON() */
if (d_unlinked(dentry))
@@ -659,7 +689,7 @@ static struct mountpoint *new_mountpoint(struct dentry *dentry)
mp->m_dentry = dentry;
mp->m_count = 1;
- list_add(&mp->m_hash, chain);
+ hlist_add_head(&mp->m_hash, chain);
return mp;
}
@@ -670,7 +700,7 @@ static void put_mountpoint(struct mountpoint *mp)
spin_lock(&dentry->d_lock);
dentry->d_flags &= ~DCACHE_MOUNTED;
spin_unlock(&dentry->d_lock);
- list_del(&mp->m_hash);
+ hlist_del(&mp->m_hash);
kfree(mp);
}
}
@@ -739,8 +769,7 @@ static void attach_mnt(struct mount *mnt,
struct mountpoint *mp)
{
mnt_set_mountpoint(parent, mp, mnt);
- list_add_tail(&mnt->mnt_hash, mount_hashtable +
- hash(&parent->mnt, mp->m_dentry));
+ list_add_tail(&mnt->mnt_hash, m_hash(&parent->mnt, mp->m_dentry));
list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
}
@@ -762,8 +791,8 @@ static void commit_tree(struct mount *mnt)
list_splice(&head, n->list.prev);
- list_add_tail(&mnt->mnt_hash, mount_hashtable +
- hash(&parent->mnt, mnt->mnt_mountpoint));
+ list_add_tail(&mnt->mnt_hash,
+ m_hash(&parent->mnt, mnt->mnt_mountpoint));
list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
touch_mnt_namespace(n);
}
@@ -2794,18 +2823,24 @@ void __init mnt_init(void)
mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount),
0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
- mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC);
- mountpoint_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC);
+ mount_hashtable = alloc_large_system_hash("Mount-cache",
+ sizeof(struct list_head),
+ mhash_entries, 19,
+ 0,
+ &m_hash_shift, &m_hash_mask, 0, 0);
+ mountpoint_hashtable = alloc_large_system_hash("Mountpoint-cache",
+ sizeof(struct hlist_head),
+ mphash_entries, 19,
+ 0,
+ &mp_hash_shift, &mp_hash_mask, 0, 0);
if (!mount_hashtable || !mountpoint_hashtable)
panic("Failed to allocate mount hash table\n");
- printk(KERN_INFO "Mount-cache hash table entries: %lu\n", HASH_SIZE);
-
- for (u = 0; u < HASH_SIZE; u++)
+ for (u = 0; u <= m_hash_mask; u++)
INIT_LIST_HEAD(&mount_hashtable[u]);
- for (u = 0; u < HASH_SIZE; u++)
- INIT_LIST_HEAD(&mountpoint_hashtable[u]);
+ for (u = 0; u <= mp_hash_mask; u++)
+ INIT_HLIST_HEAD(&mountpoint_hashtable[u]);
kernfs_init();
--
1.7.10.4
--
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