From: Nick Piggin <npiggin@kernel.dk>
Date: Fri, 7 Jan 2011 06:49:30 +0000 (+1100)
Subject: fs: dcache scale hash
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=789680d1ee9311cdf095241dc02bd9784d799cd1;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git
fs: dcache scale hash
Add a new lock, dcache_hash_lock, to protect the dcache hash table from
concurrent modification. d_hash is also protected by d_lock.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
---
diff --git a/fs/dcache.c b/fs/dcache.c
index 61beb40dd6bf..1e124d4673c6 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -35,10 +35,24 @@
#include <linux/hardirq.h>
#include "internal.h"
+/*
+ * Usage:
+ * dcache_hash_lock protects dcache hash table, s_anon lists
+ *
+ * Ordering:
+ * dcache_lock
+ * dentry->d_lock
+ * dcache_hash_lock
+ *
+ * if (dentry1 < dentry2)
+ * dentry1->d_lock
+ * dentry2->d_lock
+ */
int sysctl_vfs_cache_pressure __read_mostly = 100;
EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
- __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock);
+static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_hash_lock);
+__cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock);
__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
EXPORT_SYMBOL(dcache_lock);
@@ -196,6 +210,42 @@ static struct dentry *d_kill(struct dentry *dentry)
return parent;
}
+/**
+ * d_drop - drop a dentry
+ * @dentry: dentry to drop
+ *
+ * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
+ * be found through a VFS lookup any more. Note that this is different from
+ * deleting the dentry - d_delete will try to mark the dentry negative if
+ * possible, giving a successful _negative_ lookup, while d_drop will
+ * just make the cache lookup fail.
+ *
+ * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
+ * reason (NFS timeouts or autofs deletes).
+ *
+ * __d_drop requires dentry->d_lock.
+ */
+void __d_drop(struct dentry *dentry)
+{
+ if (!(dentry->d_flags & DCACHE_UNHASHED)) {
+ dentry->d_flags |= DCACHE_UNHASHED;
+ spin_lock(&dcache_hash_lock);
+ hlist_del_rcu(&dentry->d_hash);
+ spin_unlock(&dcache_hash_lock);
+ }
+}
+EXPORT_SYMBOL(__d_drop);
+
+void d_drop(struct dentry *dentry)
+{
+ spin_lock(&dcache_lock);
+ spin_lock(&dentry->d_lock);
+ __d_drop(dentry);
+ spin_unlock(&dentry->d_lock);
+ spin_unlock(&dcache_lock);
+}
+EXPORT_SYMBOL(d_drop);
+
/*
* This is dput
*
@@ -1199,7 +1249,9 @@ struct dentry *d_obtain_alias(struct inode *inode)
tmp->d_flags |= DCACHE_DISCONNECTED;
tmp->d_flags &= ~DCACHE_UNHASHED;
list_add(&tmp->d_alias, &inode->i_dentry);
+ spin_lock(&dcache_hash_lock);
hlist_add_head(&tmp->d_hash, &inode->i_sb->s_anon);
+ spin_unlock(&dcache_hash_lock);
spin_unlock(&tmp->d_lock);
spin_unlock(&dcache_lock);
@@ -1585,7 +1637,9 @@ void d_rehash(struct dentry * entry)
{
spin_lock(&dcache_lock);
spin_lock(&entry->d_lock);
+ spin_lock(&dcache_hash_lock);
_d_rehash(entry);
+ spin_unlock(&dcache_hash_lock);
spin_unlock(&entry->d_lock);
spin_unlock(&dcache_lock);
}
@@ -1692,8 +1746,6 @@ static void switch_names(struct dentry *dentry, struct dentry *target)
*/
static void d_move_locked(struct dentry * dentry, struct dentry * target)
{
- struct hlist_head *list;
-
if (!dentry->d_inode)
printk(KERN_WARNING "VFS: moving negative dcache entry\n");
@@ -1710,14 +1762,11 @@ static void d_move_locked(struct dentry * dentry, struct dentry * target)
}
/* Move the dentry to the target hash queue, if on different bucket */
- if (d_unhashed(dentry))
- goto already_unhashed;
-
- hlist_del_rcu(&dentry->d_hash);
-
-already_unhashed:
- list = d_hash(target->d_parent, target->d_name.hash);
- __d_rehash(dentry, list);
+ spin_lock(&dcache_hash_lock);
+ if (!d_unhashed(dentry))
+ hlist_del_rcu(&dentry->d_hash);
+ __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
+ spin_unlock(&dcache_hash_lock);
/* Unhash the target: dput() will then get rid of it */
__d_drop(target);
@@ -1914,7 +1963,9 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
found_lock:
spin_lock(&actual->d_lock);
found:
+ spin_lock(&dcache_hash_lock);
_d_rehash(actual);
+ spin_unlock(&dcache_hash_lock);
spin_unlock(&actual->d_lock);
spin_unlock(&dcache_lock);
out_nolock:
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index cea27dfca532..2feb624b67f1 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -184,39 +184,6 @@ struct dentry_operations {
extern spinlock_t dcache_lock;
extern seqlock_t rename_lock;
-/**
- * d_drop - drop a dentry
- * @dentry: dentry to drop
- *
- * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
- * be found through a VFS lookup any more. Note that this is different from
- * deleting the dentry - d_delete will try to mark the dentry negative if
- * possible, giving a successful _negative_ lookup, while d_drop will
- * just make the cache lookup fail.
- *
- * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
- * reason (NFS timeouts or autofs deletes).
- *
- * __d_drop requires dentry->d_lock.
- */
-
-static inline void __d_drop(struct dentry *dentry)
-{
- if (!(dentry->d_flags & DCACHE_UNHASHED)) {
- dentry->d_flags |= DCACHE_UNHASHED;
- hlist_del_rcu(&dentry->d_hash);
- }
-}
-
-static inline void d_drop(struct dentry *dentry)
-{
- spin_lock(&dcache_lock);
- spin_lock(&dentry->d_lock);
- __d_drop(dentry);
- spin_unlock(&dentry->d_lock);
- spin_unlock(&dcache_lock);
-}
-
static inline int dname_external(struct dentry *dentry)
{
return dentry->d_name.name != dentry->d_iname;
@@ -228,6 +195,8 @@ static inline int dname_external(struct dentry *dentry)
extern void d_instantiate(struct dentry *, struct inode *);
extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
extern struct dentry * d_materialise_unique(struct dentry *, struct inode *);
+extern void __d_drop(struct dentry *dentry);
+extern void d_drop(struct dentry *dentry);
extern void d_delete(struct dentry *);
/* allocate/de-allocate */