*/
#include <linux/config.h>
+#include <linux/syscalls.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/fs.h>
int sysctl_vfs_cache_pressure = 100;
-spinlock_t dcache_lock __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
+ __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock);
seqlock_t rename_lock __cacheline_aligned_in_smp = SEQLOCK_UNLOCKED;
EXPORT_SYMBOL(dcache_lock);
spin_unlock(&dcache_lock);
return;
}
-
+
/*
* AV: ->d_delete() is _NOT_ allowed to block now.
*/
/**
* d_find_alias - grab a hashed alias of inode
* @inode: inode in question
+ * @want_discon: flag, used by d_splice_alias, to request
+ * that only a DISCONNECTED alias be returned.
*
- * If inode has a hashed alias - acquire the reference to alias and
- * return it. Otherwise return NULL. Notice that if inode is a directory
- * there can be only one alias and it can be unhashed only if it has
- * no children.
+ * If inode has a hashed alias, or is a directory and has any alias,
+ * acquire the reference to alias and return it. Otherwise return NULL.
+ * Notice that if inode is a directory there can be only one alias and
+ * it can be unhashed only if it has no children, or if it is the root
+ * of a filesystem.
*
* If the inode has a DCACHE_DISCONNECTED alias, then prefer
- * any other hashed alias over that one.
+ * any other hashed alias over that one unless @want_discon is set,
+ * in which case only return a DCACHE_DISCONNECTED alias.
*/
static struct dentry * __d_find_alias(struct inode *inode, int want_discon)
next = tmp->next;
prefetch(next);
alias = list_entry(tmp, struct dentry, d_alias);
- if (!d_unhashed(alias)) {
+ if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
if (alias->d_flags & DCACHE_DISCONNECTED)
discon_alias = alias;
else if (!want_discon) {
struct dentry *dentry;
struct list_head *tmp;
+ cond_resched_lock(&dcache_lock);
+
tmp = dentry_unused.prev;
if (tmp == &dentry_unused)
break;
* list for prune_dcache(). We descend to the next level
* whenever the d_subdirs list is non-empty and continue
* searching.
+ *
+ * It returns zero iff there are no unused children,
+ * otherwise it returns the number of children moved to
+ * the end of the unused list. This may not be the total
+ * number of unused children, because select_parent can
+ * drop the lock and return early due to latency
+ * constraints.
*/
static int select_parent(struct dentry * parent)
{
dentry_stat.nr_unused++;
found++;
}
+
+ /*
+ * We can return to the caller if we have found some (this
+ * ensures forward progress). We'll be coming back to find
+ * the rest.
+ */
+ if (found && need_resched())
+ goto out;
+
/*
* Descend a level if the d_subdirs list is non-empty.
*/
#endif
goto resume;
}
+out:
spin_unlock(&dcache_lock);
return found;
}
atomic_set(&dentry->d_count, 1);
dentry->d_flags = DCACHE_UNHASHED;
- dentry->d_lock = SPIN_LOCK_UNLOCKED;
+ spin_lock_init(&dentry->d_lock);
dentry->d_inode = NULL;
dentry->d_parent = NULL;
dentry->d_sb = NULL;
dentry->d_fsdata = NULL;
dentry->d_mounted = 0;
dentry->d_cookie = NULL;
- dentry->d_bucket = NULL;
INIT_HLIST_NODE(&dentry->d_hash);
INIT_LIST_HEAD(&dentry->d_lru);
INIT_LIST_HEAD(&dentry->d_subdirs);
return dentry;
}
+struct dentry *d_alloc_name(struct dentry *parent, const char *name)
+{
+ struct qstr q;
+
+ q.name = name;
+ q.len = strlen(name);
+ q.hash = full_name_hash(q.name, q.len);
+ return d_alloc(parent, &q);
+}
+
/**
* d_instantiate - fill in inode information for a dentry
* @entry: dentry to complete
security_d_instantiate(entry, inode);
}
+/**
+ * d_instantiate_unique - instantiate a non-aliased dentry
+ * @entry: dentry to instantiate
+ * @inode: inode to attach to this dentry
+ *
+ * Fill in inode information in the entry. On success, it returns NULL.
+ * If an unhashed alias of "entry" already exists, then we return the
+ * aliased dentry instead.
+ *
+ * Note that in order to avoid conflicts with rename() etc, the caller
+ * had better be holding the parent directory semaphore.
+ */
+struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode)
+{
+ struct dentry *alias;
+ int len = entry->d_name.len;
+ const char *name = entry->d_name.name;
+ unsigned int hash = entry->d_name.hash;
+
+ BUG_ON(!list_empty(&entry->d_alias));
+ spin_lock(&dcache_lock);
+ if (!inode)
+ goto do_negative;
+ list_for_each_entry(alias, &inode->i_dentry, d_alias) {
+ struct qstr *qstr = &alias->d_name;
+
+ if (qstr->hash != hash)
+ continue;
+ if (alias->d_parent != entry->d_parent)
+ continue;
+ if (qstr->len != len)
+ continue;
+ if (memcmp(qstr->name, name, len))
+ continue;
+ dget_locked(alias);
+ spin_unlock(&dcache_lock);
+ BUG_ON(!d_unhashed(alias));
+ return alias;
+ }
+ list_add(&entry->d_alias, &inode->i_dentry);
+do_negative:
+ entry->d_inode = inode;
+ spin_unlock(&dcache_lock);
+ security_d_instantiate(entry, inode);
+ return NULL;
+}
+EXPORT_SYMBOL(d_instantiate_unique);
+
/**
* d_alloc_root - allocate root dentry
* @root_inode: inode to allocate the root for
res->d_sb = inode->i_sb;
res->d_parent = res;
res->d_inode = inode;
-
- /*
- * Set d_bucket to an "impossible" bucket address so
- * that d_move() doesn't get a false positive
- */
- res->d_bucket = NULL;
res->d_flags |= DCACHE_DISCONNECTED;
res->d_flags &= ~DCACHE_UNHASHED;
list_add(&res->d_alias, &inode->i_dentry);
dentry = hlist_entry(node, struct dentry, d_hash);
- smp_rmb();
-
if (dentry->d_name.hash != hash)
continue;
if (dentry->d_parent != parent)
spin_lock(&dentry->d_lock);
- /*
- * If lookup ends up in a different bucket due to concurrent
- * rename, fail it
- */
- if (unlikely(dentry->d_bucket != head))
- goto terminate;
-
/*
* Recheck the dentry after taking the lock - d_move may have
* changed things. Don't bother checking the hash because we're
if (dentry->d_parent != parent)
goto next;
- qstr = rcu_dereference(&dentry->d_name);
+ /*
+ * It is safe to compare names since d_move() cannot
+ * change the qstr (protected by d_lock).
+ */
+ qstr = &dentry->d_name;
if (parent->d_op && parent->d_op->d_compare) {
if (parent->d_op->d_compare(parent, qstr, name))
goto next;
atomic_inc(&dentry->d_count);
found = dentry;
}
-terminate:
spin_unlock(&dentry->d_lock);
break;
next:
spin_unlock(&dcache_lock);
}
+static void __d_rehash(struct dentry * entry, struct hlist_head *list)
+{
+
+ entry->d_flags &= ~DCACHE_UNHASHED;
+ hlist_add_head_rcu(&entry->d_hash, list);
+}
+
/**
* d_rehash - add an entry back to the hash
* @entry: dentry to add to the hash
spin_lock(&dcache_lock);
spin_lock(&entry->d_lock);
- entry->d_flags &= ~DCACHE_UNHASHED;
+ __d_rehash(entry, list);
spin_unlock(&entry->d_lock);
- entry->d_bucket = list;
- hlist_add_head_rcu(&entry->d_hash, list);
spin_unlock(&dcache_lock);
}
void d_move(struct dentry * dentry, struct dentry * target)
{
+ struct hlist_head *list;
+
if (!dentry->d_inode)
printk(KERN_WARNING "VFS: moving negative dcache entry\n");
/* Move the dentry to the target hash queue, if on different bucket */
if (dentry->d_flags & DCACHE_UNHASHED)
goto already_unhashed;
- if (dentry->d_bucket != target->d_bucket) {
- hlist_del_rcu(&dentry->d_hash);
+
+ hlist_del_rcu(&dentry->d_hash);
+
already_unhashed:
- dentry->d_bucket = target->d_bucket;
- hlist_add_head_rcu(&dentry->d_hash, target->d_bucket);
- dentry->d_flags &= ~DCACHE_UNHASHED;
- }
+ list = d_hash(target->d_parent, target->d_name.hash);
+ __d_rehash(dentry, list);
/* Unhash the target: dput() will then get rid of it */
__d_drop(target);
/* Switch the names.. */
switch_names(dentry, target);
- smp_wmb();
do_switch(dentry->d_name.len, target->d_name.len);
do_switch(dentry->d_name.hash, target->d_name.hash);
{
int loop;
+ /* If hashes are distributed across NUMA nodes, defer
+ * hash allocation until vmalloc space is available.
+ */
+ if (hashdist)
+ return;
+
dentry_hashtable =
alloc_large_system_hash("Dentry cache",
sizeof(struct hlist_head),
dhash_entries,
13,
- 0,
+ HASH_EARLY,
&d_hash_shift,
- &d_hash_mask);
+ &d_hash_mask,
+ 0);
for (loop = 0; loop < (1 << d_hash_shift); loop++)
INIT_HLIST_HEAD(&dentry_hashtable[loop]);
static void __init dcache_init(unsigned long mempages)
{
+ int loop;
+
/*
* A constructor could be added for stable state like the lists,
* but it is probably not worth it because of the cache nature
NULL, NULL);
set_shrinker(DEFAULT_SEEKS, shrink_dcache_memory);
+
+ /* Hash may have been set up in dcache_init_early */
+ if (!hashdist)
+ return;
+
+ dentry_hashtable =
+ alloc_large_system_hash("Dentry cache",
+ sizeof(struct hlist_head),
+ dhash_entries,
+ 13,
+ 0,
+ &d_hash_shift,
+ &d_hash_mask,
+ 0);
+
+ for (loop = 0; loop < (1 << d_hash_shift); loop++)
+ INIT_HLIST_HEAD(&dentry_hashtable[loop]);
}
/* SLAB cache for __getname() consumers */
EXPORT_SYMBOL(dput);
EXPORT_SYMBOL(find_inode_number);
EXPORT_SYMBOL(have_submounts);
-EXPORT_SYMBOL(is_subdir);
EXPORT_SYMBOL(names_cachep);
-EXPORT_SYMBOL(shrink_dcache_anon);
EXPORT_SYMBOL(shrink_dcache_parent);
EXPORT_SYMBOL(shrink_dcache_sb);
git://git.onelab.eu / linux-2.6.git / blobdiff