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Date: Mon, 1 Nov 2010 16:33:44 +1100
From: Dave Chinner <david@...morbit.com>
To: viro@...IV.linux.org.uk
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] fs: rcu protect inode hash lookups
From: Dave Chinner <dchinner@...hat.com>
Now that inodes are using RCU freeing, we can walk the hash lists
using RCU protection during lookups. Convert all the hash list
operations to use RCU-based operators and drop the inode_hash_lock
around pure lookup operations.
Signed-off-by: Dave Chinner <dchinner@...hat.com>
---
fs/inode.c | 89 ++++++++++++++++++++++++++++++++++++++---------------------
1 files changed, 57 insertions(+), 32 deletions(-)
diff --git a/fs/inode.c b/fs/inode.c
index 106ec7a..6bead3d 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -50,11 +50,12 @@
* inode->i_lock
*
* inode_hash_lock
- * inode_sb_list_lock
- * inode->i_lock
+ * rcu_read_lock
+ * inode_sb_list_lock
+ * inode->i_lock
*
* iunique_lock
- * inode_hash_lock
+ * rcu_read_lock
*/
/*
@@ -413,7 +414,7 @@ void __insert_inode_hash(struct inode *inode, unsigned long hashval)
spin_lock(&inode_hash_lock);
spin_lock(&inode->i_lock);
- hlist_add_head(&inode->i_hash, b);
+ hlist_add_head_rcu(&inode->i_hash, b);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_hash_lock);
}
@@ -429,7 +430,7 @@ void remove_inode_hash(struct inode *inode)
{
spin_lock(&inode_hash_lock);
spin_lock(&inode->i_lock);
- hlist_del_init(&inode->i_hash);
+ hlist_del_init_rcu(&inode->i_hash);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_hash_lock);
}
@@ -741,26 +742,38 @@ static void __wait_on_freeing_inode(struct inode *inode);
static struct inode *find_inode(struct super_block *sb,
struct hlist_head *head,
int (*test)(struct inode *, void *),
- void *data)
+ void *data, bool locked)
{
struct hlist_node *node;
struct inode *inode = NULL;
repeat:
+ rcu_read_lock();
hlist_for_each_entry(inode, node, head, i_hash) {
if (inode->i_sb != sb)
continue;
if (!test(inode, data))
continue;
spin_lock(&inode->i_lock);
+ if (inode_unhashed(inode)) {
+ spin_unlock(&inode->i_lock);
+ continue;
+ }
if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
+ rcu_read_unlock();
+ if (locked)
+ spin_unlock(&inode_hash_lock);
__wait_on_freeing_inode(inode);
+ if (locked)
+ spin_lock(&inode_hash_lock);
goto repeat;
}
__iget(inode);
spin_unlock(&inode->i_lock);
+ rcu_read_unlock();
return inode;
}
+ rcu_read_unlock();
return NULL;
}
@@ -769,26 +782,39 @@ repeat:
* iget_locked for details.
*/
static struct inode *find_inode_fast(struct super_block *sb,
- struct hlist_head *head, unsigned long ino)
+ struct hlist_head *head, unsigned long ino,
+ bool locked)
{
struct hlist_node *node;
struct inode *inode = NULL;
repeat:
+ rcu_read_lock();
hlist_for_each_entry(inode, node, head, i_hash) {
if (inode->i_ino != ino)
continue;
if (inode->i_sb != sb)
continue;
spin_lock(&inode->i_lock);
+ if (inode_unhashed(inode)) {
+ spin_unlock(&inode->i_lock);
+ continue;
+ }
if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
+ rcu_read_unlock();
+ if (locked)
+ spin_unlock(&inode_hash_lock);
__wait_on_freeing_inode(inode);
+ if (locked)
+ spin_lock(&inode_hash_lock);
goto repeat;
}
__iget(inode);
spin_unlock(&inode->i_lock);
+ rcu_read_unlock();
return inode;
}
+ rcu_read_unlock();
return NULL;
}
@@ -913,14 +939,14 @@ static struct inode *get_new_inode(struct super_block *sb,
spin_lock(&inode_hash_lock);
/* We released the lock, so.. */
- old = find_inode(sb, head, test, data);
+ old = find_inode(sb, head, test, data, true);
if (!old) {
if (set(inode, data))
goto set_failed;
spin_lock(&inode->i_lock);
inode->i_state = I_NEW;
- hlist_add_head(&inode->i_hash, head);
+ hlist_add_head_rcu(&inode->i_hash, head);
spin_unlock(&inode->i_lock);
inode_sb_list_add(inode);
spin_unlock(&inode_hash_lock);
@@ -964,12 +990,12 @@ static struct inode *get_new_inode_fast(struct super_block *sb,
spin_lock(&inode_hash_lock);
/* We released the lock, so.. */
- old = find_inode_fast(sb, head, ino);
+ old = find_inode_fast(sb, head, ino, true);
if (!old) {
inode->i_ino = ino;
spin_lock(&inode->i_lock);
inode->i_state = I_NEW;
- hlist_add_head(&inode->i_hash, head);
+ hlist_add_head_rcu(&inode->i_hash, head);
spin_unlock(&inode->i_lock);
inode_sb_list_add(inode);
spin_unlock(&inode_hash_lock);
@@ -1006,15 +1032,22 @@ static int test_inode_iunique(struct super_block *sb, unsigned long ino)
struct hlist_node *node;
struct inode *inode;
- spin_lock(&inode_hash_lock);
- hlist_for_each_entry(inode, node, b, i_hash) {
- if (inode->i_ino == ino && inode->i_sb == sb) {
- spin_unlock(&inode_hash_lock);
- return 0;
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(inode, node, b, i_hash) {
+ if (inode->i_ino != ino)
+ continue;
+ if (inode->i_sb != sb)
+ continue;
+ spin_lock(&inode->i_lock);
+ if (inode_unhashed(inode)) {
+ spin_unlock(&inode->i_lock);
+ continue;
}
+ spin_unlock(&inode->i_lock);
+ rcu_read_unlock();
+ return 0;
}
- spin_unlock(&inode_hash_lock);
-
+ rcu_read_unlock();
return 1;
}
@@ -1099,15 +1132,12 @@ static struct inode *ifind(struct super_block *sb,
{
struct inode *inode;
- spin_lock(&inode_hash_lock);
- inode = find_inode(sb, head, test, data);
+ inode = find_inode(sb, head, test, data, false);
if (inode) {
- spin_unlock(&inode_hash_lock);
if (likely(wait))
wait_on_inode(inode);
return inode;
}
- spin_unlock(&inode_hash_lock);
return NULL;
}
@@ -1131,14 +1161,11 @@ static struct inode *ifind_fast(struct super_block *sb,
{
struct inode *inode;
- spin_lock(&inode_hash_lock);
- inode = find_inode_fast(sb, head, ino);
+ inode = find_inode_fast(sb, head, ino, false);
if (inode) {
- spin_unlock(&inode_hash_lock);
wait_on_inode(inode);
return inode;
}
- spin_unlock(&inode_hash_lock);
return NULL;
}
@@ -1301,7 +1328,7 @@ int insert_inode_locked(struct inode *inode)
struct hlist_node *node;
struct inode *old = NULL;
spin_lock(&inode_hash_lock);
- hlist_for_each_entry(old, node, head, i_hash) {
+ hlist_for_each_entry_rcu(old, node, head, i_hash) {
if (old->i_ino != ino)
continue;
if (old->i_sb != sb)
@@ -1316,7 +1343,7 @@ int insert_inode_locked(struct inode *inode)
if (likely(!node)) {
spin_lock(&inode->i_lock);
inode->i_state |= I_NEW;
- hlist_add_head(&inode->i_hash, head);
+ hlist_add_head_rcu(&inode->i_hash, head);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_hash_lock);
return 0;
@@ -1345,7 +1372,7 @@ int insert_inode_locked4(struct inode *inode, unsigned long hashval,
struct inode *old = NULL;
spin_lock(&inode_hash_lock);
- hlist_for_each_entry(old, node, head, i_hash) {
+ hlist_for_each_entry_rcu(old, node, head, i_hash) {
if (old->i_sb != sb)
continue;
if (!test(old, data))
@@ -1360,7 +1387,7 @@ int insert_inode_locked4(struct inode *inode, unsigned long hashval,
if (likely(!node)) {
spin_lock(&inode->i_lock);
inode->i_state |= I_NEW;
- hlist_add_head(&inode->i_hash, head);
+ hlist_add_head_rcu(&inode->i_hash, head);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_hash_lock);
return 0;
@@ -1646,10 +1673,8 @@ static void __wait_on_freeing_inode(struct inode *inode)
wq = bit_waitqueue(&inode->i_state, __I_NEW);
prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_hash_lock);
schedule();
finish_wait(wq, &wait.wait);
- spin_lock(&inode_hash_lock);
}
static __initdata unsigned long ihash_entries;
--
1.7.1
--
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