linux-kernel - [PATCH 1/3] vfs: factor out inode hash head calculation

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Date:   Tue,  6 Apr 2021 22:33:41 +1000
From:   Dave Chinner <david@...morbit.com>
To:     linux-fsdevel@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] vfs: factor out inode hash head calculation

From: Dave Chinner <dchinner@...hat.com>

In preparation for changing the inode hash table implementation.

Signed-off-by: Dave Chinner <dchinner@...hat.com>
---
 fs/inode.c | 44 +++++++++++++++++++++++++-------------------
 1 file changed, 25 insertions(+), 19 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index a047ab306f9a..b8d9eb3454dc 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -60,6 +60,22 @@ static unsigned int i_hash_shift __read_mostly;
 static struct hlist_head *inode_hashtable __read_mostly;
 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock);
 
+static unsigned long hash(struct super_block *sb, unsigned long hashval)
+{
+	unsigned long tmp;
+
+	tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
+			L1_CACHE_BYTES;
+	tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> i_hash_shift);
+	return tmp & i_hash_mask;
+}
+
+static inline struct hlist_head *i_hash_head(struct super_block *sb,
+		unsigned int hashval)
+{
+	return inode_hashtable + hash(sb, hashval);
+}
+
 /*
  * Empty aops. Can be used for the cases where the user does not
  * define any of the address_space operations.
@@ -475,16 +491,6 @@ static inline void inode_sb_list_del(struct inode *inode)
 	}
 }
 
-static unsigned long hash(struct super_block *sb, unsigned long hashval)
-{
-	unsigned long tmp;
-
-	tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
-			L1_CACHE_BYTES;
-	tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> i_hash_shift);
-	return tmp & i_hash_mask;
-}
-
 /**
  *	__insert_inode_hash - hash an inode
  *	@inode: unhashed inode
@@ -1073,7 +1079,7 @@ struct inode *inode_insert5(struct inode *inode, unsigned long hashval,
 			    int (*test)(struct inode *, void *),
 			    int (*set)(struct inode *, void *), void *data)
 {
-	struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
+	struct hlist_head *head = i_hash_head(inode->i_sb, hashval);
 	struct inode *old;
 	bool creating = inode->i_state & I_CREATING;
 
@@ -1173,7 +1179,7 @@ EXPORT_SYMBOL(iget5_locked);
  */
 struct inode *iget_locked(struct super_block *sb, unsigned long ino)
 {
-	struct hlist_head *head = inode_hashtable + hash(sb, ino);
+	struct hlist_head *head = i_hash_head(sb, ino);
 	struct inode *inode;
 again:
 	spin_lock(&inode_hash_lock);
@@ -1241,7 +1247,7 @@ EXPORT_SYMBOL(iget_locked);
  */
 static int test_inode_iunique(struct super_block *sb, unsigned long ino)
 {
-	struct hlist_head *b = inode_hashtable + hash(sb, ino);
+	struct hlist_head *b = i_hash_head(sb, ino);
 	struct inode *inode;
 
 	hlist_for_each_entry_rcu(inode, b, i_hash) {
@@ -1328,7 +1334,7 @@ EXPORT_SYMBOL(igrab);
 struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
 		int (*test)(struct inode *, void *), void *data)
 {
-	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
+	struct hlist_head *head = i_hash_head(sb, hashval);
 	struct inode *inode;
 
 	spin_lock(&inode_hash_lock);
@@ -1383,7 +1389,7 @@ EXPORT_SYMBOL(ilookup5);
  */
 struct inode *ilookup(struct super_block *sb, unsigned long ino)
 {
-	struct hlist_head *head = inode_hashtable + hash(sb, ino);
+	struct hlist_head *head = i_hash_head(sb, ino);
 	struct inode *inode;
 again:
 	spin_lock(&inode_hash_lock);
@@ -1432,7 +1438,7 @@ struct inode *find_inode_nowait(struct super_block *sb,
 					     void *),
 				void *data)
 {
-	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
+	struct hlist_head *head = i_hash_head(sb, hashval);
 	struct inode *inode, *ret_inode = NULL;
 	int mval;
 
@@ -1477,7 +1483,7 @@ EXPORT_SYMBOL(find_inode_nowait);
 struct inode *find_inode_rcu(struct super_block *sb, unsigned long hashval,
 			     int (*test)(struct inode *, void *), void *data)
 {
-	struct hlist_head *head = inode_hashtable + hash(sb, hashval);
+	struct hlist_head *head = i_hash_head(sb, hashval);
 	struct inode *inode;
 
 	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
@@ -1515,7 +1521,7 @@ EXPORT_SYMBOL(find_inode_rcu);
 struct inode *find_inode_by_ino_rcu(struct super_block *sb,
 				    unsigned long ino)
 {
-	struct hlist_head *head = inode_hashtable + hash(sb, ino);
+	struct hlist_head *head = i_hash_head(sb, ino);
 	struct inode *inode;
 
 	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
@@ -1535,7 +1541,7 @@ int insert_inode_locked(struct inode *inode)
 {
 	struct super_block *sb = inode->i_sb;
 	ino_t ino = inode->i_ino;
-	struct hlist_head *head = inode_hashtable + hash(sb, ino);
+	struct hlist_head *head = i_hash_head(sb, ino);
 
 	while (1) {
 		struct inode *old = NULL;
-- 
2.31.0