linux-kernel - [PATCH] fs/inode: No need to take ->i_lock right after alloc

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Date:	Sat, 14 Dec 2013 21:54:55 +0100
From:	Richard Weinberger <richard@....at>
To:	viro@...iv.linux.org.uk
Cc:	dchinner@...hat.com, hch@....de, eric.dumazet@...il.com,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	Richard Weinberger <richard@....at>
Subject: [PATCH] fs/inode: No need to take ->i_lock right after alloc_inode()

In all three cases, new_inode_pseudo(), iget_locked() and iget5_locked(),
we own the new inode exclusively at this point and therefore taking
->i_lock to protect ->i_state/->i_hash against concurrent access is superfluous.

Signed-off-by: Richard Weinberger <richard@....at>
---
 fs/inode.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index 4bcdad3..5f2a735 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -869,9 +869,7 @@ struct inode *new_inode_pseudo(struct super_block *sb)
 	struct inode *inode = alloc_inode(sb);
 
 	if (inode) {
-		spin_lock(&inode->i_lock);
 		inode->i_state = 0;
-		spin_unlock(&inode->i_lock);
 		INIT_LIST_HEAD(&inode->i_sb_list);
 	}
 	return inode;
@@ -1025,10 +1023,8 @@ struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
 			if (set(inode, data))
 				goto set_failed;
 
-			spin_lock(&inode->i_lock);
 			inode->i_state = I_NEW;
 			hlist_add_head(&inode->i_hash, head);
-			spin_unlock(&inode->i_lock);
 			inode_sb_list_add(inode);
 			spin_unlock(&inode_hash_lock);
 
@@ -1092,10 +1088,8 @@ struct inode *iget_locked(struct super_block *sb, unsigned long ino)
 		old = find_inode_fast(sb, head, ino);
 		if (!old) {
 			inode->i_ino = ino;
-			spin_lock(&inode->i_lock);
 			inode->i_state = I_NEW;
 			hlist_add_head(&inode->i_hash, head);
-			spin_unlock(&inode->i_lock);
 			inode_sb_list_add(inode);
 			spin_unlock(&inode_hash_lock);
 
-- 
1.8.4.2

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