2013-04-09 08:06:53

by majianpeng

Subject: [PATCH] vfs: Remove the unnecessary protect.

After allocating a inode,it don't chain in superblock.At this time,it
won't be used by others.So it make no sense to protect there.

Signed-off-by: Jianpeng Ma <[email protected]>
---
fs/inode.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index f5f7c06..1d7b0dd 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -906,9 +906,7 @@ 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;
--
1.8.2.rc2.4.g7799588

2013-04-16 16:38:49

by Jan Kara

Subject: Re: [PATCH] vfs: Remove the unnecessary protect.

On Tue 09-04-13 16:06:39, majianpeng wrote:
> After allocating a inode,it don't chain in superblock.At this time,it
> won't be used by others.So it make no sense to protect there.
Something (likely your mailer) has mangled whitespace in your patch.
Please submit patches with a program that preserves whitespace (preferred)
or use text/plain attachments.

Also I don't think the argument for removing i_lock locking is as simple.
Without the lock, i_state initialization can be speculatively performed
earlier / later wrt other instructions by the CPU so it's not clear this
cannot cause problems to some of the callers.

Honza

> Signed-off-by: Jianpeng Ma <[email protected]>
> ---
> fs/inode.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/fs/inode.c b/fs/inode.c
> index f5f7c06..1d7b0dd 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -906,9 +906,7 @@ 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;
> --
> 1.8.2.rc2.4.g7799588
>
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--
Jan Kara <[email protected]>
SUSE Labs, CR