2012-02-08 07:37:14

by Kazuya Mio

Subject: [PATCH v2] ext3: Update ctime in ext3_splice_branch() only when needed

Currently ext3 updates ctime in ext3_splice_branch() which is called whenever
we allocate one block. But it is wasteful because ext3 doesn't support
nanosecond timestamp. This leads to a performance loss.

Signed-off-by: Kazuya Mio <[email protected]>
---
fs/ext3/inode.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index 2d0afec..3c7fd63 100644
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -756,6 +756,7 @@ static int ext3_splice_branch(handle_t *handle, struct inode *inode,
struct ext3_block_alloc_info *block_i;
ext3_fsblk_t current_block;
struct ext3_inode_info *ei = EXT3_I(inode);
+ struct timespec now;

block_i = ei->i_block_alloc_info;
/*
@@ -795,9 +796,11 @@ static int ext3_splice_branch(handle_t *handle, struct inode *inode,
}

/* We are done with atomic stuff, now do the rest of housekeeping */

2012-02-08 09:33:09

by Jan Kara

Subject: Re: [PATCH v2] ext3: Update ctime in ext3_splice_branch() only when needed

On Wed 08-02-12 16:34:29, Kazuya Mio wrote:
> Currently ext3 updates ctime in ext3_splice_branch() which is called whenever
> we allocate one block. But it is wasteful because ext3 doesn't support
> nanosecond timestamp. This leads to a performance loss.
>
> Signed-off-by: Kazuya Mio <[email protected]>
Thanks. The patch looks good. I've added it to my tree.

Honza

> ---
> fs/ext3/inode.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
> diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
> index 2d0afec..3c7fd63 100644
> --- a/fs/ext3/inode.c
> +++ b/fs/ext3/inode.c
> @@ -756,6 +756,7 @@ static int ext3_splice_branch(handle_t *handle, struct inode *inode,
> struct ext3_block_alloc_info *block_i;
> ext3_fsblk_t current_block;
> struct ext3_inode_info *ei = EXT3_I(inode);
> + struct timespec now;
>
> block_i = ei->i_block_alloc_info;
> /*
> @@ -795,9 +796,11 @@ static int ext3_splice_branch(handle_t *handle, struct inode *inode,
> }
>
> /* We are done with atomic stuff, now do the rest of housekeeping */
> -
> - inode->i_ctime = CURRENT_TIME_SEC;
> - ext3_mark_inode_dirty(handle, inode);
> + now = CURRENT_TIME_SEC;
> + if (!timespec_equal(&inode->i_ctime, &now) || !where->bh) {
> + inode->i_ctime = now;
> + ext3_mark_inode_dirty(handle, inode);
> + }
> /* ext3_mark_inode_dirty already updated i_sync_tid */
> atomic_set(&ei->i_datasync_tid, handle->h_transaction->t_tid);
>
--
Jan Kara <[email protected]>
SUSE Labs, CR