RE: [f2fs-dev] [PATCH] f2fs: do checkpoint for the renamed inode

[Chao Yu]

Hi Jaegeuk,

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk@xxxxxxxxxx]
> Sent: Wednesday, July 02, 2014 6:35 PM
> To: linux-kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx;
> linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: Jaegeuk Kim
> Subject: [f2fs-dev] [PATCH] f2fs: do checkpoint for the renamed inode
> 
> If an inode is renamed, it should be registered as file_lost_pino to conduct
> checkpoint at f2fs_sync_file.
> Otherwise, the inode cannot be recovered due to no dent_mark in the following
> scenario.
> 
> Note that, this scenario is from xfstests/322.
> 
> 1. create "a"
> 2. fsync "a"
> 3. rename "a" to "b"
> 4. fsync "b"
> 5. Sudden power-cut
> 
> After recovery is done, "b" should be seen.
> However, the result shows "a", since the recovery procedure does not enter
> recover_dentry due to no dent_mark.

As we know CP is expensive, how about modifying checkpointed value directly
in nat cache at step #3? So "b" could be fsynced with dent_mark at step #4.

> 
> The reason is like below.
> - The nid of "a" is checkpointed during #2, f2fs_sync_file.
> - The inode page for "b" produced by #3 is written without dent_mark by
> sync_node_pages.
> 
> So, this patch fixes this bug by assinging file_lost_pino to the "a"'s inode.
> If the pino is lost, f2fs_sync_file conducts checkpoint, and then recovers
> the latest pino and its dentry information for further recovery.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> ---
>  fs/f2fs/namei.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
> index 96f1dd1..1b3cae0 100644
> --- a/fs/f2fs/namei.c
> +++ b/fs/f2fs/namei.c
> @@ -411,9 +411,6 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
>  		}
> 
>  		f2fs_set_link(new_dir, new_entry, new_page, old_inode);
> -		down_write(&F2FS_I(old_inode)->i_sem);
> -		F2FS_I(old_inode)->i_pino = new_dir->i_ino;
> -		up_write(&F2FS_I(old_inode)->i_sem);
> 
>  		new_inode->i_ctime = CURRENT_TIME;
>  		down_write(&F2FS_I(new_inode)->i_sem);
> @@ -446,6 +443,10 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
>  		}
>  	}
> 
> +	down_write(&F2FS_I(old_inode)->i_sem);
> +	file_lost_pino(old_inode);
> +	up_write(&F2FS_I(old_inode)->i_sem);
> +
>  	old_inode->i_ctime = CURRENT_TIME;
>  	mark_inode_dirty(old_inode);
> 
> @@ -455,9 +456,6 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
>  		if (old_dir != new_dir) {
>  			f2fs_set_link(old_inode, old_dir_entry,
>  						old_dir_page, new_dir);
> -			down_write(&F2FS_I(old_inode)->i_sem);
> -			F2FS_I(old_inode)->i_pino = new_dir->i_ino;
> -			up_write(&F2FS_I(old_inode)->i_sem);
>  			update_inode_page(old_inode);
>  		} else {
>  			kunmap(old_dir_page);
> --
> 1.8.5.2 (Apple Git-48)
> 
> 
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