Re: [PATCH 4/4] ext4: add support for a lazytime mount option

Jan Kara
2014-11-25T17:34:32Z

On Fri 21-11-14 14:59:24, Ted Tso wrote:
> Add an optimization for the MS_LAZYTIME mount option so that we will
> opportunistically write out any inodes with the I_DIRTY_TIME flag set
> in a particular inode table block when we need to update some inode in
> that inode table block anyway.
>
> Also add some temporary code so that we can set the lazytime mount
> option without needing a modified /sbin/mount program which can set
> MS_LAZYTIME. We can eventually make this go away once util-linux has
> added support.
...
> diff --git a/fs/inode.c b/fs/inode.c
> index f0d6232..89cfca7 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -1292,6 +1292,42 @@ struct inode *ilookup(struct super_block *sb, unsigned long ino)
> }
> EXPORT_SYMBOL(ilookup);
>
> +/**
> + * find_active_inode_nowait - find an active inode in the inode cache
> + * @sb: super block of file system to search
> + * @ino: inode number to search for
> + *
> + * Search for an active inode @ino in the inode cache, and if the
> + * inode is in the cache, the inode is returned with an incremented
> + * reference count. If the inode is being freed or is newly
> + * initialized, return nothing instead of trying to wait for the inode
> + * initialization or destruction to be complete.
> + */
> +struct inode *find_active_inode_nowait(struct super_block *sb,
> + unsigned long ino)
> +{
> + struct hlist_head *head = inode_hashtable + hash(sb, ino);
> + struct inode *inode, *ret_inode = NULL;
> +
> + spin_lock(&inode_hash_lock);
> + hlist_for_each_entry(inode, head, i_hash) {
> + if ((inode->i_ino != ino) ||
> + (inode->i_sb != sb))
> + continue;
> + spin_lock(&inode->i_lock);
> + if ((inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW)) == 0) {
> + __iget(inode);
> + ret_inode = inode;
> + }
> + spin_unlock(&inode->i_lock);
> + goto out;
> + }
> +out:
> + spin_unlock(&inode_hash_lock);
> + return ret_inode;
> +}
> +EXPORT_SYMBOL(find_active_inode_nowait);
> +
Please move this function definition into a separate patch so that it
isn't hidden in an ext4-specific patch. Otherwise it looks good.

Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR