linux-ext4 - Re: [PATCH 5/9 v4] ext4: track all extent status in extent status tree

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Date:	Thu, 31 Jan 2013 17:50:55 +0100
From:	Jan Kara <jack@...e.cz>
To:	Zheng Liu <gnehzuil.liu@...il.com>
Cc:	linux-ext4@...r.kernel.org, Zheng Liu <wenqing.lz@...bao.com>,
	Theodore Ts'o <tytso@....edu>
Subject: Re: [PATCH 5/9 v4] ext4: track all extent status in extent status
 tree

On Thu 31-01-13 13:17:53, Zheng Liu wrote:
> From: Zheng Liu <wenqing.lz@...bao.com>
> 
> By recording the phycisal block and status, extent status tree is able
> to track the status of every extents.  When we call _map_blocks
> functions to lookup an extent or create a new written/unwritten/delayed
> extent, this extent will be inserted into extent status tree.
> 
> We don't load all extents from disk in alloc_inode() because it costs
> too much memory, and if a file is opened and closed frequently it will
> takes too much time to load all extent information.  So currently when
> we create/lookup an extent, this extent will be inserted into extent
> status tree.  Hence, the extent status tree may not comprehensively
> contain all of the extents found in the file.
> 
> Signed-off-by: Zheng Liu <wenqing.lz@...bao.com>
> Cc: "Theodore Ts'o" <tytso@....edu>
> ---
>  fs/ext4/extents.c |  5 +++-
>  fs/ext4/file.c    |  6 +++--
>  fs/ext4/inode.c   | 73 ++++++++++++++++++++++++++++++++++++-------------------
>  3 files changed, 56 insertions(+), 28 deletions(-)
> 
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index aa9a6d2..d23a654 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -2074,7 +2074,7 @@ static int ext4_fill_fiemap_extents(struct inode *inode,
>  		}
>  
>  		/* This is possible iff next == next_del == EXT_MAX_BLOCKS */
> -		if (next == next_del) {
> +		if (next == next_del && next_del == EXT_MAX_BLOCKS) {
  This doesn't seem to be related, does it?

> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index e09c7cf..f0dda2a 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -615,18 +615,27 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
>  			(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE))
>  			ext4_da_update_reserve_space(inode, retval, 1);
>  	}
> -	if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) {
> +	if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
>  		ext4_clear_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED);
>  
> -		if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
> -			int ret;
> -delayed_mapped:
> -			/* delayed allocation blocks has been allocated */
> -			ret = ext4_es_remove_extent(inode, map->m_lblk,
> -						    map->m_len);
> -			if (ret < 0)
> -				retval = ret;
> -		}
> +	if (retval > 0) {
> +		int ret, status;
> +
> +		if (flags & EXT4_GET_BLOCKS_PRE_IO)
> +			status = EXTENT_STATUS_UNWRITTEN;
> +		else if (flags & EXT4_GET_BLOCKS_CONVERT)
> +			status = EXTENT_STATUS_WRITTEN;
> +		else if (flags & EXT4_GET_BLOCKS_UNINIT_EXT)
> +			status = EXTENT_STATUS_UNWRITTEN;
> +		else if (flags & EXT4_GET_BLOCKS_CREATE)
> +			status = EXTENT_STATUS_WRITTEN;
> +		else
> +			BUG_ON(1);
> +
> +		ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
> +					    map->m_pblk, status);
> +		if (ret < 0)
> +			retval = ret;
  Hum, are you sure the extent status will be correct? Won't it be safer to
just use whatever we have in 'map'?

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