linux-kernel - Re: [PATCH] udf : skip mirror metadata FE since metadata FE is ok.

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Date:	Fri, 21 Oct 2011 01:47:03 +0200
From:	Jan Kara <jack@...e.cz>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	jack@...e.cz, linux-kernel@...r.kernel.org,
	Ashish Sangwan <ashishsangwan2@...il.com>
Subject: Re: [PATCH] udf : skip mirror metadata FE since metadata FE is ok.

On Thu 20-10-11 00:03:18, Namjae Jeon wrote:
> By Jan Kara's suggestion, This patch skip mirror metadata FE since
> metadata FE is ok. And try to read it only the first time
> udf_get_pblock_meta25() fails to map the block from metadata FE.
>
> Signed-off-by: Namjae Jeon <linkinjeon@...il.com>
> Signed-off-by: Ashish Sangwan <ashishsangwan2@...il.com>
> ---
>  fs/udf/partition.c |   20 ++++++++++++++++++++
>  fs/udf/super.c     |   33 ++++++++++++++++-----------------
>  2 files changed, 36 insertions(+), 17 deletions(-)
> 
> diff --git a/fs/udf/partition.c b/fs/udf/partition.c
> index f3e472c..8bfc25b 100644
> --- a/fs/udf/partition.c
> +++ b/fs/udf/partition.c
> @@ -311,6 +311,7 @@ uint32_t udf_get_pblock_meta25(struct super_block *sb, uint32_t block,
>  	struct udf_meta_data *mdata;
>  	uint32_t retblk;
>  	struct inode *inode;
> +	struct kernel_lb_addr addr;
>  
>  	udf_debug("READING from METADATA\n");
>  
> @@ -323,6 +324,25 @@ uint32_t udf_get_pblock_meta25(struct super_block *sb, uint32_t block,
>  	retblk = udf_try_read_meta(inode, block, partition, offset);
>  	if (retblk == 0xFFFFFFFF) {
>  		udf_warn(sb, "error reading from METADATA, trying to read from MIRROR\n");
> +		if (mdata->s_mirror_fe == NULL) {
  This won't be good because if s_mirror_fe cannot be loaded as well, you'd
just try loading it on every block mapping which failed from the primary
metadata map. So you should have a flag somewhere whether in mdata, whether
you tried loading mirror_fe or not and use that.

> +			/* mirror file entry */
> +			addr.logicalBlockNum = mdata->s_mirror_file_loc;
> +			addr.partitionReferenceNum = map->s_partition_num;
> +			udf_debug("Mirror metadata file location: block = %d part = %d\n",
> +				addr.logicalBlockNum,
> +				addr.partitionReferenceNum);
> +			mdata->s_mirror_fe = udf_iget(sb, &addr);
> +
> +			if (mdata->s_mirror_fe == NULL)
> +				udf_err(sb, "mirror inode efe not found");
> +			else if (UDF_I(mdata->s_mirror_fe)->i_alloc_type !=
> +					ICBTAG_FLAG_AD_SHORT) {
> +				udf_warn(sb, "mirror inode efe does not have short allocation descriptors!\n");
> +				iput(mdata->s_mirror_fe);
> +				mdata->s_mirror_fe = NULL;
> +			}
  Also please create a helper function for loading metadata/mirror metadat
FE so that we don't have loading duplicated in three places... Thanks.

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