linux-ext4 - Re: [PATCHv4 4/6] ext4: Make ext4_ind_map

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Date:   Thu, 27 Feb 2020 12:49:23 +0100
From:   Jan Kara <jack@...e.cz>
To:     Ritesh Harjani <riteshh@...ux.ibm.com>
Cc:     jack@...e.cz, tytso@....edu, linux-ext4@...r.kernel.org,
        adilger.kernel@...ger.ca, linux-fsdevel@...r.kernel.org,
        darrick.wong@...cle.com, hch@...radead.org, cmaiolino@...hat.com,
        david@...morbit.com
Subject: Re: [PATCHv4 4/6] ext4: Make ext4_ind_map_blocks work with fiemap

On Thu 27-02-20 16:40:25, Ritesh Harjani wrote:
> For indirect block mapping if the i_block > max supported block in inode
> then ext4_ind_map_blocks() returns a -EIO error. But in case of fiemap
> this could be a valid query to ->iomap_begin call.
> So check if the offset >= s_bitmap_maxbytes in ext4_iomap_begin_report(),
> then simply skip calling ext4_map_blocks().
> 
> Signed-off-by: Ritesh Harjani <riteshh@...ux.ibm.com>

The patch looks good to me. You can add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/ext4/inode.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 81fccbae0aea..4364864fc709 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3548,12 +3548,28 @@ static int ext4_iomap_begin_report(struct inode *inode, loff_t offset,
>  	map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
>  			  EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
>  
> +	/*
> +	 * Fiemap callers may call for offset beyond s_bitmap_maxbytes.
> +	 * So handle it here itself instead of querying ext4_map_blocks().
> +	 * Since ext4_map_blocks() will warn about it and will return
> +	 * -EIO error.
> +	 */
> +	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
> +		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> +
> +		if (offset >= sbi->s_bitmap_maxbytes) {
> +			map.m_flags = 0;
> +			goto set_iomap;
> +		}
> +	}
> +
>  	ret = ext4_map_blocks(NULL, inode, &map, 0);
>  	if (ret < 0)
>  		return ret;
>  	if (ret == 0)
>  		delalloc = ext4_iomap_is_delalloc(inode, &map);
>  
> +set_iomap:
>  	ext4_set_iomap(inode, iomap, &map, offset, length);
>  	if (delalloc && iomap->type == IOMAP_HOLE)
>  		iomap->type = IOMAP_DELALLOC;
> -- 
> 2.21.0
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR