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Subject: Re: [PATCHv3 5/6] ext4: Move ext4_fiemap to use iomap framework.
To:     Jan Kara <jack@suse.cz>
Cc:     tytso@mit.edu, linux-ext4@vger.kernel.org,
        adilger.kernel@dilger.ca, linux-fsdevel@vger.kernel.org,
        darrick.wong@oracle.com, hch@infradead.org, cmaiolino@redhat.com
References: <cover.1582702693.git.riteshh@linux.ibm.com>
 <31caeb6a880e3070ace5dfcb0623fc06f751b443.1582702694.git.riteshh@linux.ibm.com>
 <20200226132720.GQ10728@quack2.suse.cz>
From:   Ritesh Harjani <riteshh@linux.ibm.com>
Date:   Thu, 27 Feb 2020 11:08:22 +0530
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On 2/26/20 6:57 PM, Jan Kara wrote:
> On Wed 26-02-20 15:27:07, Ritesh Harjani wrote:
>> This patch moves ext4_fiemap to use iomap framework.
>> For xattr a new 'ext4_iomap_xattr_ops' is added.
>>
>> Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
> 
> ...
> 
>> -static int ext4_xattr_fiemap(struct inode *inode,
>> -				struct fiemap_extent_info *fieinfo)
>> +static int ext4_iomap_xattr_fiemap(struct inode *inode, struct iomap *iomap)
>>   {
>>   	__u64 physical = 0;
>>   	__u64 length;
>> -	__u32 flags = FIEMAP_EXTENT_LAST;
>>   	int blockbits = inode->i_sb->s_blocksize_bits;
>>   	int error = 0;
>> +	u16 iomap_type;
>>   
>>   	/* in-inode? */
>>   	if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
>> @@ -5130,40 +4928,44 @@ static int ext4_xattr_fiemap(struct inode *inode,
>>   				EXT4_I(inode)->i_extra_isize;
>>   		physical += offset;
>>   		length = EXT4_SB(inode->i_sb)->s_inode_size - offset;
>> -		flags |= FIEMAP_EXTENT_DATA_INLINE;
>>   		brelse(iloc.bh);
>> +		iomap_type = IOMAP_INLINE;
>>   	} else { /* external block */
>>   		physical = (__u64)EXT4_I(inode)->i_file_acl << blockbits;
>>   		length = inode->i_sb->s_blocksize;
>> +		iomap_type = IOMAP_MAPPED;
>>   	}
> 
> If i_file_acl is 0 (i.e., no external xattr block), then I think returned
> iomap should be different...

Yes, my bad. Let me fix this please.


> 
>> +static int ext4_iomap_xattr_begin(struct inode *inode, loff_t offset,
>> +				  loff_t length, unsigned flags,
>> +				  struct iomap *iomap, struct iomap *srcmap)
>>   {
>> -	ext4_lblk_t start_blk;
>> -	u32 ext4_fiemap_flags = FIEMAP_FLAG_SYNC|FIEMAP_FLAG_XATTR;
>> +	int error;
>>   
>> -	int error = 0;
>> -
>> -	if (ext4_has_inline_data(inode)) {
>> -		int has_inline = 1;
>> +	error = ext4_iomap_xattr_fiemap(inode, iomap);
>> +	if (error == 0 && (offset >= iomap->length))
>> +		error = -ENOENT;
> 
> Is ENOENT really correct here? It seems strange to me...
> 

Yes, -ENOENT means that there is no mapping beyond this and so iomap
core will stop querying further in iomap_fiemap.
I see that we do the same in case of inline mapping too in
ext4_iomap_begin_report().

-ritesh