On Mon, Apr 11, 2011 at 9:46 AM, Ted Ts'o <tytso@xxxxxxx> wrote:
> On Sun, Apr 10, 2011 at 10:30:13PM +0800, Yongqiang Yang wrote:
>> So the right code should beï
>>
>> Â Â Â bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
>> Â Â Â map_bh(bh, inode->i_sb, map.m_pblk);
>> Â Â Â if (buffer_unwritten(bh)) {
>> Â Â Â Â Â Â Â /* A delayed write to unwritten bh should be marked
>> Â Â Â Â Â Â Â Â* new and mapped. ÂMapped ensures that we don't do
>> Â Â Â Â Â Â Â Â* get_block multiple times when we write to the same
>> Â Â Â Â Â Â Â Â* offset and new ensures that we do proper zero out
>> Â Â Â Â Â Â Â Â* for partial write.
>> Â Â Â Â Â Â Â Â*/
>> Â Â Â Â Â Â Â set_buffer_new(bh);
>> Â Â Â }
>
> Actually, I'm much more comfortable backing out commit 6de9843da
> entirely. ÂThe above is *not* equivalent to what we had before ---
> consider the case where ext4_map_blocks returns !EXT4_MAP_MAPPED &&
> !EXT4_MAP_UNWRITTEN.
>
> I don't *think* this should happen in the case where ext4_map_blocks
> returns a value > 0, but the fact that it's not obvious, means I'd
> much rather keep things the way that they are. ÂIt's not like dropping
> the set_buffer_mapped(bh) was saving anything measurable anyway....
Agree. this way, the comment for unwritten case is also much clearer.
Yongqiang
>
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â- Ted
>
--
Best Wishes
Yongqiang Yang
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