On Sun, Feb 15, 2009 at 08:36:18AM -0500, Theodore Tso wrote:
> On Sun, Feb 15, 2009 at 04:35:28PM +0530, Aneesh Kumar K.V wrote:
> > Here is how it works. During writepages we loop through the dirty pages
> > and build largest contiguous block extent (mpage_add_bh_to_extent). Then we call
> > mpage_da_map_blocks. mpage_da_map_blocks does the mutli block request.
> > Once we have the blocks allocated we map these blocks to the pages. And
> > then we writeback one page at a time using writepage callback.
>
> mpage_da_map_blocks() calls mpd->get_block, which is set to
> ext4_da_get_block_write(), which allocates a single block at a time
> (max_blocks is set to bh->b_size >> inode->i_blkbits).
That bh>b_size indicate multiple blocks.
we do the below in mpage_add_bh_to_extent
2024 if (logical == next && (bh->b_state & BH_FLAGS) == lbh->b_state) {
2025 lbh->b_size += b_size;
2026 return;
2027 }
>
> Put another way, where is the call to ext4_get_blocks_wrap() which
> does the multi-block request? I don't see it...
>
-aneesh
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
