readahead: convert ext3/ext4 invocations
Convert ext3/ext4 dir reads to use on-demand readahead.
Readahead for dirs operates _not_ on file level, but on blockdev level. This
makes a difference when the data blocks are not continuous. And the read
routine is somehow opaque: there's no handy info about the status of current
page. So a simplified call scheme is employed: to call into readahead
whenever the current page falls out of readahead windows.
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/ext3/dir.c b/fs/ext3/dir.c
index 8528698..3c6d384 100644
--- a/fs/ext3/dir.c
+++ b/fs/ext3/dir.c
@@ -136,12 +136,14 @@
err = ext3_get_blocks_handle(NULL, inode, blk, 1,
&map_bh, 0, 0);
if (err > 0) {
- page_cache_readahead(sb->s_bdev->bd_inode->i_mapping,
- &filp->f_ra,
- filp,
- map_bh.b_blocknr >>
- (PAGE_CACHE_SHIFT - inode->i_blkbits),
- 1);
+ pgoff_t index = map_bh.b_blocknr >>
+ (PAGE_CACHE_SHIFT - inode->i_blkbits);
+ if (!ra_has_index(&filp->f_ra, index))
+ page_cache_readahead_ondemand(
+ sb->s_bdev->bd_inode->i_mapping,
+ &filp->f_ra, filp,
+ NULL, index, 1);
+ filp->f_ra.prev_index = index;
bh = ext3_bread(NULL, inode, blk, 0, &err);
}