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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>
This commit is contained in:
Fengguang Wu 2007-07-19 01:48:04 -07:00 committed by Linus Torvalds
parent a08a166fe7
commit dc7868fcb9
2 changed files with 16 additions and 12 deletions
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14
fs/ext3/dir.c
View File

@ -136,12 +136,14 @@ static int ext3_readdir(struct file * filp,
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);
}

14
fs/ext4/dir.c
View File

@ -135,12 +135,14 @@ static int ext4_readdir(struct file * filp,
map_bh.b_state = 0;
err = ext4_get_blocks_wrap(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 = ext4_bread(NULL, inode, blk, 0, &err);
}