ocfs2: implement directory read-ahead
Uptodate.c now knows about read-ahead buffers. Use some more aggressive
logic in ocfs2_readdir().
The two functions which currently use directory read-ahead are
ocfs2_find_entry() and ocfs2_readdir().
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c
index 3d494d1..04e0191 100644
--- a/fs/ocfs2/dir.c
+++ b/fs/ocfs2/dir.c
@@ -74,14 +74,14 @@
int ocfs2_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
int error = 0;
- unsigned long offset, blk;
- int i, num, stored;
+ unsigned long offset, blk, last_ra_blk = 0;
+ int i, stored;
struct buffer_head * bh, * tmp;
struct ocfs2_dir_entry * de;
int err;
struct inode *inode = filp->f_dentry->d_inode;
struct super_block * sb = inode->i_sb;
- int have_disk_lock = 0;
+ unsigned int ra_sectors = 16;
mlog_entry("dirino=%llu\n",
(unsigned long long)OCFS2_I(inode)->ip_blkno);
@@ -95,9 +95,8 @@
mlog_errno(error);
/* we haven't got any yet, so propagate the error. */
stored = error;
- goto bail;
+ goto bail_nolock;
}
- have_disk_lock = 1;
offset = filp->f_pos & (sb->s_blocksize - 1);
@@ -113,16 +112,21 @@
continue;
}
- /*
- * Do the readahead (8k)
- */
- if (!offset) {
- for (i = 16 >> (sb->s_blocksize_bits - 9), num = 0;
+ /* The idea here is to begin with 8k read-ahead and to stay
+ * 4k ahead of our current position.
+ *
+ * TODO: Use the pagecache for this. We just need to
+ * make sure it's cluster-safe... */
+ if (!last_ra_blk
+ || (((last_ra_blk - blk) << 9) <= (ra_sectors / 2))) {
+ for (i = ra_sectors >> (sb->s_blocksize_bits - 9);
i > 0; i--) {
tmp = ocfs2_bread(inode, ++blk, &err, 1);
if (tmp)
brelse(tmp);
}
+ last_ra_blk = blk;
+ ra_sectors = 8;
}
revalidate:
@@ -194,9 +198,9 @@
stored = 0;
bail:
- if (have_disk_lock)
- ocfs2_meta_unlock(inode, 0);
+ ocfs2_meta_unlock(inode, 0);
+bail_nolock:
mlog_exit(stored);
return stored;