From: Alexey Lyashkov <alexey.lyashkov@seagate.com>
Date: Wed, 1 Mar 2017 20:03:54 +0000 (-0500)
Subject: libext2fs: readahead for meta_bg
X-Git-Tag: v1.43.5~68
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=2521c50d98442dbec2733f8cf9c88d2444be9075;p=tools%2Fe2fsprogs.git

libext2fs: readahead for meta_bg

There are ~37k of random IOs with meta_bg option on 300T target.
Debugfs requires 20 minutes to be started. Enabling readahead for
group blocks metadata save time dramatically. Only 12s to start.

Signed-off-by: Alexey Lyashkov <alexey.lyashkov@seagate.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
---

diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
index ba39e01..93b02ed 100644
--- a/lib/ext2fs/openfs.c
+++ b/lib/ext2fs/openfs.c
@@ -421,6 +421,12 @@ errcode_t ext2fs_open2(const char *name, const char *io_options,
 #endif
 		dest += fs->blocksize*first_meta_bg;
 	}
+
+	for (i = first_meta_bg ; i < fs->desc_blocks; i++) {
+		blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
+		io_channel_cache_readahead(fs->io, blk, 1);
+	}
+
 	for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
 		blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
 		retval = io_channel_read_blk64(fs->io, blk, 1, dest);