From: Andrew Perepechko <andrew.perepechko@seagate.com>
Date: Sun, 30 Apr 2017 04:46:35 +0000 (-0400)
Subject: ext4: preload block group descriptors
X-Git-Tag: v4.12-rc1~73^2~5
X-Git-Url: https://repo.jachan.dev/linux.git/commitdiff_plain/85c8f176a611

ext4: preload block group descriptors

With enabled meta_bg option block group descriptors
reading IO is not sequential and requires optimization.

Signed-off-by: Andrew Perepechko <andrew.perepechko@seagate.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9ec8963ba604..9a40e0c16dcc 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3879,6 +3879,12 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 
 	bgl_lock_init(sbi->s_blockgroup_lock);
 
+	/* Pre-read the descriptors into the buffer cache */
+	for (i = 0; i < db_count; i++) {
+		block = descriptor_loc(sb, logical_sb_block, i);
+		sb_breadahead(sb, block);
+	}
+
 	for (i = 0; i < db_count; i++) {
 		block = descriptor_loc(sb, logical_sb_block, i);
 		sbi->s_group_desc[i] = sb_bread_unmovable(sb, block);