linux-ext4 - [PATCH] ext4: preload block group descriptors

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Date:   Mon, 20 Feb 2017 19:45:53 +0300
From:   Artem Blagodarenko <artem.blagodarenko@...il.com>
To:     linux-ext4@...r.kernel.org
Cc:     alexey.lyashkov@...il.com,
        Andrew Perepechko <andrew.perepechko@...gate.com>
Subject: [PATCH] ext4: preload block group descriptors

From: Andrew Perepechko <andrew.perepechko@...gate.com>

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

Signed-off-by: Andrew Perepechko <andrew.perepechko@...gate.com>
---
 fs/ext4/super.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index a673558..0e52c91 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);
-- 
1.8.3.1