On 8/16/12 1:53 PM, Theodore Ts'o wrote:
On Thu, Aug 16, 2012 at 10:42:19AM -0400, Theodore Ts'o wrote:
On Thu, Aug 16, 2012 at 10:16:48AM -0400, Calvin Walton wrote:
On Thu, 2012-08-16 at 03:09 -0600, Andreas Dilger wrote:
Is there any fix for this issue queued up for an upcoming stable
release? It still reverts cleanly on 3.5.2.
There isn't a fix queued up yet, but there will be one soon....
This patch should solve the problem (as an alternative to reverting
8aeb00ff85a).
- Ted
From dc43c7a8a6c266c31aa4f0408000c4d1b9f3c787 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@xxxxxxx>
Date: Thu, 16 Aug 2012 11:59:04 -0400
Subject: [PATCH] ext4: fix long mount times on very big file systems
Commit 8aeb00ff85a: "ext4: fix overhead calculation used by
ext4_statfs()" introduced a O(n**2) calculation which makes very large
file systems take forever to mount. Fix this with an optimization for
non-bigalloc file systems. (For bigalloc file systems the overhead
needs to be set in the the superblock.)
And mkfs with bigalloc will do that, right?
Hm.
/*
* Get the # of file system overhead blocks from the
* superblock if present.
*/
if (es->s_overhead_clusters)
sbi->s_overhead = le32_to_cpu(es->s_overhead_clusters);
else {
ret = ext4_calculate_overhead(sb);
if (ret)
goto failed_mount_wq;
}
so if we mkfs'd with bigalloc, s_overhead_clusters will be set and we
won't call ext4_calculate_overhead, right?
But if we didn't mkfs with bigalloc, we won't have the feature, and
ext4_calc_overhead will exit early.
So when does all of the code after the short-circuit ever run?
-Eric
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
fs/ext4/super.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 603023b..055c65b 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3129,6 +3129,10 @@ static int count_overhead(struct super_block *sb, ext4_group_t grp,
ext4_group_t i, ngroups = ext4_get_groups_count(sb);
int s, j, count = 0;
+ if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_BIGALLOC))
+ return (ext4_bg_has_super(sb, grp) + ext4_bg_num_gdb(sb, i) +
+ sbi->s_itb_per_group + 2);
+
first_block = le32_to_cpu(sbi->s_es->s_first_data_block) +
(grp * EXT4_BLOCKS_PER_GROUP(sb));
last_block = first_block + EXT4_BLOCKS_PER_GROUP(sb) - 1;
--
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