From: robbieko <robbieko@synology.com>
To: fstests@vger.kernel.org
Cc: linux-btrfs@vger.kernel.org, Robbie Ko <robbieko@synology.com>
Subject: [PATCH] btrfs: speedup mount time with force readahead chunk tree
Date: Wed, 1 Jul 2020 17:24:49 +0800 [thread overview]
Message-ID: <20200701092449.19545-1-robbieko@synology.com> (raw)
From: Robbie Ko <robbieko@synology.com>
When mounting, we always need to read the whole chunk tree,
when there are too many chunk items, most of the time is
spent on btrfs_read_chunk_tree, because we only read one
leaf at a time.
We fix this by adding a new readahead mode READA_FORWARD_FORCE,
which reads all the leaves after the key in the node when
reading a level 1 node.
Signed-off-by: Robbie Ko <robbieko@synology.com>
---
fs/btrfs/ctree.c | 7 +++++--
fs/btrfs/ctree.h | 2 +-
fs/btrfs/volumes.c | 1 +
3 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 3a7648bff42c..abb9108e2d7d 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -2194,7 +2194,7 @@ static void reada_for_search(struct btrfs_fs_info *fs_info,
if (nr == 0)
break;
nr--;
- } else if (path->reada == READA_FORWARD) {
+ } else if (path->reada == READA_FORWARD || path->reada == READA_FORWARD_FORCE) {
nr++;
if (nr >= nritems)
break;
@@ -2205,12 +2205,15 @@ static void reada_for_search(struct btrfs_fs_info *fs_info,
break;
}
search = btrfs_node_blockptr(node, nr);
- if ((search <= target && target - search <= 65536) ||
+ if ((path->reada == READA_FORWARD_FORCE) ||
+ (search <= target && target - search <= 65536) ||
(search > target && search - target <= 65536)) {
readahead_tree_block(fs_info, search);
nread += blocksize;
}
nscan++;
+ if (path->reada == READA_FORWARD_FORCE)
+ continue;
if ((nread > 65536 || nscan > 32))
break;
}
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index d404cce8ae40..808bcbdc9530 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -353,7 +353,7 @@ struct btrfs_node {
* The slots array records the index of the item or block pointer
* used while walking the tree.
*/
-enum { READA_NONE, READA_BACK, READA_FORWARD };
+enum { READA_NONE, READA_BACK, READA_FORWARD, READA_FORWARD_FORCE };
struct btrfs_path {
struct extent_buffer *nodes[BTRFS_MAX_LEVEL];
int slots[BTRFS_MAX_LEVEL];
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 0d6e785bcb98..78fd65abff69 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -7043,6 +7043,7 @@ int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
+ path->reada = READA_FORWARD_FORCE;
/*
* uuid_mutex is needed only if we are mounting a sprout FS
--
2.17.1
next reply other threads:[~2020-07-01 9:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-01 9:24 robbieko [this message]
2020-07-01 10:10 ` [PATCH] btrfs: speedup mount time with force readahead chunk tree Robbie Ko
2020-07-01 10:58 ` Qu Wenruo
2020-07-01 16:05 ` David Sterba
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