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authorKirill Korotaev <dev@sw.ru>2005-06-23 00:09:54 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-23 09:45:27 -0700
commit618f06362ae3f60f95d7b0e666de25ee6ae35679 (patch)
tree4415b4e590913e16535704168ea74c6af5a93c48 /fs/fs-writeback.c
parent4fea2838aa00b9e59efde974dcdb455608192811 (diff)
[PATCH] O(1) sb list traversing on syncs
This patch removes O(n^2) super block loops in sync_inodes(), sync_filesystems() etc. in favour of using __put_super_and_need_restart() which I introduced earlier. We faced a noticably long freezes on sb syncing when there are thousands of super blocks in the system. Signed-Off-By: Kirill Korotaev <dev@sw.ru> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/fs-writeback.c')
-rw-r--r--fs/fs-writeback.c64
1 files changed, 27 insertions, 37 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 8e050fa58218..e94ab398b717 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -485,32 +485,6 @@ static void set_sb_syncing(int val)
spin_unlock(&sb_lock);
}
-/*
- * Find a superblock with inodes that need to be synced
- */
-static struct super_block *get_super_to_sync(void)
-{
- struct super_block *sb;
-restart:
- spin_lock(&sb_lock);
- sb = sb_entry(super_blocks.prev);
- for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.prev)) {
- if (sb->s_syncing)
- continue;
- sb->s_syncing = 1;
- sb->s_count++;
- spin_unlock(&sb_lock);
- down_read(&sb->s_umount);
- if (!sb->s_root) {
- drop_super(sb);
- goto restart;
- }
- return sb;
- }
- spin_unlock(&sb_lock);
- return NULL;
-}
-
/**
* sync_inodes - writes all inodes to disk
* @wait: wait for completion
@@ -530,23 +504,39 @@ restart:
* outstanding dirty inodes, the writeback goes block-at-a-time within the
* filesystem's write_inode(). This is extremely slow.
*/
-void sync_inodes(int wait)
+static void __sync_inodes(int wait)
{
struct super_block *sb;
- set_sb_syncing(0);
- while ((sb = get_super_to_sync()) != NULL) {
- sync_inodes_sb(sb, 0);
- sync_blockdev(sb->s_bdev);
- drop_super(sb);
+ spin_lock(&sb_lock);
+restart:
+ list_for_each_entry(sb, &super_blocks, s_list) {
+ if (sb->s_syncing)
+ continue;
+ sb->s_syncing = 1;
+ sb->s_count++;
+ spin_unlock(&sb_lock);
+ down_read(&sb->s_umount);
+ if (sb->s_root) {
+ sync_inodes_sb(sb, wait);
+ sync_blockdev(sb->s_bdev);
+ }
+ up_read(&sb->s_umount);
+ spin_lock(&sb_lock);
+ if (__put_super_and_need_restart(sb))
+ goto restart;
}
+ spin_unlock(&sb_lock);
+}
+
+void sync_inodes(int wait)
+{
+ set_sb_syncing(0);
+ __sync_inodes(0);
+
if (wait) {
set_sb_syncing(0);
- while ((sb = get_super_to_sync()) != NULL) {
- sync_inodes_sb(sb, 1);
- sync_blockdev(sb->s_bdev);
- drop_super(sb);
- }
+ __sync_inodes(1);
}
}