From 618f06362ae3f60f95d7b0e666de25ee6ae35679 Mon Sep 17 00:00:00 2001 From: Kirill Korotaev Date: Thu, 23 Jun 2005 00:09:54 -0700 Subject: [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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fs-writeback.c | 64 +++++++++++++++++++++++-------------------------------- 1 file changed, 27 insertions(+), 37 deletions(-) (limited to 'fs/fs-writeback.c') diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 8e050fa5821..e94ab398b71 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); } } -- cgit v1.2.3