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/quota.c | 60 ++++++++++++++++++++++++------------------------------------ 1 file changed, 24 insertions(+), 36 deletions(-) (limited to 'fs/quota.c') diff --git a/fs/quota.c b/fs/quota.c index 3f0333a51a2..f5d1cff5519 100644 --- a/fs/quota.c +++ b/fs/quota.c @@ -149,36 +149,6 @@ static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t return error; } -static struct super_block *get_super_to_sync(int type) -{ - struct list_head *head; - int cnt, dirty; - -restart: - spin_lock(&sb_lock); - list_for_each(head, &super_blocks) { - struct super_block *sb = list_entry(head, struct super_block, s_list); - - /* This test just improves performance so it needn't be reliable... */ - for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++) - if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt) - && info_any_dirty(&sb_dqopt(sb)->info[cnt])) - dirty = 1; - if (!dirty) - continue; - 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; -} - static void quota_sync_sb(struct super_block *sb, int type) { int cnt; @@ -219,17 +189,35 @@ static void quota_sync_sb(struct super_block *sb, int type) void sync_dquots(struct super_block *sb, int type) { + int cnt, dirty; + if (sb) { if (sb->s_qcop->quota_sync) quota_sync_sb(sb, type); + return; } - else { - while ((sb = get_super_to_sync(type)) != NULL) { - if (sb->s_qcop->quota_sync) - quota_sync_sb(sb, type); - drop_super(sb); - } + + spin_lock(&sb_lock); +restart: + list_for_each_entry(sb, &super_blocks, s_list) { + /* This test just improves performance so it needn't be reliable... */ + for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++) + if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt) + && info_any_dirty(&sb_dqopt(sb)->info[cnt])) + dirty = 1; + if (!dirty) + continue; + sb->s_count++; + spin_unlock(&sb_lock); + down_read(&sb->s_umount); + if (sb->s_root && sb->s_qcop->quota_sync) + quota_sync_sb(sb, type); + up_read(&sb->s_umount); + spin_lock(&sb_lock); + if (__put_super_and_need_restart(sb)) + goto restart; } + spin_unlock(&sb_lock); } /* Copy parameters and call proper function */ -- cgit v1.2.3