From 7a344dba27b753bdb6d0a3ea4f41b37c162e639d Mon Sep 17 00:00:00 2001 From: Jonathan Brassow Date: Fri, 3 Dec 2010 18:12:48 -0500 Subject: [PATCH 02/10] dm log userspace: split flush queue Split the 'flush_list', which contained a mix of both 'mark' and 'clear' requests, into two distinct lists ('mark_list' and 'clear_list'). The device mapper log implementations (used by various DM targets) are allowed to cache 'mark' and 'clear' requests until a 'flush' is received. Until now, these cached requests were kept in the same list. They will now be put into distinct lists to facilitate group processing of these requests (in the next patch). Signed-off-by: Jonathan Brassow Signed-off-by: Mike Snitzer --- drivers/md/dm-log-userspace-base.c | 41 ++++++++++++++++++++++++++++--------- 1 file changed, 32 insertions(+), 9 deletions(-) Index: linux-2.6.37-rc4/drivers/md/dm-log-userspace-base.c =================================================================== --- linux-2.6.37-rc4.orig/drivers/md/dm-log-userspace-base.c +++ linux-2.6.37-rc4/drivers/md/dm-log-userspace-base.c @@ -37,8 +37,15 @@ struct log_c { */ uint64_t in_sync_hint; + /* + * Mark and clear requests are held until a flush is issued + * so that we can group, and thereby limit, the amount of + * network traffic between kernel and userspace. The 'flush_lock' + * is used to protect these lists. + */ spinlock_t flush_lock; - struct list_head flush_list; /* only for clear and mark requests */ + struct list_head mark_list; + struct list_head clear_list; }; static mempool_t *flush_entry_pool; @@ -169,7 +176,8 @@ static int userspace_ctr(struct dm_dirty strncpy(lc->uuid, argv[0], DM_UUID_LEN); spin_lock_init(&lc->flush_lock); - INIT_LIST_HEAD(&lc->flush_list); + INIT_LIST_HEAD(&lc->mark_list); + INIT_LIST_HEAD(&lc->clear_list); str_size = build_constructor_string(ti, argc - 1, argv + 1, &ctr_str); if (str_size < 0) { @@ -362,14 +370,16 @@ static int userspace_flush(struct dm_dir int r = 0; unsigned long flags; struct log_c *lc = log->context; - LIST_HEAD(flush_list); + LIST_HEAD(mark_list); + LIST_HEAD(clear_list); struct flush_entry *fe, *tmp_fe; spin_lock_irqsave(&lc->flush_lock, flags); - list_splice_init(&lc->flush_list, &flush_list); + list_splice_init(&lc->mark_list, &mark_list); + list_splice_init(&lc->clear_list, &clear_list); spin_unlock_irqrestore(&lc->flush_lock, flags); - if (list_empty(&flush_list)) + if (list_empty(&mark_list) && list_empty(&clear_list)) return 0; /* @@ -379,7 +389,16 @@ static int userspace_flush(struct dm_dir * do it one by one. */ - list_for_each_entry(fe, &flush_list, list) { + list_for_each_entry(fe, &mark_list, list) { + r = userspace_do_request(lc, lc->uuid, fe->type, + (char *)&fe->region, + sizeof(fe->region), + NULL, NULL); + if (r) + goto fail; + } + + list_for_each_entry(fe, &clear_list, list) { r = userspace_do_request(lc, lc->uuid, fe->type, (char *)&fe->region, sizeof(fe->region), @@ -397,7 +416,11 @@ fail: * Calling code will receive an error and will know that * the log facility has failed. */ - list_for_each_entry_safe(fe, tmp_fe, &flush_list, list) { + list_for_each_entry_safe(fe, tmp_fe, &mark_list, list) { + list_del(&fe->list); + mempool_free(fe, flush_entry_pool); + } + list_for_each_entry_safe(fe, tmp_fe, &clear_list, list) { list_del(&fe->list); mempool_free(fe, flush_entry_pool); } @@ -427,7 +450,7 @@ static void userspace_mark_region(struct spin_lock_irqsave(&lc->flush_lock, flags); fe->type = DM_ULOG_MARK_REGION; fe->region = region; - list_add(&fe->list, &lc->flush_list); + list_add(&fe->list, &lc->mark_list); spin_unlock_irqrestore(&lc->flush_lock, flags); return; @@ -464,7 +487,7 @@ static void userspace_clear_region(struc spin_lock_irqsave(&lc->flush_lock, flags); fe->type = DM_ULOG_CLEAR_REGION; fe->region = region; - list_add(&fe->list, &lc->flush_list); + list_add(&fe->list, &lc->clear_list); spin_unlock_irqrestore(&lc->flush_lock, flags); return;