From 961515f613f26b7958c56c5c71061a8231e02be7 Mon Sep 17 00:00:00 2001 From: Wu Fengguang Date: Fri, 9 Oct 2009 13:01:27 +0200 Subject: writeback: kill space in debugfs item name The space is not script friendly, kill it. Signed-off-by: Wu Fengguang Signed-off-by: Jens Axboe --- mm/backing-dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm/backing-dev.c') diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 3d3accb1f800..5a37e2055717 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -92,7 +92,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v) "BdiDirtyThresh: %8lu kB\n" "DirtyThresh: %8lu kB\n" "BackgroundThresh: %8lu kB\n" - "WriteBack threads:%8lu\n" + "WritebackThreads: %8lu\n" "b_dirty: %8lu\n" "b_io: %8lu\n" "b_more_io: %8lu\n" -- cgit v1.2.3 From 592b09a42fc3ae6737a0f3ecf4fee42ecd0296f8 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 29 Oct 2009 11:46:12 +0100 Subject: backing-dev: ensure that a removed bdi no longer has super_block referencing it When the bdi is being removed, we have to ensure that no super_blocks currently have that cached in sb->s_bdi. Normally this is ensured by the sb having a longer life span than the bdi, but if the device is suddenly yanked, we have to kill this reference. sb->s_bdi is pointed to freed memory at that point. This fixes a problem with sync(1) hanging when a USB stick is pulled without cleanly umounting it first. Reported-by: Pavel Machek Signed-off-by: Jens Axboe --- mm/backing-dev.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'mm/backing-dev.c') diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 5a37e2055717..1065b715ef64 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -610,6 +610,21 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi) kthread_stop(wb->task); } +/* + * This bdi is going away now, make sure that no super_blocks point to it + */ +static void bdi_prune_sb(struct backing_dev_info *bdi) +{ + struct super_block *sb; + + spin_lock(&sb_lock); + list_for_each_entry(sb, &super_blocks, s_list) { + if (sb->s_bdi == bdi) + sb->s_bdi = NULL; + } + spin_unlock(&sb_lock); +} + void bdi_unregister(struct backing_dev_info *bdi) { if (bdi->dev) { @@ -682,6 +697,7 @@ void bdi_destroy(struct backing_dev_info *bdi) spin_unlock(&inode_lock); } + bdi_prune_sb(bdi); bdi_unregister(bdi); for (i = 0; i < NR_BDI_STAT_ITEMS; i++) -- cgit v1.2.3 From 8c4db3355b0fcc9ad77431f15b955efa0645b5d0 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 3 Nov 2009 20:18:44 +0100 Subject: backing-dev: bdi sb prune should be in the unregister path, not destroy Commit 592b09a42fc3ae6737a0f3ecf4fee42ecd0296f8 was different from the tested path, in that it moved the bdi super_block prune from unregister to destroy context. This doesn't fully fix the sync hang bug on unexpected device removal, as need to prune the bdi cache pointer before killing flusher thread. Tested-by: Artur Skawina Signed-off-by: Jens Axboe --- mm/backing-dev.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'mm/backing-dev.c') diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 1065b715ef64..11aee09dd2a6 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -628,6 +628,8 @@ static void bdi_prune_sb(struct backing_dev_info *bdi) void bdi_unregister(struct backing_dev_info *bdi) { if (bdi->dev) { + bdi_prune_sb(bdi); + if (!bdi_cap_flush_forker(bdi)) bdi_wb_shutdown(bdi); bdi_debug_unregister(bdi); @@ -697,7 +699,6 @@ void bdi_destroy(struct backing_dev_info *bdi) spin_unlock(&inode_lock); } - bdi_prune_sb(bdi); bdi_unregister(bdi); for (i = 0; i < NR_BDI_STAT_ITEMS; i++) -- cgit v1.2.3 From c62b17a58ab5e97534ff6487241addd5fcc606de Mon Sep 17 00:00:00 2001 From: Romit Dasgupta Date: Thu, 12 Nov 2009 13:08:11 +0100 Subject: Thaw refrigerated bdi flusher threads before invoking kthread_stop on them Unfreezes the bdi flusher task when the said task needs to exit. Steps to reproduce this. 1) Mount a file system from MMC/SD card. 2) Unmount the file system. This creates a flusher task. 3) Attempt suspend to RAM. System is unresponsive. This is because the bdi flusher thread is already in the refrigerator and will remain so until it is thawed. The MMC driver suspend routine call stack will ultimately issue a 'kthread_stop' on the bdi flusher thread and will block until the flusher thread is exited. Since the bdi flusher thread is in the refrigerator it never cleans up until thawed. Signed-off-by: Romit Dasgupta Signed-off-by: Jens Axboe --- mm/backing-dev.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'mm/backing-dev.c') diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 11aee09dd2a6..67a33a5a1a93 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -604,10 +604,14 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi) /* * Finally, kill the kernel threads. We don't need to be RCU - * safe anymore, since the bdi is gone from visibility. + * safe anymore, since the bdi is gone from visibility. Force + * unfreeze of the thread before calling kthread_stop(), otherwise + * it would never exet if it is currently stuck in the refrigerator. */ - list_for_each_entry(wb, &bdi->wb_list, list) + list_for_each_entry(wb, &bdi->wb_list, list) { + wb->task->flags &= ~PF_FROZEN; kthread_stop(wb->task); + } } /* -- cgit v1.2.3