From f758eeabeb96f878c860e8f110f94ec8820822a9 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 21 Apr 2011 18:19:44 -0600 Subject: writeback: split inode_wb_list_lock into bdi_writeback.list_lock Split the global inode_wb_list_lock into a per-bdi_writeback list_lock, as it's currently the most contended lock in the system for metadata heavy workloads. It won't help for single-filesystem workloads for which we'll need the I/O-less balance_dirty_pages, but at least we can dedicate a cpu to spinning on each bdi now for larger systems. Based on earlier patches from Nick Piggin and Dave Chinner. It reduces lock contentions to 1/4 in this test case: 10 HDD JBOD, 100 dd on each disk, XFS, 6GB ram lock_stat version 0.3 ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- class name con-bounces contentions waittime-min waittime-max waittime-total acq-bounces acquisitions holdtime-min holdtime-max holdtime-total ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- vanilla 2.6.39-rc3: inode_wb_list_lock: 42590 44433 0.12 147.74 144127.35 252274 886792 0.08 121.34 917211.23 ------------------ inode_wb_list_lock 2 [] bdev_inode_switch_bdi+0x29/0x85 inode_wb_list_lock 34 [] inode_wb_list_del+0x22/0x49 inode_wb_list_lock 12893 [] __mark_inode_dirty+0x170/0x1d0 inode_wb_list_lock 10702 [] writeback_single_inode+0x16d/0x20a ------------------ inode_wb_list_lock 2 [] bdev_inode_switch_bdi+0x29/0x85 inode_wb_list_lock 19 [] inode_wb_list_del+0x22/0x49 inode_wb_list_lock 5550 [] __mark_inode_dirty+0x170/0x1d0 inode_wb_list_lock 8511 [] writeback_sb_inodes+0x10f/0x157 2.6.39-rc3 + patch: &(&wb->list_lock)->rlock: 11383 11657 0.14 151.69 40429.51 90825 527918 0.11 145.90 556843.37 ------------------------ &(&wb->list_lock)->rlock 10 [] inode_wb_list_del+0x5f/0x86 &(&wb->list_lock)->rlock 1493 [] writeback_inodes_wb+0x3d/0x150 &(&wb->list_lock)->rlock 3652 [] writeback_sb_inodes+0x123/0x16f &(&wb->list_lock)->rlock 1412 [] writeback_single_inode+0x17f/0x223 ------------------------ &(&wb->list_lock)->rlock 3 [] bdi_lock_two+0x46/0x4b &(&wb->list_lock)->rlock 6 [] inode_wb_list_del+0x5f/0x86 &(&wb->list_lock)->rlock 2061 [] __mark_inode_dirty+0x173/0x1cf &(&wb->list_lock)->rlock 2629 [] writeback_sb_inodes+0x123/0x16f hughd@google.com: fix recursive lock when bdi_lock_two() is called with new the same as old akpm@linux-foundation.org: cleanup bdev_inode_switch_bdi() comment Signed-off-by: Christoph Hellwig Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Wu Fengguang --- fs/block_dev.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) (limited to 'fs/block_dev.c') diff --git a/fs/block_dev.c b/fs/block_dev.c index 1a2421f908f0..3c9a03e51b62 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -44,24 +44,28 @@ inline struct block_device *I_BDEV(struct inode *inode) { return &BDEV_I(inode)->bdev; } - EXPORT_SYMBOL(I_BDEV); /* - * move the inode from it's current bdi to the a new bdi. if the inode is dirty - * we need to move it onto the dirty list of @dst so that the inode is always - * on the right list. + * Move the inode from its current bdi to a new bdi. If the inode is dirty we + * need to move it onto the dirty list of @dst so that the inode is always on + * the right list. */ static void bdev_inode_switch_bdi(struct inode *inode, struct backing_dev_info *dst) { - spin_lock(&inode_wb_list_lock); + struct backing_dev_info *old = inode->i_data.backing_dev_info; + + if (unlikely(dst == old)) /* deadlock avoidance */ + return; + bdi_lock_two(&old->wb, &dst->wb); spin_lock(&inode->i_lock); inode->i_data.backing_dev_info = dst; if (inode->i_state & I_DIRTY) list_move(&inode->i_wb_list, &dst->wb.b_dirty); spin_unlock(&inode->i_lock); - spin_unlock(&inode_wb_list_lock); + spin_unlock(&old->wb.list_lock); + spin_unlock(&dst->wb.list_lock); } static sector_t max_block(struct block_device *bdev) -- cgit v1.2.3 From 782b94cdf577b4df1feb376f372dccc28e66a771 Mon Sep 17 00:00:00 2001 From: Lachlan McIlroy Date: Thu, 30 Jun 2011 11:01:45 +1000 Subject: block: initialise bd_super in bdget() bd_super is currently reset to NULL in kill_block_super() so we rely on previous users of the block_device object to initialise this value for the next user. This quirk was exposed on RHEL5 when a third party filesystem did not always use kill_block_super() and therefore bd_super wasn't being reset when a block_device object was recycled within the cache. This may not be a problem upstream but makes sense to be defensive. Signed-off-by: Lachlan McIlroy Reviewed-by: Eric Sandeen Signed-off-by: Al Viro --- fs/block_dev.c | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/block_dev.c') diff --git a/fs/block_dev.c b/fs/block_dev.c index f55aad4d1611..f28680553288 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -552,6 +552,7 @@ struct block_device *bdget(dev_t dev) if (inode->i_state & I_NEW) { bdev->bd_contains = NULL; + bdev->bd_super = NULL; bdev->bd_inode = inode; bdev->bd_block_size = (1 << inode->i_blkbits); bdev->bd_part_count = 0; -- cgit v1.2.3 From da5aa861bea09197e6ae4d7c46618616064891e4 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Tue, 2 Aug 2011 02:17:48 +0200 Subject: fix block device fallout from ->fsync() changes blkdev_fsync() needs to write pages in pagecache... Signed-off-by: Rafael J. Wysocki Signed-off-by: Al Viro --- fs/block_dev.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'fs/block_dev.c') diff --git a/fs/block_dev.c b/fs/block_dev.c index f28680553288..ff77262e887c 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -387,6 +387,10 @@ int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync) struct inode *bd_inode = filp->f_mapping->host; struct block_device *bdev = I_BDEV(bd_inode); int error; + + error = filemap_write_and_wait_range(filp->f_mapping, start, end); + if (error) + return error; /* * There is no need to serialise calls to blkdev_issue_flush with -- cgit v1.2.3 From 94007751bb02797ba87bac7aacee2731ac2039a3 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Sat, 10 Sep 2011 17:20:21 +1000 Subject: Avoid dereferencing a 'request_queue' after last close. On the last close of an 'md' device which as been stopped, the device is destroyed and in particular the request_queue is freed. The free is done in a separate thread so it might happen a short time later. __blkdev_put calls bdev_inode_switch_bdi *after* ->release has been called. Since commit f758eeabeb96f878c860e8f110f94ec8820822a9 bdev_inode_switch_bdi will dereference the 'old' bdi, which lives inside a request_queue, to get a spin lock. This causes the last close on an md device to sometime take a spin_lock which lives in freed memory - which results in an oops. So move the called to bdev_inode_switch_bdi before the call to ->release. Cc: Christoph Hellwig Cc: Hugh Dickins Cc: Andrew Morton Cc: Wu Fengguang Acked-by: Wu Fengguang Cc: stable@kernel.org Signed-off-by: NeilBrown --- fs/block_dev.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'fs/block_dev.c') diff --git a/fs/block_dev.c b/fs/block_dev.c index ff77262e887c..95f786ec7f08 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1429,6 +1429,11 @@ static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) WARN_ON_ONCE(bdev->bd_holders); sync_blockdev(bdev); kill_bdev(bdev); + /* ->release can cause the old bdi to disappear, + * so must switch it out first + */ + bdev_inode_switch_bdi(bdev->bd_inode, + &default_backing_dev_info); } if (bdev->bd_contains == bdev) { if (disk->fops->release) @@ -1442,8 +1447,6 @@ static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) disk_put_part(bdev->bd_part); bdev->bd_part = NULL; bdev->bd_disk = NULL; - bdev_inode_switch_bdi(bdev->bd_inode, - &default_backing_dev_info); if (bdev != bdev->bd_contains) victim = bdev->bd_contains; bdev->bd_contains = NULL; -- cgit v1.2.3