From 890871be854b5f5e43e7ba2475f706209906cc24 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 2 Sep 2009 16:24:52 -0400 Subject: Btrfs: switch extent_map to a rw lock There are two main users of the extent_map tree. The first is regular file inodes, where it is evenly spread between readers and writers. The second is the chunk allocation tree, which maps blocks from logical addresses to phyiscal ones, and it is 99.99% reads. The mapping tree is a point of lock contention during heavy IO workloads, so this commit switches things to a rw lock. Signed-off-by: Chris Mason --- fs/btrfs/disk-io.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'fs/btrfs/disk-io.c') diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 20cefc6f22c4..b6cfdd9164e2 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -121,15 +121,15 @@ static struct extent_map *btree_get_extent(struct inode *inode, struct extent_map *em; int ret; - spin_lock(&em_tree->lock); + read_lock(&em_tree->lock); em = lookup_extent_mapping(em_tree, start, len); if (em) { em->bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev; - spin_unlock(&em_tree->lock); + read_unlock(&em_tree->lock); goto out; } - spin_unlock(&em_tree->lock); + read_unlock(&em_tree->lock); em = alloc_extent_map(GFP_NOFS); if (!em) { @@ -142,7 +142,7 @@ static struct extent_map *btree_get_extent(struct inode *inode, em->block_start = 0; em->bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev; - spin_lock(&em_tree->lock); + write_lock(&em_tree->lock); ret = add_extent_mapping(em_tree, em); if (ret == -EEXIST) { u64 failed_start = em->start; @@ -161,7 +161,7 @@ static struct extent_map *btree_get_extent(struct inode *inode, free_extent_map(em); em = NULL; } - spin_unlock(&em_tree->lock); + write_unlock(&em_tree->lock); if (ret) em = ERR_PTR(ret); @@ -1323,9 +1323,9 @@ static void btrfs_unplug_io_fn(struct backing_dev_info *bdi, struct page *page) offset = page_offset(page); em_tree = &BTRFS_I(inode)->extent_tree; - spin_lock(&em_tree->lock); + read_lock(&em_tree->lock); em = lookup_extent_mapping(em_tree, offset, PAGE_CACHE_SIZE); - spin_unlock(&em_tree->lock); + read_unlock(&em_tree->lock); if (!em) { __unplug_io_fn(bdi, page); return; -- cgit v1.2.2