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authorChris Mason <chris.mason@oracle.com>2009-02-04 09:24:25 -0500
committerChris Mason <chris.mason@oracle.com>2009-02-04 09:24:25 -0500
commitc487685d7c18a8481900755aa5c56a7a74193101 (patch)
treef2ff6c059e24d7fdf2e1fff498bbef0bb90bfbfc /fs
parent3935127c50c84106d654ef14962cff28c660bc62 (diff)
Btrfs: hash_lock is no longer needed
Before metadata is written to disk, it is updated to reflect that writeout has begun. Once this update is done, the block must be cow'd before it can be modified again. This update was originally synchronized by using a per-fs spinlock. Today the buffers for the metadata blocks are locked before writeout begins, and everyone that tests the flag has the buffer locked as well. So, the per-fs spinlock (called hash_lock for no good reason) is no longer required. Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/ctree.c7
-rw-r--r--fs/btrfs/ctree.h1
-rw-r--r--fs/btrfs/disk-io.c4
3 files changed, 1 insertions, 11 deletions
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 2603ee539b7a..3b6e35aafc9e 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -388,16 +388,14 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
388 WARN_ON(1); 388 WARN_ON(1);
389 } 389 }
390 390
391 spin_lock(&root->fs_info->hash_lock);
392 if (btrfs_header_generation(buf) == trans->transid && 391 if (btrfs_header_generation(buf) == trans->transid &&
393 btrfs_header_owner(buf) == root->root_key.objectid && 392 btrfs_header_owner(buf) == root->root_key.objectid &&
394 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) { 393 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) {
395 *cow_ret = buf; 394 *cow_ret = buf;
396 spin_unlock(&root->fs_info->hash_lock);
397 WARN_ON(prealloc_dest); 395 WARN_ON(prealloc_dest);
398 return 0; 396 return 0;
399 } 397 }
400 spin_unlock(&root->fs_info->hash_lock); 398
401 search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1); 399 search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
402 ret = __btrfs_cow_block(trans, root, buf, parent, 400 ret = __btrfs_cow_block(trans, root, buf, parent,
403 parent_slot, cow_ret, search_start, 0, 401 parent_slot, cow_ret, search_start, 0,
@@ -1376,14 +1374,11 @@ again:
1376 int wret; 1374 int wret;
1377 1375
1378 /* is a cow on this block not required */ 1376 /* is a cow on this block not required */
1379 spin_lock(&root->fs_info->hash_lock);
1380 if (btrfs_header_generation(b) == trans->transid && 1377 if (btrfs_header_generation(b) == trans->transid &&
1381 btrfs_header_owner(b) == root->root_key.objectid && 1378 btrfs_header_owner(b) == root->root_key.objectid &&
1382 !btrfs_header_flag(b, BTRFS_HEADER_FLAG_WRITTEN)) { 1379 !btrfs_header_flag(b, BTRFS_HEADER_FLAG_WRITTEN)) {
1383 spin_unlock(&root->fs_info->hash_lock);
1384 goto cow_done; 1380 goto cow_done;
1385 } 1381 }
1386 spin_unlock(&root->fs_info->hash_lock);
1387 1382
1388 /* ok, we have to cow, is our old prealloc the right 1383 /* ok, we have to cow, is our old prealloc the right
1389 * size? 1384 * size?
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index de103a8a815e..f2b8d26b0472 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -703,7 +703,6 @@ struct btrfs_fs_info {
703 struct super_block *sb; 703 struct super_block *sb;
704 struct inode *btree_inode; 704 struct inode *btree_inode;
705 struct backing_dev_info bdi; 705 struct backing_dev_info bdi;
706 spinlock_t hash_lock;
707 struct mutex trans_mutex; 706 struct mutex trans_mutex;
708 struct mutex tree_log_mutex; 707 struct mutex tree_log_mutex;
709 struct mutex transaction_kthread_mutex; 708 struct mutex transaction_kthread_mutex;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 9c3810047976..549271607c17 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1503,7 +1503,6 @@ struct btrfs_root *open_ctree(struct super_block *sb,
1503 INIT_LIST_HEAD(&fs_info->dead_roots); 1503 INIT_LIST_HEAD(&fs_info->dead_roots);
1504 INIT_LIST_HEAD(&fs_info->hashers); 1504 INIT_LIST_HEAD(&fs_info->hashers);
1505 INIT_LIST_HEAD(&fs_info->delalloc_inodes); 1505 INIT_LIST_HEAD(&fs_info->delalloc_inodes);
1506 spin_lock_init(&fs_info->hash_lock);
1507 spin_lock_init(&fs_info->delalloc_lock); 1506 spin_lock_init(&fs_info->delalloc_lock);
1508 spin_lock_init(&fs_info->new_trans_lock); 1507 spin_lock_init(&fs_info->new_trans_lock);
1509 spin_lock_init(&fs_info->ref_cache_lock); 1508 spin_lock_init(&fs_info->ref_cache_lock);
@@ -2361,7 +2360,6 @@ int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid)
2361int btree_lock_page_hook(struct page *page) 2360int btree_lock_page_hook(struct page *page)
2362{ 2361{
2363 struct inode *inode = page->mapping->host; 2362 struct inode *inode = page->mapping->host;
2364 struct btrfs_root *root = BTRFS_I(inode)->root;
2365 struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; 2363 struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
2366 struct extent_buffer *eb; 2364 struct extent_buffer *eb;
2367 unsigned long len; 2365 unsigned long len;
@@ -2376,9 +2374,7 @@ int btree_lock_page_hook(struct page *page)
2376 goto out; 2374 goto out;
2377 2375
2378 btrfs_tree_lock(eb); 2376 btrfs_tree_lock(eb);
2379 spin_lock(&root->fs_info->hash_lock);
2380 btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN); 2377 btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
2381 spin_unlock(&root->fs_info->hash_lock);
2382 btrfs_tree_unlock(eb); 2378 btrfs_tree_unlock(eb);
2383 free_extent_buffer(eb); 2379 free_extent_buffer(eb);
2384out: 2380out: