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authorChris Mason <chris.mason@oracle.com>2009-02-12 14:09:45 -0500
committerChris Mason <chris.mason@oracle.com>2009-02-12 14:09:45 -0500
commit4008c04a07c73ec3cb1be4c1391d2159a8f75d6d (patch)
treec0b10a7287ac810bfc406541e32b850ad4580248 /fs/btrfs/disk-io.c
parent3f3420df505e47751ef76a652b5cb660e5360d6f (diff)
Btrfs: make a lockdep class for the extent buffer locks
Btrfs is currently using spin_lock_nested with a nested value based on the tree depth of the block. But, this doesn't quite work because the max tree depth is bigger than what spin_lock_nested can deal with, and because locks are sometimes taken before the level field is filled in. The solution here is to use lockdep_set_class_and_name instead, and to set the class before unlocking the pages when the block is read from the disk and just after init of a freshly allocated tree block. btrfs_clear_path_blocking is also changed to take the locks in the proper order, and it also makes sure all the locks currently held are properly set to blocking before it tries to retake the spinlocks. Otherwise, lockdep gets upset about bad lock orderin. The lockdep magic cam from Peter Zijlstra <peterz@infradead.org> Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/disk-io.c')
-rw-r--r--fs/btrfs/disk-io.c46
1 files changed, 45 insertions, 1 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 5aebddd7119..adda739a021 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -75,6 +75,40 @@ struct async_submit_bio {
75 struct btrfs_work work; 75 struct btrfs_work work;
76}; 76};
77 77
78/* These are used to set the lockdep class on the extent buffer locks.
79 * The class is set by the readpage_end_io_hook after the buffer has
80 * passed csum validation but before the pages are unlocked.
81 *
82 * The lockdep class is also set by btrfs_init_new_buffer on freshly
83 * allocated blocks.
84 *
85 * The class is based on the level in the tree block, which allows lockdep
86 * to know that lower nodes nest inside the locks of higher nodes.
87 *
88 * We also add a check to make sure the highest level of the tree is
89 * the same as our lockdep setup here. If BTRFS_MAX_LEVEL changes, this
90 * code needs update as well.
91 */
92#ifdef CONFIG_DEBUG_LOCK_ALLOC
93# if BTRFS_MAX_LEVEL != 8
94# error
95# endif
96static struct lock_class_key btrfs_eb_class[BTRFS_MAX_LEVEL + 1];
97static const char *btrfs_eb_name[BTRFS_MAX_LEVEL + 1] = {
98 /* leaf */
99 "btrfs-extent-00",
100 "btrfs-extent-01",
101 "btrfs-extent-02",
102 "btrfs-extent-03",
103 "btrfs-extent-04",
104 "btrfs-extent-05",
105 "btrfs-extent-06",
106 "btrfs-extent-07",
107 /* highest possible level */
108 "btrfs-extent-08",
109};
110#endif
111
78/* 112/*
79 * extents on the btree inode are pretty simple, there's one extent 113 * extents on the btree inode are pretty simple, there's one extent
80 * that covers the entire device 114 * that covers the entire device
@@ -347,6 +381,15 @@ static int check_tree_block_fsid(struct btrfs_root *root,
347 return ret; 381 return ret;
348} 382}
349 383
384#ifdef CONFIG_DEBUG_LOCK_ALLOC
385void btrfs_set_buffer_lockdep_class(struct extent_buffer *eb, int level)
386{
387 lockdep_set_class_and_name(&eb->lock,
388 &btrfs_eb_class[level],
389 btrfs_eb_name[level]);
390}
391#endif
392
350static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end, 393static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
351 struct extent_state *state) 394 struct extent_state *state)
352{ 395{
@@ -392,6 +435,8 @@ static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
392 } 435 }
393 found_level = btrfs_header_level(eb); 436 found_level = btrfs_header_level(eb);
394 437
438 btrfs_set_buffer_lockdep_class(eb, found_level);
439
395 ret = csum_tree_block(root, eb, 1); 440 ret = csum_tree_block(root, eb, 1);
396 if (ret) 441 if (ret)
397 ret = -EIO; 442 ret = -EIO;
@@ -1777,7 +1822,6 @@ struct btrfs_root *open_ctree(struct super_block *sb,
1777 ret = find_and_setup_root(tree_root, fs_info, 1822 ret = find_and_setup_root(tree_root, fs_info,
1778 BTRFS_DEV_TREE_OBJECTID, dev_root); 1823 BTRFS_DEV_TREE_OBJECTID, dev_root);
1779 dev_root->track_dirty = 1; 1824 dev_root->track_dirty = 1;
1780
1781 if (ret) 1825 if (ret)
1782 goto fail_extent_root; 1826 goto fail_extent_root;
1783 1827