Btrfs: Fix some data=ordered related data corruptions

Stress testing was showing data checksum errors, most of which were caused
by a lookup bug in the extent_map tree.  The tree was caching the last
pointer returned, and searches would check the last pointer first.

But, search callers also expect the search to return the very first
matching extent in the range, which wasn't always true with the last
pointer usage.

For now, the code to cache the last return value is just removed.  It is
easy to fix, but I think lookups are rare enough that it isn't required anymore.

This commit also replaces do_sync_mapping_range with a local copy of the
related functions.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/ctree.h

@@ -1590,6 +1590,8 @@ int btrfs_csum_truncate(struct btrfs_trans_handle *trans,
 			struct btrfs_root *root, struct btrfs_path *path,
 			u64 isize);
 /* inode.c */
+int btrfs_writepages(struct address_space *mapping,
+		     struct writeback_control *wbc);
 int btrfs_create_subvol_root(struct btrfs_root *new_root,
 		struct btrfs_trans_handle *trans, u64 new_dirid,
 		struct btrfs_block_group_cache *block_group);

fs/btrfs/extent_io.c

@@ -97,7 +97,6 @@ void extent_io_tree_init(struct extent_io_tree *tree,
 	spin_lock_init(&tree->lock);
 	spin_lock_init(&tree->buffer_lock);
 	tree->mapping = mapping;
-	tree->last = NULL;
 }
 EXPORT_SYMBOL(extent_io_tree_init);
 
@@ -173,12 +172,6 @@ static struct rb_node *__etree_search(struct extent_io_tree *tree, u64 offset,
 	struct tree_entry *entry;
 	struct tree_entry *prev_entry = NULL;
 
-	if (tree->last) {
-		struct extent_state *state;
-		state = tree->last;
-		if (state->start <= offset && offset <= state->end)
-			return &tree->last->rb_node;
-	}
 	while(n) {
 		entry = rb_entry(n, struct tree_entry, rb_node);
 		prev = n;
@@ -189,7 +182,6 @@ static struct rb_node *__etree_search(struct extent_io_tree *tree, u64 offset,
 		else if (offset > entry->end)
 			n = n->rb_right;
 		else {
-			tree->last = rb_entry(n, struct extent_state, rb_node);
 			return n;
 		}
 	}
@@ -223,10 +215,6 @@ static inline struct rb_node *tree_search(struct extent_io_tree *tree,
 
 	ret = __etree_search(tree, offset, &prev, NULL);
 	if (!ret) {
-		if (prev) {
-			tree->last = rb_entry(prev, struct extent_state,
-					      rb_node);
-		}
 		return prev;
 	}
 	return ret;
@@ -301,8 +289,6 @@ static int merge_state(struct extent_io_tree *tree,
 		    other->state == state->state) {
 			state->start = other->start;
 			other->tree = NULL;
-			if (tree->last == other)
-				tree->last = state;
 			rb_erase(&other->rb_node, &tree->state);
 			free_extent_state(other);
 		}
@@ -314,8 +300,6 @@ static int merge_state(struct extent_io_tree *tree,
 		    other->state == state->state) {
 			other->start = state->start;
 			state->tree = NULL;
-			if (tree->last == state)
-				tree->last = other;
 			rb_erase(&state->rb_node, &tree->state);
 			free_extent_state(state);
 		}
@@ -378,7 +362,6 @@ static int insert_state(struct extent_io_tree *tree,
 		return -EEXIST;
 	}
 	state->tree = tree;
-	tree->last = state;
 	merge_state(tree, state);
 	return 0;
 }
@@ -444,9 +427,6 @@ static int clear_state_bit(struct extent_io_tree *tree,
 	if (delete || state->state == 0) {
 		if (state->tree) {
 			clear_state_cb(tree, state, state->state);
-			if (tree->last == state) {
-				tree->last = extent_state_next(state);
-			}
 			rb_erase(&state->rb_node, &tree->state);
 			state->tree = NULL;
 			free_extent_state(state);

fs/btrfs/extent_io.h

@@ -60,7 +60,6 @@ struct extent_io_tree {
 	spinlock_t lock;
 	spinlock_t buffer_lock;
 	struct extent_io_ops *ops;
-	struct extent_state *last;
 };
 
 struct extent_state {

fs/btrfs/extent_map.c

@@ -42,7 +42,6 @@ void extent_map_exit(void)
 void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask)
 {
 	tree->map.rb_node = NULL;
-	tree->last = NULL;
 	spin_lock_init(&tree->lock);
 }
 EXPORT_SYMBOL(extent_map_tree_init);
@@ -239,7 +238,6 @@ int add_extent_mapping(struct extent_map_tree *tree,
 		merge->in_tree = 0;
 		free_extent_map(merge);
 	}
-	tree->last = em;
 out:
 	return ret;
 }
@@ -273,10 +271,6 @@ struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
 	u64 end = range_end(start, len);
 
 	BUG_ON(spin_trylock(&tree->lock));
-	em = tree->last;
-	if (em && end > em->start && start < extent_map_end(em))
-		goto found;
-
 	rb_node = __tree_search(&tree->map, start, &prev, &next);
 	if (!rb_node && prev) {
 		em = rb_entry(prev, struct extent_map, rb_node);
@@ -305,7 +299,6 @@ struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
 
 found:
 	atomic_inc(&em->refs);
-	tree->last = em;
 out:
 	return em;
 }
@@ -327,8 +320,6 @@ int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
 	BUG_ON(spin_trylock(&tree->lock));
 	rb_erase(&em->rb_node, &tree->map);
 	em->in_tree = 0;
-	if (tree->last == em)
-		tree->last = NULL;
 	return ret;
 }
 EXPORT_SYMBOL(remove_extent_mapping);

fs/btrfs/extent_map.h

@@ -26,7 +26,6 @@ struct extent_map {
 
 struct extent_map_tree {
 	struct rb_root map;
-	struct extent_map *last;
 	spinlock_t lock;
 };
 

fs/btrfs/file.c

@@ -381,14 +381,13 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end)
 			break;
 		}
 		if (test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
-			start = em->start + em->len;
-			free_extent_map(em);
-			spin_unlock(&em_tree->lock);
-			if (start < end) {
-				len = end - start + 1;
-				continue;
-			}
-			break;
+			printk(KERN_CRIT "inode %lu trying to drop pinned "
+			       "extent start %llu end %llu, em [%llu %llu]\n",
+			       inode->i_ino,
+			       (unsigned long long)start,
+			       (unsigned long long)end,
+			       (unsigned long long)em->start,
+			       (unsigned long long)em->len);
 		}
 		remove_extent_mapping(em_tree, em);
 

fs/btrfs/inode.c

@@ -485,7 +485,7 @@ int btrfs_writepage_start_hook(struct page *page, u64 start, u64 end)
 	fixup = kzalloc(sizeof(*fixup), GFP_NOFS);
 	if (!fixup)
 		return -EAGAIN;
-printk("queueing worker to fixup page %lu %Lu\n", inode->i_ino, page_offset(page));
+
 	SetPageChecked(page);
 	page_cache_get(page);
 	fixup->work.func = btrfs_writepage_fixup_worker;
@@ -502,11 +502,13 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
 	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 	struct extent_map *em;
+	struct extent_map *em_orig;
 	u64 alloc_hint = 0;
 	u64 clear_start;
 	u64 clear_end;
 	struct list_head list;
 	struct btrfs_key ins;
+	struct rb_node *rb;
 	int ret;
 
 	ret = btrfs_dec_test_ordered_pending(inode, start, end - start + 1);
@@ -535,6 +537,22 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
 
 	mutex_lock(&BTRFS_I(inode)->extent_mutex);
 
+	spin_lock(&em_tree->lock);
+	clear_start = ordered_extent->file_offset;
+	clear_end = ordered_extent->file_offset + ordered_extent->len;
+	em = lookup_extent_mapping(em_tree, clear_start,
+				   ordered_extent->len);
+	em_orig = em;
+	while(em && clear_start < extent_map_end(em) && clear_end > em->start) {
+		clear_bit(EXTENT_FLAG_PINNED, &em->flags);
+		rb = rb_next(&em->rb_node);
+		if (!rb)
+			break;
+		em = rb_entry(rb, struct extent_map, rb_node);
+	}
+	free_extent_map(em_orig);
+	spin_unlock(&em_tree->lock);
+
 	ret = btrfs_drop_extents(trans, root, inode,
 				 ordered_extent->file_offset,
 				 ordered_extent->file_offset +
@@ -548,22 +566,6 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
 				       ordered_extent->len, 0);
 	BUG_ON(ret);
 
-	spin_lock(&em_tree->lock);
-	clear_start = ordered_extent->file_offset;
-	clear_end = ordered_extent->file_offset + ordered_extent->len;
-	while(clear_start < clear_end) {
-		em = lookup_extent_mapping(em_tree, clear_start,
-					   clear_end - clear_start);
-		if (em) {
-			clear_bit(EXTENT_FLAG_PINNED, &em->flags);
-			clear_start = em->start + em->len;
-			free_extent_map(em);
-		} else {
-			break;
-		}
-	}
-	spin_unlock(&em_tree->lock);
-
 	btrfs_drop_extent_cache(inode, ordered_extent->file_offset,
 				ordered_extent->file_offset +
 				ordered_extent->len - 1);
@@ -2318,7 +2320,7 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
 	u64 extent_end = 0;
 	u64 objectid = inode->i_ino;
 	u32 found_type;
-	struct btrfs_path *path;
+	struct btrfs_path *path = NULL;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_file_extent_item *item;
 	struct extent_buffer *leaf;
@@ -2328,9 +2330,6 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
 	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 	struct btrfs_trans_handle *trans = NULL;
 
-	path = btrfs_alloc_path();
-	BUG_ON(!path);
-
 again:
 	spin_lock(&em_tree->lock);
 	em = lookup_extent_mapping(em_tree, start, len);
@@ -2354,6 +2353,12 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
 	em->bdev = root->fs_info->fs_devices->latest_bdev;
 	em->start = EXTENT_MAP_HOLE;
 	em->len = (u64)-1;
+
+	if (!path) {
+		path = btrfs_alloc_path();
+		BUG_ON(!path);
+	}
+
 	ret = btrfs_lookup_file_extent(trans, root, path,
 				       objectid, start, trans != NULL);
 	if (ret < 0) {
@@ -2530,7 +2535,8 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
 	}
 	spin_unlock(&em_tree->lock);
 out:
-	btrfs_free_path(path);
+	if (path)
+		btrfs_free_path(path);
 	if (trans) {
 		ret = btrfs_end_transaction(trans, root);
 		if (!err) {
@@ -2643,8 +2649,8 @@ static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
 	return extent_write_full_page(tree, page, btrfs_get_extent, wbc);
 }
 
-static int btrfs_writepages(struct address_space *mapping,
-			    struct writeback_control *wbc)
+int btrfs_writepages(struct address_space *mapping,
+		     struct writeback_control *wbc)
 {
 	struct extent_io_tree *tree;
 	tree = &BTRFS_I(mapping->host)->io_tree;