Btrfs: New data=ordered implementation

The old data=ordered code would force commit to wait until
all the data extents from the transaction were fully on disk.  This
introduced large latencies into the commit and stalled new writers
in the transaction for a long time.

The new code changes the way data allocations and extents work:

* When delayed allocation is filled, data extents are reserved, and
  the extent bit EXTENT_ORDERED is set on the entire range of the extent.
  A struct btrfs_ordered_extent is allocated an inserted into a per-inode
  rbtree to track the pending extents.

* As each page is written EXTENT_ORDERED is cleared on the bytes corresponding
  to that page.

* When all of the bytes corresponding to a single struct btrfs_ordered_extent
  are written, The previously reserved extent is inserted into the FS
  btree and into the extent allocation trees.  The checksums for the file
  data are also updated.

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

1 files changed, 285 insertions, 170 deletions

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 254da82..6513270 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -22,48 +22,30 @@
 #include "ctree.h"
 #include "transaction.h"
 #include "btrfs_inode.h"
+#include "extent_io.h"
 
-struct tree_entry {
-	u64 root_objectid;
-	u64 objectid;
-	struct inode *inode;
-	struct rb_node rb_node;
-};
 
-/*
- * returns > 0 if entry passed (root, objectid) is > entry,
- * < 0 if (root, objectid) < entry and zero if they are equal
- */
-static int comp_entry(struct tree_entry *entry, u64 root_objectid,
-		      u64 objectid)
+static u64 entry_end(struct btrfs_ordered_extent *entry)
 {
-	if (root_objectid < entry->root_objectid)
-		return -1;
-	if (root_objectid > entry->root_objectid)
-		return 1;
-	if (objectid < entry->objectid)
-		return -1;
-	if (objectid > entry->objectid)
-		return 1;
-	return 0;
+	if (entry->file_offset + entry->len < entry->file_offset)
+		return (u64)-1;
+	return entry->file_offset + entry->len;
 }
 
-static struct rb_node *tree_insert(struct rb_root *root, u64 root_objectid,
-				   u64 objectid, struct rb_node *node)
+static struct rb_node *tree_insert(struct rb_root *root, u64 file_offset,
+				   struct rb_node *node)
 {
 	struct rb_node ** p = &root->rb_node;
 	struct rb_node * parent = NULL;
-	struct tree_entry *entry;
-	int comp;
+	struct btrfs_ordered_extent *entry;
 
 	while(*p) {
 		parent = *p;
-		entry = rb_entry(parent, struct tree_entry, rb_node);
+		entry = rb_entry(parent, struct btrfs_ordered_extent, rb_node);
 
-		comp = comp_entry(entry, root_objectid, objectid);
-		if (comp < 0)
+		if (file_offset < entry->file_offset)
 			p = &(*p)->rb_left;
-		else if (comp > 0)
+		else if (file_offset >= entry_end(entry))
 			p = &(*p)->rb_right;
 		else
 			return parent;
@@ -74,24 +56,23 @@ static struct rb_node *tree_insert(struct rb_root *root, u64 root_objectid,
 	return NULL;
 }
 
-static struct rb_node *__tree_search(struct rb_root *root, u64 root_objectid,
-				     u64 objectid, struct rb_node **prev_ret)
+static struct rb_node *__tree_search(struct rb_root *root, u64 file_offset,
+				     struct rb_node **prev_ret)
 {
 	struct rb_node * n = root->rb_node;
 	struct rb_node *prev = NULL;
-	struct tree_entry *entry;
-	struct tree_entry *prev_entry = NULL;
-	int comp;
+	struct rb_node *test;
+	struct btrfs_ordered_extent *entry;
+	struct btrfs_ordered_extent *prev_entry = NULL;
 
 	while(n) {
-		entry = rb_entry(n, struct tree_entry, rb_node);
+		entry = rb_entry(n, struct btrfs_ordered_extent, rb_node);
 		prev = n;
 		prev_entry = entry;
-		comp = comp_entry(entry, root_objectid, objectid);
 
-		if (comp < 0)
+		if (file_offset < entry->file_offset)
 			n = n->rb_left;
-		else if (comp > 0)
+		else if (file_offset >= entry_end(entry))
 			n = n->rb_right;
 		else
 			return n;
@@ -99,195 +80,329 @@ static struct rb_node *__tree_search(struct rb_root *root, u64 root_objectid,
 	if (!prev_ret)
 		return NULL;
 
-	while(prev && comp_entry(prev_entry, root_objectid, objectid) >= 0) {
-		prev = rb_next(prev);
-		prev_entry = rb_entry(prev, struct tree_entry, rb_node);
+	while(prev && file_offset >= entry_end(prev_entry)) {
+		test = rb_next(prev);
+		if (!test)
+			break;
+		prev_entry = rb_entry(test, struct btrfs_ordered_extent,
+				      rb_node);
+		if (file_offset < entry_end(prev_entry))
+			break;
+
+		prev = test;
+	}
+	if (prev)
+		prev_entry = rb_entry(prev, struct btrfs_ordered_extent,
+				      rb_node);
+	while(prev && file_offset < entry_end(prev_entry)) {
+		test = rb_prev(prev);
+		if (!test)
+			break;
+		prev_entry = rb_entry(test, struct btrfs_ordered_extent,
+				      rb_node);
+		prev = test;
 	}
 	*prev_ret = prev;
 	return NULL;
 }
 
-static inline struct rb_node *tree_search(struct rb_root *root,
-					  u64 root_objectid, u64 objectid)
+static int offset_in_entry(struct btrfs_ordered_extent *entry, u64 file_offset)
+{
+	if (file_offset < entry->file_offset ||
+	    entry->file_offset + entry->len <= file_offset)
+		return 0;
+	return 1;
+}
+
+static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree,
+					  u64 file_offset)
 {
+	struct rb_root *root = &tree->tree;
 	struct rb_node *prev;
 	struct rb_node *ret;
-	ret = __tree_search(root, root_objectid, objectid, &prev);
+	struct btrfs_ordered_extent *entry;
+
+	if (tree->last) {
+		entry = rb_entry(tree->last, struct btrfs_ordered_extent,
+				 rb_node);
+		if (offset_in_entry(entry, file_offset))
+			return tree->last;
+	}
+	ret = __tree_search(root, file_offset, &prev);
 	if (!ret)
-		return prev;
+		ret = prev;
+	if (ret)
+		tree->last = ret;
 	return ret;
 }
 
-int btrfs_add_ordered_inode(struct inode *inode)
+int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
+			     u64 start, u64 len)
 {
-	struct btrfs_root *root = BTRFS_I(inode)->root;
-	u64 root_objectid = root->root_key.objectid;
-	u64 transid = root->fs_info->running_transaction->transid;
-	struct tree_entry *entry;
-	struct rb_node *node;
 	struct btrfs_ordered_inode_tree *tree;
+	struct rb_node *node;
+	struct btrfs_ordered_extent *entry;
 
-	if (transid <= BTRFS_I(inode)->ordered_trans)
-		return 0;
-
-	tree = &root->fs_info->running_transaction->ordered_inode_tree;
-
-	read_lock(&tree->lock);
-	node = __tree_search(&tree->tree, root_objectid, inode->i_ino, NULL);
-	read_unlock(&tree->lock);
-	if (node) {
-		return 0;
-	}
-
-	entry = kmalloc(sizeof(*entry), GFP_NOFS);
+	tree = &BTRFS_I(inode)->ordered_tree;
+	entry = kzalloc(sizeof(*entry), GFP_NOFS);
 	if (!entry)
 		return -ENOMEM;
 
-	write_lock(&tree->lock);
-	entry->objectid = inode->i_ino;
-	entry->root_objectid = root_objectid;
+	mutex_lock(&tree->mutex);
+	entry->file_offset = file_offset;
+	entry->start = start;
+	entry->len = len;
 	entry->inode = inode;
+	/* one ref for the tree */
+	atomic_set(&entry->refs, 1);
+	init_waitqueue_head(&entry->wait);
+	INIT_LIST_HEAD(&entry->list);
 
-	node = tree_insert(&tree->tree, root_objectid,
-			   inode->i_ino, &entry->rb_node);
-
-	BTRFS_I(inode)->ordered_trans = transid;
-	if (!node)
-		igrab(inode);
-
-	write_unlock(&tree->lock);
+	node = tree_insert(&tree->tree, file_offset,
+			   &entry->rb_node);
+	if (node) {
+		entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
+		atomic_inc(&entry->refs);
+	}
+	set_extent_ordered(&BTRFS_I(inode)->io_tree, file_offset,
+			   entry_end(entry) - 1, GFP_NOFS);
 
-	if (node)
-		kfree(entry);
+	set_bit(BTRFS_ORDERED_START, &entry->flags);
+	mutex_unlock(&tree->mutex);
+	BUG_ON(node);
 	return 0;
 }
 
-int btrfs_find_first_ordered_inode(struct btrfs_ordered_inode_tree *tree,
-				   u64 *root_objectid, u64 *objectid,
-				   struct inode **inode)
+int btrfs_add_ordered_sum(struct inode *inode, struct btrfs_ordered_sum *sum)
 {
-	struct tree_entry *entry;
+	struct btrfs_ordered_inode_tree *tree;
 	struct rb_node *node;
+	struct btrfs_ordered_extent *entry;
 
-	write_lock(&tree->lock);
-	node = tree_search(&tree->tree, *root_objectid, *objectid);
+	tree = &BTRFS_I(inode)->ordered_tree;
+	mutex_lock(&tree->mutex);
+	node = tree_search(tree, sum->file_offset);
 	if (!node) {
-		write_unlock(&tree->lock);
-		return 0;
+search_fail:
+printk("add ordered sum failed to find a node for inode %lu offset %Lu\n", inode->i_ino, sum->file_offset);
+		node = rb_first(&tree->tree);
+		while(node) {
+			entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
+			printk("entry %Lu %Lu %Lu\n", entry->file_offset, entry->file_offset + entry->len, entry->start);
+			node = rb_next(node);
+		}
+		BUG();
 	}
-	entry = rb_entry(node, struct tree_entry, rb_node);
+	BUG_ON(!node);
 
-	while(comp_entry(entry, *root_objectid, *objectid) >= 0) {
-		node = rb_next(node);
-		if (!node)
-			break;
-		entry = rb_entry(node, struct tree_entry, rb_node);
-	}
-	if (!node) {
-		write_unlock(&tree->lock);
-		return 0;
+	entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
+	if (!offset_in_entry(entry, sum->file_offset)) {
+		goto search_fail;
 	}
 
-	*root_objectid = entry->root_objectid;
-	*inode = entry->inode;
-	atomic_inc(&entry->inode->i_count);
-	*objectid = entry->objectid;
-	write_unlock(&tree->lock);
-	return 1;
+	list_add_tail(&sum->list, &entry->list);
+	mutex_unlock(&tree->mutex);
+	return 0;
 }
 
-int btrfs_find_del_first_ordered_inode(struct btrfs_ordered_inode_tree *tree,
-				       u64 *root_objectid, u64 *objectid,
-				       struct inode **inode)
+int btrfs_dec_test_ordered_pending(struct inode *inode,
+				   u64 file_offset, u64 io_size)
 {
-	struct tree_entry *entry;
+	struct btrfs_ordered_inode_tree *tree;
 	struct rb_node *node;
-
-	write_lock(&tree->lock);
-	node = tree_search(&tree->tree, *root_objectid, *objectid);
+	struct btrfs_ordered_extent *entry;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	int ret;
+
+	tree = &BTRFS_I(inode)->ordered_tree;
+	mutex_lock(&tree->mutex);
+	clear_extent_ordered(io_tree, file_offset, file_offset + io_size - 1,
+			     GFP_NOFS);
+	node = tree_search(tree, file_offset);
 	if (!node) {
-		write_unlock(&tree->lock);
-		return 0;
+		ret = 1;
+		goto out;
 	}
 
-	entry = rb_entry(node, struct tree_entry, rb_node);
-	while(comp_entry(entry, *root_objectid, *objectid) >= 0) {
-		node = rb_next(node);
-		if (!node)
-			break;
-		entry = rb_entry(node, struct tree_entry, rb_node);
+	entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
+	if (!offset_in_entry(entry, file_offset)) {
+		ret = 1;
+		goto out;
 	}
-	if (!node) {
-		write_unlock(&tree->lock);
-		return 0;
+
+	ret = test_range_bit(io_tree, entry->file_offset,
+			     entry->file_offset + entry->len - 1,
+			     EXTENT_ORDERED, 0);
+	if (!test_bit(BTRFS_ORDERED_START, &entry->flags)) {
+printk("inode %lu not ready yet for extent %Lu %Lu\n", inode->i_ino, entry->file_offset, entry_end(entry));
 	}
+	if (ret == 0)
+		ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
+out:
+	mutex_unlock(&tree->mutex);
+	return ret == 0;
+}
 
-	*root_objectid = entry->root_objectid;
-	*objectid = entry->objectid;
-	*inode = entry->inode;
-	atomic_inc(&entry->inode->i_count);
-	rb_erase(node, &tree->tree);
-	write_unlock(&tree->lock);
-	kfree(entry);
-	return 1;
+int btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry)
+{
+	if (atomic_dec_and_test(&entry->refs))
+		kfree(entry);
+	return 0;
 }
 
-static void __btrfs_del_ordered_inode(struct btrfs_ordered_inode_tree *tree,
-				     struct inode *inode,
-				     u64 root_objectid, u64 objectid)
+int btrfs_remove_ordered_extent(struct inode *inode,
+				struct btrfs_ordered_extent *entry)
 {
-	struct tree_entry *entry;
+	struct btrfs_ordered_inode_tree *tree;
 	struct rb_node *node;
-	struct rb_node *prev;
 
-	write_lock(&tree->lock);
-	node = __tree_search(&tree->tree, root_objectid, objectid, &prev);
-	if (!node) {
-		write_unlock(&tree->lock);
-		return;
-	}
+	tree = &BTRFS_I(inode)->ordered_tree;
+	mutex_lock(&tree->mutex);
+	node = &entry->rb_node;
 	rb_erase(node, &tree->tree);
-	BTRFS_I(inode)->ordered_trans = 0;
-	write_unlock(&tree->lock);
-	atomic_dec(&inode->i_count);
-	entry = rb_entry(node, struct tree_entry, rb_node);
-	kfree(entry);
-	return;
+	tree->last = NULL;
+	set_bit(BTRFS_ORDERED_COMPLETE, &entry->flags);
+	mutex_unlock(&tree->mutex);
+	wake_up(&entry->wait);
+	return 0;
 }
 
-void btrfs_del_ordered_inode(struct inode *inode, int force)
+void btrfs_wait_ordered_extent(struct inode *inode,
+			       struct btrfs_ordered_extent *entry)
 {
-	struct btrfs_root *root = BTRFS_I(inode)->root;
-	u64 root_objectid = root->root_key.objectid;
+	u64 start = entry->file_offset;
+	u64 end = start + entry->len - 1;
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,22)
+	do_sync_file_range(file, start, end, SYNC_FILE_RANGE_WRITE);
+#else
+	do_sync_mapping_range(inode->i_mapping, start, end,
+			      SYNC_FILE_RANGE_WRITE);
+#endif
+	wait_event(entry->wait,
+		   test_bit(BTRFS_ORDERED_COMPLETE, &entry->flags));
+}
 
-	if (!BTRFS_I(inode)->ordered_trans) {
-		return;
-	}
+static void btrfs_start_ordered_extent(struct inode *inode,
+			       struct btrfs_ordered_extent *entry, int wait)
+{
+	u64 start = entry->file_offset;
+	u64 end = start + entry->len - 1;
 
-	if (!force && (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY) ||
-	    mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK)))
-		return;
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,22)
+	do_sync_file_range(file, start, end, SYNC_FILE_RANGE_WRITE);
+#else
+	do_sync_mapping_range(inode->i_mapping, start, end,
+			      SYNC_FILE_RANGE_WRITE);
+#endif
+	if (wait)
+		wait_event(entry->wait, test_bit(BTRFS_ORDERED_COMPLETE,
+						 &entry->flags));
+}
 
-	spin_lock(&root->fs_info->new_trans_lock);
-	if (root->fs_info->running_transaction) {
-		struct btrfs_ordered_inode_tree *tree;
-		tree = &root->fs_info->running_transaction->ordered_inode_tree;
-		 __btrfs_del_ordered_inode(tree, inode, root_objectid,
-						inode->i_ino);
+void btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)
+{
+	u64 end;
+	struct btrfs_ordered_extent *ordered;
+	int found;
+	int should_wait = 0;
+
+again:
+	if (start + len < start)
+		end = (u64)-1;
+	else
+		end = start + len - 1;
+	found = 0;
+	while(1) {
+		ordered = btrfs_lookup_first_ordered_extent(inode, end);
+		if (!ordered) {
+			break;
+		}
+		if (ordered->file_offset >= start + len) {
+			btrfs_put_ordered_extent(ordered);
+			break;
+		}
+		if (ordered->file_offset + ordered->len < start) {
+			btrfs_put_ordered_extent(ordered);
+			break;
+		}
+		btrfs_start_ordered_extent(inode, ordered, should_wait);
+		found++;
+		end = ordered->file_offset;
+		btrfs_put_ordered_extent(ordered);
+		if (end == 0)
+			break;
+		end--;
+	}
+	if (should_wait && found) {
+		should_wait = 0;
+		goto again;
 	}
-	spin_unlock(&root->fs_info->new_trans_lock);
 }
 
-int btrfs_ordered_throttle(struct btrfs_root *root, struct inode *inode)
+int btrfs_add_ordered_pending(struct inode *inode,
+			      struct btrfs_ordered_extent *ordered,
+			      u64 start, u64 len)
 {
-	struct btrfs_transaction *cur = root->fs_info->running_transaction;
-	while(cur == root->fs_info->running_transaction &&
-	      atomic_read(&BTRFS_I(inode)->ordered_writeback)) {
-#if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,18)
-		congestion_wait(WRITE, HZ/20);
-#else
-		blk_congestion_wait(WRITE, HZ/20);
-#endif
-	}
+	WARN_ON(1);
 	return 0;
+#if 0
+	int ret;
+	struct btrfs_ordered_inode_tree *tree;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+
+	tree = &BTRFS_I(inode)->ordered_tree;
+	mutex_lock(&tree->mutex);
+	if (test_bit(BTRFS_ORDERED_IO_DONE, &ordered->flags)) {
+		ret = -EAGAIN;
+		goto out;
+	}
+	set_extent_ordered(io_tree, start, start + len - 1, GFP_NOFS);
+	ret = 0;
+out:
+	mutex_unlock(&tree->mutex);
+	return ret;
+#endif
+}
+
+struct btrfs_ordered_extent *btrfs_lookup_ordered_extent(struct inode *inode,
+							 u64 file_offset)
+{
+	struct btrfs_ordered_inode_tree *tree;
+	struct rb_node *node;
+	struct btrfs_ordered_extent *entry = NULL;
+
+	tree = &BTRFS_I(inode)->ordered_tree;
+	mutex_lock(&tree->mutex);
+	node = tree_search(tree, file_offset);
+	if (!node)
+		goto out;
+
+	entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
+	if (!offset_in_entry(entry, file_offset))
+		entry = NULL;
+	if (entry)
+		atomic_inc(&entry->refs);
+out:
+	mutex_unlock(&tree->mutex);
+	return entry;
+}
+
+struct btrfs_ordered_extent *
+btrfs_lookup_first_ordered_extent(struct inode * inode, u64 file_offset)
+{
+	struct btrfs_ordered_inode_tree *tree;
+	struct rb_node *node;
+	struct btrfs_ordered_extent *entry = NULL;
+
+	tree = &BTRFS_I(inode)->ordered_tree;
+	mutex_lock(&tree->mutex);
+	node = tree_search(tree, file_offset);
+	if (!node)
+		goto out;
+
+	entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
+	atomic_inc(&entry->refs);
+out:
+	mutex_unlock(&tree->mutex);
+	return entry;
 }