Add a per-inode lock around btrfs_drop_extents

btrfs_drop_extents is always called with a range lock held on the inode.
But, it may operate on extents outside that range as it drops and splits
them.

This patch adds a per-inode mutex that is held while calling
btrfs_drop_extents and while inserting new extents into the tree.  It
prevents races from two procs working against adjacent ranges in the tree.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/btrfs_inode.h

@@ -32,6 +32,7 @@ struct btrfs_inode {
 	struct extent_io_tree io_tree;
 	struct extent_io_tree io_failure_tree;
 	struct mutex csum_mutex;
+	struct mutex extent_mutex;
 	struct inode vfs_inode;
 	struct btrfs_ordered_inode_tree ordered_tree;
 

fs/btrfs/extent-tree.c

@@ -1671,6 +1671,8 @@ static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
 	ret = __free_extent(trans, root, bytenr, num_bytes, root_objectid,
 			    ref_generation, owner_objectid, owner_offset,
 			    pin, pin == 0);
+
+	finish_current_insert(trans, root->fs_info->extent_root);
 	pending_ret = del_pending_extents(trans, root->fs_info->extent_root);
 	return ret ? ret : pending_ret;
 }

fs/btrfs/file.c

@@ -242,6 +242,7 @@ static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans,
 	u64 end_of_last_block;
 	u64 end_pos = pos + write_bytes;
 	u64 inline_size;
+	int did_inline = 0;
 	loff_t isize = i_size_read(inode);
 
 	start_pos = pos & ~((u64)root->sectorsize - 1);
@@ -275,6 +276,7 @@ static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans,
 		if (hole_size > 0) {
 			btrfs_wait_ordered_range(inode, last_pos_in_file,
 						 last_pos_in_file + hole_size);
+			mutex_lock(&BTRFS_I(inode)->extent_mutex);
 			err = btrfs_drop_extents(trans, root, inode,
 						 last_pos_in_file,
 						 last_pos_in_file + hole_size,
@@ -289,6 +291,7 @@ static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans,
 						       0, 0, hole_size, 0);
 			btrfs_drop_extent_cache(inode, last_pos_in_file,
 					last_pos_in_file + hole_size -1);
+			mutex_unlock(&BTRFS_I(inode)->extent_mutex);
 			btrfs_check_file(root, inode);
 		}
 		if (err)
@@ -321,6 +324,7 @@ static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans,
 		/* step one, delete the existing extents in this range */
 		aligned_end = (pos + write_bytes + root->sectorsize - 1) &
 			~((u64)root->sectorsize - 1);
+		mutex_lock(&BTRFS_I(inode)->extent_mutex);
 		err = btrfs_drop_extents(trans, root, inode, start_pos,
 					 aligned_end, aligned_end, &hint_byte);
 		if (err)
@@ -332,9 +336,13 @@ static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans,
 					   inline_size, pages, 0, num_pages);
 		btrfs_drop_extent_cache(inode, start_pos, aligned_end - 1);
 		BUG_ON(err);
+		mutex_unlock(&BTRFS_I(inode)->extent_mutex);
+		did_inline = 1;
 	}
 	if (end_pos > isize) {
 		i_size_write(inode, end_pos);
+		if (did_inline)
+			BTRFS_I(inode)->disk_i_size = end_pos;
 		btrfs_update_inode(trans, root, inode);
 	}
 failed:

fs/btrfs/inode.c

@@ -516,6 +516,8 @@ int btrfs_writepage_end_io_hook(struct page *page, u64 start, u64 end,
 					  trans->transid, inode->i_ino,
 					  ordered_extent->file_offset, &ins);
 	BUG_ON(ret);
+
+	mutex_lock(&BTRFS_I(inode)->extent_mutex);
 	ret = btrfs_drop_extents(trans, root, inode,
 				 ordered_extent->file_offset,
 				 ordered_extent->file_offset +
@@ -531,6 +533,8 @@ int btrfs_writepage_end_io_hook(struct page *page, u64 start, u64 end,
 	btrfs_drop_extent_cache(inode, ordered_extent->file_offset,
 				ordered_extent->file_offset +
 				ordered_extent->len - 1);
+	mutex_unlock(&BTRFS_I(inode)->extent_mutex);
+
 	inode->i_blocks += ordered_extent->len >> 9;
 	unlock_extent(io_tree, ordered_extent->file_offset,
 		    ordered_extent->file_offset + ordered_extent->len - 1,
@@ -1399,6 +1403,7 @@ static int btrfs_setattr(struct dentry *dentry, struct iattr *attr)
 
 		trans = btrfs_start_transaction(root, 1);
 		btrfs_set_trans_block_group(trans, inode);
+		mutex_lock(&BTRFS_I(inode)->extent_mutex);
 		err = btrfs_drop_extents(trans, root, inode,
 					 hole_start, block_end, hole_start,
 					 &alloc_hint);
@@ -1412,6 +1417,7 @@ static int btrfs_setattr(struct dentry *dentry, struct iattr *attr)
 						(u64)-1);
 			btrfs_check_file(root, inode);
 		}
+		mutex_unlock(&BTRFS_I(inode)->extent_mutex);
 		btrfs_end_transaction(trans, root);
 		unlock_extent(io_tree, hole_start, block_end - 1, GFP_NOFS);
 		if (err)
@@ -1578,6 +1584,7 @@ static int btrfs_init_locked_inode(struct inode *inode, void *p)
 			     inode->i_mapping, GFP_NOFS);
 	btrfs_ordered_inode_tree_init(&BTRFS_I(inode)->ordered_tree);
 	mutex_init(&BTRFS_I(inode)->csum_mutex);
+	mutex_init(&BTRFS_I(inode)->extent_mutex);
 	return 0;
 }
 
@@ -1880,6 +1887,7 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
 			     inode->i_mapping, GFP_NOFS);
 	btrfs_ordered_inode_tree_init(&BTRFS_I(inode)->ordered_tree);
 	mutex_init(&BTRFS_I(inode)->csum_mutex);
+	mutex_init(&BTRFS_I(inode)->extent_mutex);
 	BTRFS_I(inode)->delalloc_bytes = 0;
 	BTRFS_I(inode)->disk_i_size = 0;
 	BTRFS_I(inode)->root = root;
@@ -2105,6 +2113,7 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
 		extent_io_tree_init(&BTRFS_I(inode)->io_failure_tree,
 				     inode->i_mapping, GFP_NOFS);
 		mutex_init(&BTRFS_I(inode)->csum_mutex);
+		mutex_init(&BTRFS_I(inode)->extent_mutex);
 		BTRFS_I(inode)->delalloc_bytes = 0;
 		BTRFS_I(inode)->disk_i_size = 0;
 		BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
@@ -3079,6 +3088,7 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
 		extent_io_tree_init(&BTRFS_I(inode)->io_failure_tree,
 				     inode->i_mapping, GFP_NOFS);
 		mutex_init(&BTRFS_I(inode)->csum_mutex);
+		mutex_init(&BTRFS_I(inode)->extent_mutex);
 		BTRFS_I(inode)->delalloc_bytes = 0;
 		BTRFS_I(inode)->disk_i_size = 0;
 		BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;