btrfs: only update i_size in truncate paths that care

We currently will update the i_size of the inode as we truncate it down,
however we skip this if we're calling btrfs_truncate_inode_items from
the tree log code.  However we also don't care about this in the case of
evict.  Instead keep track of this value in the btrfs_truncate_control
and then have btrfs_truncate() and the free space cache truncate path
both do the i_size update themselves.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/free-space-cache.c

@@ -338,6 +338,9 @@ int btrfs_truncate_free_space_cache(struct btrfs_trans_handle *trans,
 	 * need to check for -EAGAIN.
 	 */
 	ret = btrfs_truncate_inode_items(trans, root, inode, &control);
+
+	btrfs_inode_safe_disk_i_size_write(inode, control.last_size);
+
 	unlock_extent_cached(&inode->io_tree, 0, (u64)-1, &cached_state);
 	if (ret)
 		goto fail;

fs/btrfs/inode-item.c

@@ -452,7 +452,6 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
 	u64 extent_num_bytes = 0;
 	u64 extent_offset = 0;
 	u64 item_end = 0;
-	u64 last_size = new_size;
 	u32 found_type = (u8)-1;
 	int del_item;
 	int pending_del_nr = 0;
@@ -466,6 +465,8 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
 
 	BUG_ON(new_size > 0 && control->min_type != BTRFS_EXTENT_DATA_KEY);
 
+	control->last_size = new_size;
+
 	/*
 	 * For shareable roots we want to back off from time to time, this turns
 	 * out to be subvolume roots, reloc roots, and data reloc roots.
@@ -644,9 +645,9 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
 		}
 
 		if (del_item)
-			last_size = found_key.offset;
+			control->last_size = found_key.offset;
 		else
-			last_size = new_size;
+			control->last_size = new_size;
 		if (del_item) {
 			if (!pending_del_nr) {
 				/* No pending yet, add ourselves */
@@ -739,12 +740,10 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
 			ret = err;
 		}
 	}
-	if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID) {
-		ASSERT(last_size >= new_size);
-		if (!ret && last_size > new_size)
-			last_size = new_size;
-		btrfs_inode_safe_disk_i_size_write(inode, last_size);
-	}
+
+	ASSERT(control->last_size >= new_size);
+	if (!ret && control->last_size > new_size)
+		control->last_size = new_size;
 
 	btrfs_free_path(path);
 	return ret;

fs/btrfs/inode-item.h

@@ -26,6 +26,9 @@ struct btrfs_truncate_control {
 	/* OUT: the number of extents truncated. */
 	u64 extents_found;
 
+	/* OUT: the last size we truncated this inode to. */
+	u64 last_size;
+
 	/*
 	 * IN: minimum key type to remove.  All key types with this type are
 	 * removed only if their offset >= new_size.

fs/btrfs/inode.c

@@ -8620,6 +8620,9 @@ static int btrfs_truncate(struct inode *inode, bool skip_writeback)
 
 		ret = btrfs_truncate_inode_items(trans, root, BTRFS_I(inode),
 						 &control);
+
+		btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), control.last_size);
+
 		unlock_extent_cached(&BTRFS_I(inode)->io_tree, lock_start,
 				     (u64)-1, &cached_state);