1 files changed, 75 insertions, 17 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 1fd827b99c1b..9dfde1af8a64 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -2323,25 +2323,62 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 	 */
 	btrfs_inode_unlock(inode, BTRFS_ILOCK_MMAP);
 
-	if (ret != BTRFS_NO_LOG_SYNC) {
+	if (ret == BTRFS_NO_LOG_SYNC) {
+		ret = btrfs_end_transaction(trans);
+		goto out;
+	}
+
+	/* We successfully logged the inode, attempt to sync the log. */
+	if (!ret) {
+		ret = btrfs_sync_log(trans, root, &ctx);
 		if (!ret) {
-			ret = btrfs_sync_log(trans, root, &ctx);
-			if (!ret) {
-				ret = btrfs_end_transaction(trans);
-				goto out;
-			}
-		}
-		if (!full_sync) {
-			ret = btrfs_wait_ordered_range(inode, start, len);
-			if (ret) {
-				btrfs_end_transaction(trans);
-				goto out;
-			}
+			ret = btrfs_end_transaction(trans);
+			goto out;
 		}
-		ret = btrfs_commit_transaction(trans);
-	} else {
+	}
+
+	/*
+	 * At this point we need to commit the transaction because we had
+	 * btrfs_need_log_full_commit() or some other error.
+	 *
+	 * If we didn't do a full sync we have to stop the trans handle, wait on
+	 * the ordered extents, start it again and commit the transaction.  If
+	 * we attempt to wait on the ordered extents here we could deadlock with
+	 * something like fallocate() that is holding the extent lock trying to
+	 * start a transaction while some other thread is trying to commit the
+	 * transaction while we (fsync) are currently holding the transaction
+	 * open.
+	 */
+	if (!full_sync) {
 		ret = btrfs_end_transaction(trans);
+		if (ret)
+			goto out;
+		ret = btrfs_wait_ordered_range(inode, start, len);
+		if (ret)
+			goto out;
+
+		/*
+		 * This is safe to use here because we're only interested in
+		 * making sure the transaction that had the ordered extents is
+		 * committed.  We aren't waiting on anything past this point,
+		 * we're purely getting the transaction and committing it.
+		 */
+		trans = btrfs_attach_transaction_barrier(root);
+		if (IS_ERR(trans)) {
+			ret = PTR_ERR(trans);
+
+			/*
+			 * We committed the transaction and there's no currently
+			 * running transaction, this means everything we care
+			 * about made it to disk and we are done.
+			 */
+			if (ret == -ENOENT)
+				ret = 0;
+			goto out;
+		}
 	}
+
+	ret = btrfs_commit_transaction(trans);
 out:
 	ASSERT(list_empty(&ctx.list));
 	err = file_check_and_advance_wb_err(file);
@@ -2719,7 +2756,8 @@ int btrfs_replace_file_extents(struct btrfs_inode *inode,
 
 	ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv, rsv,
 				      min_size, false);
-	BUG_ON(ret);
+	if (WARN_ON(ret))
+		goto out_trans;
 	trans->block_rsv = rsv;
 
 	cur_offset = start;
@@ -2803,6 +2841,25 @@ int btrfs_replace_file_extents(struct btrfs_inode *inode,
 			extent_info->file_offset += replace_len;
 		}
 
+		/*
+		 * We are releasing our handle on the transaction, balance the
+		 * dirty pages of the btree inode and flush delayed items, and
+		 * then get a new transaction handle, which may now point to a
+		 * new transaction in case someone else may have committed the
+		 * transaction we used to replace/drop file extent items. So
+		 * bump the inode's iversion and update mtime and ctime except
+		 * if we are called from a dedupe context. This is because a
+		 * power failure/crash may happen after the transaction is
+		 * committed and before we finish replacing/dropping all the
+		 * file extent items we need.
+		 */
+		inode_inc_iversion(&inode->vfs_inode);
+
+		if (!extent_info || extent_info->update_times) {
+			inode->vfs_inode.i_mtime = current_time(&inode->vfs_inode);
+			inode->vfs_inode.i_ctime = inode->vfs_inode.i_mtime;
+		}
+
 		ret = btrfs_update_inode(trans, root, inode);
 		if (ret)
 			break;
@@ -2819,7 +2876,8 @@ int btrfs_replace_file_extents(struct btrfs_inode *inode,
 
 		ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv,
 					      rsv, min_size, false);
-		BUG_ON(ret);	/* shouldn't happen */
+		if (WARN_ON(ret))
+			break;
 		trans->block_rsv = rsv;
 
 		cur_offset = drop_args.drop_end;