[PATCH 09/12] xfs: use goto based error unwinding in xfs_buf_read_map

This keeps the I/O error handling contained at the end of the function
and removes the indentation for it.  It also allows to reorder the
comments so that they are closer to the logic that they describe.

Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Brian Foster <[email protected]>
Reviewed-by: "Darrick J. Wong" <[email protected]>
---
 fs/xfs/xfs_buf.c | 47 ++++++++++++++++++++++++-----------------------
 1 file changed, 24 insertions(+), 23 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index d0dbe85fa20e..3d5e764e3613 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -716,6 +716,23 @@ xfs_buf_read_map(
 		ASSERT(bp->b_ops != NULL || ops == NULL);
 	}
 
+	if (error)
+		goto out_ioerror;
+
+	*bpp = bp;
+	return 0;
+
+out_ioerror:
+	/*
+	 * Check against log shutdown for error reporting because metadata
+	 * writeback may require a read first and we need to report errors in
+	 * metadata writeback until the log is shut down.  High level
+	 * transaction read functions already check against mount shutdown, so
+	 * we only need to be concerned about low level/ IO interactions here.
+	 */
+	if (!xlog_is_shutdown(target->bt_mount->m_log))
+		xfs_buf_ioerror_alert(bp, fa);
+
 	/*
 	 * If we've had a read error, then the contents of the buffer are
 	 * invalid and should not be used. To ensure that a followup read tries
@@ -725,30 +742,14 @@ xfs_buf_read_map(
 	 * future cache lookups will also treat it as an empty, uninitialised
 	 * buffer.
 	 */
-	if (error) {
-		/*
-		 * Check against log shutdown for error reporting because
-		 * metadata writeback may require a read first and we need to
-		 * report errors in metadata writeback until the log is shut
-		 * down. High level transaction read functions already check
-		 * against mount shutdown, anyway, so we only need to be
-		 * concerned about low level IO interactions here.
-		 */
-		if (!xlog_is_shutdown(target->bt_mount->m_log))
-			xfs_buf_ioerror_alert(bp, fa);
-
-		xfs_buf_clear_flags(bp, XBF_DONE);
-		xfs_buf_stale(bp);
-		xfs_buf_relse(bp);
-
-		/* bad CRC means corrupted metadata */
-		if (error == -EFSBADCRC)
-			error = -EFSCORRUPTED;
-		return error;
-	}
+	xfs_buf_clear_flags(bp, XBF_DONE);
+	xfs_buf_stale(bp);
+	xfs_buf_relse(bp);
 
-	*bpp = bp;
-	return 0;
+	/* bad CRC means corrupted metadata */
+	if (error == -EFSBADCRC)
+		return -EFSCORRUPTED;
+	return error;
 }
 
 /*
-- 
2.53.0