On Fri, Jan 24, 2020 at 12:31:52PM +1100, Dave Chinner wrote:

On Wed, Jan 22, 2020 at 11:42:22PM -0800, Darrick J. Wong wrote:

quoted

From: Darrick J. Wong <redacted>

Convert xfs_buf_read_map() to return numeric error codes like most
everywhere else in xfs.  This involves moving the open-coded logic that
reports metadata IO read / corruption errors and stales the buffer into
xfs_buf_read_map so that the logic is all in one place.

Signed-off-by: Darrick J. Wong <redacted>

.....

quoted

diff --git a/fs/xfs/xfs_trans_buf.c b/fs/xfs/xfs_trans_buf.c
index b5b3a78ef31c..56e7f8126cd7 100644
--- a/fs/xfs/xfs_trans_buf.c
+++ b/fs/xfs/xfs_trans_buf.c

@@ -298,36 +298,17 @@ xfs_trans_read_buf_map(
 		return 0;
 	}
 
-	bp = xfs_buf_read_map(target, map, nmaps, flags, ops);
-	if (!bp) {
-		if (!(flags & XBF_TRYLOCK))
-			return -ENOMEM;
-		return tp ? 0 : -EAGAIN;
-	}
-
-	/*
-	 * 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
-	 * to pull the buffer from disk again, we clear the XBF_DONE flag and
-	 * mark the buffer stale. This ensures that anyone who has a current
-	 * reference to the buffer will interpret it's contents correctly and
-	 * future cache lookups will also treat it as an empty, uninitialised
-	 * buffer.
-	 */
-	if (bp->b_error) {
-		error = bp->b_error;
-		if (!XFS_FORCED_SHUTDOWN(mp))
-			xfs_buf_ioerror_alert(bp, __func__);
-		bp->b_flags &= ~XBF_DONE;
-		xfs_buf_stale(bp);
-
+	error = xfs_buf_read_map(target, map, nmaps, flags, &bp, ops);
+	switch (error) {
+	case 0:
+		break;
+	case -EFSCORRUPTED:
+	case -EIO:
 		if (tp && (tp->t_flags & XFS_TRANS_DIRTY))
-			xfs_force_shutdown(tp->t_mountp, SHUTDOWN_META_IO_ERROR);
-		xfs_buf_relse(bp);
-
-		/* bad CRC means corrupted metadata */
-		if (error == -EFSBADCRC)
-			error = -EFSCORRUPTED;
+			xfs_force_shutdown(tp->t_mountp,
+					SHUTDOWN_META_IO_ERROR);
+		/* fall through */
+	default:
 		return error;
 	}

Same question as Christoph - we're only trying to avoid ENOMEM and
EAGAIN errors from shutting down the filesystem here, right?
Every other type of IO error that could end up on bp->b_error would
result in a shutdown, so perhaps this should be the other way
around:

	switch (error) {
	case 0:
		break;
	default:
		/* shutdown stuff */
		/* fall through */
	case -ENOMEM:
	case -EAGAIN:
		return error;
	}

I agree that ENOMEM ought to be on the list of things that don't
immediately cause a shutdown if the transaction is dirty.

--D

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com