xfs: move in-memory buftarg handling out of _xfs_buf_ioapply

No I/O to apply for in-memory buffers, so skip the function call
entirely.  Clean up the b_io_error initialization logic to allow
for this.

Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Acked-by: Dave Chinner <[email protected]>
Signed-off-by: Carlos Maiolino <[email protected]>

Author: Christoph Hellwig

fs/xfs/xfs_buf.c

@@ -1604,12 +1604,6 @@ _xfs_buf_ioapply(
 	int		size;
 	int		i;
 
-	/*
-	 * Make sure we capture only current IO errors rather than stale errors
-	 * left over from previous use of the buffer (e.g. failed readahead).
-	 */
-	bp->b_error = 0;
-
 	if (bp->b_flags & XBF_WRITE) {
 		op = REQ_OP_WRITE;
 	} else {
@@ -1621,10 +1615,6 @@ _xfs_buf_ioapply(
 	/* we only use the buffer cache for meta-data */
 	op |= REQ_META;
 
-	/* in-memory targets are directly mapped, no IO required. */
-	if (xfs_buftarg_is_mem(bp->b_target))
-		return;
-
 	/*
 	 * Walk all the vectors issuing IO on them. Set up the initial offset
 	 * into the buffer and the desired IO size before we start -
@@ -1734,7 +1724,11 @@ xfs_buf_submit(
 	if (bp->b_flags & XBF_WRITE)
 		xfs_buf_wait_unpin(bp);
 
-	/* clear the internal error state to avoid spurious errors */
+	/*
+	 * Make sure we capture only current IO errors rather than stale errors
+	 * left over from previous use of the buffer (e.g. failed readahead).
+	 */
+	bp->b_error = 0;
 	bp->b_io_error = 0;
 
 	/*
@@ -1751,6 +1745,10 @@ xfs_buf_submit(
 		goto done;
 	}
 
+	/* In-memory targets are directly mapped, no I/O required. */
+	if (xfs_buftarg_is_mem(bp->b_target))
+		goto done;
+
 	_xfs_buf_ioapply(bp);
 
 done: