xfs: normalize "infinite" retries in error configs

As it stands today, the "fail immediately" vs. "retry forever"
values for max_retries and retry_timeout_seconds in the xfs metadata
error configurations are not consistent.

A retry_timeout_seconds of 0 means "retry forever," but a
max_retries of 0 means "fail immediately."

retry_timeout_seconds < 0 is disallowed, while max_retries == -1
means "retry forever."

Make this consistent across the error configs, such that a value of
0 means "fail immediately" (i.e. wait 0 seconds, or retry 0 times),
and a value of -1 always means "retry forever."

This makes retry_timeout a signed long to accommodate the -1, even
though it stores jiffies.  Given our limit of a 1 day maximum
timeout, this should be sufficient even at much higher HZ values
than we have available today.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_buf_item.c

@@ -1095,7 +1095,8 @@ xfs_buf_iodone_callback_error(
 	     bp->b_last_error != bp->b_error) {
 		bp->b_flags |= (XBF_WRITE | XBF_DONE | XBF_WRITE_FAIL);
 		bp->b_last_error = bp->b_error;
-		if (cfg->retry_timeout && !bp->b_first_retry_time)
+		if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
+		    !bp->b_first_retry_time)
 			bp->b_first_retry_time = jiffies;
 
 		xfs_buf_ioerror(bp, 0);
@@ -1111,7 +1112,7 @@ xfs_buf_iodone_callback_error(
 	if (cfg->max_retries != XFS_ERR_RETRY_FOREVER &&
 	    ++bp->b_retries > cfg->max_retries)
 			goto permanent_error;
-	if (cfg->retry_timeout &&
+	if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
 	    time_after(jiffies, cfg->retry_timeout + bp->b_first_retry_time))
 			goto permanent_error;