From: NeilBrown <neilb@suse.de>
Date: Sat, 5 Mar 2011 00:25:20 +0000 (+1100)
Subject: Fix error-return value from seg_addr
X-Git-Url: http://git.neil.brown.name/?a=commitdiff_plain;h=1845b13a644db8b3bce767a94a07a2d541206532;p=LaFS.git

Fix error-return value from seg_addr

Returning '0' as an error indicator from seg_addr is bad
because 0 can be a valid address - the first block in the first
segment (used as a cluster header).

So return "-1" instead (as an unsigned of course).

Signed-off-by: NeilBrown <neilb@suse.de>
---

diff --git a/cluster.c b/cluster.c
index a76b0f5..6752673 100644
--- a/cluster.c
+++ b/cluster.c
@@ -339,14 +339,14 @@ static u64 seg_addr(struct fs *fs, struct segpos *seg)
 	if (seg->dev < 0)
 		/* Setting 'next' address for last cluster in
 		 * a cleaner segment */
-		return 0;
+		return (u64)-1;
 	if (seg->table > seg->nxt_table ||
 	    (seg->table == seg->nxt_table &&
 	     seg->row >= seg->nxt_row))
 		/* We have gone beyond the end of the cluster,
 		 * must be bad data during roll-forward
 		 */
-		return 0;
+		return (u64)-1;
 	addr = seg->col * dv->stride;
 	addr += seg->row;
 	addr += seg->table * dv->rows_per_table;
@@ -373,9 +373,9 @@ u64 lafs_seg_next(struct fs *fs, struct segpos *seg)
 	struct fs_dev *dv = &fs->devs[seg->dev];
 	u64 addr = seg_addr(fs, seg);
 
-	if (!addr)
+	if (!(addr+1))
 		/* Beyond end of cluster */
-		return 0;
+		return addr;
 
 	/* now step forward in column or table or seg */
 	seg->row++;
@@ -1202,7 +1202,7 @@ static void cluster_flush(struct fs *fs, int cnum)
 			current_block++;
 		cluster_incdesc(wc, desc_start, b, fs->blocksize_bits);
 		addr = lafs_seg_next(fs, &wc->seg);
-		BUG_ON(!addr);
+		BUG_ON(!addr || !(addr+1));
 		if (cnum && test_bit(B_Dirty, &b->flags))
 			/* We are cleaning but this block is now dirty.
 			 * Don't waste the UnincCredit on recording the
@@ -1220,7 +1220,7 @@ static void cluster_flush(struct fs *fs, int cnum)
 	segend = wc->seg; /* We may write zeros from here */
 	seg_step(fs, &wc->seg);
 	wc->remaining = seg_remainder(fs, &wc->seg);
-	/* Need to make sure out ->next_addr gets set properly
+	/* Need to make sure our ->next_addr gets set properly
 	 * for non-cleaning segments
 	 */
 	if (wc->remaining < 2) {