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remove whole-disk entries from cache when partitions are found

PATCH Applied Eric Sandeen 2 participants 2 messages Mar 23, 2009 – Apr 23, 2009

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Eric Sandeen

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#0 lore raw

PATCH 1/1 remove whole-disk entries from cache when partitions are found

We can get into a situation in blkid where whole disks remain in the cache, even though partitions are found. For labels such as sun disklabels which may have the first partition beginning at sector 0, this is even somewhat likely.

1) create a sun disklabel w/partitions
2) mkfs the first partition (at sector 0)
3) remove the partition table
4) run blkid - this finds the fs on the whole disk, places in cache
5) recreate the partition table
6) run blkid - this finds the partition, places in cache

And now we have both /dev/sda and /dev/sda1 in cache.

There are heuristics in probe_all to avoid putting the whole disk in cache if it has partitions, but there is nothing to remove the whole-disk entry in the above case. I think the below patch suffices, although I haven't quite convinced myself that setting the lens[which]=0; is the right logic for that bit of state...

Signed-off-by Eric Sandeen <[email protected]>

---

lib/blkid/devname.c +24 -0
Index: e2fsprogs/lib/blkid/devname.c
===================================================================
@@ -365,6 +365,7 @@ static int probe_all(blkid_cache cache, 
 	unsigned long long sz;
 	int lens[2] = { 0, 0 };
 	int which = 0, last = 0;
+	struct list_head *p, *pnext;
 
 	ptnames[0] = ptname0;
 	ptnames[1] = ptname1;

@@ -425,6 +428,29 @@ static int probe_all(blkid_cache cache, 
 		}
 
 		/*
+		 * If last was a whole disk and we just found a partition
+		 * on it, remove the whole-disk dev from the cache if
+		 * it exists.
+		 */
+		if (lens[last] && !strncmp(ptnames[last], ptname, lens[last])) {
+			list_for_each_safe(p, pnext, &cache->bic_devs) {
+				blkid_dev tmp;
+
+				/* find blkid dev for the whole-disk devno */
+				tmp = list_entry(p, struct blkid_struct_dev,
+						 bid_devs);
+				if (tmp->bid_devno == devs[last]) {
+					DBG(DEBUG_DEVNAME,
+						printf("freeing %s\n",
+						       tmp->bid_name));
+					blkid_free_dev(tmp);
+					cache->bic_flags |= BLKID_BIC_FL_CHANGED;
+					break;
+				}
+			}
+			lens[last] = 0;
+		}
+		/*
 		 * If last was not checked because it looked like a whole-disk
 		 * dev, and the device's base name has changed,
 		 * check last as well.
Applied
#1 lore raw
Quoted 4 lines · Eric Sandeen

We can get into a situation in blkid where whole disks remain in the cache, even though partitions are found. For labels such as sun disklabels which may have the first partition beginning at sector 0, this is even somewhat likely.

Applied to the e2fsprogs source repository.

- Ted