dedup

commit 5f1e1e970f10eb34b5392079a0b98827eb6a8af5
parent e2a7f03a6b43cf093fc814dd8610e2b73c1345a3
Author: sin <sin@2f30.org>
Date:   Mon,  4 Mar 2019 14:56:10 +0000

Rebuild cache if it is larger than expected

We don't want bogus cache entries that could in theory match new
blocks.

Diffstat:
M
dedup.c
 | 
27
+++++++++++++++++++--------

1 file changed, 19 insertions(+), 8 deletions(-)
diff --git a/dedup.c b/dedup.c
@@ -411,7 +411,7 @@ check_cache(struct snapshot *snap, void *arg)
 		blk_desc = &snap->blk_desc[i];
 		memcpy(&cache_entry.md, blk_desc->md, sizeof(cache_entry.md));
 		if (lookup_cache_entry(cache, &cache_entry) < 0) {
-			if (verbose)
+			if (verbose > 0)
 				fprintf(stderr, "Cache is corrupted\n");
 			args->ret = -1;
 			return WALK_STOP;
@@ -497,6 +497,16 @@ match_ver(uint64_t v)
 	     VER_MAJ, VER_MIN, maj, min);
 }
 
+static uint64_t
+cache_nr_entries(void)
+{
+	struct stat sb;
+
+	if (fstat(cfd, &sb) < 0)
+		err(1, "fstat");
+	return sb.st_size / CACHE_ENTRY_SIZE;
+}
+
 static int
 flush_cache(struct cache_entry *cache_entry)
 {
@@ -507,16 +517,12 @@ flush_cache(struct cache_entry *cache_entry)
 static void
 load_cache(void)
 {
-	struct stat sb;
 	uint64_t nr_entries;
 	uint64_t i;
 
 	xlseek(cfd, 0, SEEK_SET);
 
-	if (fstat(cfd, &sb) < 0)
-		err(1, "fstat");
-
-	nr_entries = sb.st_size / CACHE_ENTRY_SIZE;
+	nr_entries = cache_nr_entries();
 	if (nr_entries == 0) {
 		xlseek(ifd, SNAP_HDR_SIZE, SEEK_SET);
 		if (verbose > 0)
@@ -741,9 +747,14 @@ main(int argc, char *argv[])
 		xlseek(ifd, SNAP_HDR_SIZE, SEEK_SET);
 		walk_snap(check_snap, NULL);
 
-		xlseek(ifd, SNAP_HDR_SIZE, SEEK_SET);
 		args.ret = -1;
-		walk_snap(check_cache, &args);
+		if (cache_nr_entries() == snap_hdr.st.nr_blks) {
+			xlseek(ifd, SNAP_HDR_SIZE, SEEK_SET);
+			walk_snap(check_cache, &args);
+		} else {
+			if (verbose > 0)
+				fprintf(stderr, "Cache is corrupted\n");
+		}
 		if (args.ret != 0) {
 			free_cache(cache);
 			cache = alloc_cache();