dedup

commit e2a7f03a6b43cf093fc814dd8610e2b73c1345a3
parent 6d9bfc25ce2ba1ddc768c68522d05195d783472b
Author: sin <sin@2f30.org>
Date:   Mon,  4 Mar 2019 14:45:41 +0000

Check cache for consistency

Diffstat:
M
dedup.c
 | 
67
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------

1 file changed, 61 insertions(+), 6 deletions(-)
diff --git a/dedup.c b/dedup.c
@@ -25,6 +25,10 @@ enum {
 	WALK_STOP
 };
 
+struct check_cache_args {
+	int ret;
+};
+
 struct extract_args {
 	uint8_t *md;
 	int fd;
@@ -346,8 +350,12 @@ extract(struct snapshot *snap, void *arg)
 	return WALK_STOP;
 }
 
+/*
+ * For each snapshot, hash every block and check if the hash
+ * matches the one in the corresponding block descriptor.
+ */
 static int
-check(struct snapshot *snap, void *arg)
+check_snap(struct snapshot *snap, void *arg)
 {
 	uint8_t md[MDSIZE];
 	uint8_t *buf;
@@ -355,10 +363,6 @@ check(struct snapshot *snap, void *arg)
 	uint64_t i;
 
 	buf = alloc_buf(compr_size(BLKSIZE_MAX));
-	/*
-	 * Calculate hash for each block and compare
-	 * against snapshot entry block descriptor
-	 */
 	for (i = 0; i < snap->nr_blk_descs; i++) {
 		struct blk_desc *blk_desc;
 
@@ -388,6 +392,35 @@ check(struct snapshot *snap, void *arg)
 	return WALK_CONTINUE;
 }
 
+/*
+ * For each block descriptor within each snapshot, do a lookup
+ * of the block descriptor hash in the cache.  If the lookup fails
+ * the cache is corrupted.  The caller will rebuild the cache in
+ * that case.
+ */
+static int
+check_cache(struct snapshot *snap, void *arg)
+{
+	struct check_cache_args *args = arg;
+	uint64_t i;
+
+	for (i = 0; i < snap->nr_blk_descs; i++) {
+		struct blk_desc *blk_desc;
+		struct cache_entry cache_entry;
+
+		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)
+				fprintf(stderr, "Cache is corrupted\n");
+			args->ret = -1;
+			return WALK_STOP;
+		}
+	}
+	args->ret = 0;
+	return WALK_CONTINUE;
+}
+
 static int
 list(struct snapshot *snap, void *arg)
 {
@@ -703,8 +736,30 @@ main(int argc, char *argv[])
 	}
 
 	if (cflag) {
+		struct check_cache_args args;
+
+		xlseek(ifd, SNAP_HDR_SIZE, SEEK_SET);
+		walk_snap(check_snap, NULL);
+
 		xlseek(ifd, SNAP_HDR_SIZE, SEEK_SET);
-		walk_snap(check, NULL);
+		args.ret = -1;
+		walk_snap(check_cache, &args);
+		if (args.ret != 0) {
+			free_cache(cache);
+			cache = alloc_cache();
+
+			if (ftruncate(cfd, 0) < 0)
+				err(1, "ftruncate");
+
+			if (verbose > 0)
+				fprintf(stderr, "Rebuilding cache...");
+			xlseek(ifd, SNAP_HDR_SIZE, SEEK_SET);
+			xlseek(cfd, 0, SEEK_SET);
+			walk_snap(rebuild_cache, NULL);
+			if (verbose > 0)
+				fprintf(stderr, "done\n");
+		}
+
 		term();
 		return 0;
 	}