libceph: fixup error handling in osdmap_apply_incremental()

The existing error handling scheme requires resetting err to -EINVAL
prior to calling any ceph_decode_* macro.  This is ugly and fragile,
and there already are a few places where we would return 0 on error,
due to a missing reset.  Follow osdmap_decode() and fix this by adding
a special e_inval label to be used by all ceph_decode_* macros.
Signed-off-by: NIlya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: NAlex Elder <elder@linaro.org>

net/ceph/osdmap.c

@@ -867,19 +867,19 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 	__s64 new_pool_max;
 	__s32 new_flags, max;
 	void *start = *p;
-	int err = -EINVAL;
+	int err;
 	u16 version;
 
 	dout("%s %p to %p len %d\n", __func__, *p, end, (int)(end - *p));
 
-	ceph_decode_16_safe(p, end, version, bad);
+	ceph_decode_16_safe(p, end, version, e_inval);
 	if (version != 6) {
 		pr_warning("got unknown v %d != 6 of inc osdmap\n", version);
-		goto bad;
+		goto e_inval;
 	}
 
 	ceph_decode_need(p, end, sizeof(fsid)+sizeof(modified)+2*sizeof(u32),
-			 bad);
+			 e_inval);
 	ceph_decode_copy(p, &fsid, sizeof(fsid));
 	epoch = ceph_decode_32(p);
 	BUG_ON(epoch != map->epoch+1);
@@ -888,7 +888,7 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 	new_flags = ceph_decode_32(p);
 
 	/* full map? */
-	ceph_decode_32_safe(p, end, len, bad);
+	ceph_decode_32_safe(p, end, len, e_inval);
 	if (len > 0) {
 		dout("apply_incremental full map len %d, %p to %p\n",
 		     len, *p, end);
@@ -896,13 +896,14 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 	}
 
 	/* new crush? */
-	ceph_decode_32_safe(p, end, len, bad);
+	ceph_decode_32_safe(p, end, len, e_inval);
 	if (len > 0) {
-		dout("apply_incremental new crush map len %d, %p to %p\n",
-		     len, *p, end);
 		newcrush = crush_decode(*p, min(*p+len, end));
-		if (IS_ERR(newcrush))
-			return ERR_CAST(newcrush);
+		if (IS_ERR(newcrush)) {
+			err = PTR_ERR(newcrush);
+			newcrush = NULL;
+			goto bad;
+		}
 		*p += len;
 	}
 
@@ -912,13 +913,13 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 	if (new_pool_max >= 0)
 		map->pool_max = new_pool_max;
 
-	ceph_decode_need(p, end, 5*sizeof(u32), bad);
+	ceph_decode_need(p, end, 5*sizeof(u32), e_inval);
 
 	/* new max? */
 	max = ceph_decode_32(p);
 	if (max >= 0) {
 		err = osdmap_set_max_osd(map, max);
-		if (err < 0)
+		if (err)
 			goto bad;
 	}
 
@@ -932,11 +933,11 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 	}
 
 	/* new_pool */
-	ceph_decode_32_safe(p, end, len, bad);
+	ceph_decode_32_safe(p, end, len, e_inval);
 	while (len--) {
 		struct ceph_pg_pool_info *pi;
 
-		ceph_decode_64_safe(p, end, pool, bad);
+		ceph_decode_64_safe(p, end, pool, e_inval);
 		pi = __lookup_pg_pool(&map->pg_pools, pool);
 		if (!pi) {
 			pi = kzalloc(sizeof(*pi), GFP_NOFS);
@@ -953,29 +954,28 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 	}
 	if (version >= 5) {
 		err = __decode_pool_names(p, end, map);
-		if (err < 0)
+		if (err)
 			goto bad;
 	}
 
 	/* old_pool */
-	ceph_decode_32_safe(p, end, len, bad);
+	ceph_decode_32_safe(p, end, len, e_inval);
 	while (len--) {
 		struct ceph_pg_pool_info *pi;
 
-		ceph_decode_64_safe(p, end, pool, bad);
+		ceph_decode_64_safe(p, end, pool, e_inval);
 		pi = __lookup_pg_pool(&map->pg_pools, pool);
 		if (pi)
 			__remove_pg_pool(&map->pg_pools, pi);
 	}
 
 	/* new_up */
-	err = -EINVAL;
-	ceph_decode_32_safe(p, end, len, bad);
+	ceph_decode_32_safe(p, end, len, e_inval);
 	while (len--) {
 		u32 osd;
 		struct ceph_entity_addr addr;
-		ceph_decode_32_safe(p, end, osd, bad);
-		ceph_decode_copy_safe(p, end, &addr, sizeof(addr), bad);
+		ceph_decode_32_safe(p, end, osd, e_inval);
+		ceph_decode_copy_safe(p, end, &addr, sizeof(addr), e_inval);
 		ceph_decode_addr(&addr);
 		pr_info("osd%d up\n", osd);
 		BUG_ON(osd >= map->max_osd);
@@ -984,11 +984,11 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 	}
 
 	/* new_state */
-	ceph_decode_32_safe(p, end, len, bad);
+	ceph_decode_32_safe(p, end, len, e_inval);
 	while (len--) {
 		u32 osd;
 		u8 xorstate;
-		ceph_decode_32_safe(p, end, osd, bad);
+		ceph_decode_32_safe(p, end, osd, e_inval);
 		xorstate = **(u8 **)p;
 		(*p)++;  /* clean flag */
 		if (xorstate == 0)
@@ -1000,10 +1000,10 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 	}
 
 	/* new_weight */
-	ceph_decode_32_safe(p, end, len, bad);
+	ceph_decode_32_safe(p, end, len, e_inval);
 	while (len--) {
 		u32 osd, off;
-		ceph_decode_need(p, end, sizeof(u32)*2, bad);
+		ceph_decode_need(p, end, sizeof(u32)*2, e_inval);
 		osd = ceph_decode_32(p);
 		off = ceph_decode_32(p);
 		pr_info("osd%d weight 0x%x %s\n", osd, off,
@@ -1014,7 +1014,7 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 	}
 
 	/* new_pg_temp */
-	ceph_decode_32_safe(p, end, len, bad);
+	ceph_decode_32_safe(p, end, len, e_inval);
 	while (len--) {
 		struct ceph_pg_mapping *pg;
 		int j;
@@ -1024,22 +1024,22 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 		err = ceph_decode_pgid(p, end, &pgid);
 		if (err)
 			goto bad;
-		ceph_decode_need(p, end, sizeof(u32), bad);
+		ceph_decode_need(p, end, sizeof(u32), e_inval);
 		pglen = ceph_decode_32(p);
 		if (pglen) {
-			ceph_decode_need(p, end, pglen*sizeof(u32), bad);
+			ceph_decode_need(p, end, pglen*sizeof(u32), e_inval);
 
 			/* removing existing (if any) */
 			(void) __remove_pg_mapping(&map->pg_temp, pgid);
 
 			/* insert */
-			err = -EINVAL;
 			if (pglen > (UINT_MAX - sizeof(*pg)) / sizeof(u32))
-				goto bad;
-			err = -ENOMEM;
+				goto e_inval;
 			pg = kmalloc(sizeof(*pg) + sizeof(u32)*pglen, GFP_NOFS);
-			if (!pg)
+			if (!pg) {
+				err = -ENOMEM;
 				goto bad;
+			}
 			pg->pgid = pgid;
 			pg->len = pglen;
 			for (j = 0; j < pglen; j++)
@@ -1063,6 +1063,8 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 	dout("inc osdmap epoch %d max_osd %d\n", map->epoch, map->max_osd);
 	return map;
 
+e_inval:
+	err = -EINVAL;
 bad:
 	pr_err("corrupt inc osdmap (%d) epoch %d off %d (%p of %p-%p)\n",
 	       err, epoch, (int)(*p - start), *p, start, end);