Fix race between --create and --incremental

This modifies locking in Create to eliminate a situation where
--incremental can assemble a device between write_init_super() and
add_disk(), which causes Create to fail.

It sporadically occurs e.g. when metadata is written on a device,
causing an udev change event which triggers mdadm --incremental.

Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/Create.c b/Create.c
index 9247d46bbfac8545a12233cf0c2205aa188becba..98bbdd40a1612ec704674aae1a2ad2fac7f049fb 100644 (file)
--- a/Create.c
+++ b/Create.c
@@ -740,7 +740,9 @@ int Create(struct supertype *st, char *mddev,
 
        map_update(&map, fd2devnm(mdfd), info.text_version,
                   info.uuid, chosen_name);
-       map_unlock(&map);
+       /* Keep map locked until devices have been added to array
+        * to stop another mdadm from finding and using those devices.
+        */
 
        if (s->bitmap_file && vers < 9003) {
                major_num = BITMAP_MAJOR_HOSTENDIAN;
@@ -753,18 +755,18 @@ int Create(struct supertype *st, char *mddev,
        if (s->bitmap_file && strcmp(s->bitmap_file, "internal")==0) {
                if ((vers%100) < 2) {
                        pr_err("internal bitmaps not supported by this kernel.\n");
-                       goto abort;
+                       goto abort_locked;
                }
                if (!st->ss->add_internal_bitmap) {
                        pr_err("internal bitmaps not supported with %s metadata\n",
                                st->ss->name);
-                       goto abort;
+                       goto abort_locked;
                }
                if (!st->ss->add_internal_bitmap(st, &s->bitmap_chunk,
                                                 c->delay, s->write_behind,
                                                 bitmapsize, 1, major_num)) {
                        pr_err("Given bitmap chunk size not supported.\n");
-                       goto abort;
+                       goto abort_locked;
                }
                s->bitmap_file = NULL;
        }
@@ -790,7 +792,7 @@ int Create(struct supertype *st, char *mddev,
                if (container_fd < 0) {
                        pr_err("Cannot get exclusive "
                                "open on container - weird.\n");
-                       goto abort;
+                       goto abort_locked;
                }
                if (mdmon_running(st->container_devnm)) {
                        if (c->verbose)
@@ -805,7 +807,7 @@ int Create(struct supertype *st, char *mddev,
        if (rv) {
                pr_err("failed to set array info for %s: %s\n",
                        mddev, strerror(errno));
-               goto abort;
+               goto abort_locked;
        }
 
        if (s->bitmap_file) {
@@ -816,18 +818,18 @@ int Create(struct supertype *st, char *mddev,
                                 c->delay, s->write_behind,
                                 bitmapsize,
                                 major_num)) {
-                       goto abort;
+                       goto abort_locked;
                }
                bitmap_fd = open(s->bitmap_file, O_RDWR);
                if (bitmap_fd < 0) {
                        pr_err("weird: %s cannot be openned\n",
                                s->bitmap_file);
-                       goto abort;
+                       goto abort_locked;
                }
                if (ioctl(mdfd, SET_BITMAP_FILE, bitmap_fd) < 0) {
                        pr_err("Cannot set bitmap file for %s: %s\n",
                                mddev, strerror(errno));
-                       goto abort;
+                       goto abort_locked;
                }
        }
 
@@ -884,7 +886,7 @@ int Create(struct supertype *st, char *mddev,
                                                pr_err("failed to open %s "
                                                        "after earlier success - aborting\n",
                                                        dv->devname);
-                                               goto abort;
+                                               goto abort_locked;
                                        }
                                        fstat(fd, &stb);
                                        inf->disk.major = major(stb.st_rdev);
@@ -896,7 +898,7 @@ int Create(struct supertype *st, char *mddev,
                                                         fd, dv->devname,
                                                         dv->data_offset)) {
                                        ioctl(mdfd, STOP_ARRAY, NULL);
-                                       goto abort;
+                                       goto abort_locked;
                                }
                                st->ss->getinfo_super(st, inf, NULL);
                                safe_mode_delay = inf->safe_mode_delay;
@@ -922,7 +924,7 @@ int Create(struct supertype *st, char *mddev,
                                        pr_err("ADD_NEW_DISK for %s "
                                               "failed: %s\n",
                                               dv->devname, strerror(errno));
-                                       goto abort;
+                                       goto abort_locked;
                                }
                                break;
                        }
@@ -939,7 +941,6 @@ int Create(struct supertype *st, char *mddev,
                         * the subarray cursor such that ->getinfo_super once
                         * again returns container info.
                         */
-                       map_lock(&map);
                        st->ss->getinfo_super(st, &info_new, NULL);
                        if (st->ss->external && s->level != LEVEL_CONTAINER &&
                            !same_uuid(info_new.uuid, info.uuid, 0)) {
@@ -964,12 +965,12 @@ int Create(struct supertype *st, char *mddev,
                                           info_new.uuid, path);
                                free(path);
                        }
-                       map_unlock(&map);
 
                        flush_metadata_updates(st);
                        st->ss->free_super(st);
                }
        }
+       map_unlock(&map);
        free(infos);
 
        if (s->level == LEVEL_CONTAINER) {