Btrfs-progs: skip opening all devices with restore

When we go to fixup the dev items after a restore we scan all existing devices.
If you happen to be a btrfs developer you could possibly open up some random
device that you didn't just restore onto, which gives you weird errors and makes
you super cranky and waste a day trying to figure out what is failing.  This
will make it so that we use the fd we've already opened for opening our ctree.
Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>

btrfs-find-root.c

@@ -79,7 +79,7 @@ static struct btrfs_root *open_ctree_broken(int fd, const char *device)
 		return NULL;
 	}
 
-	ret = btrfs_scan_fs_devices(fd, device, &fs_devices, 0, 1);
+	ret = btrfs_scan_fs_devices(fd, device, &fs_devices, 0, 1, 0);
 	if (ret)
 		goto out;
 

btrfs-image.c

@@ -2557,16 +2557,19 @@ static int restore_metadump(const char *input, FILE *out, int old_restore,
 	ret = wait_for_worker(&mdrestore);
 
 	if (!ret && !multi_devices && !old_restore) {
+		struct btrfs_root *root;
 		struct stat st;
 
-		info = open_ctree_fs_info(target, 0, 0,
+		root = open_ctree_fd(fileno(out), target, 0,
 					  OPEN_CTREE_PARTIAL |
-					  OPEN_CTREE_WRITES);
-		if (!info) {
+					  OPEN_CTREE_WRITES |
+					  OPEN_CTREE_NO_DEVICES);
+		if (!root) {
 			fprintf(stderr, "unable to open %s\n", target);
 			ret = -EIO;
 			goto out;
 		}
+		info = root->fs_info;
 
 		if (stat(target, &st)) {
 			fprintf(stderr, "statting %s failed\n", target);

chunk-recover.c

@@ -1520,7 +1520,7 @@ static int recover_prepare(struct recover_control *rc, char *path)
 		goto fail_free_sb;
 	}
 
-	ret = btrfs_scan_fs_devices(fd, path, &fs_devices, 0, 1);
+	ret = btrfs_scan_fs_devices(fd, path, &fs_devices, 0, 1, 0);
 	if (ret)
 		goto fail_free_sb;
 

disk-io.c

@@ -1006,7 +1006,8 @@ void btrfs_cleanup_all_caches(struct btrfs_fs_info *fs_info)
 
 int btrfs_scan_fs_devices(int fd, const char *path,
 			  struct btrfs_fs_devices **fs_devices,
-			  u64 sb_bytenr, int super_recover)
+			  u64 sb_bytenr, int super_recover,
+			  int skip_devices)
 {
 	u64 total_devs;
 	u64 dev_size;
@@ -1033,7 +1034,7 @@ int btrfs_scan_fs_devices(int fd, const char *path,
 		return ret;
 	}
 
-	if (total_devs != 1) {
+	if (!skip_devices && total_devs != 1) {
 		ret = btrfs_scan_lblkid();
 		if (ret)
 			return ret;
@@ -1114,7 +1115,8 @@ static struct btrfs_fs_info *__open_ctree_fd(int fp, const char *path,
 		fs_info->on_restoring = 1;
 
 	ret = btrfs_scan_fs_devices(fp, path, &fs_devices, sb_bytenr,
-				    (flags & OPEN_CTREE_RECOVER_SUPER));
+				    (flags & OPEN_CTREE_RECOVER_SUPER),
+				    (flags & OPEN_CTREE_NO_DEVICES));
 	if (ret)
 		goto out;
 

disk-io.h

@@ -33,6 +33,7 @@ enum btrfs_open_ctree_flags {
 	OPEN_CTREE_RESTORE		= (1 << 4),
 	OPEN_CTREE_NO_BLOCK_GROUPS	= (1 << 5),
 	OPEN_CTREE_EXCLUSIVE		= (1 << 6),
+	OPEN_CTREE_NO_DEVICES		= (1 << 7),
 };
 
 static inline u64 btrfs_sb_offset(int mirror)
@@ -68,7 +69,7 @@ void btrfs_release_all_roots(struct btrfs_fs_info *fs_info);
 void btrfs_cleanup_all_caches(struct btrfs_fs_info *fs_info);
 int btrfs_scan_fs_devices(int fd, const char *path,
 			  struct btrfs_fs_devices **fs_devices, u64 sb_bytenr,
-			  int super_recover);
+			  int super_recover, int skip_devices);
 int btrfs_setup_chunk_tree_and_device_map(struct btrfs_fs_info *fs_info);
 
 struct btrfs_root *open_ctree(const char *filename, u64 sb_bytenr,

super-recover.c

@@ -279,7 +279,7 @@ int btrfs_recover_superblocks(const char *dname,
 	}
 	init_recover_superblock(&recover);
 
-	ret = btrfs_scan_fs_devices(fd, dname, &recover.fs_devices, 0, 1);
+	ret = btrfs_scan_fs_devices(fd, dname, &recover.fs_devices, 0, 1, 0);
 	close(fd);
 	if (ret) {
 		ret = 1;