btrfsprogs/btrfs-progs-restore-passing-of-super_bytenr-to-device-scan

From 3a628f64ccdf41671368474a53c093ab03df1f98 Mon Sep 17 00:00:00 2001
From: Jeff Mahoney <jeffm@suse.com>
Date: Thu, 15 Aug 2013 20:32:00 -0400
Subject: btrfs-progs: restore passing of super_bytenr to device scan

Commit 615f2867 (Btrfs-progs: cleanup similar code in open_ctree_*
and close_ctree) introduced a regression in btrfs-convert.

open_ctree takes a sb_bytenr argument to specify where to find the
superblock. Under normal conditions, this will be at BTRFS_SUPER_INFO_OFFSET,
and that commit assumed as much under all conditions.

make_btrfs allows the caller to specify which blocks to use for
certain blocks (including the superblock) and this is used by btrfs-convert
to avoid overwriting the source file system's superblock until the
conversion is complete.

When btrfs-convert goes to open the newly initialized file system, it
fails with: "No valid btrfs found" since its superblock wasn't written
to the normal location.

This patch restores the passing down of super_bytesnr to
btrfs_scan_one_device.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
---
 btrfs-find-root.c |  2 +-
 cmds-chunk.c      |  2 +-
 disk-io.c         | 10 +++++++---
 disk-io.h         |  3 ++-
 4 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/btrfs-find-root.c b/btrfs-find-root.c
index 9b3d7df..374cf81 100644
--- a/btrfs-find-root.c
+++ b/btrfs-find-root.c
@@ -82,7 +82,7 @@ static struct btrfs_root *open_ctree_broken(int fd, const char *device)
 		return NULL;
 	}
 
-	ret = btrfs_scan_fs_devices(fd, device, &fs_devices);
+	ret = btrfs_scan_fs_devices(fd, device, &fs_devices, 0);
 	if (ret)
 		goto out;
 
diff --git a/cmds-chunk.c b/cmds-chunk.c
index 03314de..6ada328 100644
--- a/cmds-chunk.c
+++ b/cmds-chunk.c
@@ -1291,7 +1291,7 @@ static int recover_prepare(struct recover_control *rc, char *path)
 		goto fail_free_sb;
 	}
 
-	ret = btrfs_scan_fs_devices(fd, path, &fs_devices);
+	ret = btrfs_scan_fs_devices(fd, path, &fs_devices, 0);
 	if (ret)
 		goto fail_free_sb;
 
diff --git a/disk-io.c b/disk-io.c
index 13dbe27..1b91de6 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -909,13 +909,17 @@ 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)
+			  struct btrfs_fs_devices **fs_devices,
+			  u64 super_bytenr)
 {
 	u64 total_devs;
 	int ret;
 
+	if (super_bytenr == 0)
+		super_bytenr = BTRFS_SUPER_INFO_OFFSET;
+
 	ret = btrfs_scan_one_device(fd, path, fs_devices,
-				    &total_devs, BTRFS_SUPER_INFO_OFFSET);
+				    &total_devs, super_bytenr);
 	if (ret) {
 		fprintf(stderr, "No valid Btrfs found on %s\n", path);
 		return ret;
@@ -1001,7 +1005,7 @@ static struct btrfs_fs_info *__open_ctree_fd(int fp, const char *path,
 	if (restore)
 		fs_info->on_restoring = 1;
 
-	ret = btrfs_scan_fs_devices(fp, path, &fs_devices);
+	ret = btrfs_scan_fs_devices(fp, path, &fs_devices, sb_bytenr);
 	if (ret)
 		goto out;
 
diff --git a/disk-io.h b/disk-io.h
index effaa9f..d7792e0 100644
--- a/disk-io.h
+++ b/disk-io.h
@@ -59,7 +59,8 @@ int btrfs_setup_all_roots(struct btrfs_fs_info *fs_info,
 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);
+			  struct btrfs_fs_devices **fs_devices,
+			  u64 super_bytenr);
 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, int writes);