As of now btrfs_read_dev_super() reads the backup super block
by default and calling function has no control. However in the
following patch we would see that is undesirable.
So with the flag BTRFS_SCAN_BACKUP_SB the calling function
can now indicate if btrfs_read_dev_super should scan for
the backup SB when primary SB fails.
This patch just provides the frame-work, keeping all the logic
in the code same with or without this patch.
Signed-off-by: Anand Jain <anand.j...@oracle.com>
---
disk-io.c | 10 +++++++---
disk-io.h | 3 ++-
find-root.c | 3 ++-
utils.h | 1 +
volumes.c | 4 +++-
5 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/disk-io.c b/disk-io.c
index 6a03e9c..8d68c2e 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -880,7 +880,8 @@ static struct btrfs_fs_info *__open_ctree_fd(int fp, const
char *path,
fs_info->super_bytenr = sb_bytenr;
disk_super = fs_info->super_copy;
ret = btrfs_read_dev_super(fs_devices->latest_bdev,
- disk_super, sb_bytenr);
+ disk_super, sb_bytenr,
+ BTRFS_SCAN_BACKUP_SB);
if (ret) {
printk("No valid btrfs found\n");
goto out_devices;
@@ -1103,7 +1104,8 @@ struct btrfs_root *open_ctree_fd(int fp, const char
*path, u64 sb_bytenr,
return info->fs_root;
}
-int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr)
+int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr,
+ u64 flags)
{
u8 fsid[BTRFS_FSID_SIZE];
int fsid_is_initialized = 0;
@@ -1112,6 +1114,7 @@ int btrfs_read_dev_super(int fd, struct btrfs_super_block
*sb, u64 sb_bytenr)
int ret;
u64 transid = 0;
u64 bytenr;
+ int max;
if (sb_bytenr != BTRFS_SUPER_INFO_OFFSET) {
ret = pread64(fd, &buf, sizeof(buf), sb_bytenr);
@@ -1126,7 +1129,8 @@ int btrfs_read_dev_super(int fd, struct btrfs_super_block
*sb, u64 sb_bytenr)
return 0;
}
- for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
+ max = flags & BTRFS_SCAN_BACKUP_SB ? BTRFS_SUPER_MIRROR_MAX : 1;
+ for (i = 0; i < max; i++) {
bytenr = btrfs_sb_offset(i);
ret = pread64(fd, &buf, sizeof(buf), bytenr);
if (ret < sizeof(buf))
diff --git a/disk-io.h b/disk-io.h
index ff87958..40b7222 100644
--- a/disk-io.h
+++ b/disk-io.h
@@ -59,7 +59,8 @@ int close_ctree(struct btrfs_root *root);
int write_all_supers(struct btrfs_root *root);
int write_ctree_super(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
-int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr);
+int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr,
+ u64 flags);
int btrfs_map_bh_to_logical(struct btrfs_root *root, struct extent_buffer *bh,
u64 logical);
struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
diff --git a/find-root.c b/find-root.c
index 16920ed..0b08358 100644
--- a/find-root.c
+++ b/find-root.c
@@ -151,7 +151,8 @@ static struct btrfs_root *open_ctree_broken(int fd, const
char *device)
fs_info->super_bytenr = BTRFS_SUPER_INFO_OFFSET;
disk_super = fs_info->super_copy;
ret = btrfs_read_dev_super(fs_devices->latest_bdev,
- disk_super, BTRFS_SUPER_INFO_OFFSET);
+ disk_super, BTRFS_SUPER_INFO_OFFSET,
+ BTRFS_SCAN_BACKUP_SB);
if (ret) {
printk("No valid btrfs found\n");
goto out_devices;
diff --git a/utils.h b/utils.h
index 1de5143..ab22b02 100644
--- a/utils.h
+++ b/utils.h
@@ -24,6 +24,7 @@
#define BTRFS_MKFS_SYSTEM_GROUP_SIZE (4 * 1024 * 1024)
#define BTRFS_SCAN_REGISTER (1ULL << 1)
+#define BTRFS_SCAN_BACKUP_SB (1ULL << 2)
int make_btrfs(int fd, const char *device, const char *label,
u64 blocks[6], u64 num_bytes, u32 nodesize,
diff --git a/volumes.c b/volumes.c
index 3e52d06..1113cb5 100644
--- a/volumes.c
+++ b/volumes.c
@@ -29,6 +29,7 @@
#include "transaction.h"
#include "print-tree.h"
#include "volumes.h"
+#include "utils.h"
struct stripe {
struct btrfs_device *dev;
@@ -226,7 +227,8 @@ int btrfs_scan_one_device(int fd, const char *path,
goto error;
}
disk_super = (struct btrfs_super_block *)buf;
- ret = btrfs_read_dev_super(fd, disk_super, super_offset);
+ ret = btrfs_read_dev_super(fd, disk_super, super_offset,
+ BTRFS_SCAN_BACKUP_SB);
if (ret < 0) {
ret = -EIO;
goto error_brelse;
--
1.8.1.227.g44fe835
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