We have enhanced super block validation check in disk_io.c, while
super-recover doesn't use that function and use a custom one.

That is duplicated, so reuse btrfs_read_dev_super to handle it, which
not only enhanced super check, but also reduce the code length.

Reported-by: hawken <haw...@thehawken.org>
Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
---
 super-recover.c | 39 +++++++++++----------------------------
 1 file changed, 11 insertions(+), 28 deletions(-)

diff --git a/super-recover.c b/super-recover.c
index ecd1215..5298d46 100644
--- a/super-recover.c
+++ b/super-recover.c
@@ -88,24 +88,6 @@ void free_recover_superblock(struct btrfs_recover_superblock 
*recover)
        }
 }
 
-static int check_super(u64 bytenr, struct btrfs_super_block *sb)
-{
-       int csum_size = btrfs_super_csum_size(sb);
-       u8 result[csum_size];
-       u32 crc = ~(u32)0;
-
-       if (btrfs_super_bytenr(sb) != bytenr)
-               return 0;
-       if (sb->magic != cpu_to_le64(BTRFS_MAGIC))
-               return 0;
-
-       crc = btrfs_csum_data(NULL, (char *)sb + BTRFS_CSUM_SIZE,
-                       crc, BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
-       btrfs_csum_final(crc, result);
-
-       return !memcmp(sb, &result, csum_size);
-}
-
 static int add_superblock_record(struct btrfs_super_block *sb, char *fname,
                        u64 bytenr, struct list_head *head)
 {
@@ -133,24 +115,20 @@ read_dev_supers(char *filename, struct 
btrfs_recover_superblock *recover)
        int i, ret, fd;
        u8 buf[BTRFS_SUPER_INFO_SIZE];
        u64 max_gen, bytenr;
+       struct btrfs_super_block *sb = (struct btrfs_super_block *)buf;
+
        /* just ignore errno that were set in btrfs_scan_fs_devices() */
        errno = 0;
 
-       struct btrfs_super_block *sb = (struct btrfs_super_block *)buf;
-
        fd = open(filename, O_RDONLY);
        if (fd < 0)
                return -errno;
 
        for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
                bytenr = btrfs_sb_offset(i);
-               ret = pread64(fd, buf, sizeof(buf), bytenr);
-               if (ret < sizeof(buf)) {
-                       ret = -errno;
-                       goto out;
-               }
-               ret = check_super(bytenr, sb);
-               if (ret) {
+
+               ret = btrfs_read_dev_super(fd, sb, bytenr, SBREAD_DEFAULT);
+               if (!ret) {
                        ret = add_superblock_record(sb, filename, bytenr,
                                                        &recover->good_supers);
                        if (ret)
@@ -158,13 +136,18 @@ read_dev_supers(char *filename, struct 
btrfs_recover_superblock *recover)
                        max_gen = btrfs_super_generation(sb);
                        if (max_gen > recover->max_generation)
                                recover->max_generation = max_gen;
-               } else {
+               } else if (ret == -EIO){
+                       /*
+                        * Skip superblock which doesn't exist, only adds
+                        * really corrupted superblock
+                        */
                        ret = add_superblock_record(sb, filename, bytenr,
                                                &recover->bad_supers);
                        if (ret)
                                goto out;
                }
        }
+       ret = 0;
 out:
        close(fd);
        return ret;
-- 
2.10.0



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