I'm very sorry that this patch breaks the open_ctree().
1) pread() only reads sizeof(struct btrfs_super_block), not
BTRFS_SUPER_INFO_SIZE.
Which makes csum always dismatch.
2) memcpy() uses wrong src(should be 'buf' not 'sb').
I'll send v2 version patch soon.
Thanks,
Qu
-------- Original Message --------
Subject: [PATCH] btrfs-progs: Check superblock's checksum in btrfs-progs.
From: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
To: linux-btrfs@xxxxxxxxxxxxxxx
Date: 2014年06月27日 10:34
Btrfs-progs will read the superblock without checking the checksum.
When all superblocks are corrupted, continuing will cause disaster.
So this patch will add checksum check for btrfs-progs when reading
superblocks.
Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
---
disk-io.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/disk-io.c b/disk-io.c
index 8db0335..3524834 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -990,7 +990,8 @@ int btrfs_scan_fs_devices(int fd, const char *path,
ret = btrfs_scan_one_device(fd, path, fs_devices,
&total_devs, sb_bytenr);
if (ret) {
- fprintf(stderr, "No valid Btrfs found on %s\n", path);
+ fprintf(stderr, "No valid Btrfs found or all superblock are corrupted on %s\n",
+ path);
return ret;
}
@@ -1100,7 +1101,7 @@ static struct btrfs_fs_info *__open_ctree_fd(int fp, const char *path,
else
ret = btrfs_read_dev_super(fp, disk_super, sb_bytenr);
if (ret) {
- printk("No valid btrfs found\n");
+ fprintf(stderr, "No valid btrfs found or all super blocks are corrupted\n");
goto out_devices;
}
@@ -1191,6 +1192,8 @@ int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr)
int ret;
u64 transid = 0;
u64 bytenr;
+ u32 crc;
+ char crc_result[BTRFS_CSUM_SIZE];
if (sb_bytenr != BTRFS_SUPER_INFO_OFFSET) {
ret = pread64(fd, &buf, sizeof(buf), sb_bytenr);
@@ -1226,6 +1229,14 @@ int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr)
if (btrfs_super_magic(&buf) != BTRFS_MAGIC)
continue;
+ /* check if the superblock is damaged */
+ crc = ~(u32)0;
+ crc = btrfs_csum_data(NULL, (char *)sb + BTRFS_CSUM_SIZE,
+ crc, BTRFS_SUPER_INFO_SIZE -
+ BTRFS_CSUM_SIZE);
+ btrfs_csum_final(crc, crc_result);
+ if (memcmp(crc_result, sb->csum, BTRFS_CSUM_SIZE))
+ continue;
if (!fsid_is_initialized) {
memcpy(fsid, buf.fsid, sizeof(fsid));
fsid_is_initialized = 1;
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
