On 2017年10月27日 15:54, Nikolay Borisov wrote:
>
>
> On 27.10.2017 10:31, Anand Jain wrote:
>> btrfs_read_dev_super() returns -1 upon not finding a suitable SB,
>> change that to return 1 instead, so that it can reserve the < 0
>> values for the errno communications.
>>
>> Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
>
> I believe this is buggy since it will be masking errors. We call
> btrfs_read_dev_super in open_ctree_with_broken_chunk if the function
> returns 1 we eventually exit as: return ERR_PTR(ret); And then perform
> IS_ERR on the returned value. IS_ERR is essentially:
> ((x) >= (unsigned long)-MAX_ERRNO) where x could be 1 and MAX_ERRNO is 4095
>
> So you just broke all functions which return the ret of
> btrfs_read_dev_super as ERR_PTR.
>
>
> NAK
This doesn't looks good to me either.
No suitable superblock is already an error.
Why not just returning -ENOENT and let caller who really needs to
distinguish this to catch that -ENOENT?
Thanks,
Qu
>
>> ---
>> An independent patch, not related to any recent patch sent to ML.
>>
>> disk-io.c | 2 +-
>> utils.c | 2 +-
>> volumes.c | 2 +-
>> 3 files changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/disk-io.c b/disk-io.c
>> index f5edc4796619..ba87bb4ce6da 100644
>> --- a/disk-io.c
>> +++ b/disk-io.c
>> @@ -1491,7 +1491,7 @@ int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr,
>> }
>> }
>>
>> - return transid > 0 ? 0 : -1;
>> + return transid > 0 ? 0 : 1;
>> }
>>
>> static int write_dev_supers(struct btrfs_fs_info *fs_info,
>> diff --git a/utils.c b/utils.c
>> index 524f463d3140..7574cda8151c 100644
>> --- a/utils.c
>> +++ b/utils.c
>> @@ -1678,7 +1678,7 @@ int get_fs_info(const char *path, struct btrfs_ioctl_fs_info_args *fi_args,
>> disk_super = (struct btrfs_super_block *)buf;
>> ret = btrfs_read_dev_super(fd, disk_super,
>> BTRFS_SUPER_INFO_OFFSET, 0);
>> - if (ret < 0) {
>> + if (ret) {
>> ret = -EIO;
>> goto out;
>> }
>> diff --git a/volumes.c b/volumes.c
>> index 2209e5a9100b..87008bfdd586 100644
>> --- a/volumes.c
>> +++ b/volumes.c
>> @@ -268,7 +268,7 @@ int btrfs_scan_one_device(int fd, const char *path,
>>
>> disk_super = (struct btrfs_super_block *)buf;
>> ret = btrfs_read_dev_super(fd, disk_super, super_offset, sbflags);
>> - if (ret < 0)
>> + if (ret)
>> return -EIO;
>> devid = btrfs_stack_device_id(&disk_super->dev_item);
>> if (btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_METADUMP)
>>
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