On 10/27/2017 04:04 PM, Qu Wenruo wrote:
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 for pointing out. Will fix it. IMO, -ENOENT is good for now.
(Though the actual cleanup would be to..
There are two parts in btrfs_read_dev_super() one to read
only the BTRFS_SUPER_INFO_OFFSET SB. And the other to pick
the latest SB by generation #. So splitting them two separate
functions will let us know where do we use what in a much
clearer way. And for 2nd pread64 we should probably use errno.)
Thanks, Anand
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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