[1/2] btrfs-progs: Return more meaningful value for btrfs_read_dev_super
diff mbox

Message ID 20160920021902.818-1-quwenruo@cn.fujitsu.com
State New
Headers show

Commit Message

Qu Wenruo Sept. 20, 2016, 2:19 a.m. UTC
btrfs_read_dev_super() only returns 0 or -1, which doesn't really help,
caller won't know if it's caused by bad superblock or superblock out of
range.

Change it to return -ENOENT for superblock which is out of range, and
return -EIO for bad superblocks.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
---
 disk-io.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

Comments

David Sterba Sept. 23, 2016, 1:22 p.m. UTC | #1
On Tue, Sep 20, 2016 at 10:19:01AM +0800, Qu Wenruo wrote:
> btrfs_read_dev_super() only returns 0 or -1, which doesn't really help,
> caller won't know if it's caused by bad superblock or superblock out of
> range.
> 
> Change it to return -ENOENT for superblock which is out of range, and
> return -EIO for bad superblocks.
> 
> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
> ---
>  disk-io.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/disk-io.c b/disk-io.c
> index 854c285..26852ee 100644
> --- a/disk-io.c
> +++ b/disk-io.c
> @@ -1590,14 +1590,15 @@ int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr,
>  
>  	if (sb_bytenr != BTRFS_SUPER_INFO_OFFSET) {
>  		ret = pread64(fd, buf, BTRFS_SUPER_INFO_SIZE, sb_bytenr);

pread64 sets errno, should be returned

> +		/* Special return value for out of dev/file range */
>  		if (ret < BTRFS_SUPER_INFO_SIZE)
> -			return -1;
> +			return -ENOENT;
>  
>  		if (btrfs_super_bytenr(buf) != sb_bytenr)
> -			return -1;
> +			return -EIO;
>  
>  		if (check_super(buf, sbflags))
> -			return -1;
> +			return -EIO;

and we should return what check_super returns, though it's -EIO in most
cases.
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Patch
diff mbox

diff --git a/disk-io.c b/disk-io.c
index 854c285..26852ee 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -1590,14 +1590,15 @@  int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr,
 
 	if (sb_bytenr != BTRFS_SUPER_INFO_OFFSET) {
 		ret = pread64(fd, buf, BTRFS_SUPER_INFO_SIZE, sb_bytenr);
+		/* Special return value for out of dev/file range */
 		if (ret < BTRFS_SUPER_INFO_SIZE)
-			return -1;
+			return -ENOENT;
 
 		if (btrfs_super_bytenr(buf) != sb_bytenr)
-			return -1;
+			return -EIO;
 
 		if (check_super(buf, sbflags))
-			return -1;
+			return -EIO;
 		memcpy(sb, buf, BTRFS_SUPER_INFO_SIZE);
 		return 0;
 	}
@@ -1641,7 +1642,7 @@  int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr,
 		}
 	}
 
-	return transid > 0 ? 0 : -1;
+	return transid > 0 ? 0 : -EIO;
 }
 
 static int write_dev_supers(struct btrfs_root *root,