Re: [PATCH v2] fs: inode: return proper error code in bmap()

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



23. 7. 16. 08:36에 Dave Chinner 이(가) 쓴 글:
On Sat, Jul 15, 2023 at 05:22:04PM +0900, Leesoo Ahn wrote:
 > Return -EOPNOTSUPP instead of -EINVAL which has the meaning of
 > the argument is an inappropriate value. The current error code doesn't
> make sense to represent that a file system doesn't support bmap operation.
 >
 > Signed-off-by: Leesoo Ahn <lsahn@xxxxxxxxxxxxxx>
 > ---
 > Changes since v1:
 > - Modify the comments of bmap()
 > - Modify subject and description requested by Markus Elfring
> https://lore.kernel.org/lkml/20230715060217.1469690-1-lsahn@xxxxxxxxxxxxxx/
 >
 > fs/inode.c | 4 ++--
 > 1 file changed, 2 insertions(+), 2 deletions(-)
 >
 > diff --git a/fs/inode.c b/fs/inode.c
 > index 8fefb69e1f84..697c51ed226a 100644
 > --- a/fs/inode.c
 > +++ b/fs/inode.c
 > @@ -1831,13 +1831,13 @@ EXPORT_SYMBOL(iput);
> * 4 in ``*block``, with disk block relative to the disk start that holds that
 > * block of the file.
 > *
> - * Returns -EINVAL in case of error, 0 otherwise. If mapping falls into a > + * Returns -EOPNOTSUPP in case of error, 0 otherwise. If mapping falls into a
 > * hole, returns 0 and ``*block`` is also set to 0.
 > */
 > int bmap(struct inode *inode, sector_t *block)
 > {
 > if (!inode->i_mapping->a_ops->bmap)
 > - return -EINVAL;
 > + return -EOPNOTSUPP;
 >
 > *block = inode->i_mapping->a_ops->bmap(inode->i_mapping, *block);
 > return 0;

What about the CONFIG_BLOCK=n wrapper?
How does it work? Could you explain that in details, pls?
However, as far as I understand, bmap operation could be NULL even though CONFIG_BLOCK is enabled. It totally depends on the implementation of file systems.


Also, all the in kernel consumers squash this error back to 0, -EIO
or -EINVAL, so this change only ever propagates out to userspace via
the return from ioctl(FIBMAP). Do we really need to change this and
risk breaking userspace that handles -EINVAL correctly but not
-EOPNOTSUPP?
That's a consideration and we must carefully modify the APIs which communicate to users. But -EINVAL could be interpreted by two cases at this point that the first, for sure an argument from user to kernel is inappropriate, on the other hand, the second case would be that a file system doesn't support bmap operation. However, I don't think there is a proper way to know which one is right from user.

For me, the big problem is that user could get confused by these two cases with the same error code.

Best regards,
Leesoo



[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [NTFS 3]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [NTFS 3]     [Samba]     [Device Mapper]     [CEPH Development]

  Powered by Linux