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SubjectRe: Re: For the condition "file->f_mode", when it failed, it should return EACCES rather than EBADF.
On Tue, Feb 05 2013, majianpeng wrote:
> >On Sun, Feb 03 2013, majianpeng wrote:
> >> Hi all,
> >> When I wanted to do discard operations,but i set the openflag was O_RDONLY,it returned a EBADF rather than EACCES or EPERM.
> >> I searched the code and found:
> >> >case BLKDISCARD:
> >> >case BLKSECDISCARD: {
> >> > uint64_t range[2];
> >>
> >> > if (!(mode & FMODE_WRITE))
> >> > return -EBADF;
> >> Initial i thought there was error.But i searched all code of kernel and found some places like this.
> >>
> >> The description of EBADF is "Bad file numbe". There are some places where returned EBADF like,
> >> >if (!f.file)
> >> > return -EBADF;
> >>
> >> So i think for checking file->f_mode when failed, it should return EACCESS.
> >
> >But that would break the ABI at this point. I agree with you, though,
> >EBADF is not the right error for this case.
> >
> >--
> >Jens Axboe
> >
> Sorry, can you explain in detail? Why can it break the ABI ?

Applications already depending on EBADF being returned for attempt to
discard on a file descriptor not opened for write. Granted it's a slim
possiblity, but it exists.

--
Jens Axboe



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