* Proper way to get device file minor number from struct file
@ 2016-07-10 15:22 Matwey V. Kornilov
2016-07-10 16:02 ` Bjørn Mork
0 siblings, 1 reply; 2+ messages in thread
From: Matwey V. Kornilov @ 2016-07-10 15:22 UTC (permalink / raw)
To: kernelnewbies
Hello,
I am looking through some legacy out of tree custom linux kernel device
driver.
It is full of lines like the following:
iminor(fp->f_dentry->d_inode)
here struct file *fp is an argument of callback of struct file_operations.
Documentation/filesystems/porting says:
"f_dentry is gone; use f_path.dentry, or, better yet, see if you can
avoid it entirely"
So, is there a proper compatible way to do the same?
^ permalink raw reply [flat|nested] 2+ messages in thread
* Proper way to get device file minor number from struct file
2016-07-10 15:22 Proper way to get device file minor number from struct file Matwey V. Kornilov
@ 2016-07-10 16:02 ` Bjørn Mork
0 siblings, 0 replies; 2+ messages in thread
From: Bjørn Mork @ 2016-07-10 16:02 UTC (permalink / raw)
To: kernelnewbies
"Matwey V. Kornilov" <matwey.kornilov@gmail.com> writes:
> Hello,
>
> I am looking through some legacy out of tree custom linux kernel device
> driver.
>
> It is full of lines like the following:
>
> iminor(fp->f_dentry->d_inode)
>
> here struct file *fp is an argument of callback of struct file_operations.
>
> Documentation/filesystems/porting says:
>
> "f_dentry is gone; use f_path.dentry, or, better yet, see if you can
> avoid it entirely"
>
> So, is there a proper compatible way to do the same?
Don't know how proper it is, but a "git grep iminor drivers/" shows that
minor = iminor(file_inode(file));
is a very common construct.
Or alternatively, do the iminor(inode) lookup once in open() to lookup
up your device struct or whatever, and then save that reference in
file->private_data, thereby avoiding the need to know the minor anywhere
else.
Bj?rn
^ permalink raw reply [flat|nested] 2+ messages in thread
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2016-07-10 15:22 Proper way to get device file minor number from struct file Matwey V. Kornilov
2016-07-10 16:02 ` Bjørn Mork
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