diff mbox series

[3/6] fs: clear FMODE_LSEEK if no llseek function

Message ID 20220624165631.2124632-4-Jason@zx2c4.com (mailing list archive)
State New, archived
Headers show
Series cleanup llseek and splice | expand

Commit Message

Jason A. Donenfeld June 24, 2022, 4:56 p.m. UTC 
This helps unify a longstanding wart where FMODE_LSEEK hasn't been
uniformly unset when it should be.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 fs/file_table.c | 2 ++
 fs/open.c       | 2 ++
 2 files changed, 4 insertions(+)

Comments

Al Viro June 24, 2022, 5:04 p.m. UTC | #1 
On Fri, Jun 24, 2022 at 06:56:28PM +0200, Jason A. Donenfeld wrote:
> This helps unify a longstanding wart where FMODE_LSEEK hasn't been
> uniformly unset when it should be.
> 
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
>  fs/file_table.c | 2 ++
>  fs/open.c       | 2 ++
>  2 files changed, 4 insertions(+)
> 
> diff --git a/fs/file_table.c b/fs/file_table.c
> index 5424e3a8df5f..15700b2e1b53 100644
> --- a/fs/file_table.c
> +++ b/fs/file_table.c
> @@ -241,6 +241,8 @@ static struct file *alloc_file(const struct path *path, int flags,
>  	if ((file->f_mode & FMODE_WRITE) &&
>  	     likely(fop->write || fop->write_iter))
>  		file->f_mode |= FMODE_CAN_WRITE;
> +	if ((file->f_mode & FMODE_LSEEK) && !file->f_op->llseek)
> +		file->f_mode &= ~FMODE_LSEEK;

	Where would FMODE_LSEEK come from in this one?  ->f_mode is set
(in __alloc_file()) to OPEN_FMODE(flags); that does deal with FMODE_READ
and FMODE_WRITE, but FMODE_LSEEK will be clear...
Jason A. Donenfeld June 24, 2022, 5:09 p.m. UTC | #2 
Hi Al,

On Fri, Jun 24, 2022 at 06:04:19PM +0100, Al Viro wrote:
> On Fri, Jun 24, 2022 at 06:56:28PM +0200, Jason A. Donenfeld wrote:
> > This helps unify a longstanding wart where FMODE_LSEEK hasn't been
> > uniformly unset when it should be.
> > 
> > Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> > ---
> >  fs/file_table.c | 2 ++
> >  fs/open.c       | 2 ++
> >  2 files changed, 4 insertions(+)
> > 
> > diff --git a/fs/file_table.c b/fs/file_table.c
> > index 5424e3a8df5f..15700b2e1b53 100644
> > --- a/fs/file_table.c
> > +++ b/fs/file_table.c
> > @@ -241,6 +241,8 @@ static struct file *alloc_file(const struct path *path, int flags,
> >  	if ((file->f_mode & FMODE_WRITE) &&
> >  	     likely(fop->write || fop->write_iter))
> >  		file->f_mode |= FMODE_CAN_WRITE;
> > +	if ((file->f_mode & FMODE_LSEEK) && !file->f_op->llseek)
> > +		file->f_mode &= ~FMODE_LSEEK;
> 
> 	Where would FMODE_LSEEK come from in this one?  ->f_mode is set
> (in __alloc_file()) to OPEN_FMODE(flags); that does deal with FMODE_READ
> and FMODE_WRITE, but FMODE_LSEEK will be clear...

From the `int flags` parameter of the function. That's an O flag not an
F flag, though, so I assume you mean that it's impossible to get LSEEK
there in practice? If so, I'll drop this hunk.

Jason
Al Viro June 24, 2022, 5:13 p.m. UTC | #3 
On Fri, Jun 24, 2022 at 07:09:17PM +0200, Jason A. Donenfeld wrote:
> Hi Al,
> 
> On Fri, Jun 24, 2022 at 06:04:19PM +0100, Al Viro wrote:
> > On Fri, Jun 24, 2022 at 06:56:28PM +0200, Jason A. Donenfeld wrote:
> > > This helps unify a longstanding wart where FMODE_LSEEK hasn't been
> > > uniformly unset when it should be.
> > > 
> > > Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> > > ---
> > >  fs/file_table.c | 2 ++
> > >  fs/open.c       | 2 ++
> > >  2 files changed, 4 insertions(+)
> > > 
> > > diff --git a/fs/file_table.c b/fs/file_table.c
> > > index 5424e3a8df5f..15700b2e1b53 100644
> > > --- a/fs/file_table.c
> > > +++ b/fs/file_table.c
> > > @@ -241,6 +241,8 @@ static struct file *alloc_file(const struct path *path, int flags,
> > >  	if ((file->f_mode & FMODE_WRITE) &&
> > >  	     likely(fop->write || fop->write_iter))
> > >  		file->f_mode |= FMODE_CAN_WRITE;
> > > +	if ((file->f_mode & FMODE_LSEEK) && !file->f_op->llseek)
> > > +		file->f_mode &= ~FMODE_LSEEK;
> > 
> > 	Where would FMODE_LSEEK come from in this one?  ->f_mode is set
> > (in __alloc_file()) to OPEN_FMODE(flags); that does deal with FMODE_READ
> > and FMODE_WRITE, but FMODE_LSEEK will be clear...
> 
> >From the `int flags` parameter of the function. That's an O flag not an
> F flag, though, so I assume you mean that it's impossible to get LSEEK
> there in practice? If so, I'll drop this hunk.

	if (file->f_op->llseek)
		file->f_mode |= FMODE_LSEEK;

you want it to match what came in file_operations...
Jason A. Donenfeld June 24, 2022, 5:17 p.m. UTC | #4 
Hi Al,

On Fri, Jun 24, 2022 at 06:13:29PM +0100, Al Viro wrote:
> On Fri, Jun 24, 2022 at 07:09:17PM +0200, Jason A. Donenfeld wrote:
> > Hi Al,
> > 
> > On Fri, Jun 24, 2022 at 06:04:19PM +0100, Al Viro wrote:
> > > On Fri, Jun 24, 2022 at 06:56:28PM +0200, Jason A. Donenfeld wrote:
> > > > This helps unify a longstanding wart where FMODE_LSEEK hasn't been
> > > > uniformly unset when it should be.
> > > > 
> > > > Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> > > > ---
> > > >  fs/file_table.c | 2 ++
> > > >  fs/open.c       | 2 ++
> > > >  2 files changed, 4 insertions(+)
> > > > 
> > > > diff --git a/fs/file_table.c b/fs/file_table.c
> > > > index 5424e3a8df5f..15700b2e1b53 100644
> > > > --- a/fs/file_table.c
> > > > +++ b/fs/file_table.c
> > > > @@ -241,6 +241,8 @@ static struct file *alloc_file(const struct path *path, int flags,
> > > >  	if ((file->f_mode & FMODE_WRITE) &&
> > > >  	     likely(fop->write || fop->write_iter))
> > > >  		file->f_mode |= FMODE_CAN_WRITE;
> > > > +	if ((file->f_mode & FMODE_LSEEK) && !file->f_op->llseek)
> > > > +		file->f_mode &= ~FMODE_LSEEK;
> > > 
> > > 	Where would FMODE_LSEEK come from in this one?  ->f_mode is set
> > > (in __alloc_file()) to OPEN_FMODE(flags); that does deal with FMODE_READ
> > > and FMODE_WRITE, but FMODE_LSEEK will be clear...
> > 
> > >From the `int flags` parameter of the function. That's an O flag not an
> > F flag, though, so I assume you mean that it's impossible to get LSEEK
> > there in practice? If so, I'll drop this hunk.
> 
> 	if (file->f_op->llseek)
> 		file->f_mode |= FMODE_LSEEK;
> 
> you want it to match what came in file_operations...

Oh, right. It's the opposite situation as open.c. I'll do it like that
for a v2 of the series.

Jason
diff mbox series

Patch

diff --git a/fs/file_table.c b/fs/file_table.c
index 5424e3a8df5f..15700b2e1b53 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -241,6 +241,8 @@  static struct file *alloc_file(const struct path *path, int flags,
 	if ((file->f_mode & FMODE_WRITE) &&
 	     likely(fop->write || fop->write_iter))
 		file->f_mode |= FMODE_CAN_WRITE;
+	if ((file->f_mode & FMODE_LSEEK) && !file->f_op->llseek)
+		file->f_mode &= ~FMODE_LSEEK;
 	file->f_mode |= FMODE_OPENED;
 	file->f_op = fop;
 	if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
diff --git a/fs/open.c b/fs/open.c
index 1d57fbde2feb..07c332753a36 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -858,6 +858,8 @@  static int do_dentry_open(struct file *f,
 	if ((f->f_mode & FMODE_WRITE) &&
 	     likely(f->f_op->write || f->f_op->write_iter))
 		f->f_mode |= FMODE_CAN_WRITE;
+	if ((f->f_mode & FMODE_LSEEK) && !f->f_op->llseek)
+		f->f_mode &= ~FMODE_LSEEK;
 	if (f->f_mapping->a_ops && f->f_mapping->a_ops->direct_IO)
 		f->f_mode |= FMODE_CAN_ODIRECT;