linux-kernel - Re: [RFC PATCH 1/6] shmem: use alloc_file instead of init

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Date:	Fri, 04 Dec 2009 09:19:13 -0500
From:	Eric Paris <eparis@...hat.com>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, viro@...iv.linux.org.uk, jmorris@...ei.org,
	npiggin@...e.de, zohar@...ibm.com, jack@...e.cz,
	jmalicki@...acarta.com, dsmith@...hat.com, serue@...ibm.com,
	hch@....de, john@...nmccutchan.com, rlove@...ve.org,
	ebiederm@...ssion.com, heiko.carstens@...ibm.com,
	penguin-kernel@...ove.SAKURA.ne.jp, mszeredi@...e.cz,
	jens.axboe@...cle.com, akpm@...ux-foundation.org, matthew@....cx,
	hugh.dickins@...cali.co.uk, kamezawa.hiroyu@...fujitsu.com,
	nishimura@....nes.nec.co.jp, davem@...emloft.net, arnd@...db.de,
	eric.dumazet@...il.com
Subject: Re: [RFC PATCH 1/6] shmem: use alloc_file instead of init_file

On Fri, 2009-12-04 at 06:58 +0100, Miklos Szeredi wrote:
> On Thu, 03 Dec 2009, Eric Paris wrote:
> > shmem uses get_empty_filp() and then init_file().  Their is no good reason
> > not to just use alloc_file() like everything else.
> 
> There's a more in this patch, though, and none of that is explained...
> 
> > 
> > Signed-off-by: Eric Paris <eparis@...hat.com>
> > ---
> > 
> >  mm/shmem.c |   20 ++++++++++----------
> >  1 files changed, 10 insertions(+), 10 deletions(-)
> > 
> > diff --git a/mm/shmem.c b/mm/shmem.c
> > index 356dd99..831f8bb 100644
> > --- a/mm/shmem.c
> > +++ b/mm/shmem.c
> > @@ -2640,32 +2640,32 @@ struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags
> >  	if (!dentry)
> >  		goto put_memory;
> >  
> > -	error = -ENFILE;
> > -	file = get_empty_filp();
> > -	if (!file)
> > -		goto put_dentry;
> > -
> >  	error = -ENOSPC;
> >  	inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0, flags);
> >  	if (!inode)
> > -		goto close_file;
> > +		goto put_dentry;
> >  
> >  	d_instantiate(dentry, inode);
> >  	inode->i_size = size;
> >  	inode->i_nlink = 0;	/* It is unlinked */
> > -	init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
> > -		  &shmem_file_operations);
> > +
> > +	error = -ENFILE;
> > +	file = alloc_file(shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
> > +			  &shmem_file_operations);
> > +	if (!file)
> > +		goto put_dentry;
> >  
> >  #ifndef CONFIG_MMU
> >  	error = ramfs_nommu_expand_for_mapping(inode, size);
> >  	if (error)
> >  		goto close_file;
> >  #endif
> > -	ima_counts_get(file);
> 
> Where's this gone?

That's the impetuous for the whole patch series.  I originally did the
ima rework first an the vfs changes second, but decided to push the vfs
stuff first and I guess I forgot to back out this bit of ima change I
had done.  This will be dropped for actual submission. 

> >  	return file;
> >  
> > +#ifndef CONFIG_MMU
> >  close_file:
> 
> I suggest moving this piece of cleanup into the ifdef above, instead
> of adding more ifdefs.

Ok.

> > -	put_filp(file);
> > +	fput(file);
> 
> OK, put_filp() seems to have been wrong here, but please document it
> in the changelog.

It was only wrong in the ifndef !CONFIG_MMU case.  The other error path
which ended up here used it correctly.  In any case, I'll mention it in
the changelog.

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