linux-kernel - Re: missing mnt_drop

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Date:	Wed, 26 Sep 2007 11:08:55 -0700
From:	Dave Hansen <haveblue@...ibm.com>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	hch@...radead.org
Subject: Re: missing mnt_drop_write() on open error

On Wed, 2007-09-26 at 19:50 +0200, Miklos Szeredi wrote:
> Maybe.  Can we do the mnt_want_write() from __dentry_open(), instead
> of may_open()?  That would be a lot cleaner.

I'll explore that.  It may make very good sense.

> Btw, may_open() doesn't do mnt_want_write() around the truncation if
> file is opened with O_TRUNC | O_RDONLY.

What's the path to may_open() in that case?  open_namei() should wrap
all callers other than nfs, and it does:

	/* O_TRUNC implies we need access checks for write permissions */
        if (flag & O_TRUNC)
                acc_mode |= MAY_WRITE;

Which should trigger the may_open() code.  

later in open_namei():
...
ok:
        error = may_open(nd, acc_mode, flag);
        if (error)
                goto exit;
        return 0;


-- Dave

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