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From: Nikita Danilov <nikita@clusterfs.com>
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Date: Fri, 14 Apr 2006 14:20:36 +0400
To: Linus Torvalds <torvalds@osdl.org>
Cc: Andrew Morton <akpm@osdl.org>, Dan Bonachea <bonachead@comcast.net>,
       linux-kernel@vger.kernel.org
Subject: Re: PROBLEM: pthread-safety bug in write(2) on Linux 2.6.x
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Linus Torvalds writes:
 > 

[...]

 > + * so it's ok to test it independently on the lock/unlock path
 > + * rather than explicitly remembering whether we locked it.
 > + */
 > +static inline loff_t file_pos_read_lock(struct file *file)
 >  {
 > +	if (file->f_mode & FMODE_LSEEK)
 > +		mutex_lock(&file->f_pos_lock);
 >  	return file->f_pos;
 >  }
 >  
 > -static inline void file_pos_write(struct file *file, loff_t pos)
 > +static inline void file_pos_write_unlock(struct file *file, loff_t pos)
 >  {
 >  	file->f_pos = pos;
 > +	if (file->f_mode & FMODE_LSEEK)
 > +		mutex_unlock(&file->f_pos_lock);
 >  }

Naming of two functions above is confusing: it looks like read/write
lock is taken. Maybe file_pos_lock_and_get() and
file_pos_set_and_unlock()?

Nikita.