Re: [ANNOUNCEMENT PATCH COW] proof of concept impementation of cowlinks

[Rob Landley]

On Tuesday 11 May 2004 09:08, Jan Harkes wrote:

> int my_file_sendfile(struct file *in_file, loff_t *ppos, size_t count,
> 		     read_actor_t actor, void __user *target)
> {
>     struct file *out_file = NULL;
>
>     /* We have to check the read_actor callback function to see if the
>      * target actually points at a struct file. */
>     if (actor != file_send_actor)
> 	goto copy_local;
>
>     /* are both source and destination within the same file system
>      * mountpoint? */
>     if (in_file->f_dentry->d_inode->i_sb !=
> out_file->f_dentry->d_inode->i_sb) goto copy_local;
>
>     /* are we copying the entire source file? */
>     if (*ppos != 0 || count != in_file->f_dentry->d_inode->i_size)
> 	goto copy_local;

Is there a race condition for i_size to change between the api getting called 
and the copy being done?  More to the point, is there some way to specify a 
count of -1 or something to easily say "to end of file"?

Rob
-- 
www.linucon.org: Linux Expo and Science Fiction Convention
October 8-10, 2004 in Austin Texas.  (I'm the con chair.)


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