Re: [PATCH] Separate FMODE_PREAD/FMODE_PWRITE into separate flags

From: Andrew Morton
Date: Wed Feb 04 2009 - 22:43:36 EST


On Wed, 4 Feb 2009 19:42:03 -0800 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:

> And I updated seq_file-properly-cope-with-pread.patch thusly:
>
> --- a/fs/seq_file.c~seq_file-properly-cope-with-pread-fix
> +++ a/fs/seq_file.c
> @@ -48,6 +48,16 @@ int seq_open(struct file *file, const st
> */
> file->f_version = 0;
>
> + /*
> + * seq_files support lseek() and pread(). They do not implement
> + * write() at all, but we clear FMODE_PWRITE here for historical
> + * reasons.
> + *
> + * If a client of seq_files a) implements file.write() and b) wishes to
> + * support pwrite() then that client will need to implement its own
> + * file.open() which calls seq_open() and then sets FMODE_WRITE.
^P
> + */
> + file->f_mode &= ~FMODE_PWRITE;
> return 0;
> }
> EXPORT_SYMBOL(seq_open);
--
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