On Fri, Nov 24, 2023 at 6:18 AM Jan Kara <jack@xxxxxxx> wrote:
>
> On Wed 22-11-23 14:27:10, Amir Goldstein wrote:
> > In many of the vfs helpers, the rw_verity_area() checks are called before
> ^^ verify
>
> > taking sb_start_write(), making them "start-write-safe".
> > do_iter_write() is an exception to this rule.
> >
> > do_iter_write() has two callers - vfs_iter_write() and vfs_writev().
> > Move rw_verify_area() and other checks from do_iter_write() out to
> > its callers to make them "start-write-safe".
> >
> > Move also the fsnotify_modify() hook to align with similar pattern
> > used in vfs_write() and other vfs helpers.
> >
> > This is needed for fanotify "pre content" events.
> >
> > Suggested-by: Jan Kara <jack@xxxxxxx>
> > Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
> > Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
>
> Just one more nit below. Otherwise feel free to add:
>
> Reviewed-by: Jan Kara <jack@xxxxxxx>
>
>
> > diff --git a/fs/read_write.c b/fs/read_write.c
> > index 87ca50f16a23..6c40468efe19 100644
> > --- a/fs/read_write.c
> > +++ b/fs/read_write.c
> > @@ -852,28 +852,10 @@ EXPORT_SYMBOL(vfs_iter_read);
> > static ssize_t do_iter_write(struct file *file, struct iov_iter *iter,
> > loff_t *pos, rwf_t flags)
> > {
> > - size_t tot_len;
> > - ssize_t ret = 0;
> > -
> > - if (!(file->f_mode & FMODE_WRITE))
> > - return -EBADF;
> > - if (!(file->f_mode & FMODE_CAN_WRITE))
> > - return -EINVAL;
> > -
> > - tot_len = iov_iter_count(iter);
> > - if (!tot_len)
> > - return 0;
> > - ret = rw_verify_area(WRITE, file, pos, tot_len);
> > - if (ret < 0)
> > - return ret;
> > -
> > if (file->f_op->write_iter)
> > - ret = do_iter_readv_writev(file, iter, pos, WRITE, flags);
> > - else
> > - ret = do_loop_readv_writev(file, iter, pos, WRITE, flags);
> > - if (ret > 0)
> > - fsnotify_modify(file);
> > - return ret;
> > + return do_iter_readv_writev(file, iter, pos, WRITE, flags);
> > +
> > + return do_loop_readv_writev(file, iter, pos, WRITE, flags);
> > }
>
> Since do_iter_write() is now trivial and has only two callers, one of which
> has made sure file->f_op->write_iter != NULL, can we perhaps just fold this
> into the callers? One less wrapper in the maze...
Yeh, nice cleanup.
Cristian,
Can you please fold this patch:
diff --git a/fs/read_write.c b/fs/read_write.c
index 6c40468efe19..46a90aa0ad56 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -849,15 +849,6 @@ ssize_t vfs_iter_read(struct file *file, struct
iov_iter *iter, loff_t *ppos,
}
EXPORT_SYMBOL(vfs_iter_read);
-static ssize_t do_iter_write(struct file *file, struct iov_iter *iter,
- loff_t *pos, rwf_t flags)
-{
- if (file->f_op->write_iter)
- return do_iter_readv_writev(file, iter, pos, WRITE, flags);
-
- return do_loop_readv_writev(file, iter, pos, WRITE, flags);
-}
-
ssize_t vfs_iocb_iter_write(struct file *file, struct kiocb *iocb,
struct iov_iter *iter)
{
@@ -908,7 +899,7 @@ ssize_t vfs_iter_write(struct file *file, struct
iov_iter *iter, loff_t *ppos,
return ret;
file_start_write(file);
- ret = do_iter_write(file, iter, ppos, flags);
+ ret = do_iter_readv_writev(file, iter, ppos, WRITE, flags);
if (ret > 0)
fsnotify_modify(file);
file_end_write(file);
@@ -962,7 +953,10 @@ static ssize_t vfs_writev(struct file *file,
const struct iovec __user *vec,
goto out;
file_start_write(file);
- ret = do_iter_write(file, &iter, pos, flags);
+ if (file->f_op->write_iter)
+ ret = do_iter_readv_writev(file, &iter, pos, WRITE, flags);
+ else
+ ret = do_loop_readv_writev(file, &iter, pos, WRITE, flags);
if (ret > 0)
fsnotify_modify(file);
file_end_write(file);
--
