Re: [PATCH 01/22] ext4: add ext4_mpage_readpages()

[Theodore Ts'o <tytso@mit.edu>]

On Mon, Apr 06, 2015 at 03:08:51PM -0600, Andreas Dilger wrote:
> On Apr 2, 2015, at 4:10 PM, Theodore Ts'o <tytso@mit.edu> wrote:
> > 
> > This takes code from fs/mpage.c and optimizes it for ext4.  Its
> > primary reason is to allow us to more easily add encryption to ext4's
> > read path in an efficient manner.
> > 
> [snip]
> > diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
> > new file mode 100644
> > index 0000000..9ca4dfc
> > --- /dev/null
> > +++ b/fs/ext4/readpage.c
> > @@ -0,0 +1,261 @@
> > +/*
> > + * linux/fs/ext4/readpage.c
> > + *
> > + * This was originally taken from fs/mpage.c
> > + *
> > + * The intent is the ext4_mpage_readpages() function here is intended
> > + * to replace mpage_readpages() in the general case, not just for
> > + * encrypted files.  It has some limitations (see below), where it
> > + * will fall back to read_block_full_page(), but these limitations
> > + * should never be hit when page_size != block_size.
> 
> Shouldn't this be "... should never be hit when page_size == block_size"?
> Otherwise, we'd hit them almost all the time...

Yes, or maybe "should only be hit when...".  Thanks, good catch.

          	      	      	      	  - Ted