From: Hugh Dickins <hughd@google.com>
To: Lukas Czerner <lczerner@redhat.com>
Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
tytso@mit.edu, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 01/15] mm: add invalidatepage_range address space operation
Date: Tue, 21 Aug 2012 11:59:42 -0700 (PDT) [thread overview]
Message-ID: <alpine.LSU.2.00.1208211144550.2178@eggly.anvils> (raw)
In-Reply-To: <5033a999.0f403a0a.19c3.ffff95deSMTPIN_ADDED@mx.google.com>
On Tue, 21 Aug 2012, Lukas Czerner wrote:
> On Sun, 19 Aug 2012, Hugh Dickins wrote:
> > > --- a/include/linux/fs.h
> > > +++ b/include/linux/fs.h
> > > @@ -620,6 +620,8 @@ struct address_space_operations {
> > > /* Unfortunately this kludge is needed for FIBMAP. Don't use it */
> > > sector_t (*bmap)(struct address_space *, sector_t);
> > > void (*invalidatepage) (struct page *, unsigned long);
> > > + void (*invalidatepage_range) (struct page *, unsigned long,
> > > + unsigned long);
> >
> > It may turn out to be bad advice, given how invalidatepage() already
> > takes an unsigned long, but I'd be tempted to make both of these args
> > unsigned int, since that helps to make it clearer that they're intended
> > to be offsets within a page, in the range 0..PAGE_CACHE_SIZE.
> >
> > (partial_start, partial_end and top in truncate_inode_pages_range()
> > are all unsigned int.)
>
> Hmm, this does not seem right. I can see that PAGE_CACHE_SIZE
> (PAGE_SIZE) can be defined as unsigned long, or am I missing
> something ?
They would be defined as unsigned long so that they can be used in
masks like ~(PAGE_SIZE - 1), and behave as expected on addresses,
without needing casts to be added all over.
We do not (currently!) expect PAGE_SIZE or PAGE_CACHE_SIZE to grow
beyond an unsigned int - but indeed they can be larger than what's
held in an unsigned short (look no further than ia64 or ppc64).
For more reassurance, see include/linux/highmem.h, which declares
zero_user_segments() and others: unsigned int (well, unsigned with
the int implicit) for offsets within a page.
Hugh
> >
> > Andrew is very keen on naming arguments in prototypes,
> > and I think there is an especially strong case for it here.
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next prev parent reply other threads:[~2012-08-21 18:59 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-27 8:00 Add invalidatepage_range address space operation Lukas Czerner
2012-07-27 8:01 ` [PATCH 01/15] mm: add " Lukas Czerner
2012-08-20 5:24 ` Hugh Dickins
[not found] ` <5033a999.0f403a0a.19c3.ffff95deSMTPIN_ADDED@mx.google.com>
2012-08-21 18:59 ` Hugh Dickins [this message]
2012-07-27 8:01 ` [PATCH 02/15] jbd2: implement jbd2_journal_invalidatepage_range Lukas Czerner
2012-07-27 8:01 ` [PATCH 03/15] ext4: implement invalidatepage_range aop Lukas Czerner
2012-07-27 8:01 ` [PATCH 04/15] xfs: " Lukas Czerner
2012-07-27 8:01 ` [PATCH 05/15] ocfs2: " Lukas Czerner
2012-07-27 8:01 ` [PATCH 06/15] mm: teach truncate_inode_pages_range() to handle non page aligned ranges Lukas Czerner
2012-08-20 4:52 ` Hugh Dickins
2012-08-20 10:26 ` Lukáš Czerner
2012-08-20 15:47 ` Hugh Dickins
[not found] ` <50339e0d.69b2340a.50ba.ffff92bcSMTPIN_ADDED@mx.google.com>
2012-08-21 18:44 ` Hugh Dickins
2012-08-20 15:53 ` Hugh Dickins
2012-07-27 8:01 ` [PATCH 07/15] ext4: Take i_mutex before punching hole Lukas Czerner
2012-07-27 9:04 ` Lukáš Czerner
2012-07-27 12:08 ` Zheng Liu
2012-08-20 5:45 ` Hugh Dickins
2012-07-27 8:01 ` [PATCH 08/15] Revert "ext4: remove no longer used functions in inode.c" Lukas Czerner
2012-07-27 8:01 ` [PATCH 09/15] Revert "ext4: fix fsx truncate failure" Lukas Czerner
2012-07-27 8:01 ` [PATCH 10/15] ext4: use ext4_zero_partial_blocks in punch_hole Lukas Czerner
2012-07-27 8:01 ` [PATCH 11/15] ext4: remove unused discard_partial_page_buffers Lukas Czerner
2012-07-27 8:01 ` [PATCH 12/15] ext4: remove unused code from ext4_remove_blocks() Lukas Czerner
2012-07-27 8:01 ` [PATCH 13/15] ext4: update ext4_ext_remove_space trace point Lukas Czerner
2012-07-27 8:01 ` [PATCH 14/15] ext4: make punch hole code path work with bigalloc Lukas Czerner
2012-07-27 8:01 ` [PATCH 15/15] ext4: Allow punch hole with bigalloc enabled Lukas Czerner
2012-08-19 0:57 ` Add invalidatepage_range address space operation Theodore Ts'o
2012-08-20 4:43 ` Hugh Dickins
2012-08-20 13:23 ` Theodore Ts'o
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