From: Hugh Dickins <hughd@google.com>
To: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
chris.mason@oracle.com
Subject: RE: [PATCH 1/14] mm: invalidate_mapping_pages flush cleancache
Date: Tue, 31 May 2011 10:05:27 -0700 (PDT) [thread overview]
Message-ID: <alpine.LSU.2.00.1105310951160.1719@sister.anvils> (raw)
In-Reply-To: <ba74b4e5-500e-4662-ade0-c0b714b8f570@default>
On Tue, 31 May 2011, Dan Magenheimer wrote:
> >
> > truncate_inode_pages_range() and invalidate_inode_pages2_range()
> > call cleancache_flush_inode(mapping) before and after: shouldn't
> > invalidate_mapping_pages() be doing the same?
>
> I don't claim to be an expert on VFS, and so I have cc'ed
> Chris Mason who originally placed the cleancache hooks
> in VFS, but I think this patch is unnecessary. Instead
> of flushing ALL of the cleancache pages belonging to
> the inode with cleancache_flush_inode, the existing code
> eventually calls __delete_from_page_cache on EACH page
> that is being invalidated.
On each one that's in pagecache (and satisfies the other "can we
do it easily?" conditions peculiar to invalidate_mapping_pages()).
But there may be other slots in the range that don't reach
__delete_from_page_cache() e.g. because not currently in pagecache,
but whose cleancache ought to be flushed. I think that's what a
caller of invalidate_mapping_pages(), e.g. drop caches, expects.
> And since __delete_from_page_cache
> calls cleancache_flush_page, only that subset of pages
> in the mapping that invalidate_mapping_pages() would
> invalidate (which, from the comment above the routine
> indicates, is only *unlocked* pages) is removed from
> cleancache.
It's nice to target the particular range asked for, rather than
throwing away all the cleancache for the whole mapping, I can
see that (though that's a defect in the cleancache_flush_inode()
interface). But then why do truncate_inode_pages_range() and
invalidate_inode_pages2_range() throw it all away, despite
going down to __delete_from_page_cache on individual pages found?
Maybe the right patch is to remove cleancache_flush_inode() from
the two instead of adding it to the one? But I think not.
Hugh
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next prev parent reply other threads:[~2011-05-31 17:05 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-31 0:33 [PATCH 0/14] mm: tmpfs and trunc changes, affecting drm Hugh Dickins
2011-05-31 0:35 ` [PATCH 1/14] mm: invalidate_mapping_pages flush cleancache Hugh Dickins
2011-05-31 15:49 ` Dan Magenheimer
2011-05-31 17:05 ` Hugh Dickins [this message]
2011-05-31 21:08 ` Chris Mason
2011-05-31 22:01 ` Hugh Dickins
2011-05-31 0:36 ` [PATCH 2/14] mm: move vmtruncate_range to truncate.c Hugh Dickins
2011-06-01 0:36 ` Christoph Hellwig
2011-05-31 0:39 ` [PATCH 3/14] tmpfs: take control of its truncate_range Hugh Dickins
2011-06-01 0:39 ` Christoph Hellwig
2011-06-01 16:58 ` Hugh Dickins
2011-06-03 5:16 ` Christoph Hellwig
2011-06-06 5:37 ` Hugh Dickins
2011-05-31 0:40 ` [PATCH 4/14] tmpfs: add shmem_read_mapping_page_gfp Hugh Dickins
2011-06-01 0:42 ` Christoph Hellwig
2011-06-01 17:02 ` Hugh Dickins
2011-05-31 0:42 ` [PATCH 5/14] drm/ttm: use shmem_read_mapping_page Hugh Dickins
2011-05-31 0:43 ` [PATCH 6/14] drm/i915: " Hugh Dickins
2011-05-31 0:45 ` [PATCH 7/14] drm/i915: adjust to new truncate_range Hugh Dickins
2011-06-01 0:43 ` Christoph Hellwig
2011-06-01 17:04 ` Hugh Dickins
2011-05-31 0:46 ` [PATCH 8/14] drm/i915: more struct_mutex locking Hugh Dickins
2011-05-31 0:48 ` [PATCH 9/14] mm: cleanup descriptions of filler arg Hugh Dickins
2011-05-31 0:49 ` [PATCH 10/14] mm: truncate functions are in truncate.c Hugh Dickins
2011-05-31 0:51 ` [PATCH 11/14] mm: tidy vmtruncate_range and related functions Hugh Dickins
2011-05-31 0:52 ` [PATCH 12/14] mm: consistent truncate and invalidate loops Hugh Dickins
2011-05-31 0:54 ` [PATCH 13/14] mm: pincer in truncate_inode_pages_range Hugh Dickins
2011-05-31 0:55 ` [PATCH 14/14] tmpfs: no need to use i_lock Hugh Dickins
2011-05-31 16:08 ` Tim Chen
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