linux-kernel - Re: [RFC/PATCH] - revert generic_fillattr stat->blksize to PAGE_CACHE

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Date:	Mon, 6 Nov 2006 22:43:44 -0500
From:	Theodore Tso <tytso@....edu>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	Christoph Hellwig <hch@...radead.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: [RFC/PATCH] - revert generic_fillattr stat->blksize to PAGE_CACHE_SIZE

On Mon, Nov 06, 2006 at 05:15:27PM -0600, Eric Sandeen wrote:
> Christoph Hellwig wrote:
> > On Mon, Nov 06, 2006 at 03:50:02PM -0600, Eric Sandeen wrote:
> >> so I would propose the following patch to make PAGE_CACHE_SIZE the default (again), 
> >> and let filesystems which need something -else- do that on their own.
> > 
> > I agree with the conclusion, but the patch is incomplete.  You went down
> > all the way to find out what the fileystems do in this messages, so add
> > the hunks to override the defaults for non-standard filesystems to the
> > patch aswell to restore the pre-inode diet state.
> 
> Well, agreed.  I put 80% or more back to pre-patch state, but not all.
> :)  So it's less broken with my patch than without, so at least it's
> moving forward.  So... Ted's patches get in w/o fixing up all the other
> filesystems (left as an exercise to the patch reader) but mine can't? :)

Note that *I* wasn't the one who changed it from PAGE_CACHE_SIZE to (1
<< inode->i_blkbits).  This was done by Andrew.  (See below, from an
e-mail dated September 19th).

Given that Steve French was cc'ed, I assume this was done as a hack to
fix CIFS, but it was a bad idea; I agree that PAGE_CACHE_SIZE is a way
better default than (1 << inode->i_blkbits).

As far as fixing all of the other filesystems, I did *try*; I know I
screwed up with XFS, but that's because I still think the code is a
screaming horror of indirections that make it impossible to understand
what the heck is going on, and I guess I screwed up with CIFS.  Some
of the changes away from "pre inode diet" state were deliberate,
though, since some filesystems had very clearly broken "optimal I/O
sizes" of 512, and one even had something incredibly bogus that was
something like 96 bytes (!) if I remember correctly.

					- Ted


Subject: inode-diet-eliminate-i_blksize-and-use-a-per-superblock-default-fix-fix
From: Andrew Morton <akpm@...l.org>

Cc: <sbenni@....de>
Cc: Theodore Ts'o <tytso@....edu>
Cc: Steven French <sfrench@...ibm.com>,
Signed-off-by: Andrew Morton <akpm@...l.org>
---

 fs/stat.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -puN
fs/stat.c~inode-diet-eliminate-i_blksize-and-use-a-per-superblock-default-fix-fi
x fs/stat.c
---
a/fs/stat.c~inode-diet-eliminate-i_blksize-and-use-a-per-superblock-default-fix-
fix
+++ a/fs/stat.c
@@ -33,7 +33,7 @@ void generic_fillattr(struct inode *inod
        stat->ctime = inode->i_ctime;
        stat->size = i_size_read(inode);
        stat->blocks = inode->i_blocks;
-       stat->blksize = PAGE_CACHE_SIZE;
+       stat->blksize = (1 << inode->i_blkbits);
 }

 EXPORT_SYMBOL(generic_fillattr);
_

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