Re: [PATCH] rd: Use a private inode for backing storage

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From: Christian Borntraeger
Date: Sunday, October 21, 2007 - 12:28 am

Am Sonntag, 21. Oktober 2007 schrieb Eric W. Biederman:

About being rare, when I force the VM to be more aggressive reclaiming buffer
by using the following patch:
--- linux-2.6.orig/fs/buffer.c
+++ linux-2.6/fs/buffer.c
@@ -3225,7 +3225,7 @@ void __init buffer_init(void)
 	 * Limit the bh occupancy to 10% of ZONE_NORMAL
 	 */
 	nrpages = (nr_free_buffer_pages() * 10) / 100;
-	max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
+	max_buffer_heads = 0;
 	hotcpu_notifier(buffer_cpu_notify, 0);
 }
 
I can actually cause data corruption within some seconds. So I think the
problem is real enough to be worth fixing.

I still dont fully understand what issues you have with my patch.
- it obviously fixes the problem
- I am not aware of any regression it introduces
- its small

One concern you had, was the fact that buffer heads are out of sync with 
struct pages. Testing your first patch revealed that this is actually needed
by reiserfs - and maybe others.
I can also see, that my patch looks a bit like a bandaid that cobbles the rd
pieces together.
Is there anything else, that makes my patch unmergeable in your opinion?


Christian






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Messages in current thread:
[PATCH resend] ramdisk: fix zeroed ramdisk pages on memory ..., Christian Borntraeger, (Mon Oct 15, 1:28 am)
Re: [PATCH resend] ramdisk: fix zeroed ramdisk pages on me ..., Christian Borntraeger, (Mon Oct 15, 2:05 am)
Re: [PATCH resend] ramdisk: fix zeroed ramdisk pages on me ..., Eric W. Biederman, (Mon Oct 15, 11:38 am)
Re: [PATCH resend] ramdisk: fix zeroed ramdisk pages on me ..., Eric W. Biederman, (Mon Oct 15, 3:37 pm)
[PATCH] rd: Preserve the dirty bit in init_page_buffers(), Eric W. Biederman, (Mon Oct 15, 3:40 pm)
[PATCH] rd: Mark ramdisk buffers heads dirty, Eric W. Biederman, (Mon Oct 15, 3:42 pm)
Re: [PATCH resend] ramdisk: fix zeroed ramdisk pages on me ..., Eric W. Biederman, (Mon Oct 15, 8:14 pm)
Re: [PATCH resend] ramdisk: fix zeroed ramdisk pages on me ..., Eric W. Biederman, (Mon Oct 15, 9:57 pm)
[patch][rfc] rewrite ramdisk, Nick Piggin, (Tue Oct 16, 12:47 am)
Re: [patch][rfc] rewrite ramdisk, Jan Engelhardt, (Tue Oct 16, 12:52 am)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Christian Borntraeger, (Tue Oct 16, 12:56 am)
Re: Re: [PATCH] rd: Mark ramdisk buffers heads dirty, rubenjr_22, (Tue Oct 16, 1:05 am)
Re: [patch][rfc] rewrite ramdisk, Nick Piggin, (Tue Oct 16, 1:07 am)
Re: Re: [PATCH] rd: Mark ramdisk buffers heads dirty, rubenjr_22, (Tue Oct 16, 1:13 am)
Re: [patch][rfc] rewrite ramdisk, Jan Engelhardt, (Tue Oct 16, 1:17 am)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Nick Piggin, (Tue Oct 16, 1:19 am)
Re: [patch][rfc] rewrite ramdisk, Nick Piggin, (Tue Oct 16, 1:26 am)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Christian Borntraeger, (Tue Oct 16, 1:48 am)
Re: [patch][rfc] rewrite ramdisk, Jan Engelhardt, (Tue Oct 16, 1:53 am)
Re: [patch][rfc] rewrite ramdisk, Eric W. Biederman, (Tue Oct 16, 2:08 am)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Eric W. Biederman, (Tue Oct 16, 2:22 am)
Re: [PATCH] rd: Preserve the dirty bit in init_page_buffers(), Eric W. Biederman, (Tue Oct 16, 2:35 am)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Eric W. Biederman, (Tue Oct 16, 12:06 pm)
Re: [patch][rfc] rewrite ramdisk, Theodore Tso, (Tue Oct 16, 2:28 pm)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Nick Piggin, (Tue Oct 16, 3:06 pm)
Re: [patch][rfc] rewrite ramdisk, Nick Piggin, (Tue Oct 16, 3:08 pm)
Re: [patch][rfc] rewrite ramdisk, Eric W. Biederman, (Tue Oct 16, 4:48 pm)
Re: [patch][rfc] rewrite ramdisk, Nick Piggin, (Tue Oct 16, 5:28 pm)
Re: [patch][rfc] rewrite ramdisk, Eric W. Biederman, (Tue Oct 16, 6:13 pm)
Re: [patch][rfc] rewrite ramdisk, Nick Piggin, (Tue Oct 16, 6:47 pm)
Re: [patch][rfc] rewrite ramdisk, Eric W. Biederman, (Wed Oct 17, 3:30 am)
Re: [patch][rfc] rewrite ramdisk, Nick Piggin, (Wed Oct 17, 5:49 am)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Christian Borntraeger, (Wed Oct 17, 9:14 am)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Eric W. Biederman, (Wed Oct 17, 10:57 am)
Re: [patch][rfc] rewrite ramdisk, Eric W. Biederman, (Wed Oct 17, 11:45 am)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Chris Mason, (Wed Oct 17, 12:14 pm)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Eric W. Biederman, (Wed Oct 17, 1:29 pm)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Chris Mason, (Wed Oct 17, 1:54 pm)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Eric W. Biederman, (Wed Oct 17, 2:30 pm)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Christian Borntraeger, (Wed Oct 17, 2:48 pm)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Eric W. Biederman, (Wed Oct 17, 3:22 pm)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Chris Mason, (Wed Oct 17, 3:58 pm)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Eric W. Biederman, (Wed Oct 17, 4:28 pm)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Chris Mason, (Wed Oct 17, 5:03 pm)
Re: [patch][rfc] rewrite ramdisk, Nick Piggin, (Wed Oct 17, 6:06 pm)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Eric W. Biederman, (Wed Oct 17, 8:27 pm)
[RFC][PATCH] block: Isolate the buffer cache in it's own m ..., Eric W. Biederman, (Wed Oct 17, 8:59 pm)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Christian Borntraeger, (Thu Oct 18, 2:26 am)
Re: [RFC][PATCH] block: Isolate the buffer cache in it's o ..., Eric W. Biederman, (Fri Oct 19, 2:27 pm)
Re: [RFC][PATCH] block: Isolate the buffer cache in it's o ..., Eric W. Biederman, (Fri Oct 19, 2:35 pm)
Re: [PATCH] rd: Mark ramdisk buffers heads dirty, Eric W. Biederman, (Fri Oct 19, 3:46 pm)
[PATCH] rd: Use a private inode for backing storage, Eric W. Biederman, (Fri Oct 19, 3:51 pm)
Re: [RFC][PATCH] block: Isolate the buffer cache in it's o ..., Eric W. Biederman, (Sat Oct 20, 9:53 pm)
Re: [PATCH] rd: Use a private inode for backing storage, Eric W. Biederman, (Sat Oct 20, 10:10 pm)
Re: [PATCH] rd: Use a private inode for backing storage, Nick Piggin, (Sat Oct 20, 10:24 pm)
Re: [PATCH] rd: Use a private inode for backing storage, Eric W. Biederman, (Sat Oct 20, 11:48 pm)
Re: [RFC][PATCH] block: Isolate the buffer cache in it's o ..., Eric W. Biederman, (Sun Oct 21, 12:09 am)
Re: [PATCH] rd: Use a private inode for backing storage, Christian Borntraeger, (Sun Oct 21, 12:28 am)
Re: [PATCH] rd: Use a private inode for backing storage, Eric W. Biederman, (Sun Oct 21, 1:23 am)
Re: [PATCH] rd: Use a private inode for backing storage, Eric W. Biederman, (Sun Oct 21, 10:56 am)
Re: [PATCH] rd: Use a private inode for backing storage, Eric W. Biederman, (Sun Oct 21, 11:39 am)