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SubjectRe: [PATCH] obsolete config in kernel source (BUFFER_DEBUG)
Andrew Morton wrote:
> On Mon, 8 Feb 2010 10:50:31 -0500 tytso@mit.edu wrote:
>
>> I don't have an objection with removing this, but does anyone have the
>> latest version of akpm's buffer debugging patches?
>
> My version is datestamped four years ago :( It normally forward-ports
> fairly easily.
>
>> I *think* what happened is that akpm forward ported the removed buffer
>> debugging patches, or maybe rewrote it from scratch, but for whatever
>> reason they never made back into mainline. Maybe they were too ugly
>> to live in mainline, but they have been really handy on occasion.
>
> I think Eric Sandeen might have a fresher version.

If "fresh" means 2.6.18, I might ;)

But yes they sure have come in handy from time to time.

> Nowadays it should
> be done with the tracing infrastructure, I guess.

that's kind of what I was thinking, too.

-Eric

> Although that
> infrastructure may not be able to do this - the ext3 debug patch
> recorded an LRU array of the below structs within every buffer_head.
> The various BUFFER_TRACE macros would emit a new record into the tail of the
> target bh's b[] ring.
>
> struct buffer_history {
> struct buffer_history_item {
> char *function;
> char *info;
> unsigned long b_state;
> unsigned b_list:3;
> unsigned b_jlist:4;
> unsigned pg_dirty:1;
> unsigned cpu:3;
> unsigned b_count:8;
> unsigned long b_blocknr; /* For src != dest */
> #if defined(CONFIG_JBD) || defined(CONFIG_JBD_MODULE)
> unsigned b_jcount:4;
> unsigned b_jbd:1;
> unsigned b_transaction:1;
> unsigned b_next_transaction:1;
> unsigned b_cp_transaction:1;
> unsigned b_trans_is_running:1;
> unsigned b_trans_is_committing:1;
> void *b_frozen_data;
> void *b_committed_data;
> #endif
> } b[BUFFER_HISTORY_SIZE];
> unsigned long b_history_head; /* Next place to write */
> unsigned long b_history_tail; /* Oldest valid entry */
> };
>
> --
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