[2.6 patch] dm: remove unused functions (fwd)

[2.6 patch] dm: remove unused functions (fwd)

[Adrian Bunk]

The patch forwarded below still applies and compiles against 
2.6.10-rc2-mm3.

Please apply or comment on it.


----- Forwarded message from Adrian Bunk <bunk@stusta.de> -----

Date:	Fri, 29 Oct 2004 02:15:49 +0200
From: Adrian Bunk <bunk@stusta.de>
To: dm-devel@redhat.com
Cc: linux-kernel@vger.kernel.org
Subject: [2.6 patch] dm: remove unused functions

[ this time without the problems due to a digital signature... ]

The patch below removes two unsed functions from dm code.


diffstat output:
 drivers/md/dm-io.c   |   16 ----------------
 drivers/md/dm-snap.c |    5 -----
 2 files changed, 21 deletions(-)


Signed-off-by: Adrian Bunk <bunk@stusta.de>

--- linux-2.6.10-rc1-mm1-full/drivers/md/dm-io.c.old	2004-10-28 23:03:35.000000000 +0200
+++ linux-2.6.10-rc1-mm1-full/drivers/md/dm-io.c	2004-10-28 23:03:44.000000000 +0200
@@ -149,22 +149,6 @@
 	return 0;
 }
 
-static inline void bs_bio_init(struct bio *bio)
-{
-	bio->bi_next = NULL;
-	bio->bi_flags = 1 << BIO_UPTODATE;
-	bio->bi_rw = 0;
-	bio->bi_vcnt = 0;
-	bio->bi_idx = 0;
-	bio->bi_phys_segments = 0;
-	bio->bi_hw_segments = 0;
-	bio->bi_size = 0;
-	bio->bi_max_vecs = 0;
-	bio->bi_end_io = NULL;
-	atomic_set(&bio->bi_cnt, 1);
-	bio->bi_private = NULL;
-}
-
 static unsigned _bio_count = 0;
 struct bio *bio_set_alloc(struct bio_set *bs, int gfp_mask, int nr_iovecs)
 {
--- linux-2.6.10-rc1-mm1-full/drivers/md/dm-snap.c.old	2004-10-28 23:04:16.000000000 +0200
+++ linux-2.6.10-rc1-mm1-full/drivers/md/dm-snap.c	2004-10-28 23:04:24.000000000 +0200
@@ -271,11 +271,6 @@
 	return e;
 }
 
-static inline void free_exception(struct exception *e)
-{
-	kmem_cache_free(exception_cache, e);
-}
-
 static inline struct pending_exception *alloc_pending_exception(void)
 {
 	return mempool_alloc(pending_pool, GFP_NOIO);
-
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----- End forwarded message -----

Re: [2.6 patch] dm: remove unused functions (fwd)

[Alasdair G Kergon]

On Mon, Nov 29, 2004 at 03:29:40AM +0100, Adrian Bunk wrote:
> Please apply or comment on it.
 
Please check *why* the functions aren't used first.

e.g. An alloc function with a corresponding free that
never gets called suggests a leak to me...
 
Alasdair
-- 
agk@redhat.com

Re: [2.6 patch] dm: remove unused functions (fwd)

[Adrian Bunk]

On Tue, Nov 30, 2004 at 11:05:25PM +0000, Alasdair G Kergon wrote:
> On Mon, Nov 29, 2004 at 03:29:40AM +0100, Adrian Bunk wrote:
> > Please apply or comment on it.
>  
> Please check *why* the functions aren't used first.
> 
> e.g. An alloc function with a corresponding free that
> never gets called suggests a leak to me...

I have to admit that I don't thoroughly check the code where I find
unused code. That's why I asked for comments on this patch. Ususally the 
maintainers of the code in question know best whether such a patch is 
correct or not.

Simply consider my patches as some kind of "list of unused functions".

> Alasdair

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

Re: [dm-devel] Re: [2.6 patch] dm: remove unused functions (fwd)

[Kevin Corry]

On Tuesday 30 November 2004 5:05 pm, Alasdair G Kergon wrote:
> On Mon, Nov 29, 2004 at 03:29:40AM +0100, Adrian Bunk wrote:
> > Please apply or comment on it.
>
> Please check *why* the functions aren't used first.
>
> e.g. An alloc function with a corresponding free that
> never gets called suggests a leak to me...

That one isn't a leak (referring to "kmem_cache_t *exception_cache" in 
dm-snap.c). Items are allocated from this cache using alloc_exception(). This 
can happen either when an existing snapshot is activated and it's exception 
table is read from disk into an in-memory hash-table, or when a copy-on-write 
completes and a new exception is added to this hash-table. As long as the 
snapshot is active, this hash-table remains in memory and items cannot be 
removed from it. When the snapshot is deactivated, we call 
exit_exception_table() and pass it a pointer to this hash-table and 
exception_cache. This routine calls kmem_cache_free() directly instead of 
using the free_exception() routine. The reason it doesn't use 
free_exception() is that exit_exception_table() is used to tear down two 
different but somewhat similar hash-tables, each of which uses a different 
kmem_cache_t.

So, it may be nice to keep the symmetric routines defined (alloc_exception() 
and free_exception()), but Adrian is correct in that the later is not being 
used, and it really can't be used without some more significant code changes.

As for bs_bio_init(), it can be safely removed. It was just a duplicate of 
bio_init() from fs/bio.c. The use of that call in dm-io.c was changed to use 
bio_init(), but apparently the routine itself was never removed.

-- 
Kevin Corry
kevcorry@us.ibm.com
http://evms.sourceforge.net/