bufferhead: revert constructor removal (b98938c3) · Commits · 戴 / test

The constructor for buffer_head slabs was removed recently. We need the constructor back in slab defrag in order to insure that slab objects always have a definite state even before we allocated them. I think we mistakenly merged the removal of the constuctor into a cleanup patch. You (ie: akpm) had a test that showed that the removal of the constructor led to a small regression. The prior state makes things easier for slab defrag. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by:

Christoph Lameter <clameter@sgi.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

fs/buffer.c

+15 −3

Original line number	Diff line number	Diff line
		@@ -3153,7 +3153,7 @@ static void recalc_bh_state(void)

		struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
		{
		struct buffer_head *ret = kmem_cache_zalloc(bh_cachep,
		struct buffer_head *ret = kmem_cache_alloc(bh_cachep,
		set_migrateflags(gfp_flags, __GFP_RECLAIMABLE));
		if (ret) {
		INIT_LIST_HEAD(&ret->b_assoc_buffers);
		@@ -3241,12 +3241,24 @@ int bh_submit_read(struct buffer_head *bh)
		}
		EXPORT_SYMBOL(bh_submit_read);

		static void
		init_buffer_head(struct kmem_cache cachep, void data)
		{
		struct buffer_head *bh = data;

		memset(bh, 0, sizeof(*bh));
		INIT_LIST_HEAD(&bh->b_assoc_buffers);
		}

		void __init buffer_init(void)
		{
		int nrpages;

		bh_cachep = KMEM_CACHE(buffer_head,
		SLAB_RECLAIM_ACCOUNT\|SLAB_PANIC\|SLAB_MEM_SPREAD);
		bh_cachep = kmem_cache_create("buffer_head",
		sizeof(struct buffer_head), 0,
		(SLAB_RECLAIM_ACCOUNT\|SLAB_PANIC\|
		SLAB_MEM_SPREAD),
		init_buffer_head);

		/*
		* Limit the bh occupancy to 10% of ZONE_NORMAL

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