[PATCH 2/2] bcache: allocate meta data pages as compound pages

[Coly Li <colyli@suse.de>]

There are some meta data of bcache are allocated by multiple pages,
and they are used as bio bv_page for I/Os to the cache device. for
example cache_set->uuids, cache->disk_buckets, journal_write->data,
bset_tree->data.

For such meta data memory, all the allocated pages should be treated
as a single memory block. Then the memory management and underlying I/O
code can treat them more clearly.

This patch adds __GFP_COMP flag to all the location allocating >0 order
pages for the above mentioned meta data. Then their pages are treated
as compound pages now.

Signed-off-by: Coly Li <colyli@suse.de>
Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Jan Kara <jack@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Mikhail Skorzhinskii <mskorzhinskiy@solarflare.com>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Vlastimil Babka <vbabka@suse.com>
Cc: stable@vger.kernel.org
---
 drivers/md/bcache/bset.c    | 2 +-
 drivers/md/bcache/btree.c   | 2 +-
 drivers/md/bcache/journal.c | 4 ++--
 drivers/md/bcache/super.c   | 2 +-
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/md/bcache/bset.c b/drivers/md/bcache/bset.c
index 4995fcaefe29..67a2c47f4201 100644
--- a/drivers/md/bcache/bset.c
+++ b/drivers/md/bcache/bset.c
@@ -322,7 +322,7 @@ int bch_btree_keys_alloc(struct btree_keys *b,
 
 	b->page_order = page_order;
 
-	t->data = (void *) __get_free_pages(gfp, b->page_order);
+	t->data = (void *) __get_free_pages(__GFP_COMP|gfp, b->page_order);
 	if (!t->data)
 		goto err;
 
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 6548a601edf0..dd116c83de80 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -785,7 +785,7 @@ int bch_btree_cache_alloc(struct cache_set *c)
 	mutex_init(&c->verify_lock);
 
 	c->verify_ondisk = (void *)
-		__get_free_pages(GFP_KERNEL, ilog2(bucket_pages(c)));
+		__get_free_pages(GFP_KERNEL|__GFP_COMP, ilog2(bucket_pages(c)));
 
 	c->verify_data = mca_bucket_alloc(c, &ZERO_KEY, GFP_KERNEL);
 
diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c
index 90aac4e2333f..d8586b6ccb76 100644
--- a/drivers/md/bcache/journal.c
+++ b/drivers/md/bcache/journal.c
@@ -999,8 +999,8 @@ int bch_journal_alloc(struct cache_set *c)
 	j->w[1].c = c;
 
 	if (!(init_fifo(&j->pin, JOURNAL_PIN, GFP_KERNEL)) ||
-	    !(j->w[0].data = (void *) __get_free_pages(GFP_KERNEL, JSET_BITS)) ||
-	    !(j->w[1].data = (void *) __get_free_pages(GFP_KERNEL, JSET_BITS)))
+	    !(j->w[0].data = (void *) __get_free_pages(GFP_KERNEL|__GFP_COMP, JSET_BITS)) ||
+	    !(j->w[1].data = (void *) __get_free_pages(GFP_KERNEL|__GFP_COMP, JSET_BITS)))
 		return -ENOMEM;
 
 	return 0;
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 2014016f9a60..daa4626024a2 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1776,7 +1776,7 @@ void bch_cache_set_unregister(struct cache_set *c)
 }
 
 #define alloc_bucket_pages(gfp, c)			\
-	((void *) __get_free_pages(__GFP_ZERO|gfp, ilog2(bucket_pages(c))))
+	((void *) __get_free_pages(__GFP_ZERO|__GFP_COMP|gfp, ilog2(bucket_pages(c))))
 
 struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
 {
-- 
2.26.2