raid5-ppl: use a single mempool for ppl_io_unit and header_page

Allocate both struct ppl_io_unit and its header_page from a shared
mempool to avoid a possible deadlock. Implement allocate and free
functions for the mempool, remove the second pool for allocating
header_page. The header_pages are now freed with their io_units, not
when the ppl bio completes. Also, use GFP_NOWAIT instead of GFP_ATOMIC
for allocating ppl_io_unit because we can handle failed allocations and
there is no reason to utilize emergency reserves.

Suggested-by: NeilBrown <neilb@suse.com>
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Signed-off-by: Shaohua Li <shli@fb.com>

diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
index 4eb0ebcf9c296c778a5b5f8dca7d1dc771a7ae74..5d25bebf3328e4967334465916aca3e3c750e447 100644 (file)
--- a/drivers/md/raid5-ppl.c
+++ b/drivers/md/raid5-ppl.c
@@ -102,7 +102,6 @@ struct ppl_conf {
        struct kmem_cache *io_kc;
        mempool_t *io_pool;
        struct bio_set *bs;
-       mempool_t *meta_pool;
 
        /* used only for recovery */
        int recovered_entries;
@@ -197,25 +196,55 @@ ops_run_partial_parity(struct stripe_head *sh, struct raid5_percpu *percpu,
        return tx;
 }
 
+static void *ppl_io_pool_alloc(gfp_t gfp_mask, void *pool_data)
+{
+       struct kmem_cache *kc = pool_data;
+       struct ppl_io_unit *io;
+
+       io = kmem_cache_alloc(kc, gfp_mask);
+       if (!io)
+               return NULL;
+
+       io->header_page = alloc_page(gfp_mask);
+       if (!io->header_page) {
+               kmem_cache_free(kc, io);
+               return NULL;
+       }
+
+       return io;
+}
+
+static void ppl_io_pool_free(void *element, void *pool_data)
+{
+       struct kmem_cache *kc = pool_data;
+       struct ppl_io_unit *io = element;
+
+       __free_page(io->header_page);
+       kmem_cache_free(kc, io);
+}
+
 static struct ppl_io_unit *ppl_new_iounit(struct ppl_log *log,
                                          struct stripe_head *sh)
 {
        struct ppl_conf *ppl_conf = log->ppl_conf;
        struct ppl_io_unit *io;
        struct ppl_header *pplhdr;
+       struct page *header_page;
 
-       io = mempool_alloc(ppl_conf->io_pool, GFP_ATOMIC);
+       io = mempool_alloc(ppl_conf->io_pool, GFP_NOWAIT);
        if (!io)
                return NULL;
 
+       header_page = io->header_page;
        memset(io, 0, sizeof(*io));
+       io->header_page = header_page;
+
        io->log = log;
        INIT_LIST_HEAD(&io->log_sibling);
        INIT_LIST_HEAD(&io->stripe_list);
        atomic_set(&io->pending_stripes, 0);
        bio_init(&io->bio, io->biovec, PPL_IO_INLINE_BVECS);
 
-       io->header_page = mempool_alloc(ppl_conf->meta_pool, GFP_NOIO);
        pplhdr = page_address(io->header_page);
        clear_page(pplhdr);
        memset(pplhdr->reserved, 0xff, PPL_HDR_RESERVED);
@@ -371,8 +400,6 @@ static void ppl_log_endio(struct bio *bio)
        if (bio->bi_error)
                md_error(ppl_conf->mddev, log->rdev);
 
-       mempool_free(io->header_page, ppl_conf->meta_pool);
-
        list_for_each_entry_safe(sh, next, &io->stripe_list, log_list) {
                list_del_init(&sh->log_list);
 
@@ -1007,7 +1034,6 @@ static void __ppl_exit_log(struct ppl_conf *ppl_conf)
 
        kfree(ppl_conf->child_logs);
 
-       mempool_destroy(ppl_conf->meta_pool);
        if (ppl_conf->bs)
                bioset_free(ppl_conf->bs);
        mempool_destroy(ppl_conf->io_pool);
@@ -1113,25 +1139,20 @@ int ppl_init_log(struct r5conf *conf)
 
        ppl_conf->io_kc = KMEM_CACHE(ppl_io_unit, 0);
        if (!ppl_conf->io_kc) {
-               ret = -EINVAL;
+               ret = -ENOMEM;
                goto err;
        }
 
-       ppl_conf->io_pool = mempool_create_slab_pool(conf->raid_disks, ppl_conf->io_kc);
+       ppl_conf->io_pool = mempool_create(conf->raid_disks, ppl_io_pool_alloc,
+                                          ppl_io_pool_free, ppl_conf->io_kc);
        if (!ppl_conf->io_pool) {
-               ret = -EINVAL;
+               ret = -ENOMEM;
                goto err;
        }
 
        ppl_conf->bs = bioset_create(conf->raid_disks, 0);
        if (!ppl_conf->bs) {
-               ret = -EINVAL;
-               goto err;
-       }
-
-       ppl_conf->meta_pool = mempool_create_page_pool(conf->raid_disks, 0);
-       if (!ppl_conf->meta_pool) {
-               ret = -EINVAL;
+               ret = -ENOMEM;
                goto err;
        }