raid5: allow r5l_io_unit allocations to fail

And propagate the error up the stack so we can add the stripe
to no_stripes_list and retry our log operation later.  This avoids
blocking raid5d due to reclaim, an it allows to get rid of the
deadlock-prone GFP_NOFAIL allocation.

shli: add missing mempool_destroy()

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: NeilBrown <neilb@suse.com>

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index fa2d6321f3a4b73e065fdc963828b3e25e168154..6d2b4789a928abd4c6058fb597e7fd9ce101660c 100644 (file)
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -75,7 +75,10 @@ struct r5l_log {
        struct list_head finished_ios;  /* io_units which settle down in log disk */
        struct bio flush_bio;
 
+       struct list_head no_mem_stripes;   /* pending stripes, -ENOMEM */
+
        struct kmem_cache *io_kc;
+       mempool_t *io_pool;
        struct bio_set *bs;
        mempool_t *meta_pool;
 
@@ -287,8 +290,11 @@ static struct r5l_io_unit *r5l_new_meta(struct r5l_log *log)
        struct r5l_io_unit *io;
        struct r5l_meta_block *block;
 
-       /* We can't handle memory allocate failure so far */
-       io = kmem_cache_zalloc(log->io_kc, GFP_NOIO | __GFP_NOFAIL);
+       io = mempool_alloc(log->io_pool, GFP_ATOMIC);
+       if (!io)
+               return NULL;
+       memset(io, 0, sizeof(*io));
+
        io->log = log;
        INIT_LIST_HEAD(&io->log_sibling);
        INIT_LIST_HEAD(&io->stripe_list);
@@ -326,8 +332,12 @@ static int r5l_get_meta(struct r5l_log *log, unsigned int payload_size)
            log->current_io->meta_offset + payload_size > PAGE_SIZE)
                r5l_submit_current_io(log);
 
-       if (!log->current_io)
+       if (!log->current_io) {
                log->current_io = r5l_new_meta(log);
+               if (!log->current_io)
+                       return -ENOMEM;
+       }
+
        return 0;
 }
 
@@ -372,11 +382,12 @@ static void r5l_append_payload_page(struct r5l_log *log, struct page *page)
        r5_reserve_log_entry(log, io);
 }
 
-static void r5l_log_stripe(struct r5l_log *log, struct stripe_head *sh,
+static int r5l_log_stripe(struct r5l_log *log, struct stripe_head *sh,
                           int data_pages, int parity_pages)
 {
        int i;
        int meta_size;
+       int ret;
        struct r5l_io_unit *io;
 
        meta_size =
@@ -385,7 +396,10 @@ static void r5l_log_stripe(struct r5l_log *log, struct stripe_head *sh,
                sizeof(struct r5l_payload_data_parity) +
                sizeof(__le32) * parity_pages;
 
-       r5l_get_meta(log, meta_size);
+       ret = r5l_get_meta(log, meta_size);
+       if (ret)
+               return ret;
+
        io = log->current_io;
 
        for (i = 0; i < sh->disks; i++) {
@@ -415,6 +429,8 @@ static void r5l_log_stripe(struct r5l_log *log, struct stripe_head *sh,
        list_add_tail(&sh->log_list, &io->stripe_list);
        atomic_inc(&io->pending_stripe);
        sh->log_io = io;
+
+       return 0;
 }
 
 static void r5l_wake_reclaim(struct r5l_log *log, sector_t space);
@@ -429,6 +445,7 @@ int r5l_write_stripe(struct r5l_log *log, struct stripe_head *sh)
        int meta_size;
        int reserve;
        int i;
+       int ret = 0;
 
        if (!log)
                return -EAGAIN;
@@ -477,17 +494,22 @@ int r5l_write_stripe(struct r5l_log *log, struct stripe_head *sh)
        mutex_lock(&log->io_mutex);
        /* meta + data */
        reserve = (1 + write_disks) << (PAGE_SHIFT - 9);
-       if (r5l_has_free_space(log, reserve))
-               r5l_log_stripe(log, sh, data_pages, parity_pages);
-       else {
+       if (!r5l_has_free_space(log, reserve)) {
                spin_lock(&log->no_space_stripes_lock);
                list_add_tail(&sh->log_list, &log->no_space_stripes);
                spin_unlock(&log->no_space_stripes_lock);
 
                r5l_wake_reclaim(log, reserve);
+       } else {
+               ret = r5l_log_stripe(log, sh, data_pages, parity_pages);
+               if (ret) {
+                       spin_lock_irq(&log->io_list_lock);
+                       list_add_tail(&sh->log_list, &log->no_mem_stripes);
+                       spin_unlock_irq(&log->io_list_lock);
+               }
        }
-       mutex_unlock(&log->io_mutex);
 
+       mutex_unlock(&log->io_mutex);
        return 0;
 }
 
@@ -540,6 +562,21 @@ static sector_t r5l_reclaimable_space(struct r5l_log *log)
                                 log->next_checkpoint);
 }
 
+static void r5l_run_no_mem_stripe(struct r5l_log *log)
+{
+       struct stripe_head *sh;
+
+       assert_spin_locked(&log->io_list_lock);
+
+       if (!list_empty(&log->no_mem_stripes)) {
+               sh = list_first_entry(&log->no_mem_stripes,
+                                     struct stripe_head, log_list);
+               list_del_init(&sh->log_list);
+               set_bit(STRIPE_HANDLE, &sh->state);
+               raid5_release_stripe(sh);
+       }
+}
+
 static bool r5l_complete_finished_ios(struct r5l_log *log)
 {
        struct r5l_io_unit *io, *next;
@@ -556,7 +593,8 @@ static bool r5l_complete_finished_ios(struct r5l_log *log)
                log->next_cp_seq = io->seq;
 
                list_del(&io->log_sibling);
-               kmem_cache_free(log->io_kc, io);
+               mempool_free(io, log->io_pool);
+               r5l_run_no_mem_stripe(log);
 
                found = true;
        }
@@ -1170,6 +1208,10 @@ int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
        if (!log->io_kc)
                goto io_kc;
 
+       log->io_pool = mempool_create_slab_pool(R5L_POOL_SIZE, log->io_kc);
+       if (!log->io_pool)
+               goto io_pool;
+
        log->bs = bioset_create(R5L_POOL_SIZE, 0);
        if (!log->bs)
                goto io_bs;
@@ -1184,6 +1226,8 @@ int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
                goto reclaim_thread;
        init_waitqueue_head(&log->iounit_wait);
 
+       INIT_LIST_HEAD(&log->no_mem_stripes);
+
        INIT_LIST_HEAD(&log->no_space_stripes);
        spin_lock_init(&log->no_space_stripes_lock);
 
@@ -1200,6 +1244,8 @@ reclaim_thread:
 out_mempool:
        bioset_free(log->bs);
 io_bs:
+       mempool_destroy(log->io_pool);
+io_pool:
        kmem_cache_destroy(log->io_kc);
 io_kc:
        kfree(log);
@@ -1211,6 +1257,7 @@ void r5l_exit_log(struct r5l_log *log)
        md_unregister_thread(&log->reclaim_thread);
        mempool_destroy(log->meta_pool);
        bioset_free(log->bs);
+       mempool_destroy(log->io_pool);
        kmem_cache_destroy(log->io_kc);
        kfree(log);
 }