raid5-ppl: move no_mem_stripes to struct ppl_conf

Use a single no_mem_stripes list instead of per member device lists for
handling stripes that need retrying in case of failed io_unit
allocation. Because io_units are allocated from a memory pool shared
between all member disks, the no_mem_stripes list should be checked when
an io_unit for any member is freed. This fixes a deadlock that could
happen if there are stripes in more than one no_mem_stripes list.

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 86ea9ad..355cf35 100644 (file)
--- a/drivers/md/raid5-ppl.c
+++ b/drivers/md/raid5-ppl.c
@@ -107,6 +107,10 @@ struct ppl_conf {
        /* used only for recovery */
        int recovered_entries;
        int mismatch_count;
+
+       /* stripes to retry if failed to allocate io_unit */
+       struct list_head no_mem_stripes;
+       spinlock_t no_mem_stripes_lock;
 };
 
 struct ppl_log {
@@ -119,8 +123,6 @@ struct ppl_log {
                                         * always at the end of io_list */
        spinlock_t io_list_lock;
        struct list_head io_list;       /* all io_units of this log */
-       struct list_head no_mem_stripes;/* stripes to retry if failed to
-                                        * allocate io_unit */
 };
 
 #define PPL_IO_INLINE_BVECS 32
@@ -347,9 +349,9 @@ int ppl_write_stripe(struct r5conf *conf, struct stripe_head *sh)
        atomic_inc(&sh->count);
 
        if (ppl_log_stripe(log, sh)) {
-               spin_lock_irq(&log->io_list_lock);
-               list_add_tail(&sh->log_list, &log->no_mem_stripes);
-               spin_unlock_irq(&log->io_list_lock);
+               spin_lock_irq(&ppl_conf->no_mem_stripes_lock);
+               list_add_tail(&sh->log_list, &ppl_conf->no_mem_stripes);
+               spin_unlock_irq(&ppl_conf->no_mem_stripes_lock);
        }
 
        mutex_unlock(&log->io_mutex);
@@ -492,25 +494,32 @@ void ppl_write_stripe_run(struct r5conf *conf)
 static void ppl_io_unit_finished(struct ppl_io_unit *io)
 {
        struct ppl_log *log = io->log;
+       struct ppl_conf *ppl_conf = log->ppl_conf;
        unsigned long flags;
 
        pr_debug("%s: seq: %llu\n", __func__, io->seq);
 
-       spin_lock_irqsave(&log->io_list_lock, flags);
+       local_irq_save(flags);
 
+       spin_lock(&log->io_list_lock);
        list_del(&io->log_sibling);
-       mempool_free(io, log->ppl_conf->io_pool);
+       spin_unlock(&log->io_list_lock);
+
+       mempool_free(io, ppl_conf->io_pool);
+
+       spin_lock(&ppl_conf->no_mem_stripes_lock);
+       if (!list_empty(&ppl_conf->no_mem_stripes)) {
+               struct stripe_head *sh;
 
-       if (!list_empty(&log->no_mem_stripes)) {
-               struct stripe_head *sh = list_first_entry(&log->no_mem_stripes,
-                                                         struct stripe_head,
-                                                         log_list);
+               sh = list_first_entry(&ppl_conf->no_mem_stripes,
+                                     struct stripe_head, log_list);
                list_del_init(&sh->log_list);
                set_bit(STRIPE_HANDLE, &sh->state);
                raid5_release_stripe(sh);
        }
+       spin_unlock(&ppl_conf->no_mem_stripes_lock);
 
-       spin_unlock_irqrestore(&log->io_list_lock, flags);
+       local_irq_restore(flags);
 }
 
 void ppl_stripe_write_finished(struct stripe_head *sh)
@@ -1135,6 +1144,8 @@ int ppl_init_log(struct r5conf *conf)
        }
 
        atomic64_set(&ppl_conf->seq, 0);
+       INIT_LIST_HEAD(&ppl_conf->no_mem_stripes);
+       spin_lock_init(&ppl_conf->no_mem_stripes_lock);
 
        if (!mddev->external) {
                ppl_conf->signature = ~crc32c_le(~0, mddev->uuid, sizeof(mddev->uuid));
@@ -1150,7 +1161,6 @@ int ppl_init_log(struct r5conf *conf)
                mutex_init(&log->io_mutex);
                spin_lock_init(&log->io_list_lock);
                INIT_LIST_HEAD(&log->io_list);
-               INIT_LIST_HEAD(&log->no_mem_stripes);
 
                log->ppl_conf = ppl_conf;
                log->rdev = rdev;