drbd: describe bitmap locking for bulk operation in finer detail

Now that we do no longer in-place endian-swap the bitmap, we allow
selected bitmap operations (testing bits, sometimes even settting bits)
during some bulk operations.

This caused us to hit a lot of FIXME asserts similar to
	FIXME asender in drbd_bm_count_bits,
	bitmap locked for 'write from resync_finished' by worker
Which now is nonsense: looking at the bitmap is perfectly legal
as long as it is not being resized.

This cosmetic patch defines some flags to describe expectations in finer
detail, so the asserts in e.g. bm_change_bits_to() can be skipped if
appropriate.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 20 insertions, 28 deletions

diff --git a/drivers/block/drbd/drbd_bitmap.c b/drivers/block/drbd/drbd_bitmap.c
index 25428bc28476..b62dd5f26c5d 100644
--- a/drivers/block/drbd/drbd_bitmap.c
+++ b/drivers/block/drbd/drbd_bitmap.c
@@ -104,26 +104,16 @@ struct drbd_bitmap {
 
         wait_queue_head_t bm_io_wait; /* used to serialize IO of single pages */
 
-        unsigned long  bm_flags;
+        enum bm_flag bm_flags;
 
         /* debugging aid, in case we are still racy somewhere */
         char          *bm_why;
         struct task_struct *bm_task;
 };
 
-/* definition of bits in bm_flags */
-#define BM_LOCKED       0
-// #define BM_MD_IO_ERROR  1 unused now.
-#define BM_P_VMALLOCED  2
-
 static int __bm_change_bits_to(struct drbd_conf *mdev, const unsigned long s,
                                unsigned long e, int val, const enum km_type km);
 
-static int bm_is_locked(struct drbd_bitmap *b)
-{
-        return test_bit(BM_LOCKED, &b->bm_flags);
-}
-
 #define bm_print_lock_info(m) __bm_print_lock_info(m, __func__)
 static void __bm_print_lock_info(struct drbd_conf *mdev, const char *func)
 {
@@ -140,7 +130,7 @@ static void __bm_print_lock_info(struct drbd_conf *mdev, const char *func)
             b->bm_task == mdev->worker.task   ? "worker"   : "?");
 }
 
-void drbd_bm_lock(struct drbd_conf *mdev, char *why)
+void drbd_bm_lock(struct drbd_conf *mdev, char *why, enum bm_flag flags)
 {
         struct drbd_bitmap *b = mdev->bitmap;
         int trylock_failed;
@@ -163,8 +153,9 @@ void drbd_bm_lock(struct drbd_conf *mdev, char *why)
                     b->bm_task == mdev->worker.task   ? "worker"   : "?");
                 mutex_lock(&b->bm_change);
         }
-        if (__test_and_set_bit(BM_LOCKED, &b->bm_flags))
+        if (BM_LOCKED_MASK & b->bm_flags)
                 dev_err(DEV, "FIXME bitmap already locked in bm_lock\n");
+        b->bm_flags |= flags & BM_LOCKED_MASK;
 
         b->bm_why  = why;
         b->bm_task = current;
@@ -178,9 +169,10 @@ void drbd_bm_unlock(struct drbd_conf *mdev)
                 return;
         }
 
-        if (!__test_and_clear_bit(BM_LOCKED, &mdev->bitmap->bm_flags))
+        if (!(BM_LOCKED_MASK & mdev->bitmap->bm_flags))
                 dev_err(DEV, "FIXME bitmap not locked in bm_unlock\n");
 
+        b->bm_flags &= ~BM_LOCKED_MASK;
         b->bm_why  = NULL;
         b->bm_task = NULL;
         mutex_unlock(&b->bm_change);
@@ -421,9 +413,9 @@ static struct page **bm_realloc_pages(struct drbd_bitmap *b, unsigned long want)
         }
 
         if (vmalloced)
-                set_bit(BM_P_VMALLOCED, &b->bm_flags);
+                b->bm_flags |= BM_P_VMALLOCED;
         else
-                clear_bit(BM_P_VMALLOCED, &b->bm_flags);
+                b->bm_flags &= ~BM_P_VMALLOCED;
 
         return new_pages;
 }
@@ -460,7 +452,7 @@ void drbd_bm_cleanup(struct drbd_conf *mdev)
 {
         ERR_IF (!mdev->bitmap) return;
         bm_free_pages(mdev->bitmap->bm_pages, mdev->bitmap->bm_number_of_pages);
-        bm_vk_free(mdev->bitmap->bm_pages, test_bit(BM_P_VMALLOCED, &mdev->bitmap->bm_flags));
+        bm_vk_free(mdev->bitmap->bm_pages, (BM_P_VMALLOCED & mdev->bitmap->bm_flags));
         kfree(mdev->bitmap);
         mdev->bitmap = NULL;
 }
@@ -623,7 +615,7 @@ int drbd_bm_resize(struct drbd_conf *mdev, sector_t capacity, int set_new_bits)
 
         ERR_IF(!b) return -ENOMEM;
 
-        drbd_bm_lock(mdev, "resize");
+        drbd_bm_lock(mdev, "resize", BM_LOCKED_MASK);
 
         dev_info(DEV, "drbd_bm_resize called with capacity == %llu\n",
                         (unsigned long long)capacity);
@@ -631,7 +623,7 @@ int drbd_bm_resize(struct drbd_conf *mdev, sector_t capacity, int set_new_bits)
         if (capacity == b->bm_dev_capacity)
                 goto out;
 
-        opages_vmalloced = test_bit(BM_P_VMALLOCED, &b->bm_flags);
+        opages_vmalloced = (BM_P_VMALLOCED & b->bm_flags);
 
         if (capacity == 0) {
                 spin_lock_irq(&b->bm_lock);
@@ -1030,7 +1022,7 @@ static int bm_rw(struct drbd_conf *mdev, int rw, unsigned lazy_writeout_upper_id
          * as we submit copies of pages anyways.
          */
         if (!ctx.flags)
-                WARN_ON(!bm_is_locked(b));
+                WARN_ON(!(BM_LOCKED_MASK & b->bm_flags));
 
         num_pages = b->bm_number_of_pages;
 
@@ -1220,7 +1212,7 @@ static unsigned long bm_find_next(struct drbd_conf *mdev,
         ERR_IF(!b->bm_pages) return i;
 
         spin_lock_irq(&b->bm_lock);
-        if (bm_is_locked(b))
+        if (BM_DONT_TEST & b->bm_flags)
                 bm_print_lock_info(mdev);
 
         i = __bm_find_next(mdev, bm_fo, find_zero_bit, KM_IRQ1);
@@ -1246,13 +1238,13 @@ unsigned long drbd_bm_find_next_zero(struct drbd_conf *mdev, unsigned long bm_fo
  * you must take drbd_bm_lock() first */
 unsigned long _drbd_bm_find_next(struct drbd_conf *mdev, unsigned long bm_fo)
 {
-        /* WARN_ON(!bm_is_locked(mdev)); */
+        /* WARN_ON(!(BM_DONT_SET & mdev->b->bm_flags)); */
         return __bm_find_next(mdev, bm_fo, 0, KM_USER1);
 }
 
 unsigned long _drbd_bm_find_next_zero(struct drbd_conf *mdev, unsigned long bm_fo)
 {
-        /* WARN_ON(!bm_is_locked(mdev)); */
+        /* WARN_ON(!(BM_DONT_SET & mdev->b->bm_flags)); */
         return __bm_find_next(mdev, bm_fo, 1, KM_USER1);
 }
 
@@ -1322,7 +1314,7 @@ static int bm_change_bits_to(struct drbd_conf *mdev, const unsigned long s,
         ERR_IF(!b->bm_pages) return 0;
 
         spin_lock_irqsave(&b->bm_lock, flags);
-        if (bm_is_locked(b))
+        if ((val ? BM_DONT_SET : BM_DONT_CLEAR) & b->bm_flags)
                 bm_print_lock_info(mdev);
 
         c = __bm_change_bits_to(mdev, s, e, val, KM_IRQ1);
@@ -1439,7 +1431,7 @@ int drbd_bm_test_bit(struct drbd_conf *mdev, const unsigned long bitnr)
         ERR_IF(!b->bm_pages) return 0;
 
         spin_lock_irqsave(&b->bm_lock, flags);
-        if (bm_is_locked(b))
+        if (BM_DONT_TEST & b->bm_flags)
                 bm_print_lock_info(mdev);
         if (bitnr < b->bm_bits) {
                 p_addr = bm_map_pidx(b, bm_bit_to_page_idx(b, bitnr));
@@ -1474,7 +1466,7 @@ int drbd_bm_count_bits(struct drbd_conf *mdev, const unsigned long s, const unsi
         ERR_IF(!b->bm_pages) return 1;
 
         spin_lock_irqsave(&b->bm_lock, flags);
-        if (bm_is_locked(b))
+        if (BM_DONT_TEST & b->bm_flags)
                 bm_print_lock_info(mdev);
         for (bitnr = s; bitnr <= e; bitnr++) {
                 unsigned int idx = bm_bit_to_page_idx(b, bitnr);
@@ -1522,7 +1514,7 @@ int drbd_bm_e_weight(struct drbd_conf *mdev, unsigned long enr)
         ERR_IF(!b->bm_pages) return 0;
 
         spin_lock_irqsave(&b->bm_lock, flags);
-        if (bm_is_locked(b))
+        if (BM_DONT_TEST & b->bm_flags)
                 bm_print_lock_info(mdev);
 
         s = S2W(enr);
@@ -1555,7 +1547,7 @@ unsigned long drbd_bm_ALe_set_all(struct drbd_conf *mdev, unsigned long al_enr)
         ERR_IF(!b->bm_pages) return 0;
 
         spin_lock_irq(&b->bm_lock);
-        if (bm_is_locked(b))
+        if (BM_DONT_SET & b->bm_flags)
                 bm_print_lock_info(mdev);
         weight = b->bm_set;