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Commit 66657b318e0e443ada229fccd40c8be86cfebdbf

Authored by Josef Bacik
Committed by Chris Mason
1 parent 1fa11e265f
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

Btrfs: barrier before waitqueue_active 

We need a barrir before calling waitqueue_active otherwise we will miss
wakeups.  So in places that do atomic_dec(); then atomic_read() use
atomic_dec_return() which imply a memory barrier (see memory-barriers.txt)
and then add an explicit memory barrier everywhere else that need them.
Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>

Showing 5 changed files with 10 additions and 12 deletions Side-by-side Diff

fs/btrfs/compression.c
Diff comments   View file @ 66657b3
... ... @@ -818,6 +818,7 @@
818 818 btrfs_compress_op[idx]->free_workspace(workspace);
819 819 atomic_dec(alloc_workspace);
820 820 wake:
  821 + smp_mb();
821 822 if (waitqueue_active(workspace_wait))
822 823 wake_up(workspace_wait);
823 824 }
fs/btrfs/delayed-inode.c
Diff comments   View file @ 66657b3
... ... @@ -512,8 +512,8 @@
512 512  
513 513 rb_erase(&delayed_item->rb_node, root);
514 514 delayed_item->delayed_node->count--;
515   - atomic_dec(&delayed_root->items);
516   - if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND &&
  515 + if (atomic_dec_return(&delayed_root->items) <
  516 + BTRFS_DELAYED_BACKGROUND &&
517 517 waitqueue_active(&delayed_root->wait))
518 518 wake_up(&delayed_root->wait);
519 519 }
... ... @@ -1056,8 +1056,7 @@
1056 1056 delayed_node->count--;
1057 1057  
1058 1058 delayed_root = delayed_node->root->fs_info->delayed_root;
1059   - atomic_dec(&delayed_root->items);
1060   - if (atomic_read(&delayed_root->items) <
  1059 + if (atomic_dec_return(&delayed_root->items) <
1061 1060 BTRFS_DELAYED_BACKGROUND &&
1062 1061 waitqueue_active(&delayed_root->wait))
1063 1062 wake_up(&delayed_root->wait);
... ... @@ -754,9 +754,7 @@
754 754 limit = btrfs_async_submit_limit(fs_info);
755 755 limit = limit * 2 / 3;
756 756  
757   - atomic_dec(&fs_info->nr_async_submits);
758   -
759   - if (atomic_read(&fs_info->nr_async_submits) < limit &&
  757 + if (atomic_dec_return(&fs_info->nr_async_submits) < limit &&
760 758 waitqueue_active(&fs_info->async_submit_wait))
761 759 wake_up(&fs_info->async_submit_wait);
762 760  
763 761  
764 762  
... ... @@ -3783,14 +3781,17 @@
3783 3781 /* FIXME: cleanup wait for commit */
3784 3782 t->in_commit = 1;
3785 3783 t->blocked = 1;
  3784 + smp_mb();
3786 3785 if (waitqueue_active(&root->fs_info->transaction_blocked_wait))
3787 3786 wake_up(&root->fs_info->transaction_blocked_wait);
3788 3787  
3789 3788 t->blocked = 0;
  3789 + smp_mb();
3790 3790 if (waitqueue_active(&root->fs_info->transaction_wait))
3791 3791 wake_up(&root->fs_info->transaction_wait);
3792 3792  
3793 3793 t->commit_done = 1;
  3794 + smp_mb();
3794 3795 if (waitqueue_active(&t->commit_wait))
3795 3796 wake_up(&t->commit_wait);
3796 3797  
... ... @@ -1007,9 +1007,7 @@
1007 1007 nr_pages = (async_cow->end - async_cow->start + PAGE_CACHE_SIZE) >>
1008 1008 PAGE_CACHE_SHIFT;
1009 1009  
1010   - atomic_sub(nr_pages, &root->fs_info->async_delalloc_pages);
1011   -
1012   - if (atomic_read(&root->fs_info->async_delalloc_pages) <
  1010 + if (atomic_sub_return(nr_pages, &root->fs_info->async_delalloc_pages) <
1013 1011 5 * 1024 * 1024 &&
1014 1012 waitqueue_active(&root->fs_info->async_submit_wait))
1015 1013 wake_up(&root->fs_info->async_submit_wait);
... ... @@ -227,9 +227,8 @@
227 227 cur = pending;
228 228 pending = pending->bi_next;
229 229 cur->bi_next = NULL;
230   - atomic_dec(&fs_info->nr_async_bios);
231 230  
232   - if (atomic_read(&fs_info->nr_async_bios) < limit &&
  231 + if (atomic_dec_return(&fs_info->nr_async_bios) < limit &&
233 232 waitqueue_active(&fs_info->async_submit_wait))
234 233 wake_up(&fs_info->async_submit_wait);
235 234