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| author | David Sterba <dsterba@suse.com> | 2015-02-16 21:36:47 +0300 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2015-10-10 19:40:04 +0300 |
| commit | a83342aa0c8f0ca90057d3837ae8d198186e5153 (patch) | |
| tree | 723d60098638e0f048ae630399d2f77d0e1a0c9d /fs/btrfs | |
| parent | 33a9eca7e4a4c2c17aebbb11f0e506a48ebc30c9 (diff) | |
| download | linux-a83342aa0c8f0ca90057d3837ae8d198186e5153.tar.xz | |
btrfs: add comments to barriers before waitqueue_active
Reduce number of undocumented barriers out there.
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/compression.c | 3 | ||||
| -rw-r--r-- | fs/btrfs/extent-tree.c | 3 | ||||
| -rw-r--r-- | fs/btrfs/locking.c | 3 | ||||
| -rw-r--r-- | fs/btrfs/ordered-data.c | 6 | ||||
| -rw-r--r-- | fs/btrfs/transaction.c | 3 |
5 files changed, 16 insertions, 2 deletions
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index 57ee8ca29b06..3a9317ce67f8 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -839,6 +839,9 @@ static void free_workspace(int type, struct list_head *workspace) btrfs_compress_op[idx]->free_workspace(workspace); atomic_dec(alloc_workspace); wake: + /* + * Make sure counter is updated before we wake up waiters. + */ smp_mb(); if (waitqueue_active(workspace_wait)) wake_up(workspace_wait); diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 9f9604201333..59eb92f65c62 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -10363,8 +10363,7 @@ void btrfs_end_write_no_snapshoting(struct btrfs_root *root) { percpu_counter_dec(&root->subv_writers->counter); /* - * Make sure counter is updated before we wake up - * waiters. + * Make sure counter is updated before we wake up waiters. */ smp_mb(); if (waitqueue_active(&root->subv_writers->wait)) diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index d7e6baf1b205..03f8630dbaf2 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -280,6 +280,9 @@ void btrfs_tree_unlock(struct extent_buffer *eb) if (blockers) { WARN_ON(atomic_read(&eb->spinning_writers)); atomic_dec(&eb->blocking_writers); + /* + * Make sure counter is updated before we wake up waiters. + */ smp_mb(); if (waitqueue_active(&eb->write_lock_wq)) wake_up(&eb->write_lock_wq); diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c index 52170cf1757e..071005f008c1 100644 --- a/fs/btrfs/ordered-data.c +++ b/fs/btrfs/ordered-data.c @@ -345,6 +345,9 @@ int btrfs_dec_test_first_ordered_pending(struct inode *inode, if (entry->bytes_left == 0) { ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags); + /* + * Implicit memory barrier after test_and_set_bit + */ if (waitqueue_active(&entry->wait)) wake_up(&entry->wait); } else { @@ -409,6 +412,9 @@ have_entry: if (entry->bytes_left == 0) { ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags); + /* + * Implicit memory barrier after test_and_set_bit + */ if (waitqueue_active(&entry->wait)) wake_up(&entry->wait); } else { diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index e8e5b5a10719..3fd70f797b7d 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -861,6 +861,9 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans, atomic_dec(&cur_trans->num_writers); extwriter_counter_dec(cur_trans, trans->type); + /* + * Make sure counter is updated before we wake up waiters. + */ smp_mb(); if (waitqueue_active(&cur_trans->writer_wait)) wake_up(&cur_trans->writer_wait); |