btrfs: assert that extent buffers are write locked instead of only locked

We currently use lockdep_assert_held() at btrfs_assert_tree_locked(), and
that checks that we hold a lock either in read mode or write mode.

However in all contexts we use btrfs_assert_tree_locked(), we actually
want to check if we are holding a write lock on the extent buffer's rw
semaphore - it would be a bug if in any of those contexts we were holding
a read lock instead.

So change btrfs_assert_tree_locked() to use lockdep_assert_held_write()
instead and, to make it more explicit, rename btrfs_assert_tree_locked()
to btrfs_assert_tree_write_locked(), so that it's clear we want to check
we are holding a write lock.

For now there are no contexts where we want to assert that we must have
a read lock, but in case that is needed in the future, we can add a new
helper function that just calls out lockdep_assert_held_read().

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index b28638c79413..37637539c5ab 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1036,7 +1036,7 @@ static int btree_set_page_dirty(struct page *page)
 		BUG_ON(!eb);
 		BUG_ON(!test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
 		BUG_ON(!atomic_read(&eb->refs));
-		btrfs_assert_tree_locked(eb);
+		btrfs_assert_tree_write_locked(eb);
 		return __set_page_dirty_nobuffers(page);
 	}
 	ASSERT(PagePrivate(page) && page->private);
@@ -1061,7 +1061,7 @@ static int btree_set_page_dirty(struct page *page)
 		ASSERT(eb);
 		ASSERT(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
 		ASSERT(atomic_read(&eb->refs));
-		btrfs_assert_tree_locked(eb);
+		btrfs_assert_tree_write_locked(eb);
 		free_extent_buffer(eb);
 
 		cur_bit += (fs_info->nodesize >> fs_info->sectorsize_bits);
@@ -1125,7 +1125,7 @@ void btrfs_clean_tree_block(struct extent_buffer *buf)
 	struct btrfs_fs_info *fs_info = buf->fs_info;
 	if (btrfs_header_generation(buf) ==
 	    fs_info->running_transaction->transid) {
-		btrfs_assert_tree_locked(buf);
+		btrfs_assert_tree_write_locked(buf);
 
 		if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &buf->bflags)) {
 			percpu_counter_add_batch(&fs_info->dirty_metadata_bytes,
@@ -4481,7 +4481,7 @@ void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
 	if (unlikely(test_bit(EXTENT_BUFFER_UNMAPPED, &buf->bflags)))
 		return;
 #endif
-	btrfs_assert_tree_locked(buf);
+	btrfs_assert_tree_write_locked(buf);
 	if (transid != fs_info->generation)
 		WARN(1, KERN_CRIT "btrfs transid mismatch buffer %llu, found %llu running %llu\n",
 			buf->start, transid, fs_info->generation);