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>

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 84627cb..d0c27a6 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -395,7 +395,7 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
        if (*cow_ret == buf)
                unlock_orig = 1;
 
-       btrfs_assert_tree_locked(buf);
+       btrfs_assert_tree_write_locked(buf);
 
        WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
                trans->transid != fs_info->running_transaction->transid);
@@ -2487,7 +2487,7 @@ static void insert_ptr(struct btrfs_trans_handle *trans,
        int ret;
 
        BUG_ON(!path->nodes[level]);
-       btrfs_assert_tree_locked(path->nodes[level]);
+       btrfs_assert_tree_write_locked(path->nodes[level]);
        lower = path->nodes[level];
        nritems = btrfs_header_nritems(lower);
        BUG_ON(slot > nritems);
@@ -2827,7 +2827,7 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
        if (slot >= btrfs_header_nritems(upper) - 1)
                return 1;
 
-       btrfs_assert_tree_locked(path->nodes[1]);
+       btrfs_assert_tree_write_locked(path->nodes[1]);
 
        right = btrfs_read_node_slot(upper, slot + 1);
        /*
@@ -3065,7 +3065,7 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
        if (right_nritems == 0)
                return 1;
 
-       btrfs_assert_tree_locked(path->nodes[1]);
+       btrfs_assert_tree_write_locked(path->nodes[1]);
 
        left = btrfs_read_node_slot(path->nodes[1], slot - 1);
        /*

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index b28638c..3763753 100644 (file)
--- 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);

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index e4b3eae..ec5de19 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5836,13 +5836,13 @@ int btrfs_drop_subtree(struct btrfs_trans_handle *trans,
                return -ENOMEM;
        }
 
-       btrfs_assert_tree_locked(parent);
+       btrfs_assert_tree_write_locked(parent);
        parent_level = btrfs_header_level(parent);
        atomic_inc(&parent->refs);
        path->nodes[parent_level] = parent;
        path->slots[parent_level] = btrfs_header_nritems(parent);
 
-       btrfs_assert_tree_locked(node);
+       btrfs_assert_tree_write_locked(node);
        level = btrfs_header_level(node);
        path->nodes[level] = node;
        path->slots[level] = 0;

diff --git a/fs/btrfs/locking.h b/fs/btrfs/locking.h
index a2e1f1f..bbc4553 100644 (file)
--- a/fs/btrfs/locking.h
+++ b/fs/btrfs/locking.h
@@ -96,11 +96,12 @@ struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root);
 struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root);
 
 #ifdef CONFIG_BTRFS_DEBUG
-static inline void btrfs_assert_tree_locked(struct extent_buffer *eb) {
-       lockdep_assert_held(&eb->lock);
+static inline void btrfs_assert_tree_write_locked(struct extent_buffer *eb)
+{
+       lockdep_assert_held_write(&eb->lock);
 }
 #else
-static inline void btrfs_assert_tree_locked(struct extent_buffer *eb) { }
+static inline void btrfs_assert_tree_write_locked(struct extent_buffer *eb) { }
 #endif
 
 void btrfs_unlock_up_safe(struct btrfs_path *path, int level);

diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index 8a45142..2837b4c 100644 (file)
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -138,7 +138,7 @@ int btrfs_setxattr(struct btrfs_trans_handle *trans, struct inode *inode,
                 * matches our target xattr, so lets check.
                 */
                ret = 0;
-               btrfs_assert_tree_locked(path->nodes[0]);
+               btrfs_assert_tree_write_locked(path->nodes[0]);
                di = btrfs_match_dir_item_name(fs_info, path, name, name_len);
                if (!di && !(flags & XATTR_REPLACE)) {
                        ret = -ENOSPC;