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

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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>
This commit is contained in:
Filipe Manana 2021-09-22 10:36:45 +01:00 committed by David Sterba
parent 8ef9dc0f14
commit 49d0c6424c
5 changed files with 15 additions and 14 deletions
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8
fs/btrfs/ctree.c
View File

@ -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);
/*

8
fs/btrfs/disk-io.c
View File

@ -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);

4
fs/btrfs/extent-tree.c
View File

@ -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;

7
fs/btrfs/locking.h
View File

@ -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);

2
fs/btrfs/xattr.c
View File

@ -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;