btrfs: remove bogus NULL checks in __btrfs_write_out_cache()

Dan reported a new smatch warning in free-space-cache.c:

New smatch warnings:
fs/btrfs/free-space-cache.c:1207 write_pinned_extent_entries() warn: variable dereferenced before check 'block_group' (see line 1203)

But the check if the block_group pointer is NULL is bogus, because to
get to this point block_group::io_ctl has already been dereferenced
further up the call-chain when calling __btrfs_write_out_cache() from
btrfs_write_out_cache().

Remove the bogus checks for block_group == NULL in
__btrfs_write_out_cache() and it's siblings.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202601170636.WsePMV5H-lkp@intel.com/
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index af5f57bd44e6c210074284f5d7b5d85d342b0660..28132b6d8f88d757ab421d53edbfd39314c913e6 100644 (file)
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -1080,7 +1080,7 @@ int write_cache_extent_entries(struct btrfs_io_ctl *io_ctl,
        struct btrfs_trim_range *trim_entry;
 
        /* Get the cluster for this block_group if it exists */
-       if (block_group && !list_empty(&block_group->cluster_list)) {
+       if (!list_empty(&block_group->cluster_list)) {
                cluster = list_first_entry(&block_group->cluster_list,
                                           struct btrfs_free_cluster, block_group_list);
        }
@@ -1204,9 +1204,6 @@ static noinline_for_stack int write_pinned_extent_entries(
        struct extent_io_tree *unpin = NULL;
        int ret;
 
-       if (!block_group)
-               return 0;
-
        /*
         * We want to add any pinned extents to our free space cache
         * so we don't leak the space
@@ -1394,7 +1391,7 @@ static int __btrfs_write_out_cache(struct inode *inode,
        if (ret)
                return ret;
 
-       if (block_group && (block_group->flags & BTRFS_BLOCK_GROUP_DATA)) {
+       if (block_group->flags & BTRFS_BLOCK_GROUP_DATA) {
                down_write(&block_group->data_rwsem);
                spin_lock(&block_group->lock);
                if (block_group->delalloc_bytes) {
@@ -1466,7 +1463,7 @@ static int __btrfs_write_out_cache(struct inode *inode,
                        goto out_nospc;
        }
 
-       if (block_group && (block_group->flags & BTRFS_BLOCK_GROUP_DATA))
+       if (block_group->flags & BTRFS_BLOCK_GROUP_DATA)
                up_write(&block_group->data_rwsem);
        /*
         * Release the pages and unlock the extent, we will flush
@@ -1501,7 +1498,7 @@ out_nospc:
        cleanup_write_cache_enospc(inode, io_ctl, &cached_state);
 
 out_unlock:
-       if (block_group && (block_group->flags & BTRFS_BLOCK_GROUP_DATA))
+       if (block_group->flags & BTRFS_BLOCK_GROUP_DATA)
                up_write(&block_group->data_rwsem);
 
 out: