[djwong-xfs:repair-reap-fixes 17/26] fs/xfs/libxfs/xfs_btree.c:5040 xfs_btree_stage_afakeroot() error: potential null dereference 'nops'. (kmem_alloc returns null)

[kbuild test robot <lkp@intel.com>]

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux.git repair-reap-fixes
head:   e55e1901603b56e1850c089a71c5b93c97c2d32f
commit: 62b4fb2c08747bb7fd6d1ccecbfddc5ccc19e450 [17/26] xfs: introduce fake roots for ag-rooted btrees

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

New smatch warnings:
fs/xfs/libxfs/xfs_btree.c:5040 xfs_btree_stage_afakeroot() error: potential null dereference 'nops'.  (kmem_alloc returns null)

Old smatch warnings:
fs/xfs/libxfs/xfs_btree.c:1762 xfs_btree_lookup_get_block() error: we previously assumed 'bp' could be null (see line 1737)

vim +/nops +5040 fs/xfs/libxfs/xfs_btree.c

  5019	
  5020	/*
  5021	 * Initialize a AG-rooted btree cursor with the given AG btree fake root.  The
  5022	 * btree cursor's bc_ops will be overridden as needed to make the staging
  5023	 * functionality work.  If new_ops is not NULL, these new ops will be passed
  5024	 * out to the caller for further overriding.
  5025	 */
  5026	void
  5027	xfs_btree_stage_afakeroot(
  5028		struct xfs_btree_cur		*cur,
  5029		struct xbtree_afakeroot		*afake,
  5030		struct xfs_btree_ops		**new_ops)
  5031	{
  5032		struct xfs_btree_ops		*nops;
  5033	
  5034		ASSERT(!(cur->bc_flags & XFS_BTREE_STAGING));
  5035		ASSERT(!(cur->bc_flags & XFS_BTREE_ROOT_IN_INODE));
  5036		ASSERT(cur->bc_tp == NULL);
  5037	
  5038		nops = kmem_alloc(sizeof(struct xfs_btree_ops), KM_NOFS);
  5039		memcpy(nops, cur->bc_ops, sizeof(struct xfs_btree_ops));
> 5040		nops->alloc_block = xfs_btree_fakeroot_alloc_block;
  5041		nops->free_block = xfs_btree_fakeroot_free_block;
  5042		nops->init_ptr_from_cur = xfs_btree_fakeroot_init_ptr_from_cur;
  5043		nops->set_root = xfs_btree_afakeroot_set_root;
  5044		nops->dup_cursor = xfs_btree_fakeroot_dup_cursor;
  5045	
  5046		cur->bc_private.a.afake = afake;
  5047		cur->bc_nlevels = afake->af_levels;
  5048		cur->bc_ops = nops;
  5049		cur->bc_flags |= XFS_BTREE_STAGING;
  5050	
  5051		if (new_ops)
  5052			*new_ops = nops;
  5053	}
  5054	

---
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