[brauner-github:vfs-6.18.inode.refcount.preliminaries 4/5] fs/inode.c:1924:45-46: WARNING: atomic_add_unless

[brauner-github:vfs-6.18.inode.refcount.preliminaries 4/5] fs/inode.c:1924:45-46: WARNING: atomic_add_unless

[kernel test robot]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
CC: Christian Brauner <christianvanbrauner@gmail.com>
TO: Josef Bacik <josef@toxicpanda.com>
CC: Christian Brauner <brauner@kernel.org>
CC: Mateusz Guzik <mjguzik@gmail.com>

tree:   https://github.com/brauner/linux.git vfs-6.18.inode.refcount.preliminaries
head:   c06366d1d6aba8c5757b0a119a948ee37bfbc560
commit: 3cba19f6a00675fbc2af0987dfc90e216e6cfb74 [4/5] fs: rework iput logic
:::::: branch date: 35 hours ago
:::::: commit date: 35 hours ago
config: x86_64-randconfig-101-20250830 (https://download.01.org/0day-ci/archive/20250831/202508310743.euHihnAz-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14+deb12u1) 12.2.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Julia Lawall <julia.lawall@inria.fr>
| Closes: https://lore.kernel.org/r/202508310743.euHihnAz-lkp@intel.com/

cocci warnings: (new ones prefixed by >>)
>> fs/inode.c:1924:45-46: WARNING: atomic_add_unless

vim +1924 fs/inode.c

^1da177e4c3f41 Linus Torvalds 2005-04-16  1899  
^1da177e4c3f41 Linus Torvalds 2005-04-16  1900  /**
^1da177e4c3f41 Linus Torvalds 2005-04-16  1901   *	iput	- put an inode
^1da177e4c3f41 Linus Torvalds 2005-04-16  1902   *	@inode: inode to put
^1da177e4c3f41 Linus Torvalds 2005-04-16  1903   *
^1da177e4c3f41 Linus Torvalds 2005-04-16  1904   *	Puts an inode, dropping its usage count. If the inode use count hits
^1da177e4c3f41 Linus Torvalds 2005-04-16  1905   *	zero, the inode is then freed and may also be destroyed.
^1da177e4c3f41 Linus Torvalds 2005-04-16  1906   *
^1da177e4c3f41 Linus Torvalds 2005-04-16  1907   *	Consequently, iput() can sleep.
^1da177e4c3f41 Linus Torvalds 2005-04-16  1908   */
^1da177e4c3f41 Linus Torvalds 2005-04-16  1909  void iput(struct inode *inode)
^1da177e4c3f41 Linus Torvalds 2005-04-16  1910  {
3cba19f6a00675 Josef Bacik    2025-08-26  1911  	if (unlikely(!inode))
0ae45f63d4ef8d Theodore Ts'o  2015-02-02  1912  		return;
3cba19f6a00675 Josef Bacik    2025-08-26  1913  
0ae45f63d4ef8d Theodore Ts'o  2015-02-02  1914  retry:
3cba19f6a00675 Josef Bacik    2025-08-26  1915  	lockdep_assert_not_held(&inode->i_lock);
3cba19f6a00675 Josef Bacik    2025-08-26  1916  	VFS_BUG_ON_INODE(inode->i_state & I_CLEAR, inode);
3cba19f6a00675 Josef Bacik    2025-08-26  1917  	/*
3cba19f6a00675 Josef Bacik    2025-08-26  1918          * Note this assert is technically racy as if the count is bogusly
3cba19f6a00675 Josef Bacik    2025-08-26  1919          * equal to one, then two CPUs racing to further drop it can both
3cba19f6a00675 Josef Bacik    2025-08-26  1920          * conclude it's fine.
3cba19f6a00675 Josef Bacik    2025-08-26  1921          */
3cba19f6a00675 Josef Bacik    2025-08-26  1922  	VFS_BUG_ON_INODE(atomic_read(&inode->i_count) < 1, inode);
3cba19f6a00675 Josef Bacik    2025-08-26  1923  
3cba19f6a00675 Josef Bacik    2025-08-26 @1924  	if (atomic_add_unless(&inode->i_count, -1, 1))
3cba19f6a00675 Josef Bacik    2025-08-26  1925  		return;
3cba19f6a00675 Josef Bacik    2025-08-26  1926  
3cba19f6a00675 Josef Bacik    2025-08-26  1927  	if ((inode->i_state & I_DIRTY_TIME) && inode->i_nlink) {
0ae45f63d4ef8d Theodore Ts'o  2015-02-02  1928  		trace_writeback_lazytime_iput(inode);
0ae45f63d4ef8d Theodore Ts'o  2015-02-02  1929  		mark_inode_dirty_sync(inode);
0ae45f63d4ef8d Theodore Ts'o  2015-02-02  1930  		goto retry;
0ae45f63d4ef8d Theodore Ts'o  2015-02-02  1931  	}
3cba19f6a00675 Josef Bacik    2025-08-26  1932  
3cba19f6a00675 Josef Bacik    2025-08-26  1933  	spin_lock(&inode->i_lock);
3cba19f6a00675 Josef Bacik    2025-08-26  1934  	if (unlikely((inode->i_state & I_DIRTY_TIME) && inode->i_nlink)) {
3cba19f6a00675 Josef Bacik    2025-08-26  1935  		spin_unlock(&inode->i_lock);
3cba19f6a00675 Josef Bacik    2025-08-26  1936  		goto retry;
^1da177e4c3f41 Linus Torvalds 2005-04-16  1937  	}
3cba19f6a00675 Josef Bacik    2025-08-26  1938  
3cba19f6a00675 Josef Bacik    2025-08-26  1939  	if (!atomic_dec_and_test(&inode->i_count)) {
3cba19f6a00675 Josef Bacik    2025-08-26  1940  		spin_unlock(&inode->i_lock);
3cba19f6a00675 Josef Bacik    2025-08-26  1941  		return;
3cba19f6a00675 Josef Bacik    2025-08-26  1942  	}
3cba19f6a00675 Josef Bacik    2025-08-26  1943  
3cba19f6a00675 Josef Bacik    2025-08-26  1944  	/*
3cba19f6a00675 Josef Bacik    2025-08-26  1945          * iput_final() drops ->i_lock, we can't assert on it as the inode may
3cba19f6a00675 Josef Bacik    2025-08-26  1946          * be deallocated by the time the call returns.
3cba19f6a00675 Josef Bacik    2025-08-26  1947          */
3cba19f6a00675 Josef Bacik    2025-08-26  1948  	iput_final(inode);
^1da177e4c3f41 Linus Torvalds 2005-04-16  1949  }
^1da177e4c3f41 Linus Torvalds 2005-04-16  1950  EXPORT_SYMBOL(iput);
^1da177e4c3f41 Linus Torvalds 2005-04-16  1951  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki