[djwong-xfs:realtime-reflink 221/233] fs/xfs/libxfs/xfs_refcount.c:1883:40: warning: suggest braces around empty body in an 'else' statement

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

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux.git realtime-reflink
head:   c886b4656afe488e5b52a406279b69c0ee4c0c48
commit: 1e4106cac5b992a3ae6e175ae211632810f92129 [221/233] xfs: refcover CoW leftovers in the realtime volume
config: mips-randconfig-r026-20201030 (attached as .config)
compiler: mipsel-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux.git/commit/?id=1e4106cac5b992a3ae6e175ae211632810f92129
        git remote add djwong-xfs https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux.git
        git fetch --no-tags djwong-xfs realtime-reflink
        git checkout 1e4106cac5b992a3ae6e175ae211632810f92129
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=mips 

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

All warnings (new ones prefixed by >>):

   fs/xfs/libxfs/xfs_refcount.c: In function 'xfs_refcount_recover_cow_leftovers':
>> fs/xfs/libxfs/xfs_refcount.c:1883:40: warning: suggest braces around empty body in an 'else' statement [-Wempty-body]
    1883 |   xfs_rtunlock(mp, XFS_RTLOCK_REFCOUNT);
         |                                        ^

vim +/else +1883 fs/xfs/libxfs/xfs_refcount.c

  1820	
  1821	/* Find and remove leftover CoW reservations. */
  1822	int
  1823	xfs_refcount_recover_cow_leftovers(
  1824		struct xfs_mount		*mp,
  1825		xfs_agnumber_t			agno)
  1826	{
  1827		struct xfs_trans		*tp;
  1828		struct xfs_btree_cur		*cur;
  1829		struct xfs_buf			*agbp = NULL;
  1830		struct xfs_refcount_recovery	*rr, *n;
  1831		struct list_head		debris;
  1832		union xfs_btree_irec		low;
  1833		union xfs_btree_irec		high;
  1834		xfs_fsblock_t			fsb;
  1835		xfs_fsblock_t			bno;
  1836		xfs_fsblock_t			cow_start;
  1837		bool				is_rt = agno == NULLAGNUMBER;
  1838		int				error;
  1839	
  1840		if (!is_rt && mp->m_sb.sb_agblocks >= XFS_REFC_COW_START)
  1841			return -EOPNOTSUPP;
  1842		if (is_rt && mp->m_sb.sb_rextents >= XFS_RTREFC_COW_START)
  1843			return -EOPNOTSUPP;
  1844	
  1845		INIT_LIST_HEAD(&debris);
  1846	
  1847		/*
  1848		 * In this first part, we use an empty transaction to gather up
  1849		 * all the leftover CoW extents so that we can subsequently
  1850		 * delete them.  The empty transaction is used to avoid
  1851		 * a buffer lock deadlock if there happens to be a loop in the
  1852		 * refcountbt because we're allowed to re-grab a buffer that is
  1853		 * already attached to our transaction.  When we're done
  1854		 * recording the CoW debris we cancel the (empty) transaction
  1855		 * and everything goes away cleanly.
  1856		 */
  1857		error = xfs_trans_alloc_empty(mp, &tp);
  1858		if (error)
  1859			return error;
  1860	
  1861		if (is_rt) {
  1862			xfs_rtlock(NULL, mp, XFS_RTLOCK_REFCOUNT);
  1863			cur = xfs_rtrefcountbt_init_cursor(mp, tp, mp->m_rrefcountip);
  1864		} else {
  1865			error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
  1866			if (error)
  1867				goto out_trans;
  1868			cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno);
  1869		}
  1870		cow_start = xrefc_cow_start(cur);
  1871	
  1872		/* Find all the leftover CoW staging extents. */
  1873		memset(&low, 0, sizeof(low));
  1874		memset(&high, 0, sizeof(high));
  1875		low.rc.rc_startblock = cow_start;
  1876		high.rc.rc_startblock = -1ULL;
  1877		error = xfs_btree_query_range(cur, &low, &high,
  1878				xfs_refcount_recover_extent, &debris);
  1879		xfs_btree_del_cursor(cur, error);
  1880		if (agbp)
  1881			xfs_trans_brelse(tp, agbp);
  1882		else
> 1883			xfs_rtunlock(mp, XFS_RTLOCK_REFCOUNT);
  1884		xfs_trans_cancel(tp);
  1885		if (error)
  1886			goto out_free;
  1887	
  1888		/* Now iterate the list to free the leftovers */
  1889		list_for_each_entry_safe(rr, n, &debris, rr_list) {
  1890			/* Set up transaction. */
  1891			error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
  1892			if (error)
  1893				goto out_free;
  1894	
  1895			trace_xfs_refcount_recover_extent(mp, agno, &rr->rr_rrec);
  1896	
  1897			/* Free the orphan record */
  1898			bno = rr->rr_rrec.rc_startblock - cow_start;
  1899			fsb = is_rt ? bno : XFS_AGB_TO_FSB(mp, agno, bno);
  1900			xfs_refcount_free_cow_extent(tp, fsb,
  1901					rr->rr_rrec.rc_blockcount, is_rt);
  1902	
  1903			/* Free the block. */
  1904			xfs_bmap_add_free(tp, fsb, rr->rr_rrec.rc_blockcount, NULL,
  1905					is_rt);
  1906	
  1907			error = xfs_trans_commit(tp);
  1908			if (error)
  1909				goto out_free;
  1910	
  1911			list_del(&rr->rr_list);
  1912			kmem_free(rr);
  1913		}
  1914	
  1915		return error;
  1916	out_trans:
  1917		xfs_trans_cancel(tp);
  1918	out_free:
  1919		/* Free the leftover list */
  1920		list_for_each_entry_safe(rr, n, &debris, rr_list) {
  1921			list_del(&rr->rr_list);
  1922			kmem_free(rr);
  1923		}
  1924		return error;
  1925	}
  1926	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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