Hi Goldwyn, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on kdave/for-next] [also build test WARNING on next-20201218] [cannot apply to btrfs/next v5.10] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/Goldwyn-Rodrigues/btrfs-Make-btr... base: https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next config: x86_64-randconfig-a013-20201217 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project cee1e7d14f4628d6174b33640d502bff3b54ae45) 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 # install x86_64 cross compiling tool for clang build # apt-get install binutils-x86-64-linux-gnu # https://github.com/0day-ci/linux/commit/e7a8dd2d9537a7ec5aeadb002fc4934be... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Goldwyn-Rodrigues/btrfs-Make-btrfs_direct_write-atomic-with-respect-to-inode_lock/20201219-001114 git checkout e7a8dd2d9537a7ec5aeadb002fc4934be1a396eb # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): if (iocb->ki_flags & IOCB_DSYNC) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~ fs/btrfs/file.c:1980:7: note: uninitialized use occurs here if (dsync) ^~~~~ fs/btrfs/file.c:1975:3: note: remove the 'if' if its condition is always true if (iocb->ki_flags & IOCB_DSYNC) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ fs/btrfs/file.c:1922:12: note: initialize the variable 'dsync' to silence this warning bool dsync; ^ = 0 1 warning generated. vim +1975 fs/btrfs/file.c 1909 1910 static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from) 1911 { 1912 struct file *file = iocb->ki_filp; 1913 struct inode *inode = file_inode(file); 1914 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); 1915 loff_t pos; 1916 ssize_t written = 0; 1917 ssize_t written_buffered; 1918 loff_t endbyte; 1919 ssize_t err; 1920 unsigned int ilock_flags = 0; 1921 struct iomap_dio *dio = NULL; 1922 bool dsync; 1923 1924 if (iocb->ki_flags & IOCB_NOWAIT) 1925 ilock_flags |= BTRFS_ILOCK_TRY; 1926 1927 /* If the write DIO is within EOF, use a shared lock */ 1928 if (iocb->ki_pos + iov_iter_count(from) <= i_size_read(inode)) 1929 ilock_flags |= BTRFS_ILOCK_SHARED; 1930 1931 relock: 1932 err = btrfs_inode_lock(inode, ilock_flags); 1933 if (err < 0) 1934 return err; 1935 1936 err = generic_write_checks(iocb, from); 1937 if (err <= 0) { 1938 btrfs_inode_unlock(inode, ilock_flags); 1939 return err; 1940 } 1941 1942 err = btrfs_write_check(iocb, from, err); 1943 if (err < 0) 1944 goto out; 1945 1946 pos = iocb->ki_pos; 1947 /* 1948 * Re-check since file size may have changed just before taking the 1949 * lock or pos may have changed because of O_APPEND in generic_write_check() 1950 */ 1951 if ((ilock_flags & BTRFS_ILOCK_SHARED) && 1952 pos + iov_iter_count(from) > i_size_read(inode)) { 1953 btrfs_inode_unlock(inode, ilock_flags); 1954 ilock_flags &= ~BTRFS_ILOCK_SHARED; 1955 goto relock; 1956 } 1957 1958 if (check_direct_IO(fs_info, from, pos)) 1959 goto buffered; 1960 1961 dio = __iomap_dio_rw(iocb, from, &btrfs_dio_iomap_ops, 1962 &btrfs_dio_ops, is_sync_kiocb(iocb)); 1963 1964 1965 if (IS_ERR_OR_NULL(dio)) { 1966 err = PTR_ERR_OR_ZERO(dio); 1967 if (err < 0 && err != -ENOTBLK) 1968 goto out; 1969 } else { 1970 /* 1971 * Remove the DSYNC flag because iomap_dio_complete() calls 1972 * generic_write_sync() which may deadlock with btrfs_sync() 1973 * on inode->i_rwsem 1974 */ 1976 dsync = true; 1977 iocb->ki_flags &= ~IOCB_DSYNC; 1978 } 1979 written = iomap_dio_complete(dio); 1980 if (dsync) 1981 iocb->ki_flags |= IOCB_DSYNC; 1982 } 1983 1984 if (written < 0 || !iov_iter_count(from)) { 1985 err = written; 1986 goto out; 1987 } 1988 1989 buffered: 1990 pos = iocb->ki_pos; 1991 written_buffered = __btrfs_buffered_write(iocb, from); 1992 if (written_buffered < 0) { 1993 err = written_buffered; 1994 goto out; 1995 } 1996 /* 1997 * Ensure all data is persisted. We want the next direct IO read to be 1998 * able to read what was just written. 1999 */ 2000 endbyte = pos + written_buffered - 1; 2001 err = btrfs_fdatawrite_range(inode, pos, endbyte); 2002 if (err) 2003 goto out; 2004 err = filemap_fdatawait_range(inode->i_mapping, pos, endbyte); 2005 if (err) 2006 goto out; 2007 written += written_buffered; 2008 iocb->ki_pos = pos + written_buffered; 2009 invalidate_mapping_pages(file->f_mapping, pos >> PAGE_SHIFT, 2010 endbyte >> PAGE_SHIFT); 2011 out: 2012 btrfs_inode_unlock(inode, ilock_flags); 2013 if (written > 0 && dsync) 2014 generic_write_sync(iocb, written); 2015 2016 return written ? written : err; 2017 } 2018 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org