On Wed, Oct 11, 2023 at 04:21:55PM +0200, Jan Kara wrote: > Gao Xiang has reported that on ext4 O_SYNC direct IO does not properly > sync file size update and thus if we crash at unfortunate moment, the > file can have smaller size although O_SYNC IO has reported successful > completion. The problem happens because update of on-disk inode size is > handled in ext4_dio_write_iter() *after* iomap_dio_rw() (and thus > dio_complete() in particular) has returned and generic_file_sync() gets > called by dio_complete(). Fix the problem by handling on-disk inode size > update directly in our ->end_io completion handler. > > References: https://lore.kernel.org/all/02d18236-26ef-09b0-90ad-030c4fe3ee20@xxxxxxxxxxxxxxxxx > Reported-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> > Signed-off-by: Jan Kara <jack@xxxxxxx> > --- > fs/ext4/file.c | 139 ++++++++++++++++++------------------------------- > 1 file changed, 52 insertions(+), 87 deletions(-) ..... > @@ -388,9 +342,28 @@ static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset, > */ > if (inode->i_nlink) > ext4_orphan_del(NULL, inode); > + return; > } > + /* > + * If i_disksize got extended due to writeback of delalloc blocks while > + * the DIO was running we could fail to cleanup the orphan list in > + * ext4_handle_inode_extension(). Do it now. > + */ > + if (!list_empty(&EXT4_I(inode)->i_orphan) && inode->i_nlink) { > + handle_t *handle = ext4_journal_start(inode, EXT4_HT_INODE, 2); So this has to be called after the DIO write completes and calls ext4_handle_inode_extension()? .... > @@ -606,9 +570,8 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from) > dio_flags, NULL, 0); > if (ret == -ENOTBLK) > ret = 0; > - > if (extend) > - ret = ext4_handle_inode_extension(inode, offset, ret, count); > + ext4_inode_extension_cleanup(inode, ret); Because this doesn't wait for AIO DIO to complete and actually extend the file before running the cleanup code... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
