From e83403959fddb6d90e8c5e54bbce3110d0c82165 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Tue, 4 Jun 2013 14:27:38 -0400 Subject: [PATCH] ext4: protect extent conversion after DIO with i_dio_count Make sure extent conversion after DIO happens while i_dio_count is still elevated so that inode_dio_wait() waits until extent conversion is done. This removes the need for explicit waiting for extent conversion in some cases. Reviewed-by: Zheng Liu Signed-off-by: Jan Kara Signed-off-by: "Theodore Ts'o" --- fs/ext4/inode.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 510dba7..eb4ddfe 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3036,11 +3036,18 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb, BUG_ON(iocb->private == NULL); + /* + * Make all waiters for direct IO properly wait also for extent + * conversion. This also disallows race between truncate() and + * overwrite DIO as i_dio_count needs to be incremented under i_mutex. + */ + if (rw == WRITE) + atomic_inc(&inode->i_dio_count); + /* If we do a overwrite dio, i_mutex locking can be released */ overwrite = *((int *)iocb->private); if (overwrite) { - atomic_inc(&inode->i_dio_count); down_read(&EXT4_I(inode)->i_data_sem); mutex_unlock(&inode->i_mutex); } @@ -3143,9 +3150,10 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb, } retake_lock: + if (rw == WRITE) + inode_dio_done(inode); /* take i_mutex locking again if we do a ovewrite dio */ if (overwrite) { - inode_dio_done(inode); up_read(&EXT4_I(inode)->i_data_sem); mutex_lock(&inode->i_mutex); } -- 2.7.4