On Wed, Sep 16, 2015 at 08:39:09AM +0000, Junichi Nomura wrote: > filemap_fdatawait() is a function to wait for on-going writeback > to complete but also consume and clear error status of the mapping > set during writeback. > The latter functionality is critical for applications to detect > writeback error with system calls like fsync(2)/fdatasync(2). > > However filemap_fdatawait() is also used by sync(2) or FIFREEZE > ioctl, which don't check error status of individual mappings. > > As a result, fsync() may not be able to detect writeback error > if events happen in the following order: > > Application System admin > ---------------------------------------------------------- > write data on page cache > Run sync command > writeback completes with error > filemap_fdatawait() clears error > fsync returns success > (but the data is not on disk) > > This patch adds filemap_fdatawait_keep_errors() for call sites where > writeback error is not handled so that they don't clear error status. > > Signed-off-by: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx> > Acked-by: Andi Kleen <ak@xxxxxxxxxxxxxxx> Reviewed-by: Tejun Heo <tj@xxxxxxxxxx> Thanks. -- tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>