On Wed, 2017-01-18 at 13:32 -0800, Dan Williams wrote: > On Wed, Jan 18, 2017 at 1:02 PM, Darrick J. Wong > <darrick.wong@xxxxxxxxxx> wrote: > > On Wed, Jan 18, 2017 at 03:39:17PM -0500, Jeff Moyer wrote: > > > Jan Kara <jack@xxxxxxx> writes: > > > > > > > On Tue 17-01-17 15:14:21, Vishal Verma wrote: > > > > > Your note on the online repair does raise another tangentially > > > > > related > > > > > topic. Currently, if there are badblocks, writes via the bio > > > > > submission > > > > > path will clear the error (if the hardware is able to remap > > > > > the bad > > > > > locations). However, if the filesystem is mounted eith DAX, > > > > > even > > > > > non-mmap operations - read() and write() will go through the > > > > > dax paths > > > > > (dax_do_io()). We haven't found a good/agreeable way to > > > > > perform > > > > > error-clearing in this case. So currently, if a dax mounted > > > > > filesystem > > > > > has badblocks, the only way to clear those badblocks is to > > > > > mount it > > > > > without DAX, and overwrite/zero the bad locations. This is a > > > > > pretty > > > > > terrible user experience, and I'm hoping this can be solved in > > > > > a better > > > > > way. > > > > > > > > Please remind me, what is the problem with DAX code doing > > > > necessary work to > > > > clear the error when it gets EIO from memcpy on write? > > > > > > You won't get an MCE for a store; only loads generate them. > > > > > > Won't fallocate FL_ZERO_RANGE clear bad blocks when mounted with > > > -o dax? > > > > Not necessarily; XFS usually implements this by punching out the > > range > > and then reallocating it as unwritten blocks. > > > > That does clear the error because the unwritten blocks are zeroed and > errors cleared when they become allocated again. Yes, the problem was that writes won't clear errors. zeroing through either hole-punch, truncate, unlinking the file should all work (assuming the hole-punch or truncate ranges wholly contain the 'badblock' sector). > _______________________________________________ > Linux-nvdimm mailing list > Linux-nvdimm@xxxxxxxxxxxx > https://lists.01.org/mailman/listinfo/linux-nvdimm��.n��������+%����;��w��{.n�����{����n�r������&��z�ޗ�zf���h���~����������_��+v���)ߣ�
