From: Andreas Gruenbacher agruenba@redhat.com
commit 97308f8b0d867e9ef59528cd97f0db55ffdf5651 upstream
In iomap_dio_rw, when iomap_apply returns an -EFAULT error and the IOMAP_DIO_PARTIAL flag is set, complete the request synchronously and return a partial result. This allows the caller to deal with the page fault and retry the remainder of the request.
Signed-off-by: Andreas Gruenbacher agruenba@redhat.com Reviewed-by: Darrick J. Wong djwong@kernel.org Signed-off-by: Anand Jain anand.jain@oracle.com --- fs/iomap/direct-io.c | 6 ++++++ include/linux/iomap.h | 7 +++++++ 2 files changed, 13 insertions(+)
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c index a2a368e824c0..a434fb7887b2 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -581,6 +581,12 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, if (iov_iter_rw(iter) == READ && iomi.pos >= dio->i_size) iov_iter_revert(iter, iomi.pos - dio->i_size);
+ if (ret == -EFAULT && dio->size && (dio_flags & IOMAP_DIO_PARTIAL)) { + if (!(iocb->ki_flags & IOCB_NOWAIT)) + wait_for_completion = true; + ret = 0; + } + /* magic error code to fall back to buffered I/O */ if (ret == -ENOTBLK) { wait_for_completion = true; diff --git a/include/linux/iomap.h b/include/linux/iomap.h index 24f8489583ca..2a213b0d1e1f 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -330,6 +330,13 @@ struct iomap_dio_ops { */ #define IOMAP_DIO_OVERWRITE_ONLY (1 << 1)
+/* + * When a page fault occurs, return a partial synchronous result and allow + * the caller to retry the rest of the operation after dealing with the page + * fault. + */ +#define IOMAP_DIO_PARTIAL (1 << 2) + ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, const struct iomap_ops *ops, const struct iomap_dio_ops *dops, unsigned int dio_flags);