Commit d32ddfeb authored by Mike Snitzer's avatar Mike Snitzer Committed by Anna Schumaker
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nfs/localio: Ensure DIO WRITE's IO on stable storage upon completion 



LOCALIO's misaligned DIO WRITE support requires synchronous IO for any
misaligned head and/or tail that are issued using buffered IO.  In
addition, it is important that the O_DIRECT middle be on stable
storage upon its completion via AIO.

Otherwise, a misaligned DIO WRITE could mix buffered IO for the
head/tail and direct IO for the DIO-aligned middle -- which could lead
to problems associated with deferred writes to stable storage (such as
out of order partial completions causing incorrect advancement of the
file's offset, etc).

Fixes: c817248f ("nfs/localio: add proper O_DIRECT support for READ and WRITE")
Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
Signed-off-by: default avatarAnna Schumaker <anna.schumaker@oracle.com>
parent d0497dd2

fs/nfs/localio.c

+5 −1
Original line number Diff line number Diff line
@@ -485,9 +485,13 @@ nfs_local_iters_init(struct nfs_local_kiocb *iocb, int rw) 
		struct nfs_local_dio local_dio;



		if (nfs_is_local_dio_possible(iocb, rw, len, &local_dio) &&

		    nfs_local_iters_setup_dio(iocb, rw, v, len, &local_dio) != 0)

		    nfs_local_iters_setup_dio(iocb, rw, v, len, &local_dio) != 0) {

			/* Ensure DIO WRITE's IO on stable storage upon completion */

			if (rw == ITER_SOURCE)

				iocb->kiocb.ki_flags |= IOCB_DSYNC|IOCB_SYNC;

			return; /* is DIO-aligned */

		}

	}



	/* Use buffered IO */

	iocb->offset[0] = hdr->args.offset;