From 7bc9fddab074d6bb630344e1969e28d20b140621 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 3 Sep 2010 11:56:18 +0200 Subject: [PATCH] lguest: replace VIRTIO_F_BARRIER support with VIRTIO_F_FLUSH support VIRTIO_F_BARRIER is deprecated. Replace it with VIRTIO_F_FLUSH support. Signed-off-by: Tejun Heo Cc: Rusty Russell Cc: Christoph Hellwig Signed-off-by: Jens Axboe --- Documentation/lguest/lguest.c | 29 +++++++++-------------------- 1 file changed, 9 insertions(+), 20 deletions(-) diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c index e9ce3c554514..fbc64b331436 100644 --- a/Documentation/lguest/lguest.c +++ b/Documentation/lguest/lguest.c @@ -1638,15 +1638,6 @@ static void blk_request(struct virtqueue *vq) */ off = out->sector * 512; - /* - * The block device implements "barriers", where the Guest indicates - * that it wants all previous writes to occur before this write. We - * don't have a way of asking our kernel to do a barrier, so we just - * synchronize all the data in the file. Pretty poor, no? - */ - if (out->type & VIRTIO_BLK_T_BARRIER) - fdatasync(vblk->fd); - /* * In general the virtio block driver is allowed to try SCSI commands. * It'd be nice if we supported eject, for example, but we don't. @@ -1679,6 +1670,13 @@ static void blk_request(struct virtqueue *vq) /* Die, bad Guest, die. */ errx(1, "Write past end %llu+%u", off, ret); } + + wlen = sizeof(*in); + *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR); + } else if (out->type & VIRTIO_BLK_T_FLUSH) { + /* Flush */ + ret = fdatasync(vblk->fd); + verbose("FLUSH fdatasync: %i\n", ret); wlen = sizeof(*in); *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR); } else { @@ -1702,15 +1700,6 @@ static void blk_request(struct virtqueue *vq) } } - /* - * OK, so we noted that it was pretty poor to use an fdatasync as a - * barrier. But Christoph Hellwig points out that we need a sync - * *afterwards* as well: "Barriers specify no reordering to the front - * or the back." And Jens Axboe confirmed it, so here we are: - */ - if (out->type & VIRTIO_BLK_T_BARRIER) - fdatasync(vblk->fd); - /* Finished that request. */ add_used(vq, head, wlen); } @@ -1735,8 +1724,8 @@ static void setup_block_file(const char *filename) vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE); vblk->len = lseek64(vblk->fd, 0, SEEK_END); - /* We support barriers. */ - add_feature(dev, VIRTIO_BLK_F_BARRIER); + /* We support FLUSH. */ + add_feature(dev, VIRTIO_BLK_F_FLUSH); /* Tell Guest how many sectors this device has. */ conf.capacity = cpu_to_le64(vblk->len / 512); -- 2.30.2