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    SubjectRe: [PATCH 18/52] virtio-fs: Map cache using the values from the capabilities
    * Liu Bo (obuil.liubo@gmail.com) wrote:
    > On Mon, Dec 10, 2018 at 9:57 AM Vivek Goyal <vgoyal@redhat.com> wrote:
    > >
    > > Instead of assuming we had the fixed bar for the cache, use the
    > > value from the capabilities.
    > >
    > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
    > > ---
    > > fs/fuse/virtio_fs.c | 32 +++++++++++++++++---------------
    > > 1 file changed, 17 insertions(+), 15 deletions(-)
    > >
    > > diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
    > > index 60d496c16841..55bac1465536 100644
    > > --- a/fs/fuse/virtio_fs.c
    > > +++ b/fs/fuse/virtio_fs.c
    > > @@ -14,11 +14,6 @@
    > > #include <uapi/linux/virtio_pci.h>
    > > #include "fuse_i.h"
    > >
    > > -enum {
    > > - /* PCI BAR number of the virtio-fs DAX window */
    > > - VIRTIO_FS_WINDOW_BAR = 2,
    > > -};
    > > -
    > > /* List of virtio-fs device instances and a lock for the list */
    > > static DEFINE_MUTEX(virtio_fs_mutex);
    > > static LIST_HEAD(virtio_fs_instances);
    > > @@ -518,7 +513,7 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs)
    > > struct dev_pagemap *pgmap;
    > > struct pci_dev *pci_dev;
    > > phys_addr_t phys_addr;
    > > - size_t len;
    > > + size_t bar_len;
    > > int ret;
    > > u8 have_cache, cache_bar;
    > > u64 cache_offset, cache_len;
    > > @@ -551,17 +546,13 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs)
    > > }
    > >
    > > /* TODO handle case where device doesn't expose BAR? */
    > > - ret = pci_request_region(pci_dev, VIRTIO_FS_WINDOW_BAR,
    > > - "virtio-fs-window");
    > > + ret = pci_request_region(pci_dev, cache_bar, "virtio-fs-window");
    > > if (ret < 0) {
    > > dev_err(&vdev->dev, "%s: failed to request window BAR\n",
    > > __func__);
    > > return ret;
    > > }
    > >
    > > - phys_addr = pci_resource_start(pci_dev, VIRTIO_FS_WINDOW_BAR);
    > > - len = pci_resource_len(pci_dev, VIRTIO_FS_WINDOW_BAR);
    > > -
    > > mi = devm_kzalloc(&pci_dev->dev, sizeof(*mi), GFP_KERNEL);
    > > if (!mi)
    > > return -ENOMEM;
    > > @@ -586,6 +577,17 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs)
    > > pgmap->ref = &mi->ref;
    > > pgmap->type = MEMORY_DEVICE_FS_DAX;
    > >
    > > + phys_addr = pci_resource_start(pci_dev, cache_bar);
    > > + bar_len = pci_resource_len(pci_dev, cache_bar);
    > > +
    > > + if (cache_offset + cache_len > bar_len) {
    > > + dev_err(&vdev->dev,
    > > + "%s: cache bar shorter than cap offset+len\n",
    > > + __func__);
    > > + return -EINVAL;
    > > + }
    > > + phys_addr += cache_offset;
    > > +
    > > /* Ideally we would directly use the PCI BAR resource but
    > > * devm_memremap_pages() wants its own copy in pgmap. So
    > > * initialize a struct resource from scratch (only the start
    > > @@ -594,7 +596,7 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs)
    > > pgmap->res = (struct resource){
    > > .name = "virtio-fs dax window",
    > > .start = phys_addr,
    > > - .end = phys_addr + len,
    > > + .end = phys_addr + cache_len,
    >
    > Just in case you haven't noticed/fixed this problem, it should be
    >
    > + .end = phys_addr + cache_len - 1,
    >
    > because resource_size() counts %size as "end - start + 1".
    > The end result of the above is a "conflicting page map" warning when
    > specifying a second virtio-fs pci device.

    Thanks for spotting this! I think we'd seen that message once but not
    noticed where from.

    > I'll send a patch for this, and feel free to take it along with the
    > patchset if needed.
    >

    Dave

    > thanks,
    > liubo
    >
    > > };
    > >
    > > fs->window_kaddr = devm_memremap_pages(&pci_dev->dev, pgmap);
    > > @@ -607,10 +609,10 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs)
    > > return ret;
    > >
    > > fs->window_phys_addr = phys_addr;
    > > - fs->window_len = len;
    > > + fs->window_len = cache_len;
    > >
    > > - dev_dbg(&vdev->dev, "%s: window kaddr 0x%px phys_addr 0x%llx len %zu\n",
    > > - __func__, fs->window_kaddr, phys_addr, len);
    > > + dev_dbg(&vdev->dev, "%s: cache kaddr 0x%px phys_addr 0x%llx len %llx\n",
    > > + __func__, fs->window_kaddr, phys_addr, cache_len);
    > >
    > > fs->dax_dev = alloc_dax(fs, NULL, &virtio_fs_dax_ops);
    > > if (!fs->dax_dev)
    > > --
    > > 2.13.6
    > >
    --
    Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

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