From: Stefan Hajnoczi <[email protected]> Setup a dax device.
Use the shm capability to find the cache entry and map it. The DAX window is accessed by the fs/dax.c infrastructure and must have struct pages (at least on x86). Use devm_memremap_pages() to map the DAX window PCI BAR and allocate struct page. Signed-off-by: Stefan Hajnoczi <[email protected]> Signed-off-by: Dr. David Alan Gilbert <[email protected]> Signed-off-by: Vivek Goyal <[email protected]> Signed-off-by: Sebastien Boeuf <[email protected]> Signed-off-by: Liu Bo <[email protected]> --- fs/fuse/virtio_fs.c | 139 +++++++++++++++++++++++++++++++++ include/uapi/linux/virtio_fs.h | 3 + 2 files changed, 142 insertions(+) diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c index add31794ca1a..e54696f778a7 100644 --- a/fs/fuse/virtio_fs.c +++ b/fs/fuse/virtio_fs.c @@ -5,6 +5,9 @@ */ #include <linux/fs.h> +#include <linux/dax.h> +#include <linux/pci.h> +#include <linux/pfn_t.h> #include <linux/module.h> #include <linux/virtio.h> #include <linux/virtio_fs.h> @@ -12,6 +15,7 @@ #include <linux/fs_context.h> #include <linux/fs_parser.h> #include <linux/highmem.h> +#include <linux/uio.h> #include "fuse_i.h" /* List of virtio-fs device instances and a lock for the list. Also provides @@ -50,6 +54,12 @@ struct virtio_fs { struct virtio_fs_vq *vqs; unsigned int nvqs; /* number of virtqueues */ unsigned int num_request_queues; /* number of request queues */ + struct dax_device *dax_dev; + + /* DAX memory window where file contents are mapped */ + void *window_kaddr; + phys_addr_t window_phys_addr; + size_t window_len; }; struct virtio_fs_forget_req { @@ -726,6 +736,131 @@ static void virtio_fs_cleanup_vqs(struct virtio_device *vdev, vdev->config->del_vqs(vdev); } +/* Map a window offset to a page frame number. The window offset will have + * been produced by .iomap_begin(), which maps a file offset to a window + * offset. + */ +static long virtio_fs_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, + long nr_pages, void **kaddr, pfn_t *pfn) +{ + struct virtio_fs *fs = dax_get_private(dax_dev); + phys_addr_t offset = PFN_PHYS(pgoff); + size_t max_nr_pages = fs->window_len/PAGE_SIZE - pgoff; + + if (kaddr) + *kaddr = fs->window_kaddr + offset; + if (pfn) + *pfn = phys_to_pfn_t(fs->window_phys_addr + offset, + PFN_DEV | PFN_MAP); + return nr_pages > max_nr_pages ? max_nr_pages : nr_pages; +} + +static size_t virtio_fs_copy_from_iter(struct dax_device *dax_dev, + pgoff_t pgoff, void *addr, + size_t bytes, struct iov_iter *i) +{ + return copy_from_iter(addr, bytes, i); +} + +static size_t virtio_fs_copy_to_iter(struct dax_device *dax_dev, + pgoff_t pgoff, void *addr, + size_t bytes, struct iov_iter *i) +{ + return copy_to_iter(addr, bytes, i); +} + +static int virtio_fs_zero_page_range(struct dax_device *dax_dev, + pgoff_t pgoff, size_t nr_pages) +{ + long rc; + void *kaddr; + + rc = dax_direct_access(dax_dev, pgoff, nr_pages, &kaddr, NULL); + if (rc < 0) + return rc; + memset(kaddr, 0, nr_pages << PAGE_SHIFT); + dax_flush(dax_dev, kaddr, nr_pages << PAGE_SHIFT); + return 0; +} + +static const struct dax_operations virtio_fs_dax_ops = { + .direct_access = virtio_fs_direct_access, + .copy_from_iter = virtio_fs_copy_from_iter, + .copy_to_iter = virtio_fs_copy_to_iter, + .zero_page_range = virtio_fs_zero_page_range, +}; + +static void virtio_fs_cleanup_dax(void *data) +{ + struct dax_device *dax_dev = data; + + kill_dax(dax_dev); + put_dax(dax_dev); +} + +static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs) +{ + struct virtio_shm_region cache_reg; + struct dev_pagemap *pgmap; + bool have_cache; + + if (!IS_ENABLED(CONFIG_DAX_DRIVER)) + return 0; + + /* Get cache region */ + have_cache = virtio_get_shm_region(vdev, &cache_reg, + (u8)VIRTIO_FS_SHMCAP_ID_CACHE); + if (!have_cache) { + dev_notice(&vdev->dev, "%s: No cache capability\n", __func__); + return 0; + } + + if (!devm_request_mem_region(&vdev->dev, cache_reg.addr, cache_reg.len, + dev_name(&vdev->dev))) { + dev_warn(&vdev->dev, "could not reserve region addr=0x%llx" + " len=0x%llx\n", cache_reg.addr, cache_reg.len); + return -EBUSY; + } + + dev_notice(&vdev->dev, "Cache len: 0x%llx @ 0x%llx\n", cache_reg.len, + cache_reg.addr); + + pgmap = devm_kzalloc(&vdev->dev, sizeof(*pgmap), GFP_KERNEL); + if (!pgmap) + return -ENOMEM; + + pgmap->type = MEMORY_DEVICE_FS_DAX; + + /* 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 + * and end fields will be used). + */ + pgmap->res = (struct resource){ + .name = "virtio-fs dax window", + .start = (phys_addr_t) cache_reg.addr, + .end = (phys_addr_t) cache_reg.addr + cache_reg.len - 1, + }; + + fs->window_kaddr = devm_memremap_pages(&vdev->dev, pgmap); + if (IS_ERR(fs->window_kaddr)) + return PTR_ERR(fs->window_kaddr); + + fs->window_phys_addr = (phys_addr_t) cache_reg.addr; + fs->window_len = (phys_addr_t) cache_reg.len; + + dev_dbg(&vdev->dev, "%s: window kaddr 0x%px phys_addr 0x%llx" + " len 0x%llx\n", __func__, fs->window_kaddr, cache_reg.addr, + cache_reg.len); + + fs->dax_dev = alloc_dax(fs, NULL, &virtio_fs_dax_ops, 0); + if (IS_ERR(fs->dax_dev)) + return PTR_ERR(fs->dax_dev); + + return devm_add_action_or_reset(&vdev->dev, virtio_fs_cleanup_dax, + fs->dax_dev); +} + static int virtio_fs_probe(struct virtio_device *vdev) { struct virtio_fs *fs; @@ -747,6 +882,10 @@ static int virtio_fs_probe(struct virtio_device *vdev) /* TODO vq affinity */ + ret = virtio_fs_setup_dax(vdev, fs); + if (ret < 0) + goto out_vqs; + /* Bring the device online in case the filesystem is mounted and * requests need to be sent before we return. */ diff --git a/include/uapi/linux/virtio_fs.h b/include/uapi/linux/virtio_fs.h index b02eb2ac3d99..2f64abce781f 100644 --- a/include/uapi/linux/virtio_fs.h +++ b/include/uapi/linux/virtio_fs.h @@ -16,4 +16,7 @@ struct virtio_fs_config { __u32 num_request_queues; } __attribute__((packed)); +/* For the id field in virtio_pci_shm_cap */ +#define VIRTIO_FS_SHMCAP_ID_CACHE 0 + #endif /* _UAPI_LINUX_VIRTIO_FS_H */ -- 2.25.4
