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udmabuf: convert udmabuf driver to use folios
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This is mainly a preparatory patch to use memfd_pin_folios() API for
pinning folios.  Using folios instead of pages makes sense as the udmabuf
driver needs to handle both shmem and hugetlb cases.  And, using the
memfd_pin_folios() API makes this easier as we no longer need to
separately handle shmem vs hugetlb cases in the udmabuf driver.

Note that, the function vmap_udmabuf() still needs a list of pages; so, we
collect all the head pages into a local array in this case.

Other changes in this patch include the addition of helpers for checking
the memfd seals and exporting dmabuf.  Moving code from udmabuf_create()
into these helpers improves readability given that udmabuf_create() is a
bit long.

Link: https://lkml.kernel.org/r/20240624063952.1572359-8-vivek.kasireddy@intel.com
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Dongwon Kim <dongwon.kim@intel.com>
Cc: Junxiao Chang <junxiao.chang@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Vivek Kasireddy authored and Andrew Morton committed Jul 12, 2024
1 parent 0c8b91e commit 5e72b2b
Showing 1 changed file with 83 additions and 56 deletions.
139 changes: 83 additions & 56 deletions drivers/dma-buf/udmabuf.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,7 @@ MODULE_PARM_DESC(size_limit_mb, "Max size of a dmabuf, in megabytes. Default is

struct udmabuf {
pgoff_t pagecount;
struct page **pages;
struct folio **folios;
struct sg_table *sg;
struct miscdevice *device;
pgoff_t *offsets;
Expand All @@ -42,7 +42,7 @@ static vm_fault_t udmabuf_vm_fault(struct vm_fault *vmf)
if (pgoff >= ubuf->pagecount)
return VM_FAULT_SIGBUS;

pfn = page_to_pfn(ubuf->pages[pgoff]);
pfn = folio_pfn(ubuf->folios[pgoff]);
pfn += ubuf->offsets[pgoff] >> PAGE_SHIFT;

return vmf_insert_pfn(vma, vmf->address, pfn);
Expand All @@ -68,11 +68,21 @@ static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma)
static int vmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)
{
struct udmabuf *ubuf = buf->priv;
struct page **pages;
void *vaddr;
pgoff_t pg;

dma_resv_assert_held(buf->resv);

vaddr = vm_map_ram(ubuf->pages, ubuf->pagecount, -1);
pages = kmalloc_array(ubuf->pagecount, sizeof(*pages), GFP_KERNEL);
if (!pages)
return -ENOMEM;

for (pg = 0; pg < ubuf->pagecount; pg++)
pages[pg] = &ubuf->folios[pg]->page;

vaddr = vm_map_ram(pages, ubuf->pagecount, -1);
kfree(pages);
if (!vaddr)
return -EINVAL;

Expand Down Expand Up @@ -107,7 +117,8 @@ static struct sg_table *get_sg_table(struct device *dev, struct dma_buf *buf,
goto err_alloc;

for_each_sg(sg->sgl, sgl, ubuf->pagecount, i)
sg_set_page(sgl, ubuf->pages[i], PAGE_SIZE, ubuf->offsets[i]);
sg_set_folio(sgl, ubuf->folios[i], PAGE_SIZE,
ubuf->offsets[i]);

ret = dma_map_sgtable(dev, sg, direction, 0);
if (ret < 0)
Expand Down Expand Up @@ -152,9 +163,9 @@ static void release_udmabuf(struct dma_buf *buf)
put_sg_table(dev, ubuf->sg, DMA_BIDIRECTIONAL);

for (pg = 0; pg < ubuf->pagecount; pg++)
put_page(ubuf->pages[pg]);
folio_put(ubuf->folios[pg]);
kfree(ubuf->offsets);
kfree(ubuf->pages);
kfree(ubuf->folios);
kfree(ubuf);
}

Expand Down Expand Up @@ -215,36 +226,33 @@ static int handle_hugetlb_pages(struct udmabuf *ubuf, struct file *memfd,
pgoff_t mapidx = offset >> huge_page_shift(hpstate);
pgoff_t subpgoff = (offset & ~huge_page_mask(hpstate)) >> PAGE_SHIFT;
pgoff_t maxsubpgs = huge_page_size(hpstate) >> PAGE_SHIFT;
struct page *hpage = NULL;
struct folio *folio;
struct folio *folio = NULL;
pgoff_t pgidx;

mapidx <<= huge_page_order(hpstate);
for (pgidx = 0; pgidx < pgcnt; pgidx++) {
if (!hpage) {
if (!folio) {
folio = __filemap_get_folio(memfd->f_mapping,
mapidx,
FGP_ACCESSED, 0);
if (IS_ERR(folio))
return PTR_ERR(folio);

hpage = &folio->page;
}

get_page(hpage);
ubuf->pages[*pgbuf] = hpage;
folio_get(folio);
ubuf->folios[*pgbuf] = folio;
ubuf->offsets[*pgbuf] = subpgoff << PAGE_SHIFT;
(*pgbuf)++;
if (++subpgoff == maxsubpgs) {
put_page(hpage);
hpage = NULL;
folio_put(folio);
folio = NULL;
subpgoff = 0;
mapidx += pages_per_huge_page(hpstate);
}
}

if (hpage)
put_page(hpage);
if (folio)
folio_put(folio);

return 0;
}
Expand All @@ -254,31 +262,69 @@ static int handle_shmem_pages(struct udmabuf *ubuf, struct file *memfd,
pgoff_t *pgbuf)
{
pgoff_t pgidx, pgoff = offset >> PAGE_SHIFT;
struct page *page;
struct folio *folio = NULL;

for (pgidx = 0; pgidx < pgcnt; pgidx++) {
page = shmem_read_mapping_page(memfd->f_mapping,
pgoff + pgidx);
if (IS_ERR(page))
return PTR_ERR(page);
folio = shmem_read_folio(memfd->f_mapping, pgoff + pgidx);
if (IS_ERR(folio))
return PTR_ERR(folio);

ubuf->pages[*pgbuf] = page;
ubuf->folios[*pgbuf] = folio;
(*pgbuf)++;
}

return 0;
}

static int check_memfd_seals(struct file *memfd)
{
int seals;

if (!memfd)
return -EBADFD;

if (!shmem_file(memfd) && !is_file_hugepages(memfd))
return -EBADFD;

seals = memfd_fcntl(memfd, F_GET_SEALS, 0);
if (seals == -EINVAL)
return -EBADFD;

if ((seals & SEALS_WANTED) != SEALS_WANTED ||
(seals & SEALS_DENIED) != 0)
return -EINVAL;

return 0;
}

static int export_udmabuf(struct udmabuf *ubuf,
struct miscdevice *device,
u32 flags)
{
DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
struct dma_buf *buf;

ubuf->device = device;
exp_info.ops = &udmabuf_ops;
exp_info.size = ubuf->pagecount << PAGE_SHIFT;
exp_info.priv = ubuf;
exp_info.flags = O_RDWR;

buf = dma_buf_export(&exp_info);
if (IS_ERR(buf))
return PTR_ERR(buf);

return dma_buf_fd(buf, flags);
}

static long udmabuf_create(struct miscdevice *device,
struct udmabuf_create_list *head,
struct udmabuf_create_item *list)
{
DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
pgoff_t pgcnt, pgbuf = 0, pglimit;
struct file *memfd = NULL;
struct udmabuf *ubuf;
struct dma_buf *buf;
pgoff_t pgcnt, pgbuf = 0, pglimit;
int seals, ret = -EINVAL;
int ret = -EINVAL;
u32 i, flags;

ubuf = kzalloc(sizeof(*ubuf), GFP_KERNEL);
Expand All @@ -299,9 +345,9 @@ static long udmabuf_create(struct miscdevice *device,
if (!ubuf->pagecount)
goto err;

ubuf->pages = kmalloc_array(ubuf->pagecount, sizeof(*ubuf->pages),
ubuf->folios = kmalloc_array(ubuf->pagecount, sizeof(*ubuf->folios),
GFP_KERNEL);
if (!ubuf->pages) {
if (!ubuf->folios) {
ret = -ENOMEM;
goto err;
}
Expand All @@ -314,18 +360,9 @@ static long udmabuf_create(struct miscdevice *device,

pgbuf = 0;
for (i = 0; i < head->count; i++) {
ret = -EBADFD;
memfd = fget(list[i].memfd);
if (!memfd)
goto err;
if (!shmem_file(memfd) && !is_file_hugepages(memfd))
goto err;
seals = memfd_fcntl(memfd, F_GET_SEALS, 0);
if (seals == -EINVAL)
goto err;
ret = -EINVAL;
if ((seals & SEALS_WANTED) != SEALS_WANTED ||
(seals & SEALS_DENIED) != 0)
ret = check_memfd_seals(memfd);
if (ret < 0)
goto err;

pgcnt = list[i].size >> PAGE_SHIFT;
Expand All @@ -344,30 +381,20 @@ static long udmabuf_create(struct miscdevice *device,
memfd = NULL;
}

exp_info.ops = &udmabuf_ops;
exp_info.size = ubuf->pagecount << PAGE_SHIFT;
exp_info.priv = ubuf;
exp_info.flags = O_RDWR;

ubuf->device = device;
buf = dma_buf_export(&exp_info);
if (IS_ERR(buf)) {
ret = PTR_ERR(buf);
flags = head->flags & UDMABUF_FLAGS_CLOEXEC ? O_CLOEXEC : 0;
ret = export_udmabuf(ubuf, device, flags);
if (ret < 0)
goto err;
}

flags = 0;
if (head->flags & UDMABUF_FLAGS_CLOEXEC)
flags |= O_CLOEXEC;
return dma_buf_fd(buf, flags);
return ret;

err:
while (pgbuf > 0)
put_page(ubuf->pages[--pgbuf]);
folio_put(ubuf->folios[--pgbuf]);
if (memfd)
fput(memfd);
kfree(ubuf->offsets);
kfree(ubuf->pages);
kfree(ubuf->folios);
kfree(ubuf);
return ret;
}
Expand Down

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