dax: Factor out getting of pfn out of iomap

Factor out code to get pfn out of iomap that is shared between PTE and
PMD fault path.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 43 insertions, 40 deletions

diff --git a/fs/dax.c b/fs/dax.c
index 0bc42ac294ca..116eef8d6c69 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -825,30 +825,53 @@ static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
         return iomap->blkno + (((pos & PAGE_MASK) - iomap->offset) >> 9);
 }
 
-static int dax_insert_mapping(struct vm_fault *vmf, struct iomap *iomap,
-                              loff_t pos, void *entry)
+static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size,
+                         pfn_t *pfnp)
 {
         const sector_t sector = dax_iomap_sector(iomap, pos);
-        struct vm_area_struct *vma = vmf->vma;
-        struct address_space *mapping = vma->vm_file->f_mapping;
-        unsigned long vaddr = vmf->address;
-        void *ret, *kaddr;
         pgoff_t pgoff;
+        void *kaddr;
         int id, rc;
-        pfn_t pfn;
+        long length;
 
-        rc = bdev_dax_pgoff(iomap->bdev, sector, PAGE_SIZE, &pgoff);
+        rc = bdev_dax_pgoff(iomap->bdev, sector, size, &pgoff);
         if (rc)
                 return rc;
-
         id = dax_read_lock();
-        rc = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(PAGE_SIZE),
-                               &kaddr, &pfn);
-        if (rc < 0) {
-                dax_read_unlock(id);
-                return rc;
+        length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size),
+                                   &kaddr, pfnp);
+        if (length < 0) {
+                rc = length;
+                goto out;
         }
+        rc = -EINVAL;
+        if (PFN_PHYS(length) < size)
+                goto out;
+        if (pfn_t_to_pfn(*pfnp) & (PHYS_PFN(size)-1))
+                goto out;
+        /* For larger pages we need devmap */
+        if (length > 1 && !pfn_t_devmap(*pfnp))
+                goto out;
+        rc = 0;
+out:
         dax_read_unlock(id);
+        return rc;
+}
+
+static int dax_insert_mapping(struct vm_fault *vmf, struct iomap *iomap,
+                              loff_t pos, void *entry)
+{
+        const sector_t sector = dax_iomap_sector(iomap, pos);
+        struct vm_area_struct *vma = vmf->vma;
+        struct address_space *mapping = vma->vm_file->f_mapping;
+        unsigned long vaddr = vmf->address;
+        void *ret;
+        int rc;
+        pfn_t pfn;
+
+        rc = dax_iomap_pfn(iomap, pos, PAGE_SIZE, &pfn);
+        if (rc < 0)
+                return rc;
 
         ret = dax_insert_mapping_entry(mapping, vmf, entry, sector, 0);
         if (IS_ERR(ret))
@@ -1223,46 +1246,26 @@ static int dax_pmd_insert_mapping(struct vm_fault *vmf, struct iomap *iomap,
 {
         struct address_space *mapping = vmf->vma->vm_file->f_mapping;
         const sector_t sector = dax_iomap_sector(iomap, pos);
-        struct dax_device *dax_dev = iomap->dax_dev;
-        struct block_device *bdev = iomap->bdev;
         struct inode *inode = mapping->host;
-        const size_t size = PMD_SIZE;
-        void *ret = NULL, *kaddr;
-        long length = 0;
-        pgoff_t pgoff;
+        void *ret = NULL;
         pfn_t pfn = {};
-        int id;
+        int rc;
 
-        if (bdev_dax_pgoff(bdev, sector, size, &pgoff) != 0)
+        rc = dax_iomap_pfn(iomap, pos, PMD_SIZE, &pfn);
+        if (rc < 0)
                 goto fallback;
 
-        id = dax_read_lock();
-        length = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr, &pfn);
-        if (length < 0)
-                goto unlock_fallback;
-        length = PFN_PHYS(length);
-
-        if (length < size)
-                goto unlock_fallback;
-        if (pfn_t_to_pfn(pfn) & PG_PMD_COLOUR)
-                goto unlock_fallback;
-        if (!pfn_t_devmap(pfn))
-                goto unlock_fallback;
-        dax_read_unlock(id);
-
         ret = dax_insert_mapping_entry(mapping, vmf, entry, sector,
                         RADIX_DAX_PMD);
         if (IS_ERR(ret))
                 goto fallback;
 
-        trace_dax_pmd_insert_mapping(inode, vmf, length, pfn, ret);
+        trace_dax_pmd_insert_mapping(inode, vmf, PMD_SIZE, pfn, ret);
         return vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd,
                         pfn, vmf->flags & FAULT_FLAG_WRITE);
 
-unlock_fallback:
-        dax_read_unlock(id);
 fallback:
-        trace_dax_pmd_insert_mapping_fallback(inode, vmf, length, pfn, ret);
+        trace_dax_pmd_insert_mapping_fallback(inode, vmf, PMD_SIZE, pfn, ret);
         return VM_FAULT_FALLBACK;
 }