1 files changed, 113 insertions, 18 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index c25639e907bd..5c0b2cba870e 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -156,11 +156,16 @@ blkdev_get_block(struct inode *inode, sector_t iblock,
         return 0;
 }
 
+static struct inode *bdev_file_inode(struct file *file)
+{
+        return file->f_mapping->host;
+}
+
 static ssize_t
 blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
 {
         struct file *file = iocb->ki_filp;
-        struct inode *inode = file->f_mapping->host;
+        struct inode *inode = bdev_file_inode(file);
 
         if (IS_DAX(inode))
                 return dax_do_io(iocb, inode, iter, offset, blkdev_get_block,
@@ -338,7 +343,7 @@ static int blkdev_write_end(struct file *file, struct address_space *mapping,
  */
 static loff_t block_llseek(struct file *file, loff_t offset, int whence)
 {
-        struct inode *bd_inode = file->f_mapping->host;
+        struct inode *bd_inode = bdev_file_inode(file);
         loff_t retval;
 
         mutex_lock(&bd_inode->i_mutex);
@@ -349,7 +354,7 @@ static loff_t block_llseek(struct file *file, loff_t offset, int whence)
         
 int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 {
-        struct inode *bd_inode = filp->f_mapping->host;
+        struct inode *bd_inode = bdev_file_inode(filp);
         struct block_device *bdev = I_BDEV(bd_inode);
         int error;
         
@@ -1230,8 +1235,11 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
                                 }
                         }
 
-                        if (!ret)
+                        if (!ret) {
                                 bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
+                                if (!blkdev_dax_capable(bdev))
+                                        bdev->bd_inode->i_flags &= ~S_DAX;
+                        }
 
                         /*
                          * If the device is invalidated, rescan partition
@@ -1245,6 +1253,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
                                 else if (ret == -ENOMEDIUM)
                                         invalidate_partitions(disk, bdev);
                         }
+
                         if (ret)
                                 goto out_clear;
                 } else {
@@ -1265,12 +1274,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
                                 goto out_clear;
                         }
                         bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
-                        /*
-                         * If the partition is not aligned on a page
-                         * boundary, we can't do dax I/O to it.
-                         */
-                        if ((bdev->bd_part->start_sect % (PAGE_SIZE / 512)) ||
-                            (bdev->bd_part->nr_sects % (PAGE_SIZE / 512)))
+                        if (!blkdev_dax_capable(bdev))
                                 bdev->bd_inode->i_flags &= ~S_DAX;
                 }
         } else {
@@ -1523,11 +1527,14 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
                 WARN_ON_ONCE(bdev->bd_holders);
                 sync_blockdev(bdev);
                 kill_bdev(bdev);
+
+                bdev_write_inode(bdev);
                 /*
-                 * ->release can cause the queue to disappear, so flush all
-                 * dirty data before.
+                 * Detaching bdev inode from its wb in __destroy_inode()
+                 * is too late: the queue which embeds its bdi (along with
+                 * root wb) can be gone as soon as we put_disk() below.
                  */
-                bdev_write_inode(bdev);
+                inode_detach_wb(bdev->bd_inode);
         }
         if (bdev->bd_contains == bdev) {
                 if (disk->fops->release)
@@ -1602,14 +1609,14 @@ EXPORT_SYMBOL(blkdev_put);
 
 static int blkdev_close(struct inode * inode, struct file * filp)
 {
-        struct block_device *bdev = I_BDEV(filp->f_mapping->host);
+        struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
         blkdev_put(bdev, filp->f_mode);
         return 0;
 }
 
 static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 {
-        struct block_device *bdev = I_BDEV(file->f_mapping->host);
+        struct block_device *bdev = I_BDEV(bdev_file_inode(file));
         fmode_t mode = file->f_mode;
 
         /*
@@ -1634,7 +1641,7 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
         struct file *file = iocb->ki_filp;
-        struct inode *bd_inode = file->f_mapping->host;
+        struct inode *bd_inode = bdev_file_inode(file);
         loff_t size = i_size_read(bd_inode);
         struct blk_plug plug;
         ssize_t ret;
@@ -1666,7 +1673,7 @@ EXPORT_SYMBOL_GPL(blkdev_write_iter);
 ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
         struct file *file = iocb->ki_filp;
-        struct inode *bd_inode = file->f_mapping->host;
+        struct inode *bd_inode = bdev_file_inode(file);
         loff_t size = i_size_read(bd_inode);
         loff_t pos = iocb->ki_pos;
 
@@ -1705,13 +1712,101 @@ static const struct address_space_operations def_blk_aops = {
         .is_dirty_writeback = buffer_check_dirty_writeback,
 };
 
+#ifdef CONFIG_FS_DAX
+/*
+ * In the raw block case we do not need to contend with truncation nor
+ * unwritten file extents.  Without those concerns there is no need for
+ * additional locking beyond the mmap_sem context that these routines
+ * are already executing under.
+ *
+ * Note, there is no protection if the block device is dynamically
+ * resized (partition grow/shrink) during a fault. A stable block device
+ * size is already not enforced in the blkdev_direct_IO path.
+ *
+ * For DAX, it is the responsibility of the block device driver to
+ * ensure the whole-disk device size is stable while requests are in
+ * flight.
+ *
+ * Finally, unlike the filemap_page_mkwrite() case there is no
+ * filesystem superblock to sync against freezing.  We still include a
+ * pfn_mkwrite callback for dax drivers to receive write fault
+ * notifications.
+ */
+static int blkdev_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+        return __dax_fault(vma, vmf, blkdev_get_block, NULL);
+}
+
+static int blkdev_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
+                pmd_t *pmd, unsigned int flags)
+{
+        return __dax_pmd_fault(vma, addr, pmd, flags, blkdev_get_block, NULL);
+}
+
+static void blkdev_vm_open(struct vm_area_struct *vma)
+{
+        struct inode *bd_inode = bdev_file_inode(vma->vm_file);
+        struct block_device *bdev = I_BDEV(bd_inode);
+
+        mutex_lock(&bd_inode->i_mutex);
+        bdev->bd_map_count++;
+        mutex_unlock(&bd_inode->i_mutex);
+}
+
+static void blkdev_vm_close(struct vm_area_struct *vma)
+{
+        struct inode *bd_inode = bdev_file_inode(vma->vm_file);
+        struct block_device *bdev = I_BDEV(bd_inode);
+
+        mutex_lock(&bd_inode->i_mutex);
+        bdev->bd_map_count--;
+        mutex_unlock(&bd_inode->i_mutex);
+}
+
+static const struct vm_operations_struct blkdev_dax_vm_ops = {
+        .open           = blkdev_vm_open,
+        .close          = blkdev_vm_close,
+        .fault          = blkdev_dax_fault,
+        .pmd_fault      = blkdev_dax_pmd_fault,
+        .pfn_mkwrite    = blkdev_dax_fault,
+};
+
+static const struct vm_operations_struct blkdev_default_vm_ops = {
+        .open           = blkdev_vm_open,
+        .close          = blkdev_vm_close,
+        .fault          = filemap_fault,
+        .map_pages      = filemap_map_pages,
+};
+
+static int blkdev_mmap(struct file *file, struct vm_area_struct *vma)
+{
+        struct inode *bd_inode = bdev_file_inode(file);
+        struct block_device *bdev = I_BDEV(bd_inode);
+
+        file_accessed(file);
+        mutex_lock(&bd_inode->i_mutex);
+        bdev->bd_map_count++;
+        if (IS_DAX(bd_inode)) {
+                vma->vm_ops = &blkdev_dax_vm_ops;
+                vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
+        } else {
+                vma->vm_ops = &blkdev_default_vm_ops;
+        }
+        mutex_unlock(&bd_inode->i_mutex);
+
+        return 0;
+}
+#else
+#define blkdev_mmap generic_file_mmap
+#endif
+
 const struct file_operations def_blk_fops = {
         .open           = blkdev_open,
         .release        = blkdev_close,
         .llseek         = block_llseek,
         .read_iter      = blkdev_read_iter,
         .write_iter     = blkdev_write_iter,
-        .mmap           = generic_file_mmap,
+        .mmap           = blkdev_mmap,
         .fsync          = blkdev_fsync,
         .unlocked_ioctl = block_ioctl,
 #ifdef CONFIG_COMPAT