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authorDan Williams <dan.j.williams@intel.com>2015-11-30 10:20:29 -0800
committerDan Williams <dan.j.williams@intel.com>2016-01-09 06:30:49 -0800
commit5a023cdba50c5f5f2bc351783b3131699deb3937 (patch)
treebae047e7bf8fb28e48563b33afc2881c226f4e31 /fs
parent4ebb16ca9a06a54cdb2e7f2ce1e506fa4d432445 (diff)
downloadlinux-5a023cdba50c5f5f2bc351783b3131699deb3937.tar.bz2
block: enable dax for raw block devices
If an application wants exclusive access to all of the persistent memory provided by an NVDIMM namespace it can use this raw-block-dax facility to forgo establishing a filesystem. This capability is targeted primarily to hypervisors wanting to provision persistent memory for guests. It can be disabled / enabled dynamically via the new BLKDAXSET ioctl. Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Dave Chinner <david@fromorbit.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Reported-by: kbuild test robot <fengguang.wu@intel.com> Reviewed-by: Jan Kara <jack@suse.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/block_dev.c103
1 files changed, 95 insertions, 8 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 52248bce42d2..5c0b2cba870e 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1235,8 +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
@@ -1250,6 +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 {
@@ -1270,12 +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 {
@@ -1713,13 +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