From: Yu Kuai <yukuai3@xxxxxxxxxx>
Currently scsi driver is reading without opening disk as file(
scsi_bios_ptable()), factor out a helper to read into block device page
cache to prevent access bd_inode directly from scsi.
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
---
block/bdev.c | 19 +++++++++++++++++++
include/linux/blkdev.h | 1 +
2 files changed, 20 insertions(+)
diff --git a/block/bdev.c b/block/bdev.c
index c0b30392563a..4335df6d1266 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -1266,6 +1266,25 @@ unsigned int block_size(struct block_device *bdev)
}
EXPORT_SYMBOL_GPL(block_size);
+/**
+ * bdev_read_folio - Read into block device page cache.
+ * @bdev: the block device which holds the cache to read.
+ * @pos: the offset that allocated folio will contain.
+ *
+ * Read one page into the block device page cache. If it succeeds, the folio
+ * returned will contain @pos;
+ *
+ * This is only used for scsi_bios_ptable(), the bdev is not opened as files.
+ *
+ * Return: Uptodate folio on success, ERR_PTR() on failure.
+ */
+struct folio *bdev_read_folio(struct block_device *bdev, loff_t pos)
+{
+ return mapping_read_folio_gfp(bdev_mapping(bdev),
+ pos >> PAGE_SHIFT, GFP_KERNEL);
+}
+EXPORT_SYMBOL_GPL(bdev_read_folio);
+
static int __init setup_bdev_allow_write_mounted(char *str)
{
if (kstrtobool(str, &bdev_allow_write_mounted))
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 08d4e6a0940c..bc840e0fb6e5 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1519,6 +1519,7 @@ struct file *bdev_file_open_by_path(const char *path, blk_mode_t mode,
int bd_prepare_to_claim(struct block_device *bdev, void *holder,
const struct blk_holder_ops *hops);
void bd_abort_claiming(struct block_device *bdev, void *holder);
+struct folio *bdev_read_folio(struct block_device *bdev, loff_t pos);
/* just for blk-cgroup, don't use elsewhere */
struct block_device *blkdev_get_no_open(dev_t dev);
--
2.39.2
