From: Yu Kuai <yukuai3@xxxxxxxxxx>
scsi_bios_ptable() is reading without opening disk as file, 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>
---
block/bdev.c | 19 +++++++++++++++++++
drivers/scsi/scsicam.c | 3 +--
include/linux/blkdev.h | 1 +
3 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/block/bdev.c b/block/bdev.c
index 60a1479eae83..b7af04d34af2 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -1211,6 +1211,25 @@ 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/drivers/scsi/scsicam.c b/drivers/scsi/scsicam.c
index e2c7d8ef205f..1c99b964a0eb 100644
--- a/drivers/scsi/scsicam.c
+++ b/drivers/scsi/scsicam.c
@@ -32,11 +32,10 @@
*/
unsigned char *scsi_bios_ptable(struct block_device *dev)
{
- struct address_space *mapping = bdev_whole(dev)->bd_inode->i_mapping;
unsigned char *res = NULL;
struct folio *folio;
- folio = read_mapping_folio(mapping, 0, NULL);
+ folio = bdev_read_folio(bdev_whole(dev), 0);
if (IS_ERR(folio))
return NULL;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index c510f334c84f..3fb02e3a527a 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1514,6 +1514,7 @@ 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
