[PATCH v2 5/9] blk: blkmap: Add linear device mapping support
Tobias Waldekranz
tobias at waldekranz.com
Thu Feb 16 16:33:51 CET 2023
Allow a slice of an existing block device to be mapped to a
blkmap. This means that filesystems that are not stored at exact
partition boundaries can be accessed by remapping a slice of the
existing device to a blkmap device.
Signed-off-by: Tobias Waldekranz <tobias at waldekranz.com>
---
drivers/block/blkmap.c | 71 ++++++++++++++++++++++++++++++++++++++++++
include/blkmap.h | 13 ++++++++
2 files changed, 84 insertions(+)
diff --git a/drivers/block/blkmap.c b/drivers/block/blkmap.c
index 6d6eed889e..2bb0acc20f 100644
--- a/drivers/block/blkmap.c
+++ b/drivers/block/blkmap.c
@@ -130,6 +130,77 @@ static int blkmap_slice_add(struct blkmap *bm, struct blkmap_slice *new)
return 0;
}
+/**
+ * struct blkmap_linear - Linear mapping to other block device
+ *
+ * @slice: Common map data
+ * @blk: Target block device of this mapping
+ * @blknr: Start block number of the target device
+ */
+struct blkmap_linear {
+ struct blkmap_slice slice;
+
+ struct udevice *blk;
+ lbaint_t blknr;
+};
+
+static ulong blkmap_linear_read(struct blkmap *bm, struct blkmap_slice *bms,
+ lbaint_t blknr, lbaint_t blkcnt, void *buffer)
+{
+ struct blkmap_linear *bml = container_of(bms, struct blkmap_linear, slice);
+
+ return blk_read(bml->blk, bml->blknr + blknr, blkcnt, buffer);
+}
+
+static ulong blkmap_linear_write(struct blkmap *bm, struct blkmap_slice *bms,
+ lbaint_t blknr, lbaint_t blkcnt,
+ const void *buffer)
+{
+ struct blkmap_linear *bml = container_of(bms, struct blkmap_linear, slice);
+
+ return blk_write(bml->blk, bml->blknr + blknr, blkcnt, buffer);
+}
+
+int blkmap_map_linear(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
+ struct udevice *lblk, lbaint_t lblknr)
+{
+ struct blkmap *bm = dev_get_plat(dev);
+ struct blkmap_linear *linear;
+ struct blk_desc *bd, *lbd;
+ int err;
+
+ bd = dev_get_uclass_plat(bm->blk);
+ lbd = dev_get_uclass_plat(lblk);
+ if (lbd->blksz != bd->blksz)
+ /* We could support block size translation, but we
+ * don't yet.
+ */
+ return -EINVAL;
+
+ linear = malloc(sizeof(*linear));
+ if (!linear)
+ return -ENOMEM;
+
+ *linear = (struct blkmap_linear) {
+ .slice = {
+ .blknr = blknr,
+ .blkcnt = blkcnt,
+
+ .read = blkmap_linear_read,
+ .write = blkmap_linear_write,
+ },
+
+ .blk = lblk,
+ .blknr = lblknr,
+ };
+
+ err = blkmap_slice_add(bm, &linear->slice);
+ if (err)
+ free(linear);
+
+ return err;
+}
+
/**
* struct blkmap_mem - Memory mapping
*
diff --git a/include/blkmap.h b/include/blkmap.h
index 74baeb19f8..af54583c7d 100644
--- a/include/blkmap.h
+++ b/include/blkmap.h
@@ -7,6 +7,19 @@
#ifndef _BLKMAP_H
#define _BLKMAP_H
+/**
+ * blkmap_map_linear() - Map region of other block device
+ *
+ * @dev: Blkmap to create the mapping on
+ * @blknr: Start block number of the mapping
+ * @blkcnt: Number of blocks to map
+ * @lblk: The target block device of the mapping
+ * @lblknr: The start block number of the target device
+ * Returns: 0 on success, negative error code on failure
+ */
+int blkmap_map_linear(struct udevice *dev, lbaint_t blknr, lbaint_t blkcnt,
+ struct udevice *lblk, lbaint_t lblknr);
+
/**
* blkmap_map_mem() - Map region of memory
*
--
2.34.1
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