UBI: introduce the VID buffer concept

Currently, all VID headers are allocated and freed using the
ubi_zalloc_vid_hdr() and ubi_free_vid_hdr() function. These functions
make sure to align allocation on ubi->vid_hdr_alsize and adjust the
vid_hdr pointer to match the ubi->vid_hdr_shift requirements.
This works fine, but is a bit convoluted.
Moreover, the future introduction of LEB consolidation (needed to support
MLC/TLC NANDs) will allows a VID buffer to contain more than one VID
header.

Hence the creation of a ubi_vid_io_buf struct to attach extra information
to the VID header.

We currently only store the actual pointer of the underlying buffer, but
will soon add the number of VID headers contained in the buffer.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 66 insertions, 31 deletions

diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index bc14522..697dbcb 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -167,6 +167,17 @@ enum {
 };
 
 /**
+ * struct ubi_vid_io_buf - VID buffer used to read/write VID info to/from the
+ *			   flash.
+ * @hdr: a pointer to the VID header stored in buffer
+ * @buffer: underlying buffer
+ */
+struct ubi_vid_io_buf {
+	struct ubi_vid_hdr *hdr;
+	void *buffer;
+};
+
+/**
  * struct ubi_wl_entry - wear-leveling entry.
  * @u.rb: link in the corresponding (free/used) RB-tree
  * @u.list: link in the protection queue
@@ -740,7 +751,7 @@ struct ubi_ainf_volume {
  * @ec_count: a temporary variable used when calculating @mean_ec
  * @aeb_slab_cache: slab cache for &struct ubi_ainf_peb objects
  * @ech: temporary EC header. Only available during scan
- * @vidh: temporary VID header. Only available during scan
+ * @vidh: temporary VID buffer. Only available during scan
  *
  * This data structure contains the result of attaching an MTD device and may
  * be used by other UBI sub-systems to build final UBI data structures, further
@@ -770,7 +781,7 @@ struct ubi_attach_info {
 	int ec_count;
 	struct kmem_cache *aeb_slab_cache;
 	struct ubi_ec_hdr *ech;
-	struct ubi_vid_hdr *vidh;
+	struct ubi_vid_io_buf *vidb;
 };
 
 /**
@@ -887,7 +898,7 @@ int ubi_eba_write_leb_st(struct ubi_device *ubi, struct ubi_volume *vol,
 int ubi_eba_atomic_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
 			      int lnum, const void *buf, int len);
 int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
-		     struct ubi_vid_hdr *vid_hdr);
+		     struct ubi_vid_io_buf *vidb);
 int ubi_eba_init(struct ubi_device *ubi, struct ubi_attach_info *ai);
 unsigned long long ubi_next_sqnum(struct ubi_device *ubi);
 int self_check_eba(struct ubi_device *ubi, struct ubi_attach_info *ai_fastmap,
@@ -922,9 +933,9 @@ int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,
 int ubi_io_write_ec_hdr(struct ubi_device *ubi, int pnum,
 			struct ubi_ec_hdr *ec_hdr);
 int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
-			struct ubi_vid_hdr *vid_hdr, int verbose);
+			struct ubi_vid_io_buf *vidb, int verbose);
 int ubi_io_write_vid_hdr(struct ubi_device *ubi, int pnum,
-			 struct ubi_vid_hdr *vid_hdr);
+			 struct ubi_vid_io_buf *vidb);
 
 /* build.c */
 int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
@@ -1045,44 +1056,68 @@ static inline void ubi_move_aeb_to_list(struct ubi_ainf_volume *av,
 }
 
 /**
- * ubi_zalloc_vid_hdr - allocate a volume identifier header object.
- * @ubi: UBI device description object
- * @gfp_flags: GFP flags to allocate with
- *
- * This function returns a pointer to the newly allocated and zero-filled
- * volume identifier header object in case of success and %NULL in case of
- * failure.
+ * ubi_init_vid_buf - Initialize a VID buffer
+ * @ubi: the UBI device
+ * @vidb: the VID buffer to initialize
+ * @buf: the underlying buffer
+ */
+static inline void ubi_init_vid_buf(const struct ubi_device *ubi,
+				    struct ubi_vid_io_buf *vidb,
+				    void *buf)
+{
+	if (buf)
+		memset(buf, 0, ubi->vid_hdr_alsize);
+
+	vidb->buffer = buf;
+	vidb->hdr = buf + ubi->vid_hdr_shift;
+}
+
+/**
+ * ubi_init_vid_buf - Allocate a VID buffer
+ * @ubi: the UBI device
+ * @gfp_flags: GFP flags to use for the allocation
  */
-static inline struct ubi_vid_hdr *
-ubi_zalloc_vid_hdr(const struct ubi_device *ubi, gfp_t gfp_flags)
+static inline struct ubi_vid_io_buf *
+ubi_alloc_vid_buf(const struct ubi_device *ubi, gfp_t gfp_flags)
 {
-	void *vid_hdr;
+	struct ubi_vid_io_buf *vidb;
+	void *buf;
 
-	vid_hdr = kzalloc(ubi->vid_hdr_alsize, gfp_flags);
-	if (!vid_hdr)
+	vidb = kzalloc(sizeof(*vidb), gfp_flags);
+	if (!vidb)
 		return NULL;
 
-	/*
-	 * VID headers may be stored at un-aligned flash offsets, so we shift
-	 * the pointer.
-	 */
-	return vid_hdr + ubi->vid_hdr_shift;
+	buf = kmalloc(ubi->vid_hdr_alsize, gfp_flags);
+	if (!buf) {
+		kfree(vidb);
+		return NULL;
+	}
+
+	ubi_init_vid_buf(ubi, vidb, buf);
+
+	return vidb;
 }
 
 /**
- * ubi_free_vid_hdr - free a volume identifier header object.
- * @ubi: UBI device description object
- * @vid_hdr: the object to free
+ * ubi_free_vid_buf - Free a VID buffer
+ * @vidb: the VID buffer to free
  */
-static inline void ubi_free_vid_hdr(const struct ubi_device *ubi,
-				    struct ubi_vid_hdr *vid_hdr)
+static inline void ubi_free_vid_buf(struct ubi_vid_io_buf *vidb)
 {
-	void *p = vid_hdr;
-
-	if (!p)
+	if (!vidb)
 		return;
 
-	kfree(p - ubi->vid_hdr_shift);
+	kfree(vidb->buffer);
+	kfree(vidb);
+}
+
+/**
+ * ubi_get_vid_hdr - Get the VID header attached to a VID buffer
+ * @vidb: VID buffer
+ */
+static inline struct ubi_vid_hdr *ubi_get_vid_hdr(struct ubi_vid_io_buf *vidb)
+{
+	return vidb->hdr;
 }
 
 /*