UBI: introduce atomic LEB change ioctl

index c4abe03..f71201d 100644
@@ -26,23 +26,6 @@
 #include <mtd/ubi-user.h>
 
 /*
- * UBI data type hint constants.
- *
- * UBI_LONGTERM: long-term data
- * UBI_SHORTTERM: short-term data
- * UBI_UNKNOWN: data persistence is unknown
- *
- * These constants are used when data is written to UBI volumes in order to
- * help the UBI wear-leveling unit to find more appropriate physical
- * eraseblocks.
- */
-enum {
-	UBI_LONGTERM = 1,
-	UBI_SHORTTERM,
-	UBI_UNKNOWN
-};
-
-/*
  * enum ubi_open_mode - UBI volume open mode constants.
  *
  * UBI_READONLY: read-only mode

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index 0c4044d..9d6aae5 100644
@@ -132,8 +132,15 @@ static int vol_cdev_release(struct inode *inode, struct file *file)
 	if (vol->updating) {
 		ubi_warn("update of volume %d not finished, volume is damaged",
 			 vol->vol_id);
+		ubi_assert(!vol->changing_leb);
 		vol->updating = 0;
 		vfree(vol->upd_buf);
+	} else if (vol->changing_leb) {
+		dbg_msg("only %lld of %lld bytes received for atomic LEB change"
+			" for volume %d:%d, cancel", vol->upd_received,
+			vol->upd_bytes, vol->ubi->ubi_num, vol->vol_id);
+		vol->changing_leb = 0;
+		vfree(vol->upd_buf);
 	}
 
 	ubi_close_volume(desc);

@@ -351,24 +358,32 @@ static ssize_t vol_cdev_write(struct file *file, const char __user *buf,
 	struct ubi_volume *vol = desc->vol;
 	struct ubi_device *ubi = vol->ubi;
 
-	if (!vol->updating)
+	if (!vol->updating && !vol->changing_leb)
 		return vol_cdev_direct_write(file, buf, count, offp);
 
-	err = ubi_more_update_data(ubi, vol, buf, count);
+	if (vol->updating)
+		err = ubi_more_update_data(ubi, vol, buf, count);
+	else
+		err = ubi_more_leb_change_data(ubi, vol, buf, count);
+
 	if (err < 0) {
-		ubi_err("cannot write %zd bytes of update data, error %d",
+		ubi_err("cannot accept more %zd bytes of data, error %d",
 			count, err);
 		return err;
 	}
 
 	if (err) {
 		/*
-		 * Update is finished, @err contains number of actually written
-		 * bytes now.
+		 * The operation is finished, @err contains number of actually
+		 * written bytes.
 		 */
 		count = err;
 
-		vol->updating = 0;
+		if (vol->changing_leb) {
+			revoke_exclusive(desc, UBI_READWRITE);
+			return count;
+		}
+
 		err = ubi_check_volume(ubi, vol->vol_id);
 		if (err < 0)
 			return err;

@@ -433,6 +448,43 @@ static int vol_cdev_ioctl(struct inode *inode, struct file *file,
 		break;
 	}
 
+	/* Atomic logical eraseblock change command */
+	case UBI_IOCEBCH:
+	{
+		struct ubi_leb_change_req req;
+
+		err = copy_from_user(&req, argp,
+				     sizeof(struct ubi_leb_change_req));
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+
+		if (desc->mode == UBI_READONLY ||
+		    vol->vol_type == UBI_STATIC_VOLUME) {
+			err = -EROFS;
+			break;
+		}
+
+		/* Validate the request */
+		err = -EINVAL;
+		if (req.lnum < 0 || req.lnum >= vol->reserved_pebs ||
+		    req.bytes < 0 || req.lnum >= vol->usable_leb_size)
+			break;
+		if (req.dtype != UBI_LONGTERM && req.dtype != UBI_SHORTTERM &&
+		    req.dtype != UBI_UNKNOWN)
+			break;
+
+		err = get_exclusive(desc);
+		if (err < 0)
+			break;
+
+		err = ubi_start_leb_change(ubi, vol, &req);
+		if (req.bytes == 0)
+			revoke_exclusive(desc, UBI_READWRITE);
+		break;
+	}
+
 #ifdef CONFIG_MTD_UBI_DEBUG_USERSPACE_IO
 	/* Logical eraseblock erasure command */
 	case UBI_IOCEBER:

@@ -445,7 +497,8 @@ static int vol_cdev_ioctl(struct inode *inode, struct file *file,
 			break;
 		}
 
-		if (desc->mode == UBI_READONLY) {
+		if (desc->mode == UBI_READONLY ||
+		    vol->vol_type == UBI_STATIC_VOLUME) {
 			err = -EROFS;
 			break;
 		}

@@ -455,11 +508,6 @@ static int vol_cdev_ioctl(struct inode *inode, struct file *file,
 			break;
 		}
 
-		if (vol->vol_type != UBI_DYNAMIC_VOLUME) {
-			err = -EROFS;
-			break;
-		}
-
 		dbg_msg("erase LEB %d:%d", vol->vol_id, lnum);
 		err = ubi_eba_unmap_leb(ubi, vol, lnum);
 		if (err)

index 3a88cf1..4577106 100644
@@ -158,15 +158,23 @@ struct ubi_volume_desc;
  * @name: volume name
  *
  * @upd_ebs: how many eraseblocks are expected to be updated
- * @upd_bytes: how many bytes are expected to be received
- * @upd_received: how many update bytes were already received
- * @upd_buf: update buffer which is used to collect update data
+ * @ch_lnum: LEB number which is being changing by the atomic LEB change
+ *           operation
+ * @ch_dtype: data persistency type which is being changing by the atomic LEB
+ *            change operation
+ * @upd_bytes: how many bytes are expected to be received for volume update or
+ *             atomic LEB change
+ * @upd_received: how many bytes were already received for volume update or
+ *                atomic LEB change
+ * @upd_buf: update buffer which is used to collect update data or data for
+ *           atomic LEB change
  *
  * @eba_tbl: EBA table of this volume (LEB->PEB mapping)
  * @checked: %1 if this static volume was checked
  * @corrupted: %1 if the volume is corrupted (static volumes only)
  * @upd_marker: %1 if the update marker is set for this volume
  * @updating: %1 if the volume is being updated
+ * @changing_leb: %1 if the atomic LEB change ioctl command is in progress
  *
  * @gluebi_desc: gluebi UBI volume descriptor
  * @gluebi_refcount: reference count of the gluebi MTD device

@@ -202,6 +210,8 @@ struct ubi_volume {
 	char name[UBI_VOL_NAME_MAX+1];
 
 	int upd_ebs;
+	int ch_lnum;
+	int ch_dtype;
 	long long upd_bytes;
 	long long upd_received;
 	void *upd_buf;

@@ -211,9 +221,14 @@ struct ubi_volume {
 	int corrupted:1;
 	int upd_marker:1;
 	int updating:1;
+	int changing_leb:1;
 
 #ifdef CONFIG_MTD_UBI_GLUEBI
-	/* Gluebi-related stuff may be compiled out */
+	/*
+	 * Gluebi-related stuff may be compiled out.
+	 * TODO: this should not be built into UBI but should be a separate
+	 * ubimtd driver which works on top of UBI and emulates MTD devices.
+	 */
 	struct ubi_volume_desc *gluebi_desc;
 	int gluebi_refcount;
 	struct mtd_info gluebi_mtd;

@@ -427,6 +442,10 @@ int ubi_start_update(struct ubi_device *ubi, struct ubi_volume *vol,
 		     long long bytes);
 int ubi_more_update_data(struct ubi_device *ubi, struct ubi_volume *vol,
 			 const void __user *buf, int count);
+int ubi_start_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
+			 const struct ubi_leb_change_req *req);
+int ubi_more_leb_change_data(struct ubi_device *ubi, struct ubi_volume *vol,
+			     const void __user *buf, int count);
 
 /* misc.c */
 int ubi_calc_data_len(const struct ubi_device *ubi, const void *buf, int length);

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