UBI: introduce new constants

This patch is a clean-up and a preparation for the following
patches. It introduece constants for the return values of the
'ubi_eba_copy_leb()' function.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

drivers/mtd/ubi/eba.c

@@ -950,12 +950,7 @@ write_error:
  * physical eraseblock @to. The @vid_hdr buffer may be changed by this
  * function. Returns:
  *   o %0 in case of success;
- *   o %1 if the operation was canceled because the volume is being deleted
- *        or because the PEB was put meanwhile;
- *   o %2 if the operation was canceled because there was a write error to the
- *        target PEB;
- *   o %-EAGAIN if the operation was canceled because a bit-flip was detected
- *     in the target PEB;
+ *   o %MOVE_CANCEL_RACE, %MOVE_TARGET_WR_ERR, or %MOVE_CANCEL_BITFLIPS;
  *   o a negative error code in case of failure.
  */
 int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
@@ -986,13 +981,12 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 	 * be locked in 'ubi_wl_put_peb()' and wait for the WL worker to finish.
 	 */
 	vol = ubi->volumes[idx];
+	spin_unlock(&ubi->volumes_lock);
 	if (!vol) {
 		/* No need to do further work, cancel */
 		dbg_eba("volume %d is being removed, cancel", vol_id);
-		spin_unlock(&ubi->volumes_lock);
-		return 1;
+		return MOVE_CANCEL_RACE;
 	}
-	spin_unlock(&ubi->volumes_lock);
 
 	/*
 	 * We do not want anybody to write to this logical eraseblock while we
@@ -1004,12 +998,13 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 	 * (@from). This task locks the LEB and goes sleep in the
 	 * 'ubi_wl_put_peb()' function on the @ubi->move_mutex. In turn, we are
 	 * holding @ubi->move_mutex and go sleep on the LEB lock. So, if the
-	 * LEB is already locked, we just do not move it and return %1.
+	 * LEB is already locked, we just do not move it and return
+	 * %MOVE_CANCEL_RACE, which means that UBI will re-try, but later.
 	 */
 	err = leb_write_trylock(ubi, vol_id, lnum);
 	if (err) {
 		dbg_eba("contention on LEB %d:%d, cancel", vol_id, lnum);
-		return err;
+		return MOVE_CANCEL_RACE;
 	}
 
 	/*
@@ -1021,14 +1016,14 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 		dbg_eba("LEB %d:%d is no longer mapped to PEB %d, mapped to "
 			"PEB %d, cancel", vol_id, lnum, from,
 			vol->eba_tbl[lnum]);
-		err = 1;
+		err = MOVE_CANCEL_RACE;
 		goto out_unlock_leb;
 	}
 
 	/*
 	 * OK, now the LEB is locked and we can safely start moving it. Since
-	 * this function utilizes the @ubi->peb1_buf buffer which is shared
-	 * with some other functions, so lock the buffer by taking the
+	 * this function utilizes the @ubi->peb_buf1 buffer which is shared
+	 * with some other functions - we lock the buffer by taking the
 	 * @ubi->buf_mutex.
 	 */
 	mutex_lock(&ubi->buf_mutex);
@@ -1059,7 +1054,7 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 	cond_resched();
 
 	/*
-	 * It may turn out to me that the whole @from physical eraseblock
+	 * It may turn out to be that the whole @from physical eraseblock
 	 * contains only 0xFF bytes. Then we have to only write the VID header
 	 * and do not write any data. This also means we should not set
 	 * @vid_hdr->copy_flag, @vid_hdr->data_size, and @vid_hdr->data_crc.
@@ -1074,7 +1069,7 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 	err = ubi_io_write_vid_hdr(ubi, to, vid_hdr);
 	if (err) {
 		if (err == -EIO)
-			err = 2;
+			err = MOVE_TARGET_WR_ERR;
 		goto out_unlock_buf;
 	}
 
@@ -1086,7 +1081,7 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 		if (err != UBI_IO_BITFLIPS)
 			ubi_warn("cannot read VID header back from PEB %d", to);
 		else
-			err = -EAGAIN;
+			err = MOVE_CANCEL_BITFLIPS;
 		goto out_unlock_buf;
 	}
 
@@ -1094,7 +1089,7 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 		err = ubi_io_write_data(ubi, ubi->peb_buf1, to, 0, aldata_size);
 		if (err) {
 			if (err == -EIO)
-				err = 2;
+				err = MOVE_TARGET_WR_ERR;
 			goto out_unlock_buf;
 		}
 
@@ -1111,7 +1106,7 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 				ubi_warn("cannot read data back from PEB %d",
 					 to);
 			else
-				err = -EAGAIN;
+				err = MOVE_CANCEL_BITFLIPS;
 			goto out_unlock_buf;
 		}
 

drivers/mtd/ubi/ubi.h

@@ -100,6 +100,22 @@ enum {
 	UBI_IO_BITFLIPS
 };
 
+/*
+ * Return codes of the 'ubi_eba_copy_leb()' function.
+ *
+ * MOVE_CANCEL_RACE: canceled because the volume is being deleted, the source
+ *                   PEB was put meanwhile, or there is I/O on the source PEB
+ * MOVE_TARGET_WR_ERR: canceled because there was a write error to the target
+ *                     PEB
+ * MOVE_CANCEL_BITFLIPS: canceled because a bit-flip was detected in the
+ *                       target PEB
+ */
+enum {
+	MOVE_CANCEL_RACE = 1,
+	MOVE_TARGET_WR_ERR,
+	MOVE_CANCEL_BITFLIPS,
+};
+
 /**
  * struct ubi_wl_entry - wear-leveling entry.
  * @u.rb: link in the corresponding (free/used) RB-tree

drivers/mtd/ubi/wl.c

@@ -756,15 +756,14 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
 
 	err = ubi_eba_copy_leb(ubi, e1->pnum, e2->pnum, vid_hdr);
 	if (err) {
-		if (err == -EAGAIN)
-			goto out_not_moved;
-		if (err < 0)
-			goto out_error;
-		if (err == 2) {
-			/* Target PEB write error, torture it */
+		if (err == MOVE_CANCEL_BITFLIPS ||
+		    err == MOVE_TARGET_WR_ERR) {
+			/* Target PEB bit-flips or write error, torture it */
 			torture = 1;
 			goto out_not_moved;
 		}
+		if (err < 0)
+			goto out_error;
 
 		/*
 		 * The LEB has not been moved because the volume is being
@@ -774,7 +773,7 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
 		 */
 
 		dbg_wl("canceled moving PEB %d", e1->pnum);
-		ubi_assert(err == 1);
+		ubi_assert(err == MOVE_CANCEL_RACE);
 
 		ubi_free_vid_hdr(ubi, vid_hdr);
 		vid_hdr = NULL;