UBI: handle write errors in WL worker

When a PEB is moved and a write error happens, UBI switches
to R/O mode, which is wrong, because we just copy the data
and may select a different PEB and re-try this. This patch
fixes WL worker's behavior.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

2 files changed, 44 insertions, 25 deletions

diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index 2e4d6bf94582..048a606cebde 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -949,10 +949,14 @@ write_error:
  * This function copies logical eraseblock from physical eraseblock @from to
  * 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 and should be tried later (e.g.,
- *     because a bit-flip was detected at the target PEB);
- *   o %2 if the volume is being deleted and this LEB should not be moved.
+ *   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 a negative error code in case of failure.
  */
 int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
                      struct ubi_vid_hdr *vid_hdr)
@@ -978,7 +982,7 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
         /*
          * Note, we may race with volume deletion, which means that the volume
          * this logical eraseblock belongs to might be being deleted. Since the
-         * volume deletion unmaps all the volume's logical eraseblocks, it will
+         * volume deletion un-maps all the volume's logical eraseblocks, it will
          * be locked in 'ubi_wl_put_peb()' and wait for the WL worker to finish.
          */
         vol = ubi->volumes[idx];
@@ -986,7 +990,7 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
                 /* No need to do further work, cancel */
                 dbg_eba("volume %d is being removed, cancel", vol_id);
                 spin_unlock(&ubi->volumes_lock);
-                return 2;
+                return 1;
         }
         spin_unlock(&ubi->volumes_lock);
 
@@ -1023,7 +1027,7 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 
         /*
          * OK, now the LEB is locked and we can safely start moving it. Since
-         * this function utilizes thie @ubi->peb1_buf buffer which is shared
+         * this function utilizes the @ubi->peb1_buf buffer which is shared
          * with some other functions, so lock the buffer by taking the
          * @ubi->buf_mutex.
          */
@@ -1068,8 +1072,11 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
         vid_hdr->sqnum = cpu_to_be64(next_sqnum(ubi));
 
         err = ubi_io_write_vid_hdr(ubi, to, vid_hdr);
-        if (err)
+        if (err) {
+                if (err == -EIO)
+                        err = 2;
                 goto out_unlock_buf;
+        }
 
         cond_resched();
 
@@ -1079,14 +1086,17 @@ 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 = 1;
+                        err = -EAGAIN;
                 goto out_unlock_buf;
         }
 
         if (data_size > 0) {
                 err = ubi_io_write_data(ubi, ubi->peb_buf1, to, 0, aldata_size);
-                if (err)
+                if (err) {
+                        if (err == -EIO)
+                                err = 2;
                         goto out_unlock_buf;
+                }
 
                 cond_resched();
 
@@ -1101,15 +1111,16 @@ 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 = 1;
+                                err = -EAGAIN;
                         goto out_unlock_buf;
                 }
 
                 cond_resched();
 
                 if (memcmp(ubi->peb_buf1, ubi->peb_buf2, aldata_size)) {
-                        ubi_warn("read data back from PEB %d - it is different",
-                                 to);
+                        ubi_warn("read data back from PEB %d and it is "
+                                 "different", to);
+                        err = -EINVAL;
                         goto out_unlock_buf;
                 }
         }
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 442099d76ec9..abf65ea414e7 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -738,7 +738,7 @@ static int schedule_erase(struct ubi_device *ubi, struct ubi_wl_entry *e,
 static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
                                 int cancel)
 {
-        int err, scrubbing = 0;
+        int err, scrubbing = 0, torture = 0;
         struct ubi_wl_prot_entry *uninitialized_var(pe);
         struct ubi_wl_entry *e1, *e2;
         struct ubi_vid_hdr *vid_hdr;
@@ -842,20 +842,26 @@ 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 == 1)
+                if (err == 2) {
+                        /* Target PEB write error, torture it */
+                        torture = 1;
                         goto out_not_moved;
+                }
 
                 /*
-                 * For some reason the LEB was not moved - it might be because
-                 * the volume is being deleted. We should prevent this PEB from
-                 * being selected for wear-levelling movement for some "time",
-                 * so put it to the protection tree.
+                 * The LEB has not been moved because the volume is being
+                 * deleted or the PEB has been put meanwhile. We should prevent
+                 * this PEB from being selected for wear-leveling movement
+                 * again, so put it to the protection tree.
                  */
 
-                dbg_wl("cancelled moving PEB %d", e1->pnum);
+                dbg_wl("canceled moving PEB %d", e1->pnum);
+                ubi_assert(err == 1);
+
                 pe = kmalloc(sizeof(struct ubi_wl_prot_entry), GFP_NOFS);
                 if (!pe) {
                         err = -ENOMEM;
@@ -920,9 +926,10 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
         /*
          * For some reasons the LEB was not moved, might be an error, might be
          * something else. @e1 was not changed, so return it back. @e2 might
-         * be changed, schedule it for erasure.
+         * have been changed, schedule it for erasure.
          */
 out_not_moved:
+        dbg_wl("canceled moving PEB %d", e1->pnum);
         ubi_free_vid_hdr(ubi, vid_hdr);
         vid_hdr = NULL;
         spin_lock(&ubi->wl_lock);
@@ -930,12 +937,13 @@ out_not_moved:
                 wl_tree_add(e1, &ubi->scrub);
         else
                 wl_tree_add(e1, &ubi->used);
+        ubi_assert(!ubi->move_to_put);
         ubi->move_from = ubi->move_to = NULL;
-        ubi->move_to_put = ubi->wl_scheduled = 0;
+        ubi->wl_scheduled = 0;
         spin_unlock(&ubi->wl_lock);
 
         e1 = NULL;
-        err = schedule_erase(ubi, e2, 0);
+        err = schedule_erase(ubi, e2, torture);
         if (err)
                 goto out_error;
 
@@ -1324,7 +1332,7 @@ int ubi_wl_flush(struct ubi_device *ubi)
         up_write(&ubi->work_sem);
 
         /*
-         * And in case last was the WL worker and it cancelled the LEB
+         * And in case last was the WL worker and it canceled the LEB
          * movement, flush again.
          */
         while (ubi->works_count) {