UBI: do not warn unnecessarily

Currently, when UBI attaches an MTD device and cannot reserve all 1% (by
default) of PEBs for bad eraseblocks handling, it prints a warning. However,
Matthew L. Creech <mlcreech@gmail.com> is not very happy to see this warning,
because he did reserve enough of PEB at the beginning, but with time some
PEBs became bad. The warning is not necessary in this case.

This patch makes UBI print the warning
 o if this is a new image
 o of this is used image and the amount of reserved PEBs is only 10% (or less)
   of the size of the reserved PEB pool.

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

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 13b05cb33b085fbb063a1024f30feb239a82c9de..78ae89488a4fbc54550bf4a7dd54877035b295ec 100644 (file)
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -593,6 +593,7 @@ static int attach_by_scanning(struct ubi_device *ubi)
        ubi->good_peb_count = ubi->peb_count - ubi->bad_peb_count;
        ubi->max_ec = si->max_ec;
        ubi->mean_ec = si->mean_ec;
+       ubi_msg("max. sequence number:       %llu", si->max_sqnum);
 
        err = ubi_read_volume_table(ubi, si);
        if (err)
@@ -981,7 +982,7 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
        ubi_msg("number of PEBs reserved for bad PEB handling: %d",
                ubi->beb_rsvd_pebs);
        ubi_msg("max/mean erase counter: %d/%d", ubi->max_ec, ubi->mean_ec);
-       ubi_msg("image sequence number: %d", ubi->image_seq);
+       ubi_msg("image sequence number:  %d", ubi->image_seq);
 
        /*
         * The below lock makes sure we do not race with 'ubi_thread()' which

diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index b582671ca3a0b3958897712d099b0b5018d0b343..fe74749e0dae734271b9a6b9e780f11e5cbb021c 100644 (file)
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -1165,6 +1165,44 @@ out_unlock_leb:
        return err;
 }
 
+/**
+ * print_rsvd_warning - warn about not having enough reserved PEBs.
+ * @ubi: UBI device description object
+ *
+ * This is a helper function for 'ubi_eba_init_scan()' which is called when UBI
+ * cannot reserve enough PEBs for bad block handling. This function makes a
+ * decision whether we have to print a warning or not. The algorithm is as
+ * follows:
+ *   o if this is a new UBI image, then just print the warning
+ *   o if this is an UBI image which has already been used for some time, print
+ *     a warning only if we can reserve less than 10% of the expected amount of
+ *     the reserved PEB.
+ *
+ * The idea is that when UBI is used, PEBs become bad, and the reserved pool
+ * of PEBs becomes smaller, which is normal and we do not want to scare users
+ * with a warning every time they attach the MTD device. This was an issue
+ * reported by real users.
+ */
+static void print_rsvd_warning(struct ubi_device *ubi,
+                              struct ubi_scan_info *si)
+{
+       /*
+        * The 1 << 18 (256KiB) number is picked randomly, just a reasonably
+        * large number to distinguish between newly flashed and used images.
+        */
+       if (si->max_sqnum > (1 << 18)) {
+               int min = ubi->beb_rsvd_level / 10;
+
+               if (!min)
+                       min = 1;
+               if (ubi->beb_rsvd_pebs > min)
+                       return;
+       }
+
+       ubi_warn("cannot reserve enough PEBs for bad PEB handling, reserved %d,"
+                " need %d", ubi->beb_rsvd_pebs, ubi->beb_rsvd_level);
+}
+
 /**
  * ubi_eba_init_scan - initialize the EBA sub-system using scanning information.
  * @ubi: UBI device description object
@@ -1237,9 +1275,7 @@ int ubi_eba_init_scan(struct ubi_device *ubi, struct ubi_scan_info *si)
                if (ubi->avail_pebs < ubi->beb_rsvd_level) {
                        /* No enough free physical eraseblocks */
                        ubi->beb_rsvd_pebs = ubi->avail_pebs;
-                       ubi_warn("cannot reserve enough PEBs for bad PEB "
-                                "handling, reserved %d, need %d",
-                                ubi->beb_rsvd_pebs, ubi->beb_rsvd_level);
+                       print_rsvd_warning(ubi, si);
                } else
                        ubi->beb_rsvd_pebs = ubi->beb_rsvd_level;