target/linux/generic/pending-6.1/450-05-mtd-ubi-introduce-pre-removal-notification-for-UBI-v.patch

   1 From 2d664266cfdd114cc7a1fa28dd64275e99222455 Mon Sep 17 00:00:00 2001
   2 From: Daniel Golle <daniel@makrotopia.org>
   3 Date: Thu, 8 Jun 2023 17:18:09 +0100
   4 Subject: [PATCH 05/15] mtd: ubi: introduce pre-removal notification for UBI
   5  volumes
   6
   7 Introduce a new notification type UBI_VOLUME_SHUTDOWN to inform users
   8 that a volume is just about to be removed.
   9 This is needed because users (such as the NVMEM subsystem) expect that
  10 at the time their removal function is called, the parenting device is
  11 still available (for removal of sysfs nodes, for example, in case of
  12 NVMEM which otherwise WARNs on volume removal).
  13
  14 Signed-off-by: Daniel Golle <daniel@makrotopia.org>
  15 ---
  16  drivers/mtd/ubi/block.c | 26 ++++++++++++++++++++++++++
  17  drivers/mtd/ubi/build.c | 20 +++++++++++++++-----
  18  drivers/mtd/ubi/kapi.c  |  2 +-
  19  drivers/mtd/ubi/ubi.h   |  2 ++
  20  drivers/mtd/ubi/vmt.c   | 17 +++++++++++++++--
  21  include/linux/mtd/ubi.h |  2 ++
  22  6 files changed, 61 insertions(+), 8 deletions(-)
  23
  24 --- a/drivers/mtd/ubi/block.c
  25 +++ b/drivers/mtd/ubi/block.c
  26 @@ -568,6 +568,29 @@ static int ubiblock_resize(struct ubi_vo
  27         return 0;
  28  }
  29
  30 +static int ubiblock_shutdown(struct ubi_volume_info *vi)
  31 +{
  32 +       struct ubiblock *dev;
  33 +       struct gendisk *disk;
  34 +       int ret = 0;
  35 +
  36 +       mutex_lock(&devices_mutex);
  37 +       dev = find_dev_nolock(vi->ubi_num, vi->vol_id);
  38 +       if (!dev) {
  39 +               ret = -ENODEV;
  40 +               goto out_unlock;
  41 +       }
  42 +       disk = dev->gd;
  43 +
  44 +out_unlock:
  45 +       mutex_unlock(&devices_mutex);
  46 +
  47 +       if (!ret)
  48 +               blk_mark_disk_dead(disk);
  49 +
  50 +       return ret;
  51 +};
  52 +
  53  static bool
  54  match_volume_desc(struct ubi_volume_info *vi, const char *name, int ubi_num, int vol_id)
  55  {
  56 @@ -659,6 +682,9 @@ static int ubiblock_notify(struct notifi
  57         case UBI_VOLUME_REMOVED:
  58                 ubiblock_remove(&nt->vi);
  59                 break;
  60 +       case UBI_VOLUME_SHUTDOWN:
  61 +               ubiblock_shutdown(&nt->vi);
  62 +               break;
  63         case UBI_VOLUME_RESIZED:
  64                 ubiblock_resize(&nt->vi);
  65                 break;
  66 --- a/drivers/mtd/ubi/build.c
  67 +++ b/drivers/mtd/ubi/build.c
  68 @@ -89,7 +89,7 @@ static struct ubi_device *ubi_devices[UB
  69  /* Serializes UBI devices creations and removals */
  70  DEFINE_MUTEX(ubi_devices_mutex);
  71
  72 -/* Protects @ubi_devices and @ubi->ref_count */
  73 +/* Protects @ubi_devices, @ubi->ref_count and @ubi->is_dead */
  74  static DEFINE_SPINLOCK(ubi_devices_lock);
  75
  76  /* "Show" method for files in '/<sysfs>/class/ubi/' */
  77 @@ -258,6 +258,9 @@ struct ubi_device *ubi_get_device(int ub
  78
  79         spin_lock(&ubi_devices_lock);
  80         ubi = ubi_devices[ubi_num];
  81 +       if (ubi && ubi->is_dead)
  82 +               ubi = NULL;
  83 +
  84         if (ubi) {
  85                 ubi_assert(ubi->ref_count >= 0);
  86                 ubi->ref_count += 1;
  87 @@ -295,7 +298,7 @@ struct ubi_device *ubi_get_by_major(int
  88         spin_lock(&ubi_devices_lock);
  89         for (i = 0; i < UBI_MAX_DEVICES; i++) {
  90                 ubi = ubi_devices[i];
  91 -               if (ubi && MAJOR(ubi->cdev.dev) == major) {
  92 +               if (ubi && !ubi->is_dead && MAJOR(ubi->cdev.dev) == major) {
  93                         ubi_assert(ubi->ref_count >= 0);
  94                         ubi->ref_count += 1;
  95                         get_device(&ubi->dev);
  96 @@ -324,7 +327,7 @@ int ubi_major2num(int major)
  97         for (i = 0; i < UBI_MAX_DEVICES; i++) {
  98                 struct ubi_device *ubi = ubi_devices[i];
  99
 100 -               if (ubi && MAJOR(ubi->cdev.dev) == major) {
 101 +               if (ubi && !ubi->is_dead && MAJOR(ubi->cdev.dev) == major) {
 102                         ubi_num = ubi->ubi_num;
 103                         break;
 104                 }
 105 @@ -511,7 +514,7 @@ static void ubi_free_volumes_from(struct
 106         int i;
 107
 108         for (i = from; i < ubi->vtbl_slots + UBI_INT_VOL_COUNT; i++) {
 109 -               if (!ubi->volumes[i])
 110 +               if (!ubi->volumes[i] || ubi->volumes[i]->is_dead)
 111                         continue;
 112                 ubi_eba_replace_table(ubi->volumes[i], NULL);
 113                 ubi_fastmap_destroy_checkmap(ubi->volumes[i]);
 114 @@ -1094,10 +1097,10 @@ int ubi_detach_mtd_dev(int ubi_num, int
 115                 return -EINVAL;
 116
 117         spin_lock(&ubi_devices_lock);
 118 -       put_device(&ubi->dev);
 119         ubi->ref_count -= 1;
 120         if (ubi->ref_count) {
 121                 if (!anyway) {
 122 +                       ubi->ref_count += 1;
 123                         spin_unlock(&ubi_devices_lock);
 124                         return -EBUSY;
 125                 }
 126 @@ -1105,6 +1108,13 @@ int ubi_detach_mtd_dev(int ubi_num, int
 127                 ubi_err(ubi, "%s reference count %d, destroy anyway",
 128                         ubi->ubi_name, ubi->ref_count);
 129         }
 130 +       ubi->is_dead = true;
 131 +       spin_unlock(&ubi_devices_lock);
 132 +
 133 +       ubi_notify_all(ubi, UBI_VOLUME_SHUTDOWN, NULL);
 134 +
 135 +       spin_lock(&ubi_devices_lock);
 136 +       put_device(&ubi->dev);
 137         ubi_devices[ubi_num] = NULL;
 138         spin_unlock(&ubi_devices_lock);
 139
 140 --- a/drivers/mtd/ubi/kapi.c
 141 +++ b/drivers/mtd/ubi/kapi.c
 142 @@ -152,7 +152,7 @@ struct ubi_volume_desc *ubi_open_volume(
 143
 144         spin_lock(&ubi->volumes_lock);
 145         vol = ubi->volumes[vol_id];
 146 -       if (!vol)
 147 +       if (!vol || vol->is_dead)
 148                 goto out_unlock;
 149
 150         err = -EBUSY;
 151 --- a/drivers/mtd/ubi/ubi.h
 152 +++ b/drivers/mtd/ubi/ubi.h
 153 @@ -345,6 +345,7 @@ struct ubi_volume {
 154         int writers;
 155         int exclusive;
 156         int metaonly;
 157 +       bool is_dead;
 158
 159         int reserved_pebs;
 160         int vol_type;
 161 @@ -564,6 +565,7 @@ struct ubi_device {
 162         spinlock_t volumes_lock;
 163         int ref_count;
 164         int image_seq;
 165 +       bool is_dead;
 166
 167         int rsvd_pebs;
 168         int avail_pebs;
 169 --- a/drivers/mtd/ubi/vmt.c
 170 +++ b/drivers/mtd/ubi/vmt.c
 171 @@ -59,7 +59,7 @@ static ssize_t vol_attribute_show(struct
 172         struct ubi_device *ubi = vol->ubi;
 173
 174         spin_lock(&ubi->volumes_lock);
 175 -       if (!ubi->volumes[vol->vol_id]) {
 176 +       if (!ubi->volumes[vol->vol_id] || ubi->volumes[vol->vol_id]->is_dead) {
 177                 spin_unlock(&ubi->volumes_lock);
 178                 return -ENODEV;
 179         }
 180 @@ -189,7 +189,7 @@ int ubi_create_volume(struct ubi_device
 181
 182         /* Ensure that the name is unique */
 183         for (i = 0; i < ubi->vtbl_slots; i++)
 184 -               if (ubi->volumes[i] &&
 185 +               if (ubi->volumes[i] && !ubi->volumes[i]->is_dead &&
 186                     ubi->volumes[i]->name_len == req->name_len &&
 187                     !strcmp(ubi->volumes[i]->name, req->name)) {
 188                         ubi_err(ubi, "volume \"%s\" exists (ID %d)",
 189 @@ -352,6 +352,19 @@ int ubi_remove_volume(struct ubi_volume_
 190                 err = -EBUSY;
 191                 goto out_unlock;
 192         }
 193 +
 194 +       /*
 195 +        * Mark volume as dead at this point to prevent that anyone
 196 +        * can take a reference to the volume from now on.
 197 +        * This is necessary as we have to release the spinlock before
 198 +        * calling ubi_volume_notify.
 199 +        */
 200 +       vol->is_dead = true;
 201 +       spin_unlock(&ubi->volumes_lock);
 202 +
 203 +       ubi_volume_notify(ubi, vol, UBI_VOLUME_SHUTDOWN);
 204 +
 205 +       spin_lock(&ubi->volumes_lock);
 206         ubi->volumes[vol_id] = NULL;
 207         spin_unlock(&ubi->volumes_lock);
 208
 209 --- a/include/linux/mtd/ubi.h
 210 +++ b/include/linux/mtd/ubi.h
 211 @@ -192,6 +192,7 @@ struct ubi_device_info {
 212   *                     or a volume was removed)
 213   * @UBI_VOLUME_RESIZED: a volume has been re-sized
 214   * @UBI_VOLUME_RENAMED: a volume has been re-named
 215 + * @UBI_VOLUME_SHUTDOWN: a volume is going to removed, shutdown users
 216   * @UBI_VOLUME_UPDATED: data has been written to a volume
 217   *
 218   * These constants define which type of event has happened when a volume
 219 @@ -202,6 +203,7 @@ enum {
 220         UBI_VOLUME_REMOVED,
 221         UBI_VOLUME_RESIZED,
 222         UBI_VOLUME_RENAMED,
 223 +       UBI_VOLUME_SHUTDOWN,
 224         UBI_VOLUME_UPDATED,
 225  };
 226