UBI: handle attach ioctl

Actually implement the MTD device attach/detach handlers.

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

1 files changed, 54 insertions, 26 deletions

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 403c10a668bd..70c0b9a9e6e3 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -621,18 +621,19 @@ static int io_init(struct ubi_device *ubi)
 /**
  * ubi_attach_mtd_dev - attach an MTD device.
  * @mtd_dev: MTD device description object
+ * @ubi_num: number to assign to the new UBI device
  * @vid_hdr_offset: VID header offset
  *
- * This function attaches an MTD device to UBI. It first treats @mtd_dev as the
- * MTD device name, and tries to open it by this name. If it is unable to open,
- * it tries to convert @mtd_dev to an integer and open the MTD device by its
- * number. Returns new UBI device's number in case of success and a negative
- * error code in case of failure.
+ * This function attaches MTD device @mtd_dev to UBI and assign @ubi_num number
+ * to the newly created UBI device, unless @ubi_num is %UBI_DEV_NUM_AUTO, in
+ * which case this function finds a vacant device nubert and assings it
+ * automatically. Returns the new UBI device number in case of success and a
+ * negative error code in case of failure.
  *
  * Note, the invocations of this function has to be serialized by the
  * @ubi_devices_mutex.
  */
-int ubi_attach_mtd_dev(struct mtd_info *mtd, int vid_hdr_offset)
+int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
 {
         struct ubi_device *ubi;
         int i, err;
@@ -643,22 +644,47 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int vid_hdr_offset)
          * Note, this function assumes that UBI devices creations and deletions
          * are serialized, so it does not take the &ubi_devices_lock.
          */
-        for (i = 0; i < UBI_MAX_DEVICES; i++)
+        for (i = 0; i < UBI_MAX_DEVICES; i++) {
                 ubi = ubi_devices[i];
                 if (ubi && mtd->index == ubi->mtd->index) {
-                        ubi_err("mtd%d is already attached to ubi%d",
+                        dbg_err("mtd%d is already attached to ubi%d",
                                 mtd->index, i);
-                        return -EINVAL;
+                        return -EEXIST;
                 }
+        }
 
-        /* Search for an empty slot in the @ubi_devices array */
-        for (i = 0; i < UBI_MAX_DEVICES; i++)
-                if (!ubi_devices[i])
-                        break;
+        /*
+         * Make sure this MTD device is not emulated on top of an UBI volume
+         * already. Well, generally this recursion works fine, but there are
+         * different problems like the UBI module takes a reference to itself
+         * by attaching (and thus, opening) the emulated MTD device. This
+         * results in inability to unload the module. And in general it makes
+         * no sense to attach emulated MTD devices, so we prohibit this.
+         */
+        if (mtd->type == MTD_UBIVOLUME) {
+                ubi_err("refuse attaching mtd%d - it is already emulated on "
+                        "top of UBI", mtd->index);
+                return -EINVAL;
+        }
+
+        if (ubi_num == UBI_DEV_NUM_AUTO) {
+                /* Search for an empty slot in the @ubi_devices array */
+                for (ubi_num = 0; ubi_num < UBI_MAX_DEVICES; ubi_num++)
+                        if (!ubi_devices[ubi_num])
+                                break;
+                if (ubi_num == UBI_MAX_DEVICES) {
+                        dbg_err("only %d UBI devices may be created", UBI_MAX_DEVICES);
+                        return -ENFILE;
+                }
+        } else {
+                if (ubi_num >= UBI_MAX_DEVICES)
+                        return -EINVAL;
 
-        if (i == UBI_MAX_DEVICES) {
-                ubi_err("only %d UBI devices may be created", UBI_MAX_DEVICES);
-                return -ENFILE;
+                /* Make sure ubi_num is not busy */
+                if (ubi_devices[ubi_num]) {
+                        dbg_err("ubi%d already exists", ubi_num);
+                        return -EEXIST;
+                }
         }
 
         ubi = kzalloc(sizeof(struct ubi_device), GFP_KERNEL);
@@ -666,11 +692,11 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int vid_hdr_offset)
                 return -ENOMEM;
 
         ubi->mtd = mtd;
-        ubi->ubi_num = i;
+        ubi->ubi_num = ubi_num;
         ubi->vid_hdr_offset = vid_hdr_offset;
 
         dbg_msg("attaching mtd%d to ubi%d: VID header offset %d",
-                mtd->index, ubi->ubi_num, vid_hdr_offset);
+                mtd->index, ubi_num, vid_hdr_offset);
 
         err = io_init(ubi);
         if (err)
@@ -710,7 +736,7 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int vid_hdr_offset)
                 goto out_uif;
         }
 
-        ubi_msg("attached mtd%d to ubi%d", mtd->index, ubi->ubi_num);
+        ubi_msg("attached mtd%d to ubi%d", mtd->index, ubi_num);
         ubi_msg("MTD device name:            \"%s\"", mtd->name);
         ubi_msg("MTD device size:            %llu MiB", ubi->flash_size >> 20);
         ubi_msg("physical eraseblock size:   %d bytes (%d KiB)",
@@ -739,8 +765,8 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int vid_hdr_offset)
                 wake_up_process(ubi->bgt_thread);
         }
 
-        ubi_devices[ubi->ubi_num] = ubi;
-        return ubi->ubi_num;
+        ubi_devices[ubi_num] = ubi;
+        return ubi_num;
 
 out_uif:
         uif_close(ubi);
@@ -781,23 +807,24 @@ int ubi_detach_mtd_dev(int ubi_num, int anyway)
         spin_lock(&ubi_devices_lock);
         ubi = ubi_devices[ubi_num];
         if (!ubi) {
-                spin_lock(&ubi_devices_lock);
+                spin_unlock(&ubi_devices_lock);
                 return -EINVAL;
         }
 
         if (ubi->ref_count) {
                 if (!anyway) {
-                        spin_lock(&ubi_devices_lock);
+                        spin_unlock(&ubi_devices_lock);
                         return -EBUSY;
                 }
                 /* This may only happen if there is a bug */
                 ubi_err("%s reference count %d, destroy anyway",
                         ubi->ubi_name, ubi->ref_count);
         }
-        ubi_devices[ubi->ubi_num] = NULL;
+        ubi_devices[ubi_num] = NULL;
         spin_unlock(&ubi_devices_lock);
 
-        dbg_msg("detaching mtd%d from ubi%d", ubi->mtd->index, ubi->ubi_num);
+        ubi_assert(ubi_num == ubi->ubi_num);
+        dbg_msg("detaching mtd%d from ubi%d", ubi->mtd->index, ubi_num);
 
         /*
          * Before freeing anything, we have to stop the background thread to
@@ -935,7 +962,8 @@ static int __init ubi_init(void)
                 }
 
                 mutex_lock(&ubi_devices_mutex);
-                err = ubi_attach_mtd_dev(mtd, p->vid_hdr_offs);
+                err = ubi_attach_mtd_dev(mtd, UBI_DEV_NUM_AUTO,
+                                         p->vid_hdr_offs);
                 mutex_unlock(&ubi_devices_mutex);
                 if (err < 0) {
                         put_mtd_device(mtd);