8 files changed, 119 insertions, 112 deletions

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 1cb22bfae750..023653977a1a 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -565,7 +565,7 @@ static int attach_mtd_dev(const char *mtd_dev, int vid_hdr_offset,
                 }
 
         ubi = ubi_devices[ubi_devices_cnt] = kzalloc(sizeof(struct ubi_device),
-                                                      GFP_KERNEL);
+                                                     GFP_KERNEL);
         if (!ubi) {
                 err = -ENOMEM;
                 goto out_mtd;
@@ -583,6 +583,22 @@ static int attach_mtd_dev(const char *mtd_dev, int vid_hdr_offset,
         if (err)
                 goto out_free;
 
+        mutex_init(&ubi->buf_mutex);
+        ubi->peb_buf1 = vmalloc(ubi->peb_size);
+        if (!ubi->peb_buf1)
+                goto out_free;
+
+        ubi->peb_buf2 = vmalloc(ubi->peb_size);
+        if (!ubi->peb_buf2)
+                 goto out_free;
+
+#ifdef CONFIG_MTD_UBI_DEBUG
+        mutex_init(&ubi->dbg_buf_mutex);
+        ubi->dbg_peb_buf = vmalloc(ubi->peb_size);
+        if (!ubi->dbg_peb_buf)
+                 goto out_free;
+#endif
+
         err = attach_by_scanning(ubi);
         if (err) {
                 dbg_err("failed to attach by scanning, error %d", err);
@@ -630,6 +646,11 @@ out_detach:
         ubi_wl_close(ubi);
         vfree(ubi->vtbl);
 out_free:
+        vfree(ubi->peb_buf1);
+        vfree(ubi->peb_buf2);
+#ifdef CONFIG_MTD_UBI_DEBUG
+        vfree(ubi->dbg_peb_buf);
+#endif
         kfree(ubi);
 out_mtd:
         put_mtd_device(mtd);
@@ -651,6 +672,11 @@ static void detach_mtd_dev(struct ubi_device *ubi)
         ubi_wl_close(ubi);
         vfree(ubi->vtbl);
         put_mtd_device(ubi->mtd);
+        vfree(ubi->peb_buf1);
+        vfree(ubi->peb_buf2);
+#ifdef CONFIG_MTD_UBI_DEBUG
+        vfree(ubi->dbg_peb_buf);
+#endif
         kfree(ubi_devices[ubi_num]);
         ubi_devices[ubi_num] = NULL;
         ubi_devices_cnt -= 1;
diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index 89193104c6c8..81bb6a33b555 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -495,16 +495,18 @@ static int recover_peb(struct ubi_device *ubi, int pnum, int vol_id, int lnum,
         int err, idx = vol_id2idx(ubi, vol_id), new_pnum, data_size, tries = 0;
         struct ubi_volume *vol = ubi->volumes[idx];
         struct ubi_vid_hdr *vid_hdr;
-        unsigned char *new_buf;
 
         vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
         if (!vid_hdr) {
                 return -ENOMEM;
         }
 
+        mutex_lock(&ubi->buf_mutex);
+
 retry:
         new_pnum = ubi_wl_get_peb(ubi, UBI_UNKNOWN);
         if (new_pnum < 0) {
+                mutex_unlock(&ubi->buf_mutex);
                 ubi_free_vid_hdr(ubi, vid_hdr);
                 return new_pnum;
         }
@@ -524,31 +526,22 @@ retry:
                 goto write_error;
 
         data_size = offset + len;
-        new_buf = vmalloc(data_size);
-        if (!new_buf) {
-                err = -ENOMEM;
-                goto out_put;
-        }
-        memset(new_buf + offset, 0xFF, len);
+        memset(ubi->peb_buf1 + offset, 0xFF, len);
 
         /* Read everything before the area where the write failure happened */
         if (offset > 0) {
-                err = ubi_io_read_data(ubi, new_buf, pnum, 0, offset);
-                if (err && err != UBI_IO_BITFLIPS) {
-                        vfree(new_buf);
+                err = ubi_io_read_data(ubi, ubi->peb_buf1, pnum, 0, offset);
+                if (err && err != UBI_IO_BITFLIPS)
                         goto out_put;
-                }
         }
 
-        memcpy(new_buf + offset, buf, len);
+        memcpy(ubi->peb_buf1 + offset, buf, len);
 
-        err = ubi_io_write_data(ubi, new_buf, new_pnum, 0, data_size);
-        if (err) {
-                vfree(new_buf);
+        err = ubi_io_write_data(ubi, ubi->peb_buf1, new_pnum, 0, data_size);
+        if (err)
                 goto write_error;
-        }
 
-        vfree(new_buf);
+        mutex_unlock(&ubi->buf_mutex);
         ubi_free_vid_hdr(ubi, vid_hdr);
 
         vol->eba_tbl[lnum] = new_pnum;
@@ -558,6 +551,7 @@ retry:
         return 0;
 
 out_put:
+        mutex_unlock(&ubi->buf_mutex);
         ubi_wl_put_peb(ubi, new_pnum, 1);
         ubi_free_vid_hdr(ubi, vid_hdr);
         return err;
@@ -570,6 +564,7 @@ write_error:
         ubi_warn("failed to write to PEB %d", new_pnum);
         ubi_wl_put_peb(ubi, new_pnum, 1);
         if (++tries > UBI_IO_RETRIES) {
+                mutex_unlock(&ubi->buf_mutex);
                 ubi_free_vid_hdr(ubi, vid_hdr);
                 return err;
         }
@@ -965,7 +960,6 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
         int err, vol_id, lnum, data_size, aldata_size, pnum, idx;
         struct ubi_volume *vol;
         uint32_t crc;
-        void *buf, *buf1 = NULL;
 
         vol_id = be32_to_cpu(vid_hdr->vol_id);
         lnum = be32_to_cpu(vid_hdr->lnum);
@@ -979,19 +973,15 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
                 data_size = aldata_size =
                             ubi->leb_size - be32_to_cpu(vid_hdr->data_pad);
 
-        buf = vmalloc(aldata_size);
-        if (!buf)
-                return -ENOMEM;
-
         /*
          * We do not want anybody to write to this logical eraseblock while we
          * are moving it, so we lock it.
          */
         err = leb_write_lock(ubi, vol_id, lnum);
-        if (err) {
-                vfree(buf);
+        if (err)
                 return err;
-        }
+
+        mutex_lock(&ubi->buf_mutex);
 
         /*
          * But the logical eraseblock might have been put by this time.
@@ -1023,7 +1013,7 @@ 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 */
 
         dbg_eba("read %d bytes of data", aldata_size);
-        err = ubi_io_read_data(ubi, buf, from, 0, aldata_size);
+        err = ubi_io_read_data(ubi, ubi->peb_buf1, from, 0, aldata_size);
         if (err && err != UBI_IO_BITFLIPS) {
                 ubi_warn("error %d while reading data from PEB %d",
                          err, from);
@@ -1042,10 +1032,10 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
          */
         if (vid_hdr->vol_type == UBI_VID_DYNAMIC)
                 aldata_size = data_size =
-                                ubi_calc_data_len(ubi, buf, data_size);
+                        ubi_calc_data_len(ubi, ubi->peb_buf1, data_size);
 
         cond_resched();
-        crc = crc32(UBI_CRC32_INIT, buf, data_size);
+        crc = crc32(UBI_CRC32_INIT, ubi->peb_buf1, data_size);
         cond_resched();
 
         /*
@@ -1076,23 +1066,18 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
         }
 
         if (data_size > 0) {
-                err = ubi_io_write_data(ubi, buf, to, 0, aldata_size);
+                err = ubi_io_write_data(ubi, ubi->peb_buf1, to, 0, aldata_size);
                 if (err)
                         goto out_unlock;
 
+                cond_resched();
+
                 /*
                  * We've written the data and are going to read it back to make
                  * sure it was written correctly.
                  */
-                buf1 = vmalloc(aldata_size);
-                if (!buf1) {
-                        err = -ENOMEM;
-                        goto out_unlock;
-                }
 
-                cond_resched();
-
-                err = ubi_io_read_data(ubi, buf1, to, 0, aldata_size);
+                err = ubi_io_read_data(ubi, ubi->peb_buf2, to, 0, aldata_size);
                 if (err) {
                         if (err != UBI_IO_BITFLIPS)
                                 ubi_warn("cannot read data back from PEB %d",
@@ -1102,7 +1087,7 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 
                 cond_resched();
 
-                if (memcmp(buf, buf1, aldata_size)) {
+                if (memcmp(ubi->peb_buf1, ubi->peb_buf2, aldata_size)) {
                         ubi_warn("read data back from PEB %d - it is different",
                                  to);
                         goto out_unlock;
@@ -1112,16 +1097,9 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
         ubi_assert(vol->eba_tbl[lnum] == from);
         vol->eba_tbl[lnum] = to;
 
-        leb_write_unlock(ubi, vol_id, lnum);
-        vfree(buf);
-        vfree(buf1);
-
-        return 0;
-
 out_unlock:
+        mutex_unlock(&ubi->buf_mutex);
         leb_write_unlock(ubi, vol_id, lnum);
-        vfree(buf);
-        vfree(buf1);
         return err;
 }
 
diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index ba5bc4a5379e..52476d884c48 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -98,8 +98,8 @@ static int paranoid_check_ec_hdr(const struct ubi_device *ubi, int pnum,
 static int paranoid_check_peb_vid_hdr(const struct ubi_device *ubi, int pnum);
 static int paranoid_check_vid_hdr(const struct ubi_device *ubi, int pnum,
                                   const struct ubi_vid_hdr *vid_hdr);
-static int paranoid_check_all_ff(const struct ubi_device *ubi, int pnum,
-                                 int offset, int len);
+static int paranoid_check_all_ff(struct ubi_device *ubi, int pnum, int offset,
+                                 int len);
 #else
 #define paranoid_check_not_bad(ubi, pnum) 0
 #define paranoid_check_peb_ec_hdr(ubi, pnum)  0
@@ -202,8 +202,8 @@ retry:
  * Note, in case of an error, it is possible that something was still written
  * to the flash media, but may be some garbage.
  */
-int ubi_io_write(const struct ubi_device *ubi, const void *buf, int pnum,
-                 int offset, int len)
+int ubi_io_write(struct ubi_device *ubi, const void *buf, int pnum, int offset,
+                 int len)
 {
         int err;
         size_t written;
@@ -285,7 +285,7 @@ static void erase_callback(struct erase_info *ei)
  * zero in case of success and a negative error code in case of failure. If
  * %-EIO is returned, the physical eraseblock most probably went bad.
  */
-static int do_sync_erase(const struct ubi_device *ubi, int pnum)
+static int do_sync_erase(struct ubi_device *ubi, int pnum)
 {
         int err, retries = 0;
         struct erase_info ei;
@@ -377,29 +377,25 @@ static uint8_t patterns[] = {0xa5, 0x5a, 0x0};
  * test, a positive number of erase operations done if the test was
  * successfully passed, and other negative error codes in case of other errors.
  */
-static int torture_peb(const struct ubi_device *ubi, int pnum)
+static int torture_peb(struct ubi_device *ubi, int pnum)
 {
-        void *buf;
         int err, i, patt_count;
 
-        buf = vmalloc(ubi->peb_size);
-        if (!buf)
-                return -ENOMEM;
-
         patt_count = ARRAY_SIZE(patterns);
         ubi_assert(patt_count > 0);
 
+        mutex_lock(&ubi->buf_mutex);
         for (i = 0; i < patt_count; i++) {
                 err = do_sync_erase(ubi, pnum);
                 if (err)
                         goto out;
 
                 /* Make sure the PEB contains only 0xFF bytes */
-                err = ubi_io_read(ubi, buf, pnum, 0, ubi->peb_size);
+                err = ubi_io_read(ubi, ubi->peb_buf1, pnum, 0, ubi->peb_size);
                 if (err)
                         goto out;
 
-                err = check_pattern(buf, 0xFF, ubi->peb_size);
+                err = check_pattern(ubi->peb_buf1, 0xFF, ubi->peb_size);
                 if (err == 0) {
                         ubi_err("erased PEB %d, but a non-0xFF byte found",
                                 pnum);
@@ -408,17 +404,17 @@ static int torture_peb(const struct ubi_device *ubi, int pnum)
                 }
 
                 /* Write a pattern and check it */
-                memset(buf, patterns[i], ubi->peb_size);
-                err = ubi_io_write(ubi, buf, pnum, 0, ubi->peb_size);
+                memset(ubi->peb_buf1, patterns[i], ubi->peb_size);
+                err = ubi_io_write(ubi, ubi->peb_buf1, pnum, 0, ubi->peb_size);
                 if (err)
                         goto out;
 
-                memset(buf, ~patterns[i], ubi->peb_size);
-                err = ubi_io_read(ubi, buf, pnum, 0, ubi->peb_size);
+                memset(ubi->peb_buf1, ~patterns[i], ubi->peb_size);
+                err = ubi_io_read(ubi, ubi->peb_buf1, pnum, 0, ubi->peb_size);
                 if (err)
                         goto out;
 
-                err = check_pattern(buf, patterns[i], ubi->peb_size);
+                err = check_pattern(ubi->peb_buf1, patterns[i], ubi->peb_size);
                 if (err == 0) {
                         ubi_err("pattern %x checking failed for PEB %d",
                                 patterns[i], pnum);
@@ -430,6 +426,7 @@ static int torture_peb(const struct ubi_device *ubi, int pnum)
         err = patt_count;
 
 out:
+        mutex_unlock(&ubi->buf_mutex);
         if (err == UBI_IO_BITFLIPS || err == -EBADMSG) {
                 /*
                  * If a bit-flip or data integrity error was detected, the test
@@ -440,7 +437,6 @@ out:
                         pnum);
                 err = -EIO;
         }
-        vfree(buf);
         return err;
 }
 
@@ -460,7 +456,7 @@ out:
  * codes in case of other errors. Note, %-EIO means that the physical
  * eraseblock is bad.
  */
-int ubi_io_sync_erase(const struct ubi_device *ubi, int pnum, int torture)
+int ubi_io_sync_erase(struct ubi_device *ubi, int pnum, int torture)
 {
         int err, ret = 0;
 
@@ -617,7 +613,7 @@ bad:
  * o %UBI_IO_PEB_EMPTY if the physical eraseblock is empty;
  * o a negative error code in case of failure.
  */
-int ubi_io_read_ec_hdr(const struct ubi_device *ubi, int pnum,
+int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,
                        struct ubi_ec_hdr *ec_hdr, int verbose)
 {
         int err, read_err = 0;
@@ -723,7 +719,7 @@ int ubi_io_read_ec_hdr(const struct ubi_device *ubi, int pnum,
  * case of failure. If %-EIO is returned, the physical eraseblock most probably
  * went bad.
  */
-int ubi_io_write_ec_hdr(const struct ubi_device *ubi, int pnum,
+int ubi_io_write_ec_hdr(struct ubi_device *ubi, int pnum,
                         struct ubi_ec_hdr *ec_hdr)
 {
         int err;
@@ -889,7 +885,7 @@ bad:
  *   header there);
  * o a negative error code in case of failure.
  */
-int ubi_io_read_vid_hdr(const struct ubi_device *ubi, int pnum,
+int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
                         struct ubi_vid_hdr *vid_hdr, int verbose)
 {
         int err, read_err = 0;
@@ -996,7 +992,7 @@ int ubi_io_read_vid_hdr(const struct ubi_device *ubi, int pnum,
  * case of failure. If %-EIO is returned, the physical eraseblock probably went
  * bad.
  */
-int ubi_io_write_vid_hdr(const struct ubi_device *ubi, int pnum,
+int ubi_io_write_vid_hdr(struct ubi_device *ubi, int pnum,
                          struct ubi_vid_hdr *vid_hdr)
 {
         int err;
@@ -1219,44 +1215,40 @@ exit:
  * @offset of the physical eraseblock @pnum, %1 if not, and a negative error
  * code if an error occurred.
  */
-static int paranoid_check_all_ff(const struct ubi_device *ubi, int pnum,
-                                 int offset, int len)
+static int paranoid_check_all_ff(struct ubi_device *ubi, int pnum, int offset,
+                                 int len)
 {
         size_t read;
         int err;
-        void *buf;
         loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
 
-        buf = vmalloc(len);
-        if (!buf)
-                return -ENOMEM;
-        memset(buf, 0, len);
-
-        err = ubi->mtd->read(ubi->mtd, addr, len, &read, buf);
+        mutex_lock(&ubi->dbg_buf_mutex);
+        err = ubi->mtd->read(ubi->mtd, addr, len, &read, ubi->dbg_peb_buf);
         if (err && err != -EUCLEAN) {
                 ubi_err("error %d while reading %d bytes from PEB %d:%d, "
                         "read %zd bytes", err, len, pnum, offset, read);
                 goto error;
         }
 
-        err = check_pattern(buf, 0xFF, len);
+        err = check_pattern(ubi->dbg_peb_buf, 0xFF, len);
         if (err == 0) {
                 ubi_err("flash region at PEB %d:%d, length %d does not "
                         "contain all 0xFF bytes", pnum, offset, len);
                 goto fail;
         }
+        mutex_unlock(&ubi->dbg_buf_mutex);
 
-        vfree(buf);
         return 0;
 
 fail:
         ubi_err("paranoid check failed for PEB %d", pnum);
         dbg_msg("hex dump of the %d-%d region", offset, offset + len);
-        print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 4, buf, len, 1);
+        print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 4,
+                       ubi->dbg_peb_buf, len, 1);
         err = 1;
 error:
         ubi_dbg_dump_stack();
-        vfree(buf);
+        mutex_unlock(&ubi->dbg_buf_mutex);
         return err;
 }
 
diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c
index 1c1401d6958b..44d87e8158c6 100644
--- a/drivers/mtd/ubi/scan.c
+++ b/drivers/mtd/ubi/scan.c
@@ -45,8 +45,7 @@
 #include "ubi.h"
 
 #ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
-static int paranoid_check_si(const struct ubi_device *ubi,
-                             struct ubi_scan_info *si);
+static int paranoid_check_si(struct ubi_device *ubi, struct ubi_scan_info *si);
 #else
 #define paranoid_check_si(ubi, si) 0
 #endif
@@ -259,9 +258,8 @@ static struct ubi_scan_volume *add_volume(struct ubi_scan_info *si, int vol_id,
  *     o bit 2 is cleared: the older LEB is not corrupted;
  *     o bit 2 is set: the older LEB is corrupted.
  */
-static int compare_lebs(const struct ubi_device *ubi,
-                        const struct ubi_scan_leb *seb, int pnum,
-                        const struct ubi_vid_hdr *vid_hdr)
+static int compare_lebs(struct ubi_device *ubi, const struct ubi_scan_leb *seb,
+                        int pnum, const struct ubi_vid_hdr *vid_hdr)
 {
         void *buf;
         int len, err, second_is_newer, bitflips = 0, corrupted = 0;
@@ -413,7 +411,7 @@ out_free_vidh:
  * to be picked, while the older one has to be dropped. This function returns
  * zero in case of success and a negative error code in case of failure.
  */
-int ubi_scan_add_used(const struct ubi_device *ubi, struct ubi_scan_info *si,
+int ubi_scan_add_used(struct ubi_device *ubi, struct ubi_scan_info *si,
                       int pnum, int ec, const struct ubi_vid_hdr *vid_hdr,
                       int bitflips)
 {
@@ -667,8 +665,8 @@ void ubi_scan_rm_volume(struct ubi_scan_info *si, struct ubi_scan_volume *sv)
  * function returns zero in case of success and a negative error code in case
  * of failure.
  */
-int ubi_scan_erase_peb(const struct ubi_device *ubi,
-                       const struct ubi_scan_info *si, int pnum, int ec)
+int ubi_scan_erase_peb(struct ubi_device *ubi, const struct ubi_scan_info *si,
+                       int pnum, int ec)
 {
         int err;
         struct ubi_ec_hdr *ec_hdr;
@@ -712,7 +710,7 @@ out_free:
  * This function returns scanning physical eraseblock information in case of
  * success and an error code in case of failure.
  */
-struct ubi_scan_leb *ubi_scan_get_free_peb(const struct ubi_device *ubi,
+struct ubi_scan_leb *ubi_scan_get_free_peb(struct ubi_device *ubi,
                                            struct ubi_scan_info *si)
 {
         int err = 0, i;
@@ -1110,8 +1108,7 @@ void ubi_scan_destroy_si(struct ubi_scan_info *si)
  * This function returns zero if the scanning information is all right, %1 if
  * not and a negative error code if an error occurred.
  */
-static int paranoid_check_si(const struct ubi_device *ubi,
-                             struct ubi_scan_info *si)
+static int paranoid_check_si(struct ubi_device *ubi, struct ubi_scan_info *si)
 {
         int pnum, err, vols_found = 0;
         struct rb_node *rb1, *rb2;
diff --git a/drivers/mtd/ubi/scan.h b/drivers/mtd/ubi/scan.h
index 140e82e26534..46d444af471a 100644
--- a/drivers/mtd/ubi/scan.h
+++ b/drivers/mtd/ubi/scan.h
@@ -147,7 +147,7 @@ static inline void ubi_scan_move_to_list(struct ubi_scan_volume *sv,
                 list_add_tail(&seb->u.list, list);
 }
 
-int ubi_scan_add_used(const struct ubi_device *ubi, struct ubi_scan_info *si,
+int ubi_scan_add_used(struct ubi_device *ubi, struct ubi_scan_info *si,
                       int pnum, int ec, const struct ubi_vid_hdr *vid_hdr,
                       int bitflips);
 struct ubi_scan_volume *ubi_scan_find_sv(const struct ubi_scan_info *si,
@@ -155,10 +155,10 @@ struct ubi_scan_volume *ubi_scan_find_sv(const struct ubi_scan_info *si,
 struct ubi_scan_leb *ubi_scan_find_seb(const struct ubi_scan_volume *sv,
                                        int lnum);
 void ubi_scan_rm_volume(struct ubi_scan_info *si, struct ubi_scan_volume *sv);
-struct ubi_scan_leb *ubi_scan_get_free_peb(const struct ubi_device *ubi,
+struct ubi_scan_leb *ubi_scan_get_free_peb(struct ubi_device *ubi,
                                            struct ubi_scan_info *si);
-int ubi_scan_erase_peb(const struct ubi_device *ubi,
-                       const struct ubi_scan_info *si, int pnum, int ec);
+int ubi_scan_erase_peb(struct ubi_device *ubi, const struct ubi_scan_info *si,
+                       int pnum, int ec);
 struct ubi_scan_info *ubi_scan(struct ubi_device *ubi);
 void ubi_scan_destroy_si(struct ubi_scan_info *si);
 
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 329663188772..cc010111264f 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -274,6 +274,12 @@ struct ubi_wl_entry;
  * @bad_allowed: whether the MTD device admits of bad physical eraseblocks or
  * not
  * @mtd: MTD device descriptor
+ *
+ * @peb_buf1: a buffer of PEB size used for different purposes
+ * @peb_buf2: another buffer of PEB size used for different purposes
+ * @buf_mutex: proptects @peb_buf1 and @peb_buf2
+ * @dbg_peb_buf:  buffer of PEB size used for debugging
+ * @dbg_buf_mutex: proptects @dbg_peb_buf
  */
 struct ubi_device {
         struct cdev cdev;
@@ -343,6 +349,14 @@ struct ubi_device {
         int vid_hdr_shift;
         int bad_allowed;
         struct mtd_info *mtd;
+
+        void *peb_buf1;
+        void *peb_buf2;
+        struct mutex buf_mutex;
+#ifdef CONFIG_MTD_UBI_DEBUG
+        void *dbg_peb_buf;
+        struct mutex dbg_buf_mutex;
+#endif
 };
 
 extern struct file_operations ubi_cdev_operations;
@@ -409,18 +423,18 @@ void ubi_wl_close(struct ubi_device *ubi);
 /* io.c */
 int ubi_io_read(const struct ubi_device *ubi, void *buf, int pnum, int offset,
                 int len);
-int ubi_io_write(const struct ubi_device *ubi, const void *buf, int pnum,
-                 int offset, int len);
-int ubi_io_sync_erase(const struct ubi_device *ubi, int pnum, int torture);
+int ubi_io_write(struct ubi_device *ubi, const void *buf, int pnum, int offset,
+                 int len);
+int ubi_io_sync_erase(struct ubi_device *ubi, int pnum, int torture);
 int ubi_io_is_bad(const struct ubi_device *ubi, int pnum);
 int ubi_io_mark_bad(const struct ubi_device *ubi, int pnum);
-int ubi_io_read_ec_hdr(const struct ubi_device *ubi, int pnum,
+int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,
                        struct ubi_ec_hdr *ec_hdr, int verbose);
-int ubi_io_write_ec_hdr(const struct ubi_device *ubi, int pnum,
+int ubi_io_write_ec_hdr(struct ubi_device *ubi, int pnum,
                         struct ubi_ec_hdr *ec_hdr);
-int ubi_io_read_vid_hdr(const struct ubi_device *ubi, int pnum,
+int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
                         struct ubi_vid_hdr *vid_hdr, int verbose);
-int ubi_io_write_vid_hdr(const struct ubi_device *ubi, int pnum,
+int ubi_io_write_vid_hdr(struct ubi_device *ubi, int pnum,
                          struct ubi_vid_hdr *vid_hdr);
 
 /*
@@ -494,7 +508,7 @@ static inline int ubi_io_read_data(const struct ubi_device *ubi, void *buf,
  * the beginning of the logical eraseblock, not to the beginning of the
  * physical eraseblock.
  */
-static inline int ubi_io_write_data(const struct ubi_device *ubi, const void *buf,
+static inline int ubi_io_write_data(struct ubi_device *ubi, const void *buf,
                                     int pnum, int offset, int len)
 {
         ubi_assert(offset >= 0);
diff --git a/drivers/mtd/ubi/vtbl.c b/drivers/mtd/ubi/vtbl.c
index b0a1e8426456..25b3bd61c7ec 100644
--- a/drivers/mtd/ubi/vtbl.c
+++ b/drivers/mtd/ubi/vtbl.c
@@ -254,7 +254,7 @@ bad:
  * This function returns zero in case of success and a negative error code in
  * case of failure.
  */
-static int create_vtbl(const struct ubi_device *ubi, struct ubi_scan_info *si,
+static int create_vtbl(struct ubi_device *ubi, struct ubi_scan_info *si,
                        int copy, void *vtbl)
 {
         int err, tries = 0;
@@ -339,7 +339,7 @@ out_free:
  * not corrupted, and recovering from corruptions if needed. Returns volume
  * table in case of success and a negative error code in case of failure.
  */
-static struct ubi_vtbl_record *process_lvol(const struct ubi_device *ubi,
+static struct ubi_vtbl_record *process_lvol(struct ubi_device *ubi,
                                             struct ubi_scan_info *si,
                                             struct ubi_scan_volume *sv)
 {
@@ -453,7 +453,7 @@ out_free:
  * This function returns volume table contents in case of success and a
  * negative error code in case of failure.
  */
-static struct ubi_vtbl_record *create_empty_lvol(const struct ubi_device *ubi,
+static struct ubi_vtbl_record *create_empty_lvol(struct ubi_device *ubi,
                                                  struct ubi_scan_info *si)
 {
         int i;
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 248ff9e477e7..6e5315bf5e1b 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -208,7 +208,7 @@ struct ubi_work {
 };
 
 #ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
-static int paranoid_check_ec(const struct ubi_device *ubi, int pnum, int ec);
+static int paranoid_check_ec(struct ubi_device *ubi, int pnum, int ec);
 static int paranoid_check_in_wl_tree(struct ubi_wl_entry *e,
                                      struct rb_root *root);
 #else
@@ -1625,7 +1625,7 @@ void ubi_wl_close(struct ubi_device *ubi)
  * is equivalent to @ec, %1 if not, and a negative error code if an error
  * occurred.
  */
-static int paranoid_check_ec(const struct ubi_device *ubi, int pnum, int ec)
+static int paranoid_check_ec(struct ubi_device *ubi, int pnum, int ec)
 {
         int err;
         long long read_ec;