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;