[PATCH 10/20 take 4] UBI: EBA unit

[Artem Bityutskiy]

diff -auNrp tmp-from/drivers/mtd/ubi/eba.c tmp-to/drivers/mtd/ubi/eba.c
--- tmp-from/drivers/mtd/ubi/eba.c	1970-01-01 02:00:00.000000000 +0200
+++ tmp-to/drivers/mtd/ubi/eba.c	2007-03-23 18:20:01.000000000 +0200
@@ -0,0 +1,1132 @@
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Author: Artem Bityutskiy (Ð?иÑ?Ñ?Ñ?кий Ð?Ñ?Ñ?Ñ?м)
+ */
+
+/*
+ * The UBI Eraseblock Association (EBA) unit.
+ *
+ * This unit is responsible for I/O to/from logical eraseblock.
+ *
+ * Although in this implementation the EBA table is fully kept and managed in
+ * RAM, which assumes poor scalability, it might be (partially) maintained on
+ * flash in future implementations.
+ *
+ * The EBA unit implements per-logical eraseblock locking. Before accessing a
+ * logical eraseblock it is locked for reading or writing. The per-logical
+ * eraseblock locking is implemented by means of the lock tree. The lock tree
+ * is an RB-tree which refers all the currently locked logical eraseblocks. The
+ * lock tree elements are &struct ltree_entry objects. They are indexed by
+ * (@vol_id, @lnum) pairs.
+ *
+ * EBA also maintains the global sequence counter which is incremented each
+ * time a logical eraseblock is mapped to a physical eraseblock and it is
+ * stored in the volume identifier header. This means that each VID header has
+ * a unique sequence number. The sequence number is only increased an we assume
+ * 64 bits is enough to never overflow.
+ */
+
+#include <linux/slab.h>
+#include <linux/crc32.h>
+#include <linux/err.h>
+#include "ubi.h"
+
+/**
+ * struct ltree_entry - an entry in the lock tree.
+ * @rb: links RB-tree nodes
+ * @vol_id: volume ID of the locked logical eraseblock
+ * @lnum: locked logical eraseblock number
+ * @users: how many tasks are using this logical eraseblock or wait for it
+ * @mutex: read/write mutex to implement read/write access serialization to
+ * the (@vol_id, @lnum) logical eraseblock
+ *
+ * When a logical eraseblock is being locked - corresponding &struct ltree_entry
+ * object is inserted to the lock tree (@ubi->ltree).
+ */
+struct ltree_entry {
+	struct rb_node rb;
+	int vol_id;
+	int lnum;
+	int users;
+	struct rw_semaphore mutex;
+};
+
+/* Slab cache for lock-tree entries */
+static struct kmem_cache *ltree_slab;
+
+/**
+ * next_sqnum - get next sequence number.
+ * @ubi: UBI device description object
+ *
+ * This function returns next sequence number to use, which is just the current
+ * global sequence counter value. It also increases the global sequence
+ * counter.
+ */
+static unsigned long long next_sqnum(struct ubi_device *ubi)
+{
+	unsigned long long sqnum;
+
+	spin_lock(&ubi->ltree_lock);
+	sqnum = ubi->global_sqnum++;
+	spin_unlock(&ubi->ltree_lock);
+
+	return sqnum;
+}
+
+/**
+ * ubi_get_compat - get compatibility flags of a volume.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ *
+ * This function returns compatibility flags for an internal volume. User
+ * volumes have no compatibility flags, so %0 is returned.
+ */
+static int ubi_get_compat(const struct ubi_device *ubi, int vol_id)
+{
+	if (vol_id == UBI_LAYOUT_VOL_ID)
+		return UBI_LAYOUT_VOLUME_COMPAT;
+	return 0;
+}
+
+/**
+ * ltree_lookup - look up the lock tree.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ *
+ * This function returns a pointer to the corresponding &struct ltree_entry
+ * object if the logical eraseblock is locked and %NULL if it is not.
+ * @ubi->ltree_lock has to be locked.
+ */
+static struct ltree_entry *ltree_lookup(struct ubi_device *ubi, int vol_id,
+					int lnum)
+{
+	struct rb_node *p;
+
+	p = ubi->ltree.rb_node;
+	while (p) {
+		struct ltree_entry *le;
+
+		le = rb_entry(p, struct ltree_entry, rb);
+
+		if (vol_id < le->vol_id)
+			p = p->rb_left;
+		else if (vol_id > le->vol_id)
+			p = p->rb_right;
+		else {
+			if (lnum < le->lnum)
+				p = p->rb_left;
+			else if (lnum > le->lnum)
+				p = p->rb_right;
+			else
+				return le;
+		}
+	}
+
+	return NULL;
+}
+
+/**
+ * ltree_add_entry - add new entry to the lock tree.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ *
+ * This function adds new entry for logical eraseblock (@vol_id, @lnum) to the
+ * lock tree. If such entry is already there, its usage counter is increased.
+ * Returns pointer to the lock tree entry or %-ENOMEM if memory allocation
+ * failed.
+ */
+static struct ltree_entry *ltree_add_entry(struct ubi_device *ubi, int vol_id,
+					   int lnum)
+{
+	struct ltree_entry *le, *le1, *le_free;
+
+	le = kmem_cache_alloc(ltree_slab, GFP_KERNEL);
+	if (unlikely(!le))
+		return ERR_PTR(-ENOMEM);
+
+	le->vol_id = vol_id;
+	le->lnum = lnum;
+
+	spin_lock(&ubi->ltree_lock);
+	le1 = ltree_lookup(ubi, vol_id, lnum);
+
+	if (le1) {
+		/*
+		 * This logical eraseblock is already locked. The newly
+		 * allocated lock entry is not needed.
+		 */
+		le_free = le;
+		le = le1;
+	} else {
+		struct rb_node **p, *parent = NULL;
+
+		/*
+		 * No lock entry, add the newly allocated one to the
+		 * @ubi->ltree RB-tree.
+		 */
+		le_free = NULL;
+
+		p = &ubi->ltree.rb_node;
+		while (*p) {
+			parent = *p;
+			le1 = rb_entry(parent, struct ltree_entry, rb);
+
+			if (vol_id < le1->vol_id)
+				p = &(*p)->rb_left;
+			else if (vol_id > le1->vol_id)
+				p = &(*p)->rb_right;
+			else {
+				ubi_assert(lnum != le1->lnum);
+				if (lnum < le1->lnum)
+					p = &(*p)->rb_left;
+				else
+					p = &(*p)->rb_right;
+			}
+		}
+
+		rb_link_node(&le->rb, parent, p);
+		rb_insert_color(&le->rb, &ubi->ltree);
+	}
+	le->users += 1;
+	spin_unlock(&ubi->ltree_lock);
+
+	if (le_free)
+		kmem_cache_free(ltree_slab, le_free);
+
+	return le;
+}
+
+/**
+ * leb_read_lock - lock logical eraseblock for reading.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ *
+ * This function locks a logical eraseblock for reading. Returns zero in case
+ * of success and a negative error code in case of failure.
+ */
+static int leb_read_lock(struct ubi_device *ubi, int vol_id, int lnum)
+{
+	struct ltree_entry *le;
+
+	le = ltree_add_entry(ubi, vol_id, lnum);
+	if (unlikely(IS_ERR(le)))
+		return PTR_ERR(le);
+	down_read(&le->mutex);
+	return 0;
+}
+
+/**
+ * leb_read_unlock - unlock logical eraseblock.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ */
+static void leb_read_unlock(struct ubi_device *ubi, int vol_id, int lnum)
+{
+	int free = 0;
+	struct ltree_entry *le;
+
+	spin_lock(&ubi->ltree_lock);
+	le = ltree_lookup(ubi, vol_id, lnum);
+	le->users -= 1;
+	ubi_assert(le->users >= 0);
+	if (le->users == 0) {
+		rb_erase(&le->rb, &ubi->ltree);
+		free = 1;
+	}
+	spin_unlock(&ubi->ltree_lock);
+
+	up_read(&le->mutex);
+	if (free)
+		kmem_cache_free(ltree_slab, le);
+}
+
+/**
+ * leb_write_lock - lock logical eraseblock for writing.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ *
+ * This function locks a logical eraseblock for writing. Returns zero in case
+ * of success and a negative error code in case of failure.
+ */
+static int leb_write_lock(struct ubi_device *ubi, int vol_id, int lnum)
+{
+	struct ltree_entry *le;
+
+	le = ltree_add_entry(ubi, vol_id, lnum);
+	if (unlikely(IS_ERR(le)))
+		return PTR_ERR(le);
+	down_write(&le->mutex);
+	return 0;
+}
+
+/**
+ * leb_write_unlock - unlock logical eraseblock.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ */
+static void leb_write_unlock(struct ubi_device *ubi, int vol_id, int lnum)
+{
+	int free;
+	struct ltree_entry *le;
+
+	spin_lock(&ubi->ltree_lock);
+	le = ltree_lookup(ubi, vol_id, lnum);
+	le->users -= 1;
+	ubi_assert(le->users >= 0);
+	if (le->users == 0) {
+		rb_erase(&le->rb, &ubi->ltree);
+		free = 1;
+	} else
+		free = 0;
+	spin_unlock(&ubi->ltree_lock);
+
+	up_write(&le->mutex);
+	if (free)
+		kmem_cache_free(ltree_slab, le);
+}
+
+/**
+ * ubi_eba_unmap_leb - un-map logical eraseblock.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ *
+ * This function un-maps logical eraseblock @lnum and schedules corresponding
+ * physical eraseblock for erasure. Returns zero in case of success and a
+ * negative error code in case of failure.
+ */
+int ubi_eba_unmap_leb(struct ubi_device *ubi, int vol_id, int lnum)
+{
+	int idx = vol_id2idx(ubi, vol_id), err, pnum;
+	struct ubi_volume *vol = ubi->volumes[idx];
+
+	if (unlikely(ubi->ro_mode))
+		return -EROFS;
+
+	err = leb_write_lock(ubi, vol_id, lnum);
+	if (unlikely(err))
+		return err;
+
+	pnum = vol->eba_tbl[lnum];
+	if (pnum < 0)
+		/* This logical eraseblock is already unmapped */
+		goto out_unlock;
+
+	dbg_eba("erase LEB %d:%d, PEB %d", vol_id, lnum, pnum);
+
+	vol->eba_tbl[lnum] = UBI_LEB_UNMAPPED;
+	err = ubi_wl_put_peb(ubi, pnum, 0);
+
+out_unlock:
+	leb_write_unlock(ubi, vol_id, lnum);
+	return err;
+}
+
+/**
+ * ubi_eba_read_leb - read data.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ * @buf: buffer to store the read data
+ * @offset: offset from where to read
+ * @len: how many bytes to read
+ * @check: data CRC check flag
+ *
+ * If the logical eraseblock @lnum is unmapped, @buf is filled with 0xFF
+ * bytes. The @check flag only makes sense for static volumes and forces
+ * eraseblock data CRC checking.
+ *
+ * In case of success this function returns zero. In case of a static volume,
+ * if data CRC mismatches - %-EBADMSG is returned. %-EBADMSG may also be
+ * returned for any volume type if an ECC error was detected by the MTD device
+ * driver. Other negative error cored may be returned in case of other errors.
+ */
+int ubi_eba_read_leb(struct ubi_device *ubi, int vol_id, int lnum, void *buf,
+		     int offset, int len, int check)
+{
+	int err, pnum, scrub = 0, idx = vol_id2idx(ubi, vol_id);
+	struct ubi_vid_hdr *vid_hdr;
+	struct ubi_volume *vol = ubi->volumes[idx];
+	uint32_t crc, crc1;
+
+	err = leb_read_lock(ubi, vol_id, lnum);
+	if (unlikely(err))
+		return err;
+
+	pnum = vol->eba_tbl[lnum];
+	if (pnum < 0) {
+		/*
+		 * The logical eraseblock is not mapped, fill the whole buffer
+		 * with 0xFF bytes. The exception is static volumes for which
+		 * it is an error to read unmapped logical eraseblocks.
+		 */
+		dbg_eba("read %d bytes from offset %d of LEB %d:%d (unmapped)",
+			len, offset, vol_id, lnum);
+		leb_read_unlock(ubi, vol_id, lnum);
+		ubi_assert(vol->vol_type != UBI_STATIC_VOLUME);
+		memset(buf, 0xFF, len);
+		return 0;
+	}
+
+	dbg_eba("read %d bytes from offset %d of LEB %d:%d, PEB %d",
+		len, offset, vol_id, lnum, pnum);
+
+	if (vol->vol_type == UBI_DYNAMIC_VOLUME)
+		check = 0;
+
+retry:
+	if (check) {
+		vid_hdr = ubi_zalloc_vid_hdr(ubi);
+		if (unlikely(!vid_hdr)) {
+			err = -ENOMEM;
+			goto out_unlock;
+		}
+
+		err = ubi_io_read_vid_hdr(ubi, pnum, vid_hdr, 1);
+		if (unlikely(err) && err != UBI_IO_BITFLIPS) {
+			if (err > 0) {
+				/*
+				 * The header is either absent or corrupted.
+				 * The former case means there is a bug -
+				 * switch to read-only mode just in case.
+				 * The latter case means a real corruption - we
+				 * may try to recover data. FIXME: but this is
+				 * not implemented.
+				 */
+				if (err == UBI_IO_BAD_VID_HDR) {
+					ubi_warn("bad VID header at PEB %d, LEB"
+						 "%d:%d", pnum, vol_id, lnum);
+					err = -EBADMSG;
+				} else
+					ubi_ro_mode(ubi);
+			}
+			goto out_free;
+		} else if (unlikely(err == UBI_IO_BITFLIPS))
+			scrub = 1;
+
+		ubi_assert(lnum < ubi32_to_cpu(vid_hdr->used_ebs));
+		ubi_assert(len == ubi32_to_cpu(vid_hdr->data_size));
+
+		crc = ubi32_to_cpu(vid_hdr->data_crc);
+		ubi_free_vid_hdr(ubi, vid_hdr);
+	}
+
+	err = ubi_io_read_data(ubi, buf, pnum, offset, len);
+	if (unlikely(err)) {
+		if (err == UBI_IO_BITFLIPS) {
+			scrub = 1;
+			err = 0;
+		} else if (err == -EBADMSG) {
+			if (vol->vol_type == UBI_DYNAMIC_VOLUME)
+				goto out_unlock;
+			scrub = 1;
+			if (!check) {
+				ubi_msg("force data checking");
+				check = 1;
+				goto retry;
+			}
+		} else
+			goto out_unlock;
+	}
+
+	if (check) {
+		crc1 = crc32(UBI_CRC32_INIT, buf, len);
+		if (unlikely(crc1 != crc)) {
+			ubi_warn("CRC error: calculated %#08x, must be %#08x",
+				 crc1, crc);
+			err = -EBADMSG;
+			goto out_unlock;
+		}
+	}
+
+	if (unlikely(scrub))
+		err = ubi_wl_scrub_peb(ubi, pnum);
+
+	leb_read_unlock(ubi, vol_id, lnum);
+	return err;
+
+out_free:
+	ubi_free_vid_hdr(ubi, vid_hdr);
+out_unlock:
+	leb_read_unlock(ubi, vol_id, lnum);
+	return err;
+}
+
+/**
+ * recover_peb - recover from write failure.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock to recover
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ * @buf: data which was not written because of the write failure
+ * @offset: offset of the failed write
+ * @len: how many bytes should have been written
+ *
+ * This function is called in case of a write failure and moves all good data
+ * from the potentially bad physical eraseblock to a good physical eraseblock.
+ * This function also writes the data which was not written due to the failure.
+ * Returns new physical eraseblock number in case of success, and a negative
+ * error code in case of failure.
+ */
+int recover_peb(struct ubi_device *ubi, int pnum, int vol_id, int lnum,
+		const void *buf, int offset, int len)
+{
+	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);
+	if (!vid_hdr) {
+		return -ENOMEM;
+	}
+
+retry:
+	new_pnum = ubi_wl_get_peb(ubi, UBI_DATA_UNKNOWN);
+	if (new_pnum < 0) {
+		ubi_free_vid_hdr(ubi, vid_hdr);
+		return new_pnum;
+	}
+
+	ubi_msg("recover PEB %d, move data to PEB %d", pnum, new_pnum);
+
+	err = ubi_io_read_vid_hdr(ubi, pnum, vid_hdr, 1);
+	if (err && err != UBI_IO_BITFLIPS) {
+		if (err > 0)
+			err = -EIO;
+		goto out_put;
+	}
+
+	vid_hdr->sqnum = cpu_to_ubi64(next_sqnum(ubi));
+	err = ubi_io_write_vid_hdr(ubi, new_pnum, vid_hdr);
+	if (err)
+		goto write_error;
+
+	data_size = offset + len;
+	new_buf = kmalloc(data_size, GFP_KERNEL);
+	if (unlikely(!new_buf)) {
+		err = -ENOMEM;
+		goto out_put;
+	}
+	memset(new_buf + 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) {
+			kfree(new_buf);
+			goto out_put;
+		}
+	}
+
+	memcpy(new_buf + offset, buf, len);
+
+	err = ubi_io_write_data(ubi, new_buf, new_pnum, 0, data_size);
+	if (err) {
+		kfree(new_buf);
+		goto write_error;
+	}
+
+	kfree(new_buf);
+	ubi_free_vid_hdr(ubi, vid_hdr);
+
+	vol->eba_tbl[lnum] = new_pnum;
+	ubi_wl_put_peb(ubi, pnum, 1);
+
+	ubi_msg("data was successfully recovered");
+	return 0;
+
+out_put:
+	ubi_wl_put_peb(ubi, new_pnum, 1);
+	ubi_free_vid_hdr(ubi, vid_hdr);
+	return err;
+
+write_error:
+	/*
+	 * Bad luck? This physical eraseblock is bad too? Crud. Let's try to
+	 * get another one.
+	 */
+	ubi_warn("failed to write to PEB %d", new_pnum);
+	ubi_wl_put_peb(ubi, new_pnum, 1);
+	if (++tries > UBI_IO_RETRIES) {
+		ubi_free_vid_hdr(ubi, vid_hdr);
+		return err;
+	}
+	ubi_msg("try again");
+	goto retry;
+}
+
+/**
+ * ubi_eba_write_leb - write data to dynamic volume.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ * @buf: the data to write
+ * @offset: offset within the logical eraseblock where to write
+ * @len: how many bytes to write
+ * @dtype: data type
+ *
+ * This function writes data to logical eraseblock @lnum of a dynamic volume
+ * @vol_id. Returns zero in case of success and a negative error code in case
+ * of failure. In case of error, it is possible that something was still
+ * written to the flash media, but may be some garbage.
+ */
+int ubi_eba_write_leb(struct ubi_device *ubi, int vol_id, int lnum,
+		      const void *buf, int offset, int len,
+		      enum ubi_data_type dtype)
+{
+	int idx = vol_id2idx(ubi, vol_id), err, pnum, tries = 0;
+	struct ubi_volume *vol = ubi->volumes[idx];
+	struct ubi_vid_hdr *vid_hdr;
+
+	if (unlikely(ubi->ro_mode))
+		return -EROFS;
+
+	err = leb_write_lock(ubi, vol_id, lnum);
+	if (unlikely(err))
+		return err;
+
+	pnum = vol->eba_tbl[lnum];
+	if (pnum >= 0) {
+		dbg_eba("write %d bytes at offset %d of LEB %d:%d, PEB %d",
+			len, offset, vol_id, lnum, pnum);
+
+		err = ubi_io_write_data(ubi, buf, pnum, offset, len);
+		if (unlikely(err)) {
+			ubi_warn("failed to write data to PEB %d", pnum);
+			if (err == -EIO && ubi->bad_allowed)
+				err = recover_peb(ubi, pnum, vol_id, lnum, buf, offset, len);
+			if (err)
+				ubi_ro_mode(ubi);
+		}
+		leb_write_unlock(ubi, vol_id, lnum);
+		return err;
+	}
+
+	/*
+	 * The logical eraseblock is not mapped. We have to get a free physical
+	 * eraseblock and write the volume identifier header there first.
+	 */
+	vid_hdr = ubi_zalloc_vid_hdr(ubi);
+	if (unlikely(!vid_hdr)) {
+		leb_write_unlock(ubi, vol_id, lnum);
+		return -ENOMEM;
+	}
+
+	vid_hdr->vol_type = UBI_VID_DYNAMIC;
+	vid_hdr->sqnum = cpu_to_ubi64(next_sqnum(ubi));
+	vid_hdr->vol_id = cpu_to_ubi32(vol_id);
+	vid_hdr->lnum = cpu_to_ubi32(lnum);
+	vid_hdr->compat = ubi_get_compat(ubi, vol_id);
+	vid_hdr->data_pad = cpu_to_ubi32(vol->data_pad);
+
+retry:
+	pnum = ubi_wl_get_peb(ubi, dtype);
+	if (unlikely(pnum < 0)) {
+		ubi_free_vid_hdr(ubi, vid_hdr);
+		leb_write_unlock(ubi, vol_id, lnum);
+		return pnum;
+	}
+
+	dbg_eba("write VID hdr and %d bytes at offset %d of LEB %d:%d, PEB %d",
+		len, offset, vol_id, lnum, pnum);
+
+	err = ubi_io_write_vid_hdr(ubi, pnum, vid_hdr);
+	if (unlikely(err)) {
+		ubi_warn("failed to write VID header to LEB %d:%d, PEB %d",
+			 vol_id, lnum, pnum);
+		goto write_error;
+	}
+
+	err = ubi_io_write_data(ubi, buf, pnum, offset, len);
+	if (unlikely(err)) {
+		ubi_warn("failed to write %d bytes at offset %d of LEB %d:%d, "
+			 "PEB %d", len, offset, vol_id, lnum, pnum);
+		goto write_error;
+	}
+
+	vol->eba_tbl[lnum] = pnum;
+
+	leb_write_unlock(ubi, vol_id, lnum);
+	ubi_free_vid_hdr(ubi, vid_hdr);
+	return 0;
+
+write_error:
+	if (err != -EIO || !ubi->bad_allowed) {
+		ubi_ro_mode(ubi);
+		leb_write_unlock(ubi, vol_id, lnum);
+		ubi_free_vid_hdr(ubi, vid_hdr);
+		return err;
+	}
+
+	/*
+	 * Fortunately, this is the first write operation to this physical
+	 * eraseblock, so just put it and request a new one. We assume that if
+	 * this physical eraseblock went bad, the erase code will handle that.
+	 */
+	err = ubi_wl_put_peb(ubi, pnum, 1);
+	if (err || ++tries > UBI_IO_RETRIES) {
+		ubi_ro_mode(ubi);
+		leb_write_unlock(ubi, vol_id, lnum);
+		ubi_free_vid_hdr(ubi, vid_hdr);
+		return err;
+	}
+
+	vid_hdr->sqnum = cpu_to_ubi64(next_sqnum(ubi));
+	ubi_msg("try another PEB");
+	goto retry;
+}
+
+/**
+ * ubi_eba_write_leb_st - write data to static volume.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ * @buf: data to write
+ * @len: how many bytes to write
+ * @dtype: data type
+ * @used_ebs: how many logical eraseblocks will this volume contain
+ *
+ * This function writes data to logical eraseblock @lnum of static volume
+ * @vol_id. The @used_ebs argument should contain total number of logical
+ * eraseblock in this static volume.
+ *
+ * When writing to the last logical eraseblock, the @len argument doesn't have
+ * to be aligned to the minimal I/O unit size. Instead, it has to be equivalent
+ * to the real data size, although the @buf buffer has to contain the
+ * alignment. In all other cases, @len has to be aligned.
+ *
+ * It is prohibited to write more then once to logical eraseblocks of static
+ * volumes. This function returns zero in case of success and a negative error
+ * code in case of failure.
+ */
+int ubi_eba_write_leb_st(struct ubi_device *ubi, int vol_id, int lnum,
+			 const void *buf, int len, enum ubi_data_type dtype,
+			 int used_ebs)
+{
+	int err, pnum, tries = 0, data_size = len;
+	int idx = vol_id2idx(ubi, vol_id);
+	struct ubi_volume *vol = ubi->volumes[idx];
+	struct ubi_vid_hdr *vid_hdr;
+	uint32_t crc;
+
+	if (unlikely(ubi->ro_mode))
+		return -EROFS;
+
+	if (lnum == used_ebs - 1)
+		/* If this is the last LEB @len may be unaligned */
+		len = ubi_align_up(data_size, ubi->min_io_size);
+	else
+		ubi_assert(len % ubi->min_io_size == 0);
+
+	vid_hdr = ubi_zalloc_vid_hdr(ubi);
+	if (unlikely(!vid_hdr))
+		return -ENOMEM;
+
+	err = leb_write_lock(ubi, vol_id, lnum);
+	if (unlikely(err)) {
+		ubi_free_vid_hdr(ubi, vid_hdr);
+		return err;
+	}
+
+	vid_hdr->sqnum = cpu_to_ubi64(next_sqnum(ubi));
+	vid_hdr->vol_id = cpu_to_ubi32(vol_id);
+	vid_hdr->lnum = cpu_to_ubi32(lnum);
+	vid_hdr->compat = ubi_get_compat(ubi, vol_id);
+	vid_hdr->data_pad = cpu_to_ubi32(vol->data_pad);
+
+	crc = crc32(UBI_CRC32_INIT, buf, data_size);
+	vid_hdr->vol_type = UBI_VID_STATIC;
+	vid_hdr->data_size = cpu_to_ubi32(data_size);
+	vid_hdr->used_ebs = cpu_to_ubi32(used_ebs);
+	vid_hdr->data_crc = cpu_to_ubi32(crc);
+
+retry:
+	pnum = ubi_wl_get_peb(ubi, dtype);
+	if (unlikely(pnum < 0)) {
+		ubi_free_vid_hdr(ubi, vid_hdr);
+		leb_write_unlock(ubi, vol_id, lnum);
+		return pnum;
+	}
+
+	dbg_eba("write VID hdr and %d bytes at LEB %d:%d, PEB %d, used_ebs %d",
+		len, vol_id, lnum, pnum, used_ebs);
+
+	err = ubi_io_write_vid_hdr(ubi, pnum, vid_hdr);
+	if (unlikely(err)) {
+		ubi_warn("failed to write VID header to LEB %d:%d, PEB %d",
+			 vol_id, lnum, pnum);
+		goto write_error;
+	}
+
+	err = ubi_io_write_data(ubi, buf, pnum, 0, len);
+	if (unlikely(err)) {
+		ubi_warn("failed to write %d bytes of data to PEB %d",
+			 len, pnum);
+		goto write_error;
+	}
+
+	ubi_assert(vol->eba_tbl[lnum] < 0);
+	vol->eba_tbl[lnum] = pnum;
+
+	leb_write_unlock(ubi, vol_id, lnum);
+	ubi_free_vid_hdr(ubi, vid_hdr);
+	return 0;
+
+write_error:
+	if (err != -EIO || !ubi->bad_allowed) {
+		/*
+		 * This flash device does not admit of bad eraseblocks or
+		 * something nasty and unexpected happened. Switch to read-only
+		 * mode just in case.
+		 */
+		ubi_ro_mode(ubi);
+		leb_write_unlock(ubi, vol_id, lnum);
+		ubi_free_vid_hdr(ubi, vid_hdr);
+		return err;
+	}
+
+	err = ubi_wl_put_peb(ubi, pnum, 1);
+	if (err || ++tries > UBI_IO_RETRIES) {
+		ubi_ro_mode(ubi);
+		leb_write_unlock(ubi, vol_id, lnum);
+		ubi_free_vid_hdr(ubi, vid_hdr);
+		return err;
+	}
+
+	vid_hdr->sqnum = cpu_to_ubi64(next_sqnum(ubi));
+	ubi_msg("try another PEB");
+	goto retry;
+}
+
+/**
+ * ltree_entry_ctor - lock tree entries slab cache constructor.
+ * @obj: the lock-tree entry to construct
+ * @cache: the lock tree entry slab cache
+ * @flags: constructor flags
+ */
+static void ltree_entry_ctor(void *obj, struct kmem_cache *cache,
+			     unsigned long flags)
+{
+	struct ltree_entry *le = obj;
+
+	if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) !=
+	    SLAB_CTOR_CONSTRUCTOR)
+		return;
+
+	le->users = 0;
+	init_rwsem(&le->mutex);
+}
+
+/**
+ * ubi_eba_copy_leb - copy logical eraseblock.
+ * @ubi: UBI device description object
+ * @from: physical eraseblock number from where to copy
+ * @to: physical eraseblock number where to copy
+ * @vid_hdr: VID header of the @from physical eraseblock
+ *
+ * This function copies logical eraseblock from physical eraseblock @from to
+ * physical eraseblock @to. The @vid_hdr buffer may be changed by this
+ * function. Returns zero in case of success, %UBI_IO_BITFLIPS if the operation
+ * was canceled because bit-flips were detected at the target PEB, and a
+ * negative error code in case of failure.
+ */
+int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
+		     struct ubi_vid_hdr *vid_hdr)
+{
+	int err, vol_id, lnum, data_size, aldata_size, pnum, idx;
+	struct ubi_volume *vol;
+	uint32_t crc;
+	void *buf, *buf1 = NULL;
+
+	vol_id = ubi32_to_cpu(vid_hdr->vol_id);
+	lnum = ubi32_to_cpu(vid_hdr->lnum);
+
+	dbg_eba("copy LEB %d:%d, PEB %d to PEB %d", vol_id, lnum, from, to);
+
+	if (vid_hdr->vol_type == UBI_VID_STATIC) {
+		data_size = ubi32_to_cpu(vid_hdr->data_size);
+		aldata_size = ubi_align_up(data_size, ubi->min_io_size);
+	} else
+		data_size = aldata_size =
+			    ubi->leb_size - ubi32_to_cpu(vid_hdr->data_pad);
+
+	buf = kmalloc(aldata_size, GFP_KERNEL);
+	if (unlikely(!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 (unlikely(err)) {
+		kfree(buf);
+		return err;
+	}
+
+	/*
+	 * But the logical eraseblock might have been put by this time.
+	 * Cancel if it is true.
+	 */
+	idx = vol_id2idx(ubi, vol_id);
+
+	/*
+	 * We may race with volume deletion/resize, so we have to hold
+	 * @ubi->volumes_lock.
+	 */
+	spin_lock(&ubi->volumes_lock);
+	vol = ubi->volumes[idx];
+	if (!vol) {
+		dbg_eba("volume %d was removed meanwhile", vol_id);
+		spin_unlock(&ubi->volumes_lock);
+		goto out_unlock;
+	}
+
+	pnum = vol->eba_tbl[lnum];
+	if (pnum != from) {
+		dbg_eba("LEB %d:%d is no longer mapped to PEB %d, mapped to "
+			"PEB %d, cancel", vol_id, lnum, from, pnum);
+		spin_unlock(&ubi->volumes_lock);
+		goto out_unlock;
+	}
+	spin_unlock(&ubi->volumes_lock);
+
+	/* 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);
+	if (unlikely(err) && err != UBI_IO_BITFLIPS) {
+		ubi_warn("error %d while reading data from PEB %d",
+			 err, from);
+		goto out_unlock;
+	}
+
+	/*
+	 * Now we have got to calculate how much data we have to to copy. In
+	 * case of a static volume it is fairly easy - the VID header contains
+	 * the data size. In case of a dynamic volume it is more difficult - we
+	 * have to read the contents, cut 0xFF bytes from the end and copy only
+	 * the first part. We must do this to avoid writing 0xFF bytes as it
+	 * may have some side-effects. And not only this. It is important not
+	 * to include those 0xFFs to CRC because later the they may be filled
+	 * by data.
+	 */
+	if (vid_hdr->vol_type == UBI_VID_DYNAMIC)
+		aldata_size = data_size =
+				ubi_calc_data_len(ubi, buf, data_size);
+
+	cond_resched();
+	crc = crc32(UBI_CRC32_INIT, buf, data_size);
+	cond_resched();
+
+	/*
+	 * It may turn out to me that the whole @from physical eraseblock
+	 * contains only 0xFF bytes. Then we have to only write the VID header
+	 * and do not write any data. This also means we should not set
+	 * @vid_hdr->copy_flag, @vid_hdr->data_size, and @vid_hdr->data_crc.
+	 */
+	if (likely(data_size > 0)) {
+		vid_hdr->copy_flag = 1;
+		vid_hdr->data_size = cpu_to_ubi32(data_size);
+		vid_hdr->data_crc = cpu_to_ubi32(crc);
+	}
+	vid_hdr->sqnum = cpu_to_ubi64(next_sqnum(ubi));
+
+	err = ubi_io_write_vid_hdr(ubi, to, vid_hdr);
+	if (unlikely(err))
+		goto out_unlock;
+
+	cond_resched();
+
+	/* Read the VID header back and check if it was written correctly */
+	err = ubi_io_read_vid_hdr(ubi, to, vid_hdr, 1);
+	if (unlikely(err)) {
+		if (err != UBI_IO_BITFLIPS)
+			ubi_warn("cannot read VID header back from PEB %d", to);
+		goto out_unlock;
+	}
+
+	if (likely(data_size > 0)) {
+		err = ubi_io_write_data(ubi, buf, to, 0, aldata_size);
+		if (unlikely(err))
+			goto out_unlock;
+
+		/*
+		 * We've written the data and are going to read it back to make
+		 * sure it was written correctly.
+		 */
+		buf1 = kmalloc(aldata_size, GFP_KERNEL);
+		if (unlikely(!buf1)) {
+			err = -ENOMEM;
+			goto out_unlock;
+		}
+
+		cond_resched();
+
+		err = ubi_io_read_data(ubi, buf1, to, 0, aldata_size);
+		if (unlikely(err)) {
+			if (err != UBI_IO_BITFLIPS)
+				ubi_warn("cannot read data back from PEB %d",
+					 to);
+			goto out_unlock;
+		}
+
+		cond_resched();
+
+		if (unlikely(memcmp(buf, buf1, aldata_size))) {
+			ubi_warn("read data back from PEB %d - it is different",
+				 to);
+			goto out_unlock;
+		}
+	}
+
+	ubi_assert(vol->eba_tbl[lnum] == from);
+	vol->eba_tbl[lnum] = to;
+
+	leb_write_unlock(ubi, vol_id, lnum);
+	kfree(buf);
+	kfree(buf1);
+
+	return 0;
+
+out_unlock:
+	leb_write_unlock(ubi, vol_id, lnum);
+	kfree(buf);
+	kfree(buf1);
+	return err;
+}
+
+/**
+ * ubi_eba_init_scan - initialize the EBA unit using scanning information.
+ * @ubi: UBI device description object
+ * @si: scanning information
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+int ubi_eba_init_scan(struct ubi_device *ubi, struct ubi_scan_info *si)
+{
+	int i, j, err, num_volumes;
+	struct ubi_scan_volume *sv;
+	struct ubi_volume *vol;
+	struct ubi_scan_leb *seb;
+	struct rb_node *rb;
+
+	dbg_eba("initialize EBA unit");
+
+	spin_lock_init(&ubi->ltree_lock);
+	ubi->ltree = RB_ROOT;
+
+	if (ubi_devices_cnt == 0) {
+		ltree_slab = kmem_cache_create("ubi_ltree_slab",
+					       sizeof(struct ltree_entry), 0,
+					       0, &ltree_entry_ctor, NULL);
+		if (!ltree_slab)
+			return -ENOMEM;
+	}
+
+	ubi->global_sqnum = si->max_sqnum + 1;
+	num_volumes = ubi->vtbl_slots + UBI_INT_VOL_COUNT;
+
+	for (i = 0; i < num_volumes; i++) {
+		vol = ubi->volumes[i];
+		if (!vol)
+			continue;
+
+		cond_resched();
+
+		vol->eba_tbl = kmalloc(vol->reserved_pebs * sizeof(int),
+				       GFP_KERNEL);
+		if (unlikely(!vol->eba_tbl)) {
+			err = -ENOMEM;
+			goto out_free;
+		}
+
+		for (j = 0; j < vol->reserved_pebs; j++)
+			vol->eba_tbl[j] = UBI_LEB_UNMAPPED;
+
+		sv = ubi_scan_find_sv(si, idx2vol_id(ubi, i));
+		if (!sv)
+			continue;
+
+		ubi_rb_for_each_entry(rb, seb, &sv->root, u.rb) {
+			if (seb->lnum >= vol->reserved_pebs)
+				/*
+				 * This may happen in case of an unclean reboot
+				 * during re-size.
+				 */
+				ubi_scan_move_to_list(sv, seb, &si->erase);
+			vol->eba_tbl[seb->lnum] = seb->pnum;
+		}
+	}
+
+	if (ubi->bad_allowed) {
+		ubi_calculate_reserved(ubi);
+
+		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);
+		} else
+			ubi->beb_rsvd_pebs = ubi->beb_rsvd_level;
+
+		ubi->avail_pebs -= ubi->beb_rsvd_pebs;
+		ubi->rsvd_pebs  += ubi->beb_rsvd_pebs;
+	}
+
+	dbg_eba("EBA unit is initialized");
+	return 0;
+
+out_free:
+	for (i = 0; i < num_volumes; i++) {
+		if (!ubi->volumes[i])
+			continue;
+		kfree(ubi->volumes[i]->eba_tbl);
+	}
+	if (ubi_devices_cnt == 0)
+		kmem_cache_destroy(ltree_slab);
+	return err;
+}
+
+/**
+ * ubi_eba_close - close EBA unit.
+ * @ubi: UBI device description object
+ */
+void ubi_eba_close(const struct ubi_device *ubi)
+{
+	int i, num_volumes = ubi->vtbl_slots + UBI_INT_VOL_COUNT;
+
+	dbg_eba("close EBA unit");
+
+	for (i = 0; i < num_volumes; i++) {
+		if (!ubi->volumes[i])
+			continue;
+		kfree(ubi->volumes[i]->eba_tbl);
+	}
+	if (ubi_devices_cnt == 1)
+		kmem_cache_destroy(ltree_slab);
+}
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