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 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (c) International Business Machines Corp., 2006
  *
  * Author: Artem Bityutskiy (Битюцкий Артём)
  */
 
 /*
  * The UBI Eraseblock Association (EBA) sub-system.
  *
  * This sub-system 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 sub-system 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 ubi_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"
 
 /* Number of physical eraseblocks reserved for atomic LEB change operation */
 #define EBA_RESERVED_PEBS 1
 
 /**
  * struct ubi_eba_entry - structure encoding a single LEB -> PEB association
  * @pnum: the physical eraseblock number attached to the LEB
  *
  * This structure is encoding a LEB -> PEB association. Note that the LEB
  * number is not stored here, because it is the index used to access the
  * entries table.
  */
 struct ubi_eba_entry {
     int pnum;
 };
 
 /**
  * struct ubi_eba_table - LEB -> PEB association information
  * @entries: the LEB to PEB mapping (one entry per LEB).
  *
  * This structure is private to the EBA logic and should be kept here.
  * It is encoding the LEB to PEB association table, and is subject to
  * changes.
  */
 struct ubi_eba_table {
     struct ubi_eba_entry *entries;
 };
 
 /**
  * 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.
  */
 unsigned long long ubi_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_VOLUME_ID)
         return UBI_LAYOUT_VOLUME_COMPAT;
     return 0;
 }
 
 /**
  * ubi_eba_get_ldesc - get information about a LEB
  * @vol: volume description object
  * @lnum: logical eraseblock number
  * @ldesc: the LEB descriptor to fill
  *
  * Used to query information about a specific LEB.
  * It is currently only returning the physical position of the LEB, but will be
  * extended to provide more information.
  */
 void ubi_eba_get_ldesc(struct ubi_volume *vol, int lnum,
                struct ubi_eba_leb_desc *ldesc)
 {
     ldesc->lnum = lnum;
     ldesc->pnum = vol->eba_tbl->entries[lnum].pnum;
 }
 
 /**
  * ubi_eba_create_table - allocate a new EBA table and initialize it with all
  *            LEBs unmapped
  * @vol: volume containing the EBA table to copy
  * @nentries: number of entries in the table
  *
  * Allocate a new EBA table and initialize it with all LEBs unmapped.
  * Returns a valid pointer if it succeed, an ERR_PTR() otherwise.
  */
 struct ubi_eba_table *ubi_eba_create_table(struct ubi_volume *vol,
                        int nentries)
 {
     struct ubi_eba_table *tbl;
     int err = -ENOMEM;
     int i;
 
     tbl = kzalloc(sizeof(*tbl), GFP_KERNEL);
     if (!tbl)
         return ERR_PTR(-ENOMEM);
 
     tbl->entries = kmalloc_array(nentries, sizeof(*tbl->entries),
                      GFP_KERNEL);
     if (!tbl->entries)
         goto err;
 
     for (i = 0; i < nentries; i++)
         tbl->entries[i].pnum = UBI_LEB_UNMAPPED;
 
     return tbl;
 
 err:
     kfree(tbl);
 
     return ERR_PTR(err);
 }
 
 /**
  * ubi_eba_destroy_table - destroy an EBA table
  * @tbl: the table to destroy
  *
  * Destroy an EBA table.
  */
 void ubi_eba_destroy_table(struct ubi_eba_table *tbl)
 {
     if (!tbl)
         return;
 
     kfree(tbl->entries);
     kfree(tbl);
 }
 
 /**
  * ubi_eba_copy_table - copy the EBA table attached to vol into another table
  * @vol: volume containing the EBA table to copy
  * @dst: destination
  * @nentries: number of entries to copy
  *
  * Copy the EBA table stored in vol into the one pointed by dst.
  */
 void ubi_eba_copy_table(struct ubi_volume *vol, struct ubi_eba_table *dst,
             int nentries)
 {
     struct ubi_eba_table *src;
     int i;
 
     ubi_assert(dst && vol && vol->eba_tbl);
 
     src = vol->eba_tbl;
 
     for (i = 0; i < nentries; i++)
         dst->entries[i].pnum = src->entries[i].pnum;
 }
 
 /**
  * ubi_eba_replace_table - assign a new EBA table to a volume
  * @vol: volume containing the EBA table to copy
  * @tbl: new EBA table
  *
  * Assign a new EBA table to the volume and release the old one.
  */
 void ubi_eba_replace_table(struct ubi_volume *vol, struct ubi_eba_table *tbl)
 {
     ubi_eba_destroy_table(vol->eba_tbl);
     vol->eba_tbl = tbl;
 }
 
 /**
  * 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 ubi_ltree_entry
  * object if the logical eraseblock is locked and %NULL if it is not.
  * @ubi->ltree_lock has to be locked.
  */
 static struct ubi_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 ubi_ltree_entry *le;
 
         le = rb_entry(p, struct ubi_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 ubi_ltree_entry *ltree_add_entry(struct ubi_device *ubi,
                            int vol_id, int lnum)
 {
     struct ubi_ltree_entry *le, *le1, *le_free;
 
     le = kmalloc(sizeof(struct ubi_ltree_entry), GFP_NOFS);
     if (!le)
         return ERR_PTR(-ENOMEM);
 
     le->users = 0;
     init_rwsem(&le->mutex);
     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 ubi_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);
 
     kfree(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 ubi_ltree_entry *le;
 
     le = ltree_add_entry(ubi, vol_id, lnum);
     if (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)
 {
     struct ubi_ltree_entry *le;
 
     spin_lock(&ubi->ltree_lock);
     le = ltree_lookup(ubi, vol_id, lnum);
     le->users -= 1;
     ubi_assert(le->users >= 0);
     up_read(&le->mutex);
     if (le->users == 0) {
         rb_erase(&le->rb, &ubi->ltree);
         kfree(le);
     }
     spin_unlock(&ubi->ltree_lock);
 }
 
 /**
  * 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 ubi_ltree_entry *le;
 
     le = ltree_add_entry(ubi, vol_id, lnum);
     if (IS_ERR(le))
         return PTR_ERR(le);
     down_write(&le->mutex);
     return 0;
 }
 
 /**
  * leb_write_trylock - try to 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 if there is no
  * contention and does nothing if there is contention. Returns %0 in case of
  * success, %1 in case of contention, and and a negative error code in case of
  * failure.
  */
 static int leb_write_trylock(struct ubi_device *ubi, int vol_id, int lnum)
 {
     struct ubi_ltree_entry *le;
 
     le = ltree_add_entry(ubi, vol_id, lnum);
     if (IS_ERR(le))
         return PTR_ERR(le);
     if (down_write_trylock(&le->mutex))
         return 0;
 
     /* Contention, cancel */
     spin_lock(&ubi->ltree_lock);
     le->users -= 1;
     ubi_assert(le->users >= 0);
     if (le->users == 0) {
         rb_erase(&le->rb, &ubi->ltree);
         kfree(le);
     }
     spin_unlock(&ubi->ltree_lock);
 
     return 1;
 }
 
 /**
  * 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)
 {
     struct ubi_ltree_entry *le;
 
     spin_lock(&ubi->ltree_lock);
     le = ltree_lookup(ubi, vol_id, lnum);
     le->users -= 1;
     ubi_assert(le->users >= 0);
     up_write(&le->mutex);
     if (le->users == 0) {
         rb_erase(&le->rb, &ubi->ltree);
         kfree(le);
     }
     spin_unlock(&ubi->ltree_lock);
 }
 
 /**
  * ubi_eba_is_mapped - check if a LEB is mapped.
  * @vol: volume description object
  * @lnum: logical eraseblock number
  *
  * This function returns true if the LEB is mapped, false otherwise.
  */
 bool ubi_eba_is_mapped(struct ubi_volume *vol, int lnum)
 {
     return vol->eba_tbl->entries[lnum].pnum >= 0;
 }
 
 /**
  * ubi_eba_unmap_leb - un-map logical eraseblock.
  * @ubi: UBI device description object
  * @vol: volume description object
  * @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, struct ubi_volume *vol,
               int lnum)
 {
     int err, pnum, vol_id = vol->vol_id;
 
     if (ubi->ro_mode)
         return -EROFS;
 
     err = leb_write_lock(ubi, vol_id, lnum);
     if (err)
         return err;
 
     pnum = vol->eba_tbl->entries[lnum].pnum;
     if (pnum < 0)
         /* This logical eraseblock is already unmapped */
         goto out_unlock;
 
     dbg_eba("erase LEB %d:%d, PEB %d", vol_id, lnum, pnum);
 
     down_read(&ubi->fm_eba_sem);
     vol->eba_tbl->entries[lnum].pnum = UBI_LEB_UNMAPPED;
     up_read(&ubi->fm_eba_sem);
     err = ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 0);
 
 out_unlock:
     leb_write_unlock(ubi, vol_id, lnum);
     return err;
 }
 
 #ifdef CONFIG_MTD_UBI_FASTMAP
 /**
  * check_mapping - check and fixup a mapping
  * @ubi: UBI device description object
  * @vol: volume description object
  * @lnum: logical eraseblock number
  * @pnum: physical eraseblock number
  *
  * Checks whether a given mapping is valid. Fastmap cannot track LEB unmap
  * operations, if such an operation is interrupted the mapping still looks
  * good, but upon first read an ECC is reported to the upper layer.
  * Normaly during the full-scan at attach time this is fixed, for Fastmap
  * we have to deal with it while reading.
  * If the PEB behind a LEB shows this symthom we change the mapping to
  * %UBI_LEB_UNMAPPED and schedule the PEB for erasure.
  *
  * Returns 0 on success, negative error code in case of failure.
  */
 static int check_mapping(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
              int *pnum)
 {
     int err;
     struct ubi_vid_io_buf *vidb;
     struct ubi_vid_hdr *vid_hdr;
 
     if (!ubi->fast_attach)
         return 0;
 
     if (!vol->checkmap || test_bit(lnum, vol->checkmap))
         return 0;
 
     vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
     if (!vidb)
         return -ENOMEM;
 
     err = ubi_io_read_vid_hdr(ubi, *pnum, vidb, 0);
     if (err > 0 && err != UBI_IO_BITFLIPS) {
         int torture = 0;
 
         switch (err) {
             case UBI_IO_FF:
             case UBI_IO_FF_BITFLIPS:
             case UBI_IO_BAD_HDR:
             case UBI_IO_BAD_HDR_EBADMSG:
                 break;
             default:
                 ubi_assert(0);
         }
 
         if (err == UBI_IO_BAD_HDR_EBADMSG || err == UBI_IO_FF_BITFLIPS)
             torture = 1;
 
         down_read(&ubi->fm_eba_sem);
         vol->eba_tbl->entries[lnum].pnum = UBI_LEB_UNMAPPED;
         up_read(&ubi->fm_eba_sem);
         ubi_wl_put_peb(ubi, vol->vol_id, lnum, *pnum, torture);
 
         *pnum = UBI_LEB_UNMAPPED;
     } else if (err < 0) {
         ubi_err(ubi, "unable to read VID header back from PEB %i: %i",
             *pnum, err);
 
         goto out_free;
     } else {
         int found_vol_id, found_lnum;
 
         ubi_assert(err == 0 || err == UBI_IO_BITFLIPS);
 
         vid_hdr = ubi_get_vid_hdr(vidb);
         found_vol_id = be32_to_cpu(vid_hdr->vol_id);
         found_lnum = be32_to_cpu(vid_hdr->lnum);
 
         if (found_lnum != lnum || found_vol_id != vol->vol_id) {
             ubi_err(ubi, "EBA mismatch! PEB %i is LEB %i:%i instead of LEB %i:%i",
                 *pnum, found_vol_id, found_lnum, vol->vol_id, lnum);
             ubi_ro_mode(ubi);
             err = -EINVAL;
             goto out_free;
         }
     }
 
     set_bit(lnum, vol->checkmap);
     err = 0;
 
 out_free:
     ubi_free_vid_buf(vidb);
 
     return err;
 }
 #else
 static int check_mapping(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
           int *pnum)
 {
     return 0;
 }
 #endif
 
 /**
  * ubi_eba_read_leb - read data.
  * @ubi: UBI device description object
  * @vol: volume description object
  * @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, struct ubi_volume *vol, int lnum,
              void *buf, int offset, int len, int check)
 {
     int err, pnum, scrub = 0, vol_id = vol->vol_id;
     struct ubi_vid_io_buf *vidb;
     struct ubi_vid_hdr *vid_hdr;
     uint32_t crc;
 
     err = leb_read_lock(ubi, vol_id, lnum);
     if (err)
         return err;
 
     pnum = vol->eba_tbl->entries[lnum].pnum;
     if (pnum >= 0) {
         err = check_mapping(ubi, vol, lnum, &pnum);
         if (err < 0)
             goto out_unlock;
     }
 
     if (pnum == UBI_LEB_UNMAPPED) {
         /*
          * 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) {
         vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
         if (!vidb) {
             err = -ENOMEM;
             goto out_unlock;
         }
 
         vid_hdr = ubi_get_vid_hdr(vidb);
 
         err = ubi_io_read_vid_hdr(ubi, pnum, vidb, 1);
         if (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_HDR_EBADMSG ||
                     err == UBI_IO_BAD_HDR) {
                     ubi_warn(ubi, "corrupted VID header at PEB %d, LEB %d:%d",
                          pnum, vol_id, lnum);
                     err = -EBADMSG;
                 } else {
                     /*
                      * Ending up here in the non-Fastmap case
                      * is a clear bug as the VID header had to
                      * be present at scan time to have it referenced.
                      * With fastmap the story is more complicated.
                      * Fastmap has the mapping info without the need
                      * of a full scan. So the LEB could have been
                      * unmapped, Fastmap cannot know this and keeps
                      * the LEB referenced.
                      * This is valid and works as the layer above UBI
                      * has to do bookkeeping about used/referenced
                      * LEBs in any case.
                      */
                     if (ubi->fast_attach) {
                         err = -EBADMSG;
                     } else {
                         err = -EINVAL;
                         ubi_ro_mode(ubi);
                     }
                 }
             }
             goto out_free;
         } else if (err == UBI_IO_BITFLIPS)
             scrub = 1;
 
         ubi_assert(lnum < be32_to_cpu(vid_hdr->used_ebs));
         ubi_assert(len == be32_to_cpu(vid_hdr->data_size));
 
         crc = be32_to_cpu(vid_hdr->data_crc);
         ubi_free_vid_buf(vidb);
     }
 
     err = ubi_io_read_data(ubi, buf, pnum, offset, len);
     if (err) {
         if (err == UBI_IO_BITFLIPS)
             scrub = 1;
         else if (mtd_is_eccerr(err)) {
             if (vol->vol_type == UBI_DYNAMIC_VOLUME)
                 goto out_unlock;
             scrub = 1;
             if (!check) {
                 ubi_msg(ubi, "force data checking");
                 check = 1;
                 goto retry;
             }
         } else
             goto out_unlock;
     }
 
     if (check) {
         uint32_t crc1 = crc32(UBI_CRC32_INIT, buf, len);
         if (crc1 != crc) {
             ubi_warn(ubi, "CRC error: calculated %#08x, must be %#08x",
                  crc1, crc);
             err = -EBADMSG;
             goto out_unlock;
         }
     }
 
     if (scrub)
         err = ubi_wl_scrub_peb(ubi, pnum);
 
     leb_read_unlock(ubi, vol_id, lnum);
     return err;
 
 out_free:
     ubi_free_vid_buf(vidb);
 out_unlock:
     leb_read_unlock(ubi, vol_id, lnum);
     return err;
 }
 
 /**
  * ubi_eba_read_leb_sg - read data into a scatter gather list.
  * @ubi: UBI device description object
  * @vol: volume description object
  * @lnum: logical eraseblock number
  * @sgl: UBI scatter gather list to store the read data
  * @offset: offset from where to read
  * @len: how many bytes to read
  * @check: data CRC check flag
  *
  * This function works exactly like ubi_eba_read_leb(). But instead of
  * storing the read data into a buffer it writes to an UBI scatter gather
  * list.
  */
 int ubi_eba_read_leb_sg(struct ubi_device *ubi, struct ubi_volume *vol,
             struct ubi_sgl *sgl, int lnum, int offset, int len,
             int check)
 {
     int to_read;
     int ret;
     struct scatterlist *sg;
 
     for (;;) {
         ubi_assert(sgl->list_pos < UBI_MAX_SG_COUNT);
         sg = &sgl->sg[sgl->list_pos];
         if (len < sg->length - sgl->page_pos)
             to_read = len;
         else
             to_read = sg->length - sgl->page_pos;
 
         ret = ubi_eba_read_leb(ubi, vol, lnum,
                        sg_virt(sg) + sgl->page_pos, offset,
                        to_read, check);
         if (ret < 0)
             return ret;
 
         offset += to_read;
         len -= to_read;
         if (!len) {
             sgl->page_pos += to_read;
             if (sgl->page_pos == sg->length) {
                 sgl->list_pos++;
                 sgl->page_pos = 0;
             }
 
             break;
         }
 
         sgl->list_pos++;
         sgl->page_pos = 0;
     }
 
     return ret;
 }
 
 /**
  * try_recover_peb - try to recover from write failure.
  * @vol: volume description object
  * @pnum: the physical eraseblock to recover
  * @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
  * @vidb: VID buffer
  * @retry: whether the caller should retry in case of failure
  *
  * 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 0 in case of success, and a negative error code in case of failure.
  * In case of failure, the %retry parameter is set to false if this is a fatal
  * error (retrying won't help), and true otherwise.
  */
 static int try_recover_peb(struct ubi_volume *vol, int pnum, int lnum,
                const void *buf, int offset, int len,
                struct ubi_vid_io_buf *vidb, bool *retry)
 {
     struct ubi_device *ubi = vol->ubi;
     struct ubi_vid_hdr *vid_hdr;
     int new_pnum, err, vol_id = vol->vol_id, data_size;
     uint32_t crc;
 
     *retry = false;
 
     new_pnum = ubi_wl_get_peb(ubi);
     if (new_pnum < 0) {
         err = new_pnum;
         goto out_put;
     }
 
     ubi_msg(ubi, "recover PEB %d, move data to PEB %d",
         pnum, new_pnum);
 
     err = ubi_io_read_vid_hdr(ubi, pnum, vidb, 1);
     if (err && err != UBI_IO_BITFLIPS) {
         if (err > 0)
             err = -EIO;
         goto out_put;
     }
 
     vid_hdr = ubi_get_vid_hdr(vidb);
     ubi_assert(vid_hdr->vol_type == UBI_VID_DYNAMIC);
 
     mutex_lock(&ubi->buf_mutex);
     memset(ubi->peb_buf + offset, 0xFF, len);
 
     /* Read everything before the area where the write failure happened */
     if (offset > 0) {
         err = ubi_io_read_data(ubi, ubi->peb_buf, pnum, 0, offset);
         if (err && err != UBI_IO_BITFLIPS)
             goto out_unlock;
     }
 
     *retry = true;
 
     memcpy(ubi->peb_buf + offset, buf, len);
 
     data_size = offset + len;
     crc = crc32(UBI_CRC32_INIT, ubi->peb_buf, data_size);
     vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
     vid_hdr->copy_flag = 1;
     vid_hdr->data_size = cpu_to_be32(data_size);
     vid_hdr->data_crc = cpu_to_be32(crc);
     err = ubi_io_write_vid_hdr(ubi, new_pnum, vidb);
     if (err)
         goto out_unlock;
 
     err = ubi_io_write_data(ubi, ubi->peb_buf, new_pnum, 0, data_size);
 
 out_unlock:
     mutex_unlock(&ubi->buf_mutex);
 
     if (!err)
         vol->eba_tbl->entries[lnum].pnum = new_pnum;
 
 out_put:
     up_read(&ubi->fm_eba_sem);
 
     if (!err) {
         ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 1);
         ubi_msg(ubi, "data was successfully recovered");
     } else if (new_pnum >= 0) {
         /*
          * Bad luck? This physical eraseblock is bad too? Crud. Let's
          * try to get another one.
          */
         ubi_wl_put_peb(ubi, vol_id, lnum, new_pnum, 1);
         ubi_warn(ubi, "failed to write to PEB %d", new_pnum);
     }
 
     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 0 in case of success, and a negative error code in case of failure.
  * This function tries %UBI_IO_RETRIES before giving up.
  */
 static 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), tries;
     struct ubi_volume *vol = ubi->volumes[idx];
     struct ubi_vid_io_buf *vidb;
 
     vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
     if (!vidb)
         return -ENOMEM;
 
     for (tries = 0; tries <= UBI_IO_RETRIES; tries++) {
         bool retry;
 
         err = try_recover_peb(vol, pnum, lnum, buf, offset, len, vidb,
                       &retry);
         if (!err || !retry)
             break;
 
         ubi_msg(ubi, "try again");
     }
 
     ubi_free_vid_buf(vidb);
 
     return err;
 }
 
 /**
  * try_write_vid_and_data - try to write VID header and data to a new PEB.
  * @vol: volume description object
  * @lnum: logical eraseblock number
  * @vidb: the VID buffer to write
  * @buf: buffer containing the data
  * @offset: where to start writing data
  * @len: how many bytes should be written
  *
  * This function tries to write VID header and data belonging to logical
  * eraseblock @lnum of volume @vol to a new physical eraseblock. 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.
  */
 static int try_write_vid_and_data(struct ubi_volume *vol, int lnum,
                   struct ubi_vid_io_buf *vidb, const void *buf,
                   int offset, int len)
 {
     struct ubi_device *ubi = vol->ubi;
     int pnum, opnum, err, vol_id = vol->vol_id;
 
     pnum = ubi_wl_get_peb(ubi);
     if (pnum < 0) {
         err = pnum;
         goto out_put;
     }
 
     opnum = vol->eba_tbl->entries[lnum].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, vidb);
     if (err) {
         ubi_warn(ubi, "failed to write VID header to LEB %d:%d, PEB %d",
              vol_id, lnum, pnum);
         goto out_put;
     }
 
     if (len) {
         err = ubi_io_write_data(ubi, buf, pnum, offset, len);
         if (err) {
             ubi_warn(ubi,
                  "failed to write %d bytes at offset %d of LEB %d:%d, PEB %d",
                  len, offset, vol_id, lnum, pnum);
             goto out_put;
         }
     }
 
     vol->eba_tbl->entries[lnum].pnum = pnum;
 
 out_put:
     up_read(&ubi->fm_eba_sem);
 
     if (err && pnum >= 0)
         err = ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 1);
     else if (!err && opnum >= 0)
         err = ubi_wl_put_peb(ubi, vol_id, lnum, opnum, 0);
 
     return err;
 }
 
 /**
  * ubi_eba_write_leb - write data to dynamic volume.
  * @ubi: UBI device description object
  * @vol: volume description object
  * @lnum: logical eraseblock number
  * @buf: the data to write
  * @offset: offset within the logical eraseblock where to write
  * @len: how many bytes to write
  *
  * This function writes data to logical eraseblock @lnum of a dynamic volume
  * @vol. 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.
  * This function retries %UBI_IO_RETRIES times before giving up.
  */
 int ubi_eba_write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
               const void *buf, int offset, int len)
 {
     int err, pnum, tries, vol_id = vol->vol_id;
     struct ubi_vid_io_buf *vidb;
     struct ubi_vid_hdr *vid_hdr;
 
     if (ubi->ro_mode)
         return -EROFS;
 
     err = leb_write_lock(ubi, vol_id, lnum);
     if (err)
         return err;
 
     pnum = vol->eba_tbl->entries[lnum].pnum;
     if (pnum >= 0) {
         err = check_mapping(ubi, vol, lnum, &pnum);
         if (err < 0)
             goto out;
     }
 
     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 (err) {
             ubi_warn(ubi, "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);
         }
 
         goto out;
     }
 
     /*
      * The logical eraseblock is not mapped. We have to get a free physical
      * eraseblock and write the volume identifier header there first.
      */
     vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
     if (!vidb) {
         leb_write_unlock(ubi, vol_id, lnum);
         return -ENOMEM;
     }
 
     vid_hdr = ubi_get_vid_hdr(vidb);
 
     vid_hdr->vol_type = UBI_VID_DYNAMIC;
     vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
     vid_hdr->vol_id = cpu_to_be32(vol_id);
     vid_hdr->lnum = cpu_to_be32(lnum);
     vid_hdr->compat = ubi_get_compat(ubi, vol_id);
     vid_hdr->data_pad = cpu_to_be32(vol->data_pad);
 
     for (tries = 0; tries <= UBI_IO_RETRIES; tries++) {
         err = try_write_vid_and_data(vol, lnum, vidb, buf, offset, len);
         if (err != -EIO || !ubi->bad_allowed)
             break;
 
         /*
          * 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.
          */
         vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
         ubi_msg(ubi, "try another PEB");
     }
 
     ubi_free_vid_buf(vidb);
 
 out:
     if (err)
         ubi_ro_mode(ubi);
 
     leb_write_unlock(ubi, vol_id, lnum);
 
     return err;
 }
 
 /**
  * ubi_eba_write_leb_st - write data to static volume.
  * @ubi: UBI device description object
  * @vol: volume description object
  * @lnum: logical eraseblock number
  * @buf: data to write
  * @len: how many bytes to write
  * @used_ebs: how many logical eraseblocks will this volume contain
  *
  * This function writes data to logical eraseblock @lnum of static volume
  * @vol. 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 than 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, struct ubi_volume *vol,
              int lnum, const void *buf, int len, int used_ebs)
 {
     int err, tries, data_size = len, vol_id = vol->vol_id;
     struct ubi_vid_io_buf *vidb;
     struct ubi_vid_hdr *vid_hdr;
     uint32_t crc;
 
     if (ubi->ro_mode)
         return -EROFS;
 
     if (lnum == used_ebs - 1)
         /* If this is the last LEB @len may be unaligned */
         len = ALIGN(data_size, ubi->min_io_size);
     else
         ubi_assert(!(len & (ubi->min_io_size - 1)));
 
     vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
     if (!vidb)
         return -ENOMEM;
 
     vid_hdr = ubi_get_vid_hdr(vidb);
 
     err = leb_write_lock(ubi, vol_id, lnum);
     if (err)
         goto out;
 
     vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
     vid_hdr->vol_id = cpu_to_be32(vol_id);
     vid_hdr->lnum = cpu_to_be32(lnum);
     vid_hdr->compat = ubi_get_compat(ubi, vol_id);
     vid_hdr->data_pad = cpu_to_be32(vol->data_pad);
 
     crc = crc32(UBI_CRC32_INIT, buf, data_size);
     vid_hdr->vol_type = UBI_VID_STATIC;
     vid_hdr->data_size = cpu_to_be32(data_size);
     vid_hdr->used_ebs = cpu_to_be32(used_ebs);
     vid_hdr->data_crc = cpu_to_be32(crc);
 
     ubi_assert(vol->eba_tbl->entries[lnum].pnum < 0);
 
     for (tries = 0; tries <= UBI_IO_RETRIES; tries++) {
         err = try_write_vid_and_data(vol, lnum, vidb, buf, 0, len);
         if (err != -EIO || !ubi->bad_allowed)
             break;
 
         vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
         ubi_msg(ubi, "try another PEB");
     }
 
     if (err)
         ubi_ro_mode(ubi);
 
     leb_write_unlock(ubi, vol_id, lnum);
 
 out:
     ubi_free_vid_buf(vidb);
 
     return err;
 }
 
 /*
  * ubi_eba_atomic_leb_change - change logical eraseblock atomically.
  * @ubi: UBI device description object
  * @vol: volume description object
  * @lnum: logical eraseblock number
  * @buf: data to write
  * @len: how many bytes to write
  *
  * This function changes the contents of a logical eraseblock atomically. @buf
  * has to contain new logical eraseblock data, and @len - the length of the
  * data, which has to be aligned. This function guarantees that in case of an
  * unclean reboot the old contents is preserved. Returns zero in case of
  * success and a negative error code in case of failure.
  *
  * UBI reserves one LEB for the "atomic LEB change" operation, so only one
  * LEB change may be done at a time. This is ensured by @ubi->alc_mutex.
  */
 int ubi_eba_atomic_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
                   int lnum, const void *buf, int len)
 {
     int err, tries, vol_id = vol->vol_id;
     struct ubi_vid_io_buf *vidb;
     struct ubi_vid_hdr *vid_hdr;
     uint32_t crc;
 
     if (ubi->ro_mode)
         return -EROFS;
 
     if (len == 0) {
         /*
          * Special case when data length is zero. In this case the LEB
          * has to be unmapped and mapped somewhere else.
          */
         err = ubi_eba_unmap_leb(ubi, vol, lnum);
         if (err)
             return err;
         return ubi_eba_write_leb(ubi, vol, lnum, NULL, 0, 0);
     }
 
     vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
     if (!vidb)
         return -ENOMEM;
 
     vid_hdr = ubi_get_vid_hdr(vidb);
 
     mutex_lock(&ubi->alc_mutex);
     err = leb_write_lock(ubi, vol_id, lnum);
     if (err)
         goto out_mutex;
 
     vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
     vid_hdr->vol_id = cpu_to_be32(vol_id);
     vid_hdr->lnum = cpu_to_be32(lnum);
     vid_hdr->compat = ubi_get_compat(ubi, vol_id);
     vid_hdr->data_pad = cpu_to_be32(vol->data_pad);
 
     crc = crc32(UBI_CRC32_INIT, buf, len);
     vid_hdr->vol_type = UBI_VID_DYNAMIC;
     vid_hdr->data_size = cpu_to_be32(len);
     vid_hdr->copy_flag = 1;
     vid_hdr->data_crc = cpu_to_be32(crc);
 
     dbg_eba("change LEB %d:%d", vol_id, lnum);
 
     for (tries = 0; tries <= UBI_IO_RETRIES; tries++) {
         err = try_write_vid_and_data(vol, lnum, vidb, buf, 0, len);
         if (err != -EIO || !ubi->bad_allowed)
             break;
 
         vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
         ubi_msg(ubi, "try another PEB");
     }
 
     /*
      * This flash device does not admit of bad eraseblocks or
      * something nasty and unexpected happened. Switch to read-only
      * mode just in case.
      */
     if (err)
         ubi_ro_mode(ubi);
 
     leb_write_unlock(ubi, vol_id, lnum);
 
 out_mutex:
     mutex_unlock(&ubi->alc_mutex);
     ubi_free_vid_buf(vidb);
     return err;
 }
 
 /**
  * is_error_sane - check whether a read error is sane.
  * @err: code of the error happened during reading
  *
  * This is a helper function for 'ubi_eba_copy_leb()' which is called when we
  * cannot read data from the target PEB (an error @err happened). If the error
  * code is sane, then we treat this error as non-fatal. Otherwise the error is
  * fatal and UBI will be switched to R/O mode later.
  *
  * The idea is that we try not to switch to R/O mode if the read error is
  * something which suggests there was a real read problem. E.g., %-EIO. Or a
  * memory allocation failed (-%ENOMEM). Otherwise, it is safer to switch to R/O
  * mode, simply because we do not know what happened at the MTD level, and we
  * cannot handle this. E.g., the underlying driver may have become crazy, and
  * it is safer to switch to R/O mode to preserve the data.
  *
  * And bear in mind, this is about reading from the target PEB, i.e. the PEB
  * which we have just written.
  */
 static int is_error_sane(int err)
 {
     if (err == -EIO || err == -ENOMEM || err == UBI_IO_BAD_HDR ||
         err == UBI_IO_BAD_HDR_EBADMSG || err == -ETIMEDOUT)
         return 0;
     return 1;
 }
 
 /**
  * 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
  * @vidb: data structure from where the VID header is derived
  *
  * This function copies logical eraseblock from physical eraseblock @from to
  * physical eraseblock @to. The @vid_hdr buffer may be changed by this
  * function. Returns:
  *   o %0 in case of success;
  *   o %MOVE_CANCEL_RACE, %MOVE_TARGET_WR_ERR, %MOVE_TARGET_BITFLIPS, etc;
  *   o a negative error code in case of failure.
  */
 int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
              struct ubi_vid_io_buf *vidb)
 {
     int err, vol_id, lnum, data_size, aldata_size, idx;
     struct ubi_vid_hdr *vid_hdr = ubi_get_vid_hdr(vidb);
     struct ubi_volume *vol;
     uint32_t crc;
 
     ubi_assert(rwsem_is_locked(&ubi->fm_eba_sem));
 
     vol_id = be32_to_cpu(vid_hdr->vol_id);
     lnum = be32_to_cpu(vid_hdr->lnum);
 
     dbg_wl("copy LEB %d:%d, PEB %d to PEB %d", vol_id, lnum, from, to);
 
     if (vid_hdr->vol_type == UBI_VID_STATIC) {
         data_size = be32_to_cpu(vid_hdr->data_size);
         aldata_size = ALIGN(data_size, ubi->min_io_size);
     } else
         data_size = aldata_size =
                 ubi->leb_size - be32_to_cpu(vid_hdr->data_pad);
 
     idx = vol_id2idx(ubi, vol_id);
     spin_lock(&ubi->volumes_lock);
     /*
      * Note, we may race with volume deletion, which means that the volume
      * this logical eraseblock belongs to might be being deleted. Since the
      * volume deletion un-maps all the volume's logical eraseblocks, it will
      * be locked in 'ubi_wl_put_peb()' and wait for the WL worker to finish.
      */
     vol = ubi->volumes[idx];
     spin_unlock(&ubi->volumes_lock);
     if (!vol) {
         /* No need to do further work, cancel */
         dbg_wl("volume %d is being removed, cancel", vol_id);
         return MOVE_CANCEL_RACE;
     }
 
     /*
      * We do not want anybody to write to this logical eraseblock while we
      * are moving it, so lock it.
      *
      * Note, we are using non-waiting locking here, because we cannot sleep
      * on the LEB, since it may cause deadlocks. Indeed, imagine a task is
      * unmapping the LEB which is mapped to the PEB we are going to move
      * (@from). This task locks the LEB and goes sleep in the
      * 'ubi_wl_put_peb()' function on the @ubi->move_mutex. In turn, we are
      * holding @ubi->move_mutex and go sleep on the LEB lock. So, if the
      * LEB is already locked, we just do not move it and return
      * %MOVE_RETRY. Note, we do not return %MOVE_CANCEL_RACE here because
      * we do not know the reasons of the contention - it may be just a
      * normal I/O on this LEB, so we want to re-try.
      */
     err = leb_write_trylock(ubi, vol_id, lnum);
     if (err) {
         dbg_wl("contention on LEB %d:%d, cancel", vol_id, lnum);
         return MOVE_RETRY;
     }
 
     /*
      * The LEB might have been put meanwhile, and the task which put it is
      * probably waiting on @ubi->move_mutex. No need to continue the work,
      * cancel it.
      */
     if (vol->eba_tbl->entries[lnum].pnum != from) {
         dbg_wl("LEB %d:%d is no longer mapped to PEB %d, mapped to PEB %d, cancel",
                vol_id, lnum, from, vol->eba_tbl->entries[lnum].pnum);
         err = MOVE_CANCEL_RACE;
         goto out_unlock_leb;
     }
 
     /*
      * OK, now the LEB is locked and we can safely start moving it. Since
      * this function utilizes the @ubi->peb_buf buffer which is shared
      * with some other functions - we lock the buffer by taking the
      * @ubi->buf_mutex.
      */
     mutex_lock(&ubi->buf_mutex);
     dbg_wl("read %d bytes of data", aldata_size);
     err = ubi_io_read_data(ubi, ubi->peb_buf, from, 0, aldata_size);
     if (err && err != UBI_IO_BITFLIPS) {
         ubi_warn(ubi, "error %d while reading data from PEB %d",
              err, from);
         err = MOVE_SOURCE_RD_ERR;
         goto out_unlock_buf;
     }
 
     /*
      * Now we have got to calculate how much data we have 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, ubi->peb_buf, data_size);
 
     cond_resched();
     crc = crc32(UBI_CRC32_INIT, ubi->peb_buf, data_size);
     cond_resched();
 
     /*
      * It may turn out to be 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 (data_size > 0) {
         vid_hdr->copy_flag = 1;
         vid_hdr->data_size = cpu_to_be32(data_size);
         vid_hdr->data_crc = cpu_to_be32(crc);
     }
     vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
 
     err = ubi_io_write_vid_hdr(ubi, to, vidb);
     if (err) {
         if (err == -EIO)
             err = MOVE_TARGET_WR_ERR;
         goto out_unlock_buf;
     }
 
     cond_resched();
 
     /* Read the VID header back and check if it was written correctly */
     err = ubi_io_read_vid_hdr(ubi, to, vidb, 1);
     if (err) {
         if (err != UBI_IO_BITFLIPS) {
             ubi_warn(ubi, "error %d while reading VID header back from PEB %d",
                  err, to);
             if (is_error_sane(err))
                 err = MOVE_TARGET_RD_ERR;
         } else
             err = MOVE_TARGET_BITFLIPS;
         goto out_unlock_buf;
     }
 
     if (data_size > 0) {
         err = ubi_io_write_data(ubi, ubi->peb_buf, to, 0, aldata_size);
         if (err) {
             if (err == -EIO)
                 err = MOVE_TARGET_WR_ERR;
             goto out_unlock_buf;
         }
 
         cond_resched();
     }
 
     ubi_assert(vol->eba_tbl->entries[lnum].pnum == from);
     vol->eba_tbl->entries[lnum].pnum = to;
 
 out_unlock_buf:
     mutex_unlock(&ubi->buf_mutex);
 out_unlock_leb:
     leb_write_unlock(ubi, vol_id, lnum);
     return err;
 }
 
 /**
  * print_rsvd_warning - warn about not having enough reserved PEBs.
  * @ubi: UBI device description object
  * @ai: UBI attach info object
  *
  * This is a helper function for 'ubi_eba_init()' which is called when UBI
  * cannot reserve enough PEBs for bad block handling. This function makes a
  * decision whether we have to print a warning or not. The algorithm is as
  * follows:
  *   o if this is a new UBI image, then just print the warning
  *   o if this is an UBI image which has already been used for some time, print
  *     a warning only if we can reserve less than 10% of the expected amount of
  *     the reserved PEB.
  *
  * The idea is that when UBI is used, PEBs become bad, and the reserved pool
  * of PEBs becomes smaller, which is normal and we do not want to scare users
  * with a warning every time they attach the MTD device. This was an issue
  * reported by real users.
  */
 static void print_rsvd_warning(struct ubi_device *ubi,
                    struct ubi_attach_info *ai)
 {
     /*
      * The 1 << 18 (256KiB) number is picked randomly, just a reasonably
      * large number to distinguish between newly flashed and used images.
      */
     if (ai->max_sqnum > (1 << 18)) {
         int min = ubi->beb_rsvd_level / 10;
 
         if (!min)
             min = 1;
         if (ubi->beb_rsvd_pebs > min)
             return;
     }
 
     ubi_warn(ubi, "cannot reserve enough PEBs for bad PEB handling, reserved %d, need %d",
          ubi->beb_rsvd_pebs, ubi->beb_rsvd_level);
     if (ubi->corr_peb_count)
         ubi_warn(ubi, "%d PEBs are corrupted and not used",
              ubi->corr_peb_count);
 }
 
 /**
  * self_check_eba - run a self check on the EBA table constructed by fastmap.
  * @ubi: UBI device description object
  * @ai_fastmap: UBI attach info object created by fastmap
  * @ai_scan: UBI attach info object created by scanning
  *
  * Returns < 0 in case of an internal error, 0 otherwise.
  * If a bad EBA table entry was found it will be printed out and
  * ubi_assert() triggers.
  */
 int self_check_eba(struct ubi_device *ubi, struct ubi_attach_info *ai_fastmap,
            struct ubi_attach_info *ai_scan)
 {
     int i, j, num_volumes, ret = 0;
     int **scan_eba, **fm_eba;
     struct ubi_ainf_volume *av;
     struct ubi_volume *vol;
     struct ubi_ainf_peb *aeb;
     struct rb_node *rb;
 
     num_volumes = ubi->vtbl_slots + UBI_INT_VOL_COUNT;
 
     scan_eba = kmalloc_array(num_volumes, sizeof(*scan_eba), GFP_KERNEL);
     if (!scan_eba)
         return -ENOMEM;
 
     fm_eba = kmalloc_array(num_volumes, sizeof(*fm_eba), GFP_KERNEL);
     if (!fm_eba) {
         kfree(scan_eba);
         return -ENOMEM;
     }
 
     for (i = 0; i < num_volumes; i++) {
         vol = ubi->volumes[i];
         if (!vol)
             continue;
 
         scan_eba[i] = kmalloc_array(vol->reserved_pebs,
                         sizeof(**scan_eba),
                         GFP_KERNEL);
         if (!scan_eba[i]) {
             ret = -ENOMEM;
             goto out_free;
         }
 
         fm_eba[i] = kmalloc_array(vol->reserved_pebs,
                       sizeof(**fm_eba),
                       GFP_KERNEL);
         if (!fm_eba[i]) {
             ret = -ENOMEM;
             goto out_free;
         }
 
         for (j = 0; j < vol->reserved_pebs; j++)
             scan_eba[i][j] = fm_eba[i][j] = UBI_LEB_UNMAPPED;
 
         av = ubi_find_av(ai_scan, idx2vol_id(ubi, i));
         if (!av)
             continue;
 
         ubi_rb_for_each_entry(rb, aeb, &av->root, u.rb)
             scan_eba[i][aeb->lnum] = aeb->pnum;
 
         av = ubi_find_av(ai_fastmap, idx2vol_id(ubi, i));
         if (!av)
             continue;
 
         ubi_rb_for_each_entry(rb, aeb, &av->root, u.rb)
             fm_eba[i][aeb->lnum] = aeb->pnum;
 
         for (j = 0; j < vol->reserved_pebs; j++) {
             if (scan_eba[i][j] != fm_eba[i][j]) {
                 if (scan_eba[i][j] == UBI_LEB_UNMAPPED ||
                     fm_eba[i][j] == UBI_LEB_UNMAPPED)
                     continue;
 
                 ubi_err(ubi, "LEB:%i:%i is PEB:%i instead of %i!",
                     vol->vol_id, j, fm_eba[i][j],
                     scan_eba[i][j]);
                 ubi_assert(0);
             }
         }
     }
 
 out_free:
     for (i = 0; i < num_volumes; i++) {
         if (!ubi->volumes[i])
             continue;
 
         kfree(scan_eba[i]);
         kfree(fm_eba[i]);
     }
 
     kfree(scan_eba);
     kfree(fm_eba);
     return ret;
 }
 
 /**
  * ubi_eba_init - initialize the EBA sub-system using attaching information.
  * @ubi: UBI device description object
  * @ai: attaching information
  *
  * This function returns zero in case of success and a negative error code in
  * case of failure.
  */
 int ubi_eba_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
 {
     int i, err, num_volumes;
     struct ubi_ainf_volume *av;
     struct ubi_volume *vol;
     struct ubi_ainf_peb *aeb;
     struct rb_node *rb;
 
     dbg_eba("initialize EBA sub-system");
 
     spin_lock_init(&ubi->ltree_lock);
     mutex_init(&ubi->alc_mutex);
     ubi->ltree = RB_ROOT;
 
     ubi->global_sqnum = ai->max_sqnum + 1;
     num_volumes = ubi->vtbl_slots + UBI_INT_VOL_COUNT;
 
     for (i = 0; i < num_volumes; i++) {
         struct ubi_eba_table *tbl;
 
         vol = ubi->volumes[i];
         if (!vol)
             continue;
 
         cond_resched();
 
         tbl = ubi_eba_create_table(vol, vol->reserved_pebs);
         if (IS_ERR(tbl)) {
             err = PTR_ERR(tbl);
             goto out_free;
         }
 
         ubi_eba_replace_table(vol, tbl);
 
         av = ubi_find_av(ai, idx2vol_id(ubi, i));
         if (!av)
             continue;
 
         ubi_rb_for_each_entry(rb, aeb, &av->root, u.rb) {
             if (aeb->lnum >= vol->reserved_pebs) {
                 /*
                  * This may happen in case of an unclean reboot
                  * during re-size.
                  */
                 ubi_move_aeb_to_list(av, aeb, &ai->erase);
             } else {
                 struct ubi_eba_entry *entry;
 
                 entry = &vol->eba_tbl->entries[aeb->lnum];
                 entry->pnum = aeb->pnum;
             }
         }
     }
 
     if (ubi->avail_pebs < EBA_RESERVED_PEBS) {
         ubi_err(ubi, "no enough physical eraseblocks (%d, need %d)",
             ubi->avail_pebs, EBA_RESERVED_PEBS);
         if (ubi->corr_peb_count)
             ubi_err(ubi, "%d PEBs are corrupted and not used",
                 ubi->corr_peb_count);
         err = -ENOSPC;
         goto out_free;
     }
     ubi->avail_pebs -= EBA_RESERVED_PEBS;
     ubi->rsvd_pebs += EBA_RESERVED_PEBS;
 
     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;
             print_rsvd_warning(ubi, ai);
         } 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 sub-system is initialized");
     return 0;
 
 out_free:
     for (i = 0; i < num_volumes; i++) {
         if (!ubi->volumes[i])
             continue;
         ubi_eba_replace_table(ubi->volumes[i], NULL);
     }
     return err;
 }

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