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* This file is part of UBIFS.
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* Copyright (C) 2006-2008 Nokia Corporation
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 51
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* Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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* Authors: Adrian Hunter
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* Artem Bityutskiy (ŠŠøŃŃŃŠŗŠøŠ¹ ŠŃŃŃŠ¼)
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* This file implements the scan which is a general-purpose function for
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* determining what nodes are in an eraseblock. The scan is used to replay the
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* journal, to do garbage collection. for the TNC in-the-gaps method, and by
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* debugging functions.
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* scan_padding_bytes - scan for padding bytes.
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* @buf: buffer to scan
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* @len: length of buffer
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* This function returns the number of padding bytes on success and
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* %SCANNED_GARBAGE on failure.
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static int scan_padding_bytes(void *buf, int len)
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int pad_len = 0, max_pad_len = min_t(int, UBIFS_PAD_NODE_SZ, len);
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dbg_scan("not a node");
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while (pad_len < max_pad_len && *p++ == UBIFS_PADDING_BYTE)
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if (!pad_len || (pad_len & 7))
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return SCANNED_GARBAGE;
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dbg_scan("%d padding bytes", pad_len);
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* ubifs_scan_a_node - scan for a node or padding.
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* @c: UBIFS file-system description object
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* @buf: buffer to scan
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* @len: length of buffer
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* @lnum: logical eraseblock number
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* @offs: offset within the logical eraseblock
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* @quiet: print no messages
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* This function returns a scanning code to indicate what was scanned.
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int ubifs_scan_a_node(const struct ubifs_info *c, void *buf, int len, int lnum,
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struct ubifs_ch *ch = buf;
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magic = le32_to_cpu(ch->magic);
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if (magic == 0xFFFFFFFF) {
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dbg_scan("hit empty space");
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return SCANNED_EMPTY_SPACE;
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if (magic != UBIFS_NODE_MAGIC)
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return scan_padding_bytes(buf, len);
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if (len < UBIFS_CH_SZ)
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return SCANNED_GARBAGE;
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dbg_scan("scanning %s", dbg_ntype(ch->node_type));
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if (ubifs_check_node(c, buf, lnum, offs, quiet, 1))
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return SCANNED_A_CORRUPT_NODE;
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if (ch->node_type == UBIFS_PAD_NODE) {
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struct ubifs_pad_node *pad = buf;
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int pad_len = le32_to_cpu(pad->pad_len);
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int node_len = le32_to_cpu(ch->len);
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/* Validate the padding node */
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offs + node_len + pad_len > c->leb_size) {
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ubifs_err("bad pad node at LEB %d:%d",
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dbg_dump_node(c, pad);
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return SCANNED_A_BAD_PAD_NODE;
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/* Make the node pads to 8-byte boundary */
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if ((node_len + pad_len) & 7) {
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dbg_err("bad padding length %d - %d",
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offs, offs + node_len + pad_len);
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return SCANNED_A_BAD_PAD_NODE;
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dbg_scan("%d bytes padded, offset now %d",
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pad_len, ALIGN(offs + node_len + pad_len, 8));
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return node_len + pad_len;
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return SCANNED_A_NODE;
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* ubifs_start_scan - create LEB scanning information at start of scan.
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* @c: UBIFS file-system description object
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* @lnum: logical eraseblock number
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* @offs: offset to start at (usually zero)
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* @sbuf: scan buffer (must be c->leb_size)
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* This function returns %0 on success and a negative error code on failure.
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struct ubifs_scan_leb *ubifs_start_scan(const struct ubifs_info *c, int lnum,
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int offs, void *sbuf)
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struct ubifs_scan_leb *sleb;
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dbg_scan("scan LEB %d:%d", lnum, offs);
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sleb = kzalloc(sizeof(struct ubifs_scan_leb), GFP_NOFS);
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return ERR_PTR(-ENOMEM);
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INIT_LIST_HEAD(&sleb->nodes);
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err = ubi_read(c->ubi, lnum, sbuf + offs, offs, c->leb_size - offs);
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if (err && err != -EBADMSG) {
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ubifs_err("cannot read %d bytes from LEB %d:%d,"
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" error %d", c->leb_size - offs, lnum, offs, err);
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* ubifs_end_scan - update LEB scanning information at end of scan.
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* @c: UBIFS file-system description object
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* @sleb: scanning information
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* @lnum: logical eraseblock number
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* @offs: offset to start at (usually zero)
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* This function returns %0 on success and a negative error code on failure.
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void ubifs_end_scan(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
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dbg_scan("stop scanning LEB %d at offset %d", lnum, offs);
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ubifs_assert(offs % c->min_io_size == 0);
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sleb->endpt = ALIGN(offs, c->min_io_size);
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* ubifs_add_snod - add a scanned node to LEB scanning information.
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* @c: UBIFS file-system description object
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* @sleb: scanning information
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* @buf: buffer containing node
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* @offs: offset of node on flash
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* This function returns %0 on success and a negative error code on failure.
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int ubifs_add_snod(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
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struct ubifs_ch *ch = buf;
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struct ubifs_ino_node *ino = buf;
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struct ubifs_scan_node *snod;
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snod = kzalloc(sizeof(struct ubifs_scan_node), GFP_NOFS);
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snod->sqnum = le64_to_cpu(ch->sqnum);
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snod->type = ch->node_type;
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snod->len = le32_to_cpu(ch->len);
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switch (ch->node_type) {
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case UBIFS_DENT_NODE:
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case UBIFS_XENT_NODE:
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case UBIFS_DATA_NODE:
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case UBIFS_TRUN_NODE:
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* The key is in the same place in all keyed
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key_read(c, &ino->key, &snod->key);
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list_add_tail(&snod->list, &sleb->nodes);
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sleb->nodes_cnt += 1;
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* ubifs_scanned_corruption - print information after UBIFS scanned corruption.
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* @c: UBIFS file-system description object
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* @lnum: LEB number of corruption
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* @offs: offset of corruption
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* @buf: buffer containing corruption
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void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
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ubifs_err("corrupted data at LEB %d:%d", lnum, offs);
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if (dbg_failure_mode)
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len = c->leb_size - offs;
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dbg_err("first %d bytes from LEB %d:%d", len, lnum, offs);
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print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 4, buf, len, 1);
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* ubifs_scan - scan a logical eraseblock.
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* @c: UBIFS file-system description object
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* @lnum: logical eraseblock number
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* @offs: offset to start at (usually zero)
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* @sbuf: scan buffer (must be c->leb_size)
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* This function scans LEB number @lnum and returns complete information about
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* its contents. Returns an error code in case of failure.
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struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
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int offs, void *sbuf)
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void *buf = sbuf + offs;
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int err, len = c->leb_size - offs;
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struct ubifs_scan_leb *sleb;
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sleb = ubifs_start_scan(c, lnum, offs, sbuf);
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struct ubifs_ch *ch = buf;
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dbg_scan("look at LEB %d:%d (%d bytes left)",
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ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 0);
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/* Padding bytes or a valid padding node */
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if (ret == SCANNED_EMPTY_SPACE)
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/* Empty space is checked later */
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case SCANNED_GARBAGE:
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case SCANNED_A_CORRUPT_NODE:
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case SCANNED_A_BAD_PAD_NODE:
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err = ubifs_add_snod(c, sleb, buf, offs);
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node_len = ALIGN(le32_to_cpu(ch->len), 8);
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if (offs % c->min_io_size)
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ubifs_end_scan(c, sleb, lnum, offs);
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for (; len > 4; offs += 4, buf = buf + 4, len -= 4)
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if (*(uint32_t *)buf != 0xffffffff)
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for (; len; offs++, buf++, len--)
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if (*(uint8_t *)buf != 0xff) {
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ubifs_err("corrupt empty space at LEB %d:%d",
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ubifs_scanned_corruption(c, lnum, offs, buf);
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ubifs_err("LEB %d scanning failed", lnum);
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ubifs_scan_destroy(sleb);
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* ubifs_scan_destroy - destroy LEB scanning information.
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* @sleb: scanning information to free
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void ubifs_scan_destroy(struct ubifs_scan_leb *sleb)
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struct ubifs_scan_node *node;
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struct list_head *head;
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while (!list_empty(head)) {
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node = list_entry(head->next, struct ubifs_scan_node, list);
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list_del(&node->list);