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DEFINITIONS
This source file includes following definitions.
- scan_padding_bytes
- ubifs_scan_a_node
- ubifs_start_scan
- ubifs_end_scan
- ubifs_add_snod
- ubifs_scanned_corruption
- ubifs_scan_destroy
/*
* This file is part of UBIFS.
*
* Copyright (C) 2006-2008 Nokia Corporation
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*
* 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., 51
* Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* Authors: Adrian Hunter
* Artem Bityutskiy (Битюцкий Артём)
*/
/*
* This file implements the scan which is a general-purpose function for
* determining what nodes are in an eraseblock. The scan is used to replay the
* journal, to do garbage collection. for the TNC in-the-gaps method, and by
* debugging functions.
*/
#include "ubifs.h"
/**
* scan_padding_bytes - scan for padding bytes.
* @buf: buffer to scan
* @len: length of buffer
*
* This function returns the number of padding bytes on success and
* %SCANNED_GARBAGE on failure.
*/
static int scan_padding_bytes(void *buf, int len)
{
int pad_len = 0, max_pad_len = min_t(int, UBIFS_PAD_NODE_SZ, len);
uint8_t *p = buf;
dbg_scan("not a node");
while (pad_len < max_pad_len && *p++ == UBIFS_PADDING_BYTE)
pad_len += 1;
if (!pad_len || (pad_len & 7))
return SCANNED_GARBAGE;
dbg_scan("%d padding bytes", pad_len);
return pad_len;
}
/**
* ubifs_scan_a_node - scan for a node or padding.
* @c: UBIFS file-system description object
* @buf: buffer to scan
* @len: length of buffer
* @lnum: logical eraseblock number
* @offs: offset within the logical eraseblock
* @quiet: print no messages
*
* This function returns a scanning code to indicate what was scanned.
*/
int ubifs_scan_a_node(const struct ubifs_info *c, void *buf, int len, int lnum,
int offs, int quiet)
{
struct ubifs_ch *ch = buf;
uint32_t magic;
magic = le32_to_cpu(ch->magic);
if (magic == 0xFFFFFFFF) {
dbg_scan("hit empty space");
return SCANNED_EMPTY_SPACE;
}
if (magic != UBIFS_NODE_MAGIC)
return scan_padding_bytes(buf, len);
if (len < UBIFS_CH_SZ)
return SCANNED_GARBAGE;
dbg_scan("scanning %s", dbg_ntype(ch->node_type));
if (ubifs_check_node(c, buf, lnum, offs, quiet))
return SCANNED_A_CORRUPT_NODE;
if (ch->node_type == UBIFS_PAD_NODE) {
struct ubifs_pad_node *pad = buf;
int pad_len = le32_to_cpu(pad->pad_len);
int node_len = le32_to_cpu(ch->len);
/* Validate the padding node */
if (pad_len < 0 ||
offs + node_len + pad_len > c->leb_size) {
if (!quiet) {
ubifs_err("bad pad node at LEB %d:%d",
lnum, offs);
dbg_dump_node(c, pad);
}
return SCANNED_A_BAD_PAD_NODE;
}
/* Make the node pads to 8-byte boundary */
if ((node_len + pad_len) & 7) {
if (!quiet) {
dbg_err("bad padding length %d - %d",
offs, offs + node_len + pad_len);
}
return SCANNED_A_BAD_PAD_NODE;
}
dbg_scan("%d bytes padded, offset now %d",
pad_len, ALIGN(offs + node_len + pad_len, 8));
return node_len + pad_len;
}
return SCANNED_A_NODE;
}
/**
* ubifs_start_scan - create LEB scanning information at start of scan.
* @c: UBIFS file-system description object
* @lnum: logical eraseblock number
* @offs: offset to start at (usually zero)
* @sbuf: scan buffer (must be c->leb_size)
*
* This function returns %0 on success and a negative error code on failure.
*/
struct ubifs_scan_leb *ubifs_start_scan(const struct ubifs_info *c, int lnum,
int offs, void *sbuf)
{
struct ubifs_scan_leb *sleb;
int err;
dbg_scan("scan LEB %d:%d", lnum, offs);
sleb = kzalloc(sizeof(struct ubifs_scan_leb), GFP_NOFS);
if (!sleb)
return ERR_PTR(-ENOMEM);
sleb->lnum = lnum;
INIT_LIST_HEAD(&sleb->nodes);
sleb->buf = sbuf;
err = ubi_read(c->ubi, lnum, sbuf + offs, offs, c->leb_size - offs);
if (err && err != -EBADMSG) {
ubifs_err("cannot read %d bytes from LEB %d:%d,"
" error %d", c->leb_size - offs, lnum, offs, err);
kfree(sleb);
return ERR_PTR(err);
}
if (err == -EBADMSG)
sleb->ecc = 1;
return sleb;
}
/**
* ubifs_end_scan - update LEB scanning information at end of scan.
* @c: UBIFS file-system description object
* @sleb: scanning information
* @lnum: logical eraseblock number
* @offs: offset to start at (usually zero)
*
* This function returns %0 on success and a negative error code on failure.
*/
void ubifs_end_scan(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
int lnum, int offs)
{
lnum = lnum;
dbg_scan("stop scanning LEB %d at offset %d", lnum, offs);
ubifs_assert(offs % c->min_io_size == 0);
sleb->endpt = ALIGN(offs, c->min_io_size);
}
/**
* ubifs_add_snod - add a scanned node to LEB scanning information.
* @c: UBIFS file-system description object
* @sleb: scanning information
* @buf: buffer containing node
* @offs: offset of node on flash
*
* This function returns %0 on success and a negative error code on failure.
*/
int ubifs_add_snod(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
void *buf, int offs)
{
struct ubifs_ch *ch = buf;
struct ubifs_ino_node *ino = buf;
struct ubifs_scan_node *snod;
snod = kzalloc(sizeof(struct ubifs_scan_node), GFP_NOFS);
if (!snod)
return -ENOMEM;
snod->sqnum = le64_to_cpu(ch->sqnum);
snod->type = ch->node_type;
snod->offs = offs;
snod->len = le32_to_cpu(ch->len);
snod->node = buf;
switch (ch->node_type) {
case UBIFS_INO_NODE:
case UBIFS_DENT_NODE:
case UBIFS_XENT_NODE:
case UBIFS_DATA_NODE:
case UBIFS_TRUN_NODE:
/*
* The key is in the same place in all keyed
* nodes.
*/
key_read(c, &ino->key, &snod->key);
break;
}
list_add_tail(&snod->list, &sleb->nodes);
sleb->nodes_cnt += 1;
return 0;
}
/**
* ubifs_scanned_corruption - print information after UBIFS scanned corruption.
* @c: UBIFS file-system description object
* @lnum: LEB number of corruption
* @offs: offset of corruption
* @buf: buffer containing corruption
*/
void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
void *buf)
{
int len;
ubifs_err("corrupted data at LEB %d:%d", lnum, offs);
if (dbg_failure_mode)
return;
len = c->leb_size - offs;
if (len > 4096)
len = 4096;
dbg_err("first %d bytes from LEB %d:%d", len, lnum, offs);
print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 4, buf, len, 1);
}
/**
* ubifs_scan - scan a logical eraseblock.
* @c: UBIFS file-system description object
* @lnum: logical eraseblock number
* @offs: offset to start at (usually zero)
* @sbuf: scan buffer (must be c->leb_size)
*
* This function scans LEB number @lnum and returns complete information about
* its contents. Returns an error code in case of failure.
*/
struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
int offs, void *sbuf)
{
void *buf = sbuf + offs;
int err, len = c->leb_size - offs;
struct ubifs_scan_leb *sleb;
sleb = ubifs_start_scan(c, lnum, offs, sbuf);
if (IS_ERR(sleb))
return sleb;
while (len >= 8) {
struct ubifs_ch *ch = buf;
int node_len, ret;
dbg_scan("look at LEB %d:%d (%d bytes left)",
lnum, offs, len);
cond_resched();
ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 0);
if (ret > 0) {
/* Padding bytes or a valid padding node */
offs += ret;
buf += ret;
len -= ret;
continue;
}
if (ret == SCANNED_EMPTY_SPACE)
/* Empty space is checked later */
break;
switch (ret) {
case SCANNED_GARBAGE:
dbg_err("garbage");
goto corrupted;
case SCANNED_A_NODE:
break;
case SCANNED_A_CORRUPT_NODE:
case SCANNED_A_BAD_PAD_NODE:
dbg_err("bad node");
goto corrupted;
default:
dbg_err("unknown");
goto corrupted;
}
err = ubifs_add_snod(c, sleb, buf, offs);
if (err)
goto error;
node_len = ALIGN(le32_to_cpu(ch->len), 8);
offs += node_len;
buf += node_len;
len -= node_len;
}
if (offs % c->min_io_size)
goto corrupted;
ubifs_end_scan(c, sleb, lnum, offs);
for (; len > 4; offs += 4, buf = buf + 4, len -= 4)
if (*(uint32_t *)buf != 0xffffffff)
break;
for (; len; offs++, buf++, len--)
if (*(uint8_t *)buf != 0xff) {
ubifs_err("corrupt empty space at LEB %d:%d",
lnum, offs);
goto corrupted;
}
return sleb;
corrupted:
ubifs_scanned_corruption(c, lnum, offs, buf);
err = -EUCLEAN;
error:
ubifs_err("LEB %d scanning failed", lnum);
ubifs_scan_destroy(sleb);
return ERR_PTR(err);
}
/**
* ubifs_scan_destroy - destroy LEB scanning information.
* @sleb: scanning information to free
*/
void ubifs_scan_destroy(struct ubifs_scan_leb *sleb)
{
struct ubifs_scan_node *node;
struct list_head *head;
head = &sleb->nodes;
while (!list_empty(head)) {
node = list_entry(head->next, struct ubifs_scan_node, list);
list_del(&node->list);
kfree(node);
}
kfree(sleb);
}