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recovery.c
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/*
* 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 functions needed to recover from unclean un-mounts.
* When UBIFS is mounted, it checks a flag on the master node to determine if
* an un-mount was completed successfully. If not, the process of mounting
* incorparates additional checking and fixing of on-flash data structures.
* UBIFS always cleans away all remnants of an unclean un-mount, so that
* errors do not accumulate. However UBIFS defers recovery if it is mounted
* read-only, and the flash is not modified in that case.
*/
#include <linux/crc32.h>
#include "ubifs.h"
/**
* is_empty - determine whether a buffer is empty (contains all 0xff).
* @buf: buffer to clean
* @len: length of buffer
*
* This function returns %1 if the buffer is empty (contains all 0xff) otherwise
* %0 is returned.
*/
static int is_empty(void *buf, int len)
{
uint8_t *p = buf;
int i;
for (i = 0; i < len; i++)
if (*p++ != 0xff)
return 0;
return 1;
}
/**
* first_non_ff - find offset of the first non-0xff byte.
* @buf: buffer to search in
* @len: length of buffer
*
* This function returns offset of the first non-0xff byte in @buf or %-1 if
* the buffer contains only 0xff bytes.
*/
static int first_non_ff(void *buf, int len)
{
uint8_t *p = buf;
int i;
for (i = 0; i < len; i++)
if (*p++ != 0xff)
return i;
return -1;
}
/**
* get_master_node - get the last valid master node allowing for corruption.
* @c: UBIFS file-system description object
* @lnum: LEB number
* @pbuf: buffer containing the LEB read, is returned here
* @mst: master node, if found, is returned here
* @cor: corruption, if found, is returned here
*
* This function allocates a buffer, reads the LEB into it, and finds and
* returns the last valid master node allowing for one area of corruption.
* The corrupt area, if there is one, must be consistent with the assumption
* that it is the result of an unclean unmount while the master node was being
* written. Under those circumstances, it is valid to use the previously written
* master node.
*
* This function returns %0 on success and a negative error code on failure.
*/
static int get_master_node(const struct ubifs_info *c, int lnum, void **pbuf,
struct ubifs_mst_node **mst, void **cor)
{
const int sz = c->mst_node_alsz;
int err, offs, len;
void *sbuf, *buf;
sbuf = vmalloc(c->leb_size);
if (!sbuf)
return -ENOMEM;
err = ubi_read(c->ubi, lnum, sbuf, 0, c->leb_size);
if (err && err != -EBADMSG)
goto out_free;
/* Find the first position that is definitely not a node */
offs = 0;
buf = sbuf;
len = c->leb_size;
while (offs + UBIFS_MST_NODE_SZ <= c->leb_size) {
struct ubifs_ch *ch = buf;
if (le32_to_cpu(ch->magic) != UBIFS_NODE_MAGIC)
break;
offs += sz;
buf += sz;
len -= sz;
}
/* See if there was a valid master node before that */
if (offs) {
int ret;
offs -= sz;
buf -= sz;
len += sz;
ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 1);
if (ret != SCANNED_A_NODE && offs) {
/* Could have been corruption so check one place back */
offs -= sz;
buf -= sz;
len += sz;
ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 1);
if (ret != SCANNED_A_NODE)
/*
* We accept only one area of corruption because
* we are assuming that it was caused while
* trying to write a master node.
*/
goto out_err;
}
if (ret == SCANNED_A_NODE) {
struct ubifs_ch *ch = buf;
if (ch->node_type != UBIFS_MST_NODE)
goto out_err;
dbg_rcvry("found a master node at %d:%d", lnum, offs);
*mst = buf;
offs += sz;
buf += sz;
len -= sz;
}
}
/* Check for corruption */
if (offs < c->leb_size) {
if (!is_empty(buf, min_t(int, len, sz))) {
*cor = buf;
dbg_rcvry("found corruption at %d:%d", lnum, offs);
}
offs += sz;
buf += sz;
len -= sz;
}
/* Check remaining empty space */
if (offs < c->leb_size)
if (!is_empty(buf, len))
goto out_err;
*pbuf = sbuf;
return 0;
out_err:
err = -EINVAL;
out_free:
vfree(sbuf);
*mst = NULL;
*cor = NULL;
return err;
}
/**
* write_rcvrd_mst_node - write recovered master node.
* @c: UBIFS file-system description object
* @mst: master node
*
* This function returns %0 on success and a negative error code on failure.
*/
static int write_rcvrd_mst_node(struct ubifs_info *c,
struct ubifs_mst_node *mst)
{
int err = 0, lnum = UBIFS_MST_LNUM, sz = c->mst_node_alsz;
__le32 save_flags;
dbg_rcvry("recovery");
save_flags = mst->flags;
mst->flags |= cpu_to_le32(UBIFS_MST_RCVRY);
ubifs_prepare_node(c, mst, UBIFS_MST_NODE_SZ, 1);
err = ubi_leb_change(c->ubi, lnum, mst, sz, UBI_SHORTTERM);
if (err)
goto out;
err = ubi_leb_change(c->ubi, lnum + 1, mst, sz, UBI_SHORTTERM);
if (err)
goto out;
out:
mst->flags = save_flags;
return err;
}
/**
* ubifs_recover_master_node - recover the master node.
* @c: UBIFS file-system description object
*
* This function recovers the master node from corruption that may occur due to
* an unclean unmount.
*
* This function returns %0 on success and a negative error code on failure.
*/
int ubifs_recover_master_node(struct ubifs_info *c)
{
void *buf1 = NULL, *buf2 = NULL, *cor1 = NULL, *cor2 = NULL;
struct ubifs_mst_node *mst1 = NULL, *mst2 = NULL, *mst;
const int sz = c->mst_node_alsz;
int err, offs1, offs2;
dbg_rcvry("recovery");
err = get_master_node(c, UBIFS_MST_LNUM, &buf1, &mst1, &cor1);
if (err)
goto out_free;
err = get_master_node(c, UBIFS_MST_LNUM + 1, &buf2, &mst2, &cor2);
if (err)
goto out_free;
if (mst1) {
offs1 = (void *)mst1 - buf1;
if ((le32_to_cpu(mst1->flags) & UBIFS_MST_RCVRY) &&
(offs1 == 0 && !cor1)) {
/*
* mst1 was written by recovery at offset 0 with no
* corruption.
*/
dbg_rcvry("recovery recovery");
mst = mst1;
} else if (mst2) {
offs2 = (void *)mst2 - buf2;
if (offs1 == offs2) {
/* Same offset, so must be the same */
if (memcmp((void *)mst1 + UBIFS_CH_SZ,
(void *)mst2 + UBIFS_CH_SZ,
UBIFS_MST_NODE_SZ - UBIFS_CH_SZ))
goto out_err;
mst = mst1;
} else if (offs2 + sz == offs1) {
/* 1st LEB was written, 2nd was not */
if (cor1)
goto out_err;
mst = mst1;
} else if (offs1 == 0 && offs2 + sz >= c->leb_size) {
/* 1st LEB was unmapped and written, 2nd not */
if (cor1)
goto out_err;
mst = mst1;
} else
goto out_err;
} else {
/*
* 2nd LEB was unmapped and about to be written, so
* there must be only one master node in the first LEB
* and no corruption.
*/
if (offs1 != 0 || cor1)
goto out_err;
mst = mst1;
}
} else {
if (!mst2)
goto out_err;
/*
* 1st LEB was unmapped and about to be written, so there must
* be no room left in 2nd LEB.
*/
offs2 = (void *)mst2 - buf2;
if (offs2 + sz + sz <= c->leb_size)
goto out_err;
mst = mst2;
}
ubifs_msg("recovered master node from LEB %d",
(mst == mst1 ? UBIFS_MST_LNUM : UBIFS_MST_LNUM + 1));
memcpy(c->mst_node, mst, UBIFS_MST_NODE_SZ);
if ((c->vfs_sb->s_flags & MS_RDONLY)) {
/* Read-only mode. Keep a copy for switching to rw mode */
c->rcvrd_mst_node = kmalloc(sz, GFP_KERNEL);
if (!c->rcvrd_mst_node) {
err = -ENOMEM;
goto out_free;
}
memcpy(c->rcvrd_mst_node, c->mst_node, UBIFS_MST_NODE_SZ);
} else {
/* Write the recovered master node */
c->max_sqnum = le64_to_cpu(mst->ch.sqnum) - 1;
err = write_rcvrd_mst_node(c, c->mst_node);
if (err)
goto out_free;
}
vfree(buf2);
vfree(buf1);
return 0;
out_err:
err = -EINVAL;
out_free:
ubifs_err("failed to recover master node");
if (mst1) {
dbg_err("dumping first master node");
dbg_dump_node(c, mst1);
}
if (mst2) {
dbg_err("dumping second master node");
dbg_dump_node(c, mst2);
}
vfree(buf2);
vfree(buf1);
return err;
}
/**
* ubifs_write_rcvrd_mst_node - write the recovered master node.
* @c: UBIFS file-system description object
*
* This function writes the master node that was recovered during mounting in
* read-only mode and must now be written because we are remounting rw.
*
* This function returns %0 on success and a negative error code on failure.
*/
int ubifs_write_rcvrd_mst_node(struct ubifs_info *c)
{
int err;
if (!c->rcvrd_mst_node)
return 0;
c->rcvrd_mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
c->mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
err = write_rcvrd_mst_node(c, c->rcvrd_mst_node);
if (err)
return err;
kfree(c->rcvrd_mst_node);
c->rcvrd_mst_node = NULL;
return 0;
}
/**
* is_last_write - determine if an offset was in the last write to a LEB.
* @c: UBIFS file-system description object
* @buf: buffer to check
* @offs: offset to check
*
* This function returns %1 if @offs was in the last write to the LEB whose data
* is in @buf, otherwise %0 is returned. The determination is made by checking
* for subsequent empty space starting from the next @c->min_io_size boundary.
*/
static int is_last_write(const struct ubifs_info *c, void *buf, int offs)
{
int empty_offs, check_len;
uint8_t *p;
/*
* Round up to the next @c->min_io_size boundary i.e. @offs is in the
* last wbuf written. After that should be empty space.
*/
empty_offs = ALIGN(offs + 1, c->min_io_size);
check_len = c->leb_size - empty_offs;
p = buf + empty_offs - offs;
return is_empty(p, check_len);
}
/**
* clean_buf - clean the data from an LEB sitting in a buffer.
* @c: UBIFS file-system description object
* @buf: buffer to clean
* @lnum: LEB number to clean
* @offs: offset from which to clean
* @len: length of buffer
*
* This function pads up to the next min_io_size boundary (if there is one) and
* sets empty space to all 0xff. @buf, @offs and @len are updated to the next
* @c->min_io_size boundary.
*/
static void clean_buf(const struct ubifs_info *c, void **buf, int lnum,
int *offs, int *len)
{
int empty_offs, pad_len;
lnum = lnum;
dbg_rcvry("cleaning corruption at %d:%d", lnum, *offs);
ubifs_assert(!(*offs & 7));
empty_offs = ALIGN(*offs, c->min_io_size);
pad_len = empty_offs - *offs;
ubifs_pad(c, *buf, pad_len);
*offs += pad_len;
*buf += pad_len;
*len -= pad_len;
memset(*buf, 0xff, c->leb_size - empty_offs);
}
/**
* no_more_nodes - determine if there are no more nodes in a buffer.
* @c: UBIFS file-system description object
* @buf: buffer to check
* @len: length of buffer
* @lnum: LEB number of the LEB from which @buf was read
* @offs: offset from which @buf was read
*
* This function ensures that the corrupted node at @offs is the last thing
* written to a LEB. This function returns %1 if more data is not found and
* %0 if more data is found.
*/
static int no_more_nodes(const struct ubifs_info *c, void *buf, int len,
int lnum, int offs)
{
struct ubifs_ch *ch = buf;
int skip, dlen = le32_to_cpu(ch->len);
/* Check for empty space after the corrupt node's common header */
skip = ALIGN(offs + UBIFS_CH_SZ, c->min_io_size) - offs;
if (is_empty(buf + skip, len - skip))
return 1;
/*
* The area after the common header size is not empty, so the common
* header must be intact. Check it.
*/
if (ubifs_check_node(c, buf, lnum, offs, 1, 0) != -EUCLEAN) {
dbg_rcvry("unexpected bad common header at %d:%d", lnum, offs);
return 0;
}
/* Now we know the corrupt node's length we can skip over it */
skip = ALIGN(offs + dlen, c->min_io_size) - offs;
/* After which there should be empty space */
if (is_empty(buf + skip, len - skip))
return 1;
dbg_rcvry("unexpected data at %d:%d", lnum, offs + skip);
return 0;
}
/**
* fix_unclean_leb - fix an unclean LEB.
* @c: UBIFS file-system description object
* @sleb: scanned LEB information
* @start: offset where scan started
*/
static int fix_unclean_leb(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
int start)
{
int lnum = sleb->lnum, endpt = start;
/* Get the end offset of the last node we are keeping */
if (!list_empty(&sleb->nodes)) {
struct ubifs_scan_node *snod;
snod = list_entry(sleb->nodes.prev,
struct ubifs_scan_node, list);
endpt = snod->offs + snod->len;
}
if ((c->vfs_sb->s_flags & MS_RDONLY) && !c->remounting_rw) {
/* Add to recovery list */
struct ubifs_unclean_leb *ucleb;
dbg_rcvry("need to fix LEB %d start %d endpt %d",
lnum, start, sleb->endpt);
ucleb = kzalloc(sizeof(struct ubifs_unclean_leb), GFP_NOFS);
if (!ucleb)
return -ENOMEM;
ucleb->lnum = lnum;
ucleb->endpt = endpt;
list_add_tail(&ucleb->list, &c->unclean_leb_list);
} else {
/* Write the fixed LEB back to flash */
int err;
dbg_rcvry("fixing LEB %d start %d endpt %d",
lnum, start, sleb->endpt);
if (endpt == 0) {
err = ubifs_leb_unmap(c, lnum);
if (err)
return err;
} else {
int len = ALIGN(endpt, c->min_io_size);
if (start) {
err = ubi_read(c->ubi, lnum, sleb->buf, 0,
start);
if (err)
return err;
}
/* Pad to min_io_size */
if (len > endpt) {
int pad_len = len - ALIGN(endpt, 8);
if (pad_len > 0) {
void *buf = sleb->buf + len - pad_len;
ubifs_pad(c, buf, pad_len);
}
}
err = ubi_leb_change(c->ubi, lnum, sleb->buf, len,
UBI_UNKNOWN);
if (err)
return err;
}
}
return 0;
}
/**
* drop_incomplete_group - drop nodes from an incomplete group.
* @sleb: scanned LEB information
* @offs: offset of dropped nodes is returned here
*
* This function returns %1 if nodes are dropped and %0 otherwise.
*/
static int drop_incomplete_group(struct ubifs_scan_leb *sleb, int *offs)
{
int dropped = 0;
while (!list_empty(&sleb->nodes)) {
struct ubifs_scan_node *snod;
struct ubifs_ch *ch;
snod = list_entry(sleb->nodes.prev, struct ubifs_scan_node,
list);
ch = snod->node;
if (ch->group_type != UBIFS_IN_NODE_GROUP)
return dropped;
dbg_rcvry("dropping node at %d:%d", sleb->lnum, snod->offs);
*offs = snod->offs;
list_del(&snod->list);
kfree(snod);
sleb->nodes_cnt -= 1;
dropped = 1;
}
return dropped;
}
/**
* ubifs_recover_leb - scan and recover a LEB.
* @c: UBIFS file-system description object
* @lnum: LEB number
* @offs: offset
* @sbuf: LEB-sized buffer to use
* @grouped: nodes may be grouped for recovery
*
* This function does a scan of a LEB, but caters for errors that might have
* been caused by the unclean unmount from which we are attempting to recover.
* Returns %0 in case of success, %-EUCLEAN if an unrecoverable corruption is
* found, and a negative error code in case of failure.
*/
struct ubifs_scan_leb *ubifs_recover_leb(struct ubifs_info *c, int lnum,
int offs, void *sbuf, int grouped)
{
int err, len = c->leb_size - offs, need_clean = 0, quiet = 1;
int empty_chkd = 0, start = offs;
struct ubifs_scan_leb *sleb;
void *buf = sbuf + offs;
dbg_rcvry("%d:%d", lnum, offs);
sleb = ubifs_start_scan(c, lnum, offs, sbuf);
if (IS_ERR(sleb))
return sleb;
if (sleb->ecc)
need_clean = 1;
while (len >= 8) {
int ret;
dbg_scan("look at LEB %d:%d (%d bytes left)",
lnum, offs, len);
cond_resched();
/*
* Scan quietly until there is an error from which we cannot
* recover
*/
ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
if (ret == SCANNED_A_NODE) {
/* A valid node, and not a padding node */
struct ubifs_ch *ch = buf;
int node_len;
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;
continue;
}
if (ret > 0) {
/* Padding bytes or a valid padding node */
offs += ret;
buf += ret;
len -= ret;
continue;
}
if (ret == SCANNED_EMPTY_SPACE) {
if (!is_empty(buf, len)) {
if (!is_last_write(c, buf, offs))
break;
clean_buf(c, &buf, lnum, &offs, &len);
need_clean = 1;
}
empty_chkd = 1;
break;
}
if (ret == SCANNED_GARBAGE || ret == SCANNED_A_BAD_PAD_NODE)
if (is_last_write(c, buf, offs)) {
clean_buf(c, &buf, lnum, &offs, &len);
need_clean = 1;
empty_chkd = 1;
break;
}
if (ret == SCANNED_A_CORRUPT_NODE)
if (no_more_nodes(c, buf, len, lnum, offs)) {
clean_buf(c, &buf, lnum, &offs, &len);
need_clean = 1;
empty_chkd = 1;
break;
}
if (quiet) {
/* Redo the last scan but noisily */
quiet = 0;
continue;
}
switch (ret) {
case SCANNED_GARBAGE:
dbg_err("garbage");
goto corrupted;
case SCANNED_A_CORRUPT_NODE:
case SCANNED_A_BAD_PAD_NODE:
dbg_err("bad node");
goto corrupted;
default:
dbg_err("unknown");
err = -EINVAL;
goto error;
}
}
if (!empty_chkd && !is_empty(buf, len)) {
if (is_last_write(c, buf, offs)) {
clean_buf(c, &buf, lnum, &offs, &len);
need_clean = 1;
} else {
int corruption = first_non_ff(buf, len);
ubifs_err("corrupt empty space LEB %d:%d, corruption "
"starts at %d", lnum, offs, corruption);
/* Make sure we dump interesting non-0xFF data */
offs = corruption;
buf += corruption;
goto corrupted;
}
}
/* Drop nodes from incomplete group */
if (grouped && drop_incomplete_group(sleb, &offs)) {
buf = sbuf + offs;
len = c->leb_size - offs;
clean_buf(c, &buf, lnum, &offs, &len);
need_clean = 1;
}
if (offs % c->min_io_size) {
clean_buf(c, &buf, lnum, &offs, &len);
need_clean = 1;
}
ubifs_end_scan(c, sleb, lnum, offs);
if (need_clean) {
err = fix_unclean_leb(c, sleb, start);
if (err)
goto error;
}
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);
}
/**
* get_cs_sqnum - get commit start sequence number.
* @c: UBIFS file-system description object
* @lnum: LEB number of commit start node
* @offs: offset of commit start node
* @cs_sqnum: commit start sequence number is returned here
*
* This function returns %0 on success and a negative error code on failure.
*/
static int get_cs_sqnum(struct ubifs_info *c, int lnum, int offs,
unsigned long long *cs_sqnum)
{
struct ubifs_cs_node *cs_node = NULL;
int err, ret;
dbg_rcvry("at %d:%d", lnum, offs);
cs_node = kmalloc(UBIFS_CS_NODE_SZ, GFP_KERNEL);
if (!cs_node)
return -ENOMEM;
if (c->leb_size - offs < UBIFS_CS_NODE_SZ)
goto out_err;
err = ubi_read(c->ubi, lnum, (void *)cs_node, offs, UBIFS_CS_NODE_SZ);
if (err && err != -EBADMSG)
goto out_free;
ret = ubifs_scan_a_node(c, cs_node, UBIFS_CS_NODE_SZ, lnum, offs, 0);
if (ret != SCANNED_A_NODE) {
dbg_err("Not a valid node");
goto out_err;
}
if (cs_node->ch.node_type != UBIFS_CS_NODE) {
dbg_err("Node a CS node, type is %d", cs_node->ch.node_type);
goto out_err;
}
if (le64_to_cpu(cs_node->cmt_no) != c->cmt_no) {
dbg_err("CS node cmt_no %llu != current cmt_no %llu",
(unsigned long long)le64_to_cpu(cs_node->cmt_no),
c->cmt_no);
goto out_err;
}
*cs_sqnum = le64_to_cpu(cs_node->ch.sqnum);
dbg_rcvry("commit start sqnum %llu", *cs_sqnum);
kfree(cs_node);
return 0;
out_err:
err = -EINVAL;
out_free:
ubifs_err("failed to get CS sqnum");
kfree(cs_node);
return err;
}
/**
* ubifs_recover_log_leb - scan and recover a log LEB.
* @c: UBIFS file-system description object
* @lnum: LEB number
* @offs: offset
* @sbuf: LEB-sized buffer to use
*
* This function does a scan of a LEB, but caters for errors that might have
* been caused by the unclean unmount from which we are attempting to recover.
*
* This function returns %0 on success and a negative error code on failure.
*/
struct ubifs_scan_leb *ubifs_recover_log_leb(struct ubifs_info *c, int lnum,
int offs, void *sbuf)
{
struct ubifs_scan_leb *sleb;
int next_lnum;
dbg_rcvry("LEB %d", lnum);
next_lnum = lnum + 1;
if (next_lnum >= UBIFS_LOG_LNUM + c->log_lebs)
next_lnum = UBIFS_LOG_LNUM;
if (next_lnum != c->ltail_lnum) {
/*
* We can only recover at the end of the log, so check that the
* next log LEB is empty or out of date.
*/
sleb = ubifs_scan(c, next_lnum, 0, sbuf, 0);
if (IS_ERR(sleb))
return sleb;
if (sleb->nodes_cnt) {
struct ubifs_scan_node *snod;
unsigned long long cs_sqnum = c->cs_sqnum;
snod = list_entry(sleb->nodes.next,
struct ubifs_scan_node, list);
if (cs_sqnum == 0) {
int err;
err = get_cs_sqnum(c, lnum, offs, &cs_sqnum);
if (err) {
ubifs_scan_destroy(sleb);
return ERR_PTR(err);
}
}
if (snod->sqnum > cs_sqnum) {
ubifs_err("unrecoverable log corruption "
"in LEB %d", lnum);
ubifs_scan_destroy(sleb);
return ERR_PTR(-EUCLEAN);
}
}
ubifs_scan_destroy(sleb);
}
return ubifs_recover_leb(c, lnum, offs, sbuf, 0);
}
/**
* recover_head - recover a head.
* @c: UBIFS file-system description object
* @lnum: LEB number of head to recover
* @offs: offset of head to recover
* @sbuf: LEB-sized buffer to use
*
* This function ensures that there is no data on the flash at a head location.
*
* This function returns %0 on success and a negative error code on failure.
*/
static int recover_head(const struct ubifs_info *c, int lnum, int offs,
void *sbuf)
{
int len, err;
if (c->min_io_size > 1)
len = c->min_io_size;
else
len = 512;
if (offs + len > c->leb_size)
len = c->leb_size - offs;
if (!len)
return 0;
/* Read at the head location and check it is empty flash */
err = ubi_read(c->ubi, lnum, sbuf, offs, len);
if (err || !is_empty(sbuf, len)) {
dbg_rcvry("cleaning head at %d:%d", lnum, offs);
if (offs == 0)
return ubifs_leb_unmap(c, lnum);
err = ubi_read(c->ubi, lnum, sbuf, 0, offs);
if (err)
return err;
return ubi_leb_change(c->ubi, lnum, sbuf, offs, UBI_UNKNOWN);
}
return 0;
}
/**
* ubifs_recover_inl_heads - recover index and LPT heads.
* @c: UBIFS file-system description object
* @sbuf: LEB-sized buffer to use
*
* This function ensures that there is no data on the flash at the index and
* LPT head locations.
*
* This deals with the recovery of a half-completed journal commit. UBIFS is
* careful never to overwrite the last version of the index or the LPT. Because
* the index and LPT are wandering trees, data from a half-completed commit will
* not be referenced anywhere in UBIFS. The data will be either in LEBs that are
* assumed to be empty and will be unmapped anyway before use, or in the index
* and LPT heads.
*
* This function returns %0 on success and a negative error code on failure.
*/
int ubifs_recover_inl_heads(const struct ubifs_info *c, void *sbuf)
{
int err;
ubifs_assert(!(c->vfs_sb->s_flags & MS_RDONLY) || c->remounting_rw);
dbg_rcvry("checking index head at %d:%d", c->ihead_lnum, c->ihead_offs);
err = recover_head(c, c->ihead_lnum, c->ihead_offs, sbuf);
if (err)
return err;
dbg_rcvry("checking LPT head at %d:%d", c->nhead_lnum, c->nhead_offs);
err = recover_head(c, c->nhead_lnum, c->nhead_offs, sbuf);
if (err)
return err;
return 0;
}
/**
* clean_an_unclean_leb - read and write a LEB to remove corruption.
* @c: UBIFS file-system description object
* @ucleb: unclean LEB information
* @sbuf: LEB-sized buffer to use
*
* This function reads a LEB up to a point pre-determined by the mount recovery,
* checks the nodes, and writes the result back to the flash, thereby cleaning
* off any following corruption, or non-fatal ECC errors.
*
* This function returns %0 on success and a negative error code on failure.
*/
static int clean_an_unclean_leb(const struct ubifs_info *c,
struct ubifs_unclean_leb *ucleb, void *sbuf)
{
int err, lnum = ucleb->lnum, offs = 0, len = ucleb->endpt, quiet = 1;
void *buf = sbuf;
dbg_rcvry("LEB %d len %d", lnum, len);
if (len == 0) {
/* Nothing to read, just unmap it */
err = ubifs_leb_unmap(c, lnum);
if (err)
return err;
return 0;
}
err = ubi_read(c->ubi, lnum, buf, offs, len);
if (err && err != -EBADMSG)
return err;
while (len >= 8) {
int ret;
cond_resched();
/* Scan quietly until there is an error */
ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
if (ret == SCANNED_A_NODE) {
/* A valid node, and not a padding node */
struct ubifs_ch *ch = buf;
int node_len;
node_len = ALIGN(le32_to_cpu(ch->len), 8);
offs += node_len;
buf += node_len;
len -= node_len;
continue;
}
if (ret > 0) {
/* Padding bytes or a valid padding node */
offs += ret;
buf += ret;
len -= ret;
continue;
}
if (ret == SCANNED_EMPTY_SPACE) {
ubifs_err("unexpected empty space at %d:%d",
lnum, offs);
return -EUCLEAN;
}
if (quiet) {
/* Redo the last scan but noisily */
quiet = 0;
continue;
}
ubifs_scanned_corruption(c, lnum, offs, buf);
return -EUCLEAN;
}
/* Pad to min_io_size */
len = ALIGN(ucleb->endpt, c->min_io_size);
if (len > ucleb->endpt) {
int pad_len = len - ALIGN(ucleb->endpt, 8);
if (pad_len > 0) {
buf = c->sbuf + len - pad_len;
ubifs_pad(c, buf, pad_len);
}
}
/* Write back the LEB atomically */
err = ubi_leb_change(c->ubi, lnum, sbuf, len, UBI_UNKNOWN);
if (err)
return err;
dbg_rcvry("cleaned LEB %d", lnum);
return 0;
}
/**
* ubifs_clean_lebs - clean LEBs recovered during read-only mount.
* @c: UBIFS file-system description object
* @sbuf: LEB-sized buffer to use