- 根目录:
- fs
- ubifs
- recovery.c
/*
* 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
* incorporates 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.
*
* The general UBIFS approach to the recovery is that it recovers from
* corruptions which could be caused by power cuts, but it refuses to recover
* from corruption caused by other reasons. And UBIFS tries to distinguish
* between these 2 reasons of corruptions and silently recover in the former
* case and loudly complain in the latter case.
*
* UBIFS writes only to erased LEBs, so it writes only to the flash space
* containing only 0xFFs. UBIFS also always writes strictly from the beginning
* of the LEB to the end. And UBIFS assumes that the underlying flash media
* writes in @c->max_write_size bytes at a time.
*
* Hence, if UBIFS finds a corrupted node at offset X, it expects only the min.
* I/O unit corresponding to offset X to contain corrupted data, all the
* following min. I/O units have to contain empty space (all 0xFFs). If this is
* not true, the corruption cannot be the result of a power cut, and UBIFS
* refuses to mount.
*/
#include <linux/crc32.h>
#include <linux/slab.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 = ubifs_leb_read(c, lnum, sbuf, 0, c->leb_size, 0);
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 = ubifs_leb_change(c, lnum, mst, sz);
if (err)
goto out;
err = ubifs_leb_change(c, lnum + 1, mst, sz);
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 &&
c->leb_size - offs2 - sz < sz) {
/* 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->ro_mount) {
/* 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);
/*
* We had to recover the master node, which means there was an
* unclean reboot. However, it is possible that the master node
* is clean at this point, i.e., %UBIFS_MST_DIRTY is not set.
* E.g., consider the following chain of events:
*
* 1. UBIFS was cleanly unmounted, so the master node is clean
* 2. UBIFS is being mounted R/W and starts changing the master
* node in the first (%UBIFS_MST_LNUM). A power cut happens,
* so this LEB ends up with some amount of garbage at the
* end.
* 3. UBIFS is being mounted R/O. We reach this place and
* recover the master node from the second LEB
* (%UBIFS_MST_LNUM + 1). But we cannot update the media
* because we are being mounted R/O. We have to defer the
* operation.
* 4. However, this master node (@c->mst_node) is marked as
* clean (since the step 1). And if we just return, the
* mount code will be confused and won't recover the master
* node when it is re-mounter R/W later.
*
* Thus, to force the recovery by marking the master node as
* dirty.
*/
c->mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
} 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) {
ubifs_err("dumping first master node");
ubifs_dump_node(c, mst1);
}
if (mst2) {
ubifs_err("dumping second master node");
ubifs_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->max_write_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->max_write_size boundary i.e. @offs is in
* the last wbuf written. After that should be empty space.
*/
empty_offs = ALIGN(offs + 1, c->max_write_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->max_write_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->max_write_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->ro_mount && !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 = ubifs_leb_read(c, lnum, sleb->buf, 0,
start, 1);
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 = ubifs_leb_change(c, lnum, sleb->buf, len);
if (err)
return err;
}
}
return 0;
}
/**
* drop_last_group - drop the last group of nodes.
* @sleb: scanned LEB information
* @offs: offset of dropped nodes is returned here
*
* This is a helper function for 'ubifs_recover_leb()' which drops the last
* group of nodes of the scanned LEB.
*/
static void drop_last_group(struct ubifs_scan_leb *sleb, int *offs)
{
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)
break;
dbg_rcvry("dropping grouped node at %d:%d",
sleb->lnum, snod->offs);
*offs = snod->offs;
list_del(&snod->list);
kfree(snod);
sleb->nodes_cnt -= 1;
}
}
/**
* drop_last_node - drop the last node.
* @sleb: scanned LEB information
* @offs: offset of dropped nodes is returned here
* @grouped: non-zero if whole group of nodes have to be dropped
*
* This is a helper function for 'ubifs_recover_leb()' which drops the last
* node of the scanned LEB.
*/
static void drop_last_node(struct ubifs_scan_leb *sleb, int *offs)
{
struct ubifs_scan_node *snod;
if (!list_empty(&sleb->nodes)) {
snod = list_entry(sleb->nodes.prev, struct ubifs_scan_node,
list);
dbg_rcvry("dropping last node at %d:%d",
sleb->lnum, snod->offs);
*offs = snod->offs;
list_del(&snod->list);
kfree(snod);
sleb->nodes_cnt -= 1;
}
}
/**
* 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
* @jhead: journal head number this LEB belongs to (%-1 if the LEB does not
* belong to any journal head)
*
* 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 jhead)
{
int ret = 0, err, len = c->leb_size - offs, start = offs, min_io_unit;
int grouped = jhead == -1 ? 0 : c->jheads[jhead].grouped;
struct ubifs_scan_leb *sleb;
void *buf = sbuf + offs;
dbg_rcvry("%d:%d, jhead %d, grouped %d", lnum, offs, jhead, grouped);
sleb = ubifs_start_scan(c, lnum, offs, sbuf);
if (IS_ERR(sleb))
return sleb;
ubifs_assert(len >= 8);
while (len >= 8) {
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, 1);
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;
} else if (ret > 0) {
/* Padding bytes or a valid padding node */
offs += ret;
buf += ret;
len -= ret;
} else if (ret == SCANNED_EMPTY_SPACE ||
ret == SCANNED_GARBAGE ||
ret == SCANNED_A_BAD_PAD_NODE ||
ret == SCANNED_A_CORRUPT_NODE) {
dbg_rcvry("found corruption (%d) at %d:%d",
ret, lnum, offs);
break;
} else {
ubifs_err("unexpected return value %d", ret);
err = -EINVAL;
goto error;
}
}
if (ret == SCANNED_GARBAGE || ret == SCANNED_A_BAD_PAD_NODE) {
if (!is_last_write(c, buf, offs))
goto corrupted_rescan;
} else if (ret == SCANNED_A_CORRUPT_NODE) {
if (!no_more_nodes(c, buf, len, lnum, offs))
goto corrupted_rescan;
} else if (!is_empty(buf, len)) {
if (!is_last_write(c, buf, offs)) {
int corruption = first_non_ff(buf, len);
/*
* See header comment for this file for more
* explanations about the reasons we have this check.
*/
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;
}
}
min_io_unit = round_down(offs, c->min_io_size);
if (grouped)
/*
* If nodes are grouped, always drop the incomplete group at
* the end.
*/
drop_last_group(sleb, &offs);
if (jhead == GCHD) {
/*
* If this LEB belongs to the GC head then while we are in the
* middle of the same min. I/O unit keep dropping nodes. So
* basically, what we want is to make sure that the last min.
* I/O unit where we saw the corruption is dropped completely
* with all the uncorrupted nodes which may possibly sit there.
*
* In other words, let's name the min. I/O unit where the
* corruption starts B, and the previous min. I/O unit A. The
* below code tries to deal with a situation when half of B
* contains valid nodes or the end of a valid node, and the
* second half of B contains corrupted data or garbage. This
* means that UBIFS had been writing to B just before the power
* cut happened. I do not know how realistic is this scenario
* that half of the min. I/O unit had been written successfully
* and the other half not, but this is possible in our 'failure
* mode emulation' infrastructure at least.
*
* So what is the problem, why we need to drop those nodes? Why
* can't we just clean-up the second half of B by putting a
* padding node there? We can, and this works fine with one
* exception which was reproduced with power cut emulation
* testing and happens extremely rarely.
*
* Imagine the file-system is full, we run GC which starts
* moving valid nodes from LEB X to LEB Y (obviously, LEB Y is
* the current GC head LEB). The @c->gc_lnum is -1, which means
* that GC will retain LEB X and will try to continue. Imagine
* that LEB X is currently the dirtiest LEB, and the amount of
* used space in LEB Y is exactly the same as amount of free
* space in LEB X.
*
* And a power cut happens when nodes are moved from LEB X to
* LEB Y. We are here trying to recover LEB Y which is the GC
* head LEB. We find the min. I/O unit B as described above.
* Then we clean-up LEB Y by padding min. I/O unit. And later
* 'ubifs_rcvry_gc_commit()' function fails, because it cannot
* find a dirty LEB which could be GC'd into LEB Y! Even LEB X
* does not match because the amount of valid nodes there does
* not fit the free space in LEB Y any more! And this is
* because of the padding node which we added to LEB Y. The
* user-visible effect of this which I once observed and
* analysed is that we cannot mount the file-system with
* -ENOSPC error.
*
* So obviously, to make sure that situation does not happen we
* should free min. I/O unit B in LEB Y completely and the last
* used min. I/O unit in LEB Y should be A. This is basically
* what the below code tries to do.
*/
while (offs > min_io_unit)
drop_last_node(sleb, &offs);
}
buf = sbuf + offs;
len = c->leb_size - offs;
clean_buf(c, &buf, lnum, &offs, &len);
ubifs_end_scan(c, sleb, lnum, offs);
err = fix_unclean_leb(c, sleb, start);
if (err)
goto error;
return sleb;
corrupted_rescan:
/* Re-scan the corrupted data with verbose messages */
ubifs_err("corruption %d", ret);
ubifs_scan_a_node(c, buf, len, lnum, offs, 1);
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 = ubifs_leb_read(c, lnum, (void *)cs_node, offs,
UBIFS_CS_NODE_SZ, 0);
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) {
ubifs_err("Not a valid node");
goto out_err;
}
if (cs_node->ch.node_type != UBIFS_CS_NODE) {
ubifs_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) {
ubifs_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 unclean reboots from which we are attempting to recover
* (assume that only the last log LEB can be corrupted by an unclean reboot).
*
* 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, -1);
}
/**
* 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(struct ubifs_info *c, int lnum, int offs, void *sbuf)
{
int len = c->max_write_size, err;
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 = ubifs_leb_read(c, lnum, sbuf, offs, len, 1);
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 = ubifs_leb_read(c, lnum, sbuf, 0, offs, 1);
if (err)
return err;
return ubifs_leb_change(c, lnum, sbuf, offs);
}
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(struct ubifs_info *c, void *sbuf)
{
int err;
ubifs_assert(!c->ro_mount || 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(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 = ubifs_leb_read(c, lnum, buf, offs, len, 0);
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 = ubifs_leb_change(c, lnum, sbuf, len);
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
*
* This function cleans a LEB identified during recovery that needs to be
* written but was not because UBIFS was mounted read-only. This happens when
* remounting to read-write mode.
*
* This function returns %0 on success and a negative error code on failure.
*/
int ubifs_clean_lebs(struct ubifs_info *c, void *sbuf)
{
dbg_rcvry("recovery");
while (!list_empty(&c->unclean_leb_list)) {
struct ubifs_unclean_leb *ucleb;
int err;
ucleb = list_entry(c->unclean_leb_list.next,
struct ubifs_unclean_leb, list);
err = clean_an_unclean_leb(c, ucleb, sbuf);
if (err)
return err;
list_del(&ucleb->list);
kfree(ucleb);
}
return 0;
}
/**
* grab_empty_leb - grab an empty LEB to use as GC LEB and run commit.
* @c: UBIFS file-system description object
*
* This is a helper function for 'ubifs_rcvry_gc_commit()' which grabs an empty
* LEB to be used as GC LEB (@c->gc_lnum), and then runs the commit. Returns
* zero in case of success and a negative error code in case of failure.
*/
static int grab_empty_leb(struct ubifs_info *c)
{
int lnum, err;
/*
* Note, it is very important to first search for an empty LEB and then
* run the commit, not vice-versa. The reason is that there might be
* only one empty LEB at the moment, the one which has been the
* @c->gc_lnum just before the power cut happened. During the regular
* UBIFS operation (not now) @c->gc_lnum is marked as "taken", so no
* one but GC can grab it. But at this moment this single empty LEB is
* not marked as taken, so if we run commit - what happens? Right, the
* commit will grab it and write the index there. Remember that the
* index always expands as long as there is free space, and it only
* starts consolidating when we run out of space.
*
* IOW, if we run commit now, we might not be able to find a free LEB
* after this.
*/
lnum = ubifs_find_free_leb_for_idx(c);
if (lnum < 0) {
ubifs_err("could not find an empty LEB");
ubifs_dump_lprops(c);
ubifs_dump_budg(c, &c->bi);
return lnum;
}
/* Reset the index flag */
err = ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
LPROPS_INDEX, 0);
if (err)
return err;
c->gc_lnum = lnum;
dbg_rcvry("found empty LEB %d, run commit", lnum);
return ubifs_run_commit(c);
}
/**
* ubifs_rcvry_gc_commit - recover the GC LEB number and run the commit.
* @c: UBIFS file-system description object
*
* Out-of-place garbage collection requires always one empty LEB with which to
* start garbage collection. The LEB number is recorded in c->gc_lnum and is
* written to the master node on unmounting. In the case of an unclean unmount
* the value of gc_lnum recorded in the master node is out of date and cannot
* be used. Instead, recovery must allocate an empty LEB for this purpose.
* However, there may not be enough empty space, in which case it must be
* possible to GC the dirtiest LEB into the GC head LEB.
*
* This function also runs the commit which causes the TNC updates from
* size-recovery and orphans to be written to the flash. That is important to
* ensure correct replay order for subsequent mounts.
*
* This function returns %0 on success and a negative error code on failure.
*/
int ubifs_rcvry_gc_commit(struct ubifs_info *c)
{
struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;
struct ubifs_lprops lp;
int err;
dbg_rcvry("GC head LEB %d, offs %d", wbuf->lnum, wbuf->offs);
c->gc_lnum = -1;
if (wbuf->lnum == -1 || wbuf->offs == c->leb_size)
return grab_empty_leb(c);
err = ubifs_find_dirty_leb(c, &lp, wbuf->offs, 2);
if (err) {
if (err != -ENOSPC)
return err;
dbg_rcvry("could not find a dirty LEB");
return grab_empty_leb(c);
}
ubifs_assert(!(lp.flags & LPROPS_INDEX));
ubifs_assert(lp.free + lp.dirty >= wbuf->offs);
/*
* We run the commit before garbage collection otherwise subsequent
* mounts will see the GC and orphan deletion in a different order.
*/
dbg_rcvry("committing");
err = ubifs_run_commit(c);
if (err)
return err;
dbg_rcvry("GC'ing LEB %d", lp.lnum);
mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
err = ubifs_garbage_collect_leb(c, &lp);
if (err >= 0) {
int err2 = ubifs_wbuf_sync_nolock(wbuf);
if (err2)
err = err2;
}
mutex_unlock(&wbuf->io_mutex);
if (err < 0) {
ubifs_err("GC failed, error %d", err);
if (err == -EAGAIN)
err = -EINVAL;
return err;
}
ubifs_assert(err == LEB_RETAINED);
if (err != LEB_RETAINED)
return -EINVAL;
err = ubifs_leb_unmap(c, c->gc_lnum);
if (err)
return err;
dbg_rcvry("allocated LEB %d for GC", lp.lnum);
return 0;
}
/**
* struct size_entry - inode size information for recovery.
* @rb: link in the RB-tree of sizes
* @inum: inode number
* @i_size: size on inode
* @d_size: maximum size based on data nodes
* @exists: indicates whether the inode exists
* @inode: inode if pinned in memory awaiting rw mode to fix it
*/
struct size_entry {
struct rb_node rb;
ino_t inum;
loff_t i_size;
loff_t d_size;
int exists;
struct inode *inode;
};
/**
* add_ino - add an entry to the size tree.
* @c: UBIFS file-system description object
* @inum: inode number
* @i_size: size on inode
* @d_size: maximum size based on data nodes
* @exists: indicates whether the inode exists
*/
static int add_ino(struct ubifs_info *c, ino_t inum, loff_t i_size,
loff_t d_size, int exists)
{
struct rb_node **p = &c->size_tree.rb_node, *parent = NULL;
struct size_entry *e;
while (*p) {
parent = *p;
e = rb_entry(parent, struct size_entry, rb);
if (inum < e->inum)
p = &(*p)->rb_left;
else
p = &(*p)->rb_right;
}
e = kzalloc(sizeof(struct size_entry), GFP_KERNEL);
if (!e)
return -ENOMEM;
e->inum = inum;
e->i_size = i_size;
e->d_size = d_size;
e->exists = exists;
rb_link_node(&e->rb, parent, p);
rb_insert_color(&e->rb, &c->size_tree);
return 0;
}
/**
* find_ino - find an entry on the size tree.
* @c: UBIFS file-system description object
* @inum: inode number
*/
static struct size_entry *find_ino(struct ubifs_info *c, ino_t inum)
{
struct rb_node *p = c->size_tree.rb_node;
struct size_entry *e;
while (p) {
e = rb_entry(p, struct size_entry, rb);
if (inum < e->inum)
p = p->rb_left;
else if (inum > e->inum)
p = p->rb_right;
else
return e;
}
return NULL;
}
/**
* remove_ino - remove an entry from the size tree.
* @c: UBIFS file-system description object
* @inum: inode number
*/
static void remove_ino(struct ubifs_info *c, ino_t inum)
{
struct size_entry *e = find_ino(c, inum);
if (!e)
return;
rb_erase(&e->rb, &c->size_tree);
kfree(e);
}
/**
* ubifs_destroy_size_tree - free resources related to the size tree.
* @c: UBIFS file-system description object
*/
void ubifs_destroy_size_tree(struct ubifs_info *c)
{
struct size_entry *e, *n;
rbtree_postorder_for_each_entry_safe(e, n, &c->size_tree, rb) {
if (e->inode)
iput(e->inode);
kfree(e);
}
c->size_tree = RB_ROOT;
}
/**
* ubifs_recover_size_accum - accumulate inode sizes for recovery.
* @c: UBIFS file-system description object
* @key: node key
* @deletion: node is for a deletion
* @new_size: inode size
*
* This function has two purposes:
* 1) to ensure there are no data nodes that fall outside the inode size
* 2) to ensure there are no data nodes for inodes that do not exist
* To accomplish those purposes, a rb-tree is constructed containing an entry
* for each inode number in the journal that has not been deleted, and recording
* the size from the inode node, the maximum size of any data node (also altered
* by truncations) and a flag indicating a inode number for which no inode node
* was present in the journal.
*
* Note that there is still the possibility that there are data nodes that have
* been committed that are beyond the inode size, however the only way to find
* them would be to scan the entire index. Alternatively, some provision could
* be made to record the size of inodes at the start of commit, which would seem
* very cumbersome for a scenario that is quite unlikely and the only negative
* consequence of which is wasted space.
*
* This functions returns %0 on success and a negative error code on failure.
*/
int ubifs_recover_size_accum(struct ubifs_info *c, union ubifs_key *key,
int deletion, loff_t new_size)
{
ino_t inum = key_inum(c, key);
struct size_entry *e;
int err;
switch (key_type(c, key)) {
case UBIFS_INO_KEY:
if (deletion)
remove_ino(c, inum);
else {
e = find_ino(c, inum);
if (e) {
e->i_size = new_size;
e->exists = 1;
} else {
err = add_ino(c, inum, new_size, 0, 1);
if (err)
return err;
}
}
break;
case UBIFS_DATA_KEY:
e = find_ino(c, inum);
if (e) {
if (new_size > e->d_size)
e->d_size = new_size;
} else {
err = add_ino(c, inum, 0, new_size, 0);
if (err)
return err;
}
break;
case UBIFS_TRUN_KEY:
e = find_ino(c, inum);
if (e)
e->d_size = new_size;
break;
}
return 0;
}
/**
* fix_size_in_place - fix inode size in place on flash.
* @c: UBIFS file-system description object
* @e: inode size information for recovery
*/
static int fix_size_in_place(struct ubifs_info *c, struct size_entry *e)
{
struct ubifs_ino_node *ino = c->sbuf;
unsigned char *p;
union ubifs_key key;
int err, lnum, offs, len;
loff_t i_size;
uint32_t crc;
/* Locate the inode node LEB number and offset */
ino_key_init(c, &key, e->inum);
err = ubifs_tnc_locate(c, &key, ino, &lnum, &offs);
if (err)
goto out;
/*
* If the size recorded on the inode node is greater than the size that
* was calculated from nodes in the journal then don't change the inode.
*/
i_size = le64_to_cpu(ino->size);
if (i_size >= e->d_size)
return 0;
/* Read the LEB */
err = ubifs_leb_read(c, lnum, c->sbuf, 0, c->leb_size, 1);
if (err)
goto out;
/* Change the size field and recalculate the CRC */
ino = c->sbuf + offs;
ino->size = cpu_to_le64(e->d_size);
len = le32_to_cpu(ino->ch.len);
crc = crc32(UBIFS_CRC32_INIT, (void *)ino + 8, len - 8);
ino->ch.crc = cpu_to_le32(crc);
/* Work out where data in the LEB ends and free space begins */
p = c->sbuf;
len = c->leb_size - 1;
while (p[len] == 0xff)
len -= 1;
len = ALIGN(len + 1, c->min_io_size);
/* Atomically write the fixed LEB back again */
err = ubifs_leb_change(c, lnum, c->sbuf, len);
if (err)
goto out;
dbg_rcvry("inode %lu at %d:%d size %lld -> %lld",
(unsigned long)e->inum, lnum, offs, i_size, e->d_size);
return 0;
out:
ubifs_warn("inode %lu failed to fix size %lld -> %lld error %d",
(unsigned long)e->inum, e->i_size, e->d_size, err);
return err;
}
/**
* ubifs_recover_size - recover inode size.
* @c: UBIFS file-system description object
*
* This function attempts to fix inode size discrepancies identified by the
* 'ubifs_recover_size_accum()' function.
*
* This functions returns %0 on success and a negative error code on failure.
*/
int ubifs_recover_size(struct ubifs_info *c)
{
struct rb_node *this = rb_first(&c->size_tree);
while (this) {
struct size_entry *e;
int err;
e = rb_entry(this, struct size_entry, rb);
if (!e->exists) {
union ubifs_key key;
ino_key_init(c, &key, e->inum);
err = ubifs_tnc_lookup(c, &key, c->sbuf);
if (err && err != -ENOENT)
return err;
if (err == -ENOENT) {
/* Remove data nodes that have no inode */
dbg_rcvry("removing ino %lu",
(unsigned long)e->inum);
err = ubifs_tnc_remove_ino(c, e->inum);
if (err)
return err;
} else {
struct ubifs_ino_node *ino = c->sbuf;
e->exists = 1;
e->i_size = le64_to_cpu(ino->size);
}
}
if (e->exists && e->i_size < e->d_size) {
if (c->ro_mount) {
/* Fix the inode size and pin it in memory */
struct inode *inode;
struct ubifs_inode *ui;
ubifs_assert(!e->inode);
inode = ubifs_iget(c->vfs_sb, e->inum);
if (IS_ERR(inode))
return PTR_ERR(inode);
ui = ubifs_inode(inode);
if (inode->i_size < e->d_size) {
dbg_rcvry("ino %lu size %lld -> %lld",
(unsigned long)e->inum,
inode->i_size, e->d_size);
inode->i_size = e->d_size;
ui->ui_size = e->d_size;
ui->synced_i_size = e->d_size;
e->inode = inode;
this = rb_next(this);
continue;
}
iput(inode);
} else {
/* Fix the size in place */
err = fix_size_in_place(c, e);
if (err)
return err;
if (e->inode)
iput(e->inode);
}
}
this = rb_next(this);
rb_erase(&e->rb, &c->size_tree);
kfree(e);
}
return 0;
}