linux/fs/ubifs/recovery.c
Artem Bityutskiy 7c47bfd0db UBIFS: always cleanup the recovered LEB
Now when we call 'ubifs_recover_leb()' only for LEBs which are potentially
corrupted (i.e., only for last buds, not for all of them), we can cleanup every
LEB, not only those where we find corruption. The reason - unstable bits. Even
though the LEB may look good now, it might contain unstable bits which may hit
us a bit later.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2011-05-16 15:48:48 +03:00

1491 lines
40 KiB
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 = 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->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) {
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->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 = 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 ret = 0, err, len = c->leb_size - offs;
int 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;
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, 0);
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", ret);
break;
} else {
dbg_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))
clean_buf(c, &buf, lnum, &offs, &len);
else
goto corrupted_rescan;
} else if (ret == SCANNED_A_CORRUPT_NODE) {
if (no_more_nodes(c, buf, len, lnum, offs))
clean_buf(c, &buf, lnum, &offs, &len);
else
goto corrupted_rescan;
} else if (!is_empty(buf, len)) {
if (is_last_write(c, buf, offs)) {
clean_buf(c, &buf, lnum, &offs, &len);
} else {
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;
}
}
/* 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);
}
if (offs % c->min_io_size)
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 */
dbg_err("corruptio %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 = 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 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, 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 = 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 = 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->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(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
*
* 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(const 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) {
dbg_err("could not find an empty LEB");
dbg_dump_lprops(c);
dbg_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) {
dbg_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 rb_node *this = c->size_tree.rb_node;
struct size_entry *e;
while (this) {
if (this->rb_left) {
this = this->rb_left;
continue;
} else if (this->rb_right) {
this = this->rb_right;
continue;
}
e = rb_entry(this, struct size_entry, rb);
if (e->inode)
iput(e->inode);
this = rb_parent(this);
if (this) {
if (this->rb_left == &e->rb)
this->rb_left = NULL;
else
this->rb_right = NULL;
}
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 = ubi_read(c->ubi, lnum, c->sbuf, 0, c->leb_size);
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 = ubi_leb_change(c->ubi, lnum, c->sbuf, len, UBI_UNKNOWN);
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;
}