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linux/fs/gfs2/recovery.c
Steven Whitehouse fe64d517df GFS2: Umount recovery race fix 
This patch fixes a race condition where we can receive recovery
requests part way through processing a umount. This was causing
problems since the recovery thread had already gone away.

Looking in more detail at the recovery code, it was really trying
to implement a slight variation on a work queue, and that happens to
align nicely with the recently introduced slow-work subsystem. As a
result I've updated the code to use slow-work, rather than its own home
grown variety of work queue.

When using the wait_on_bit() function, I noticed that the wait function
that was supplied as an argument was appearing in the WCHAN field, so
I've updated the function names in order to produce more meaningful
output.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2009-05-19 10:01:18 +01:00

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/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU General Public License version 2.
*/
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/gfs2_ondisk.h>
#include <linux/crc32.h>
#include <linux/slow-work.h>
#include "gfs2.h"
#include "incore.h"
#include "bmap.h"
#include "glock.h"
#include "glops.h"
#include "lops.h"
#include "meta_io.h"
#include "recovery.h"
#include "super.h"
#include "util.h"
#include "dir.h"
int gfs2_replay_read_block(struct gfs2_jdesc *jd, unsigned int blk,
struct buffer_head **bh)
{
struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
struct gfs2_glock *gl = ip->i_gl;
int new = 0;
u64 dblock;
u32 extlen;
int error;
error = gfs2_extent_map(&ip->i_inode, blk, &new, &dblock, &extlen);
if (error)
return error;
if (!dblock) {
gfs2_consist_inode(ip);
return -EIO;
}
*bh = gfs2_meta_ra(gl, dblock, extlen);
return error;
}
int gfs2_revoke_add(struct gfs2_sbd *sdp, u64 blkno, unsigned int where)
{
struct list_head *head = &sdp->sd_revoke_list;
struct gfs2_revoke_replay *rr;
int found = 0;
list_for_each_entry(rr, head, rr_list) {
if (rr->rr_blkno == blkno) {
found = 1;
break;
}
}
if (found) {
rr->rr_where = where;
return 0;
}
rr = kmalloc(sizeof(struct gfs2_revoke_replay), GFP_NOFS);
if (!rr)
return -ENOMEM;
rr->rr_blkno = blkno;
rr->rr_where = where;
list_add(&rr->rr_list, head);
return 1;
}
int gfs2_revoke_check(struct gfs2_sbd *sdp, u64 blkno, unsigned int where)
{
struct gfs2_revoke_replay *rr;
int wrap, a, b, revoke;
int found = 0;
list_for_each_entry(rr, &sdp->sd_revoke_list, rr_list) {
if (rr->rr_blkno == blkno) {
found = 1;
break;
}
}
if (!found)
return 0;
wrap = (rr->rr_where < sdp->sd_replay_tail);
a = (sdp->sd_replay_tail < where);
b = (where < rr->rr_where);
revoke = (wrap) ? (a || b) : (a && b);
return revoke;
}
void gfs2_revoke_clean(struct gfs2_sbd *sdp)
{
struct list_head *head = &sdp->sd_revoke_list;
struct gfs2_revoke_replay *rr;
while (!list_empty(head)) {
rr = list_entry(head->next, struct gfs2_revoke_replay, rr_list);
list_del(&rr->rr_list);
kfree(rr);
}
}
static int gfs2_log_header_in(struct gfs2_log_header_host *lh, const void *buf)
{
const struct gfs2_log_header *str = buf;
if (str->lh_header.mh_magic != cpu_to_be32(GFS2_MAGIC) ||
str->lh_header.mh_type != cpu_to_be32(GFS2_METATYPE_LH))
return 1;
lh->lh_sequence = be64_to_cpu(str->lh_sequence);
lh->lh_flags = be32_to_cpu(str->lh_flags);
lh->lh_tail = be32_to_cpu(str->lh_tail);
lh->lh_blkno = be32_to_cpu(str->lh_blkno);
lh->lh_hash = be32_to_cpu(str->lh_hash);
return 0;
}
/**
* get_log_header - read the log header for a given segment
* @jd: the journal
* @blk: the block to look at
* @lh: the log header to return
*
* Read the log header for a given segement in a given journal. Do a few
* sanity checks on it.
*
* Returns: 0 on success,
* 1 if the header was invalid or incomplete,
* errno on error
*/
static int get_log_header(struct gfs2_jdesc *jd, unsigned int blk,
struct gfs2_log_header_host *head)
{
struct buffer_head *bh;
struct gfs2_log_header_host uninitialized_var(lh);
const u32 nothing = 0;
u32 hash;
int error;
error = gfs2_replay_read_block(jd, blk, &bh);
if (error)
return error;
hash = crc32_le((u32)~0, bh->b_data, sizeof(struct gfs2_log_header) -
sizeof(u32));
hash = crc32_le(hash, (unsigned char const *)&nothing, sizeof(nothing));
hash ^= (u32)~0;
error = gfs2_log_header_in(&lh, bh->b_data);
brelse(bh);
if (error || lh.lh_blkno != blk || lh.lh_hash != hash)
return 1;
*head = lh;
return 0;
}
/**
* find_good_lh - find a good log header
* @jd: the journal
* @blk: the segment to start searching from
* @lh: the log header to fill in
* @forward: if true search forward in the log, else search backward
*
* Call get_log_header() to get a log header for a segment, but if the
* segment is bad, either scan forward or backward until we find a good one.
*
* Returns: errno
*/
static int find_good_lh(struct gfs2_jdesc *jd, unsigned int *blk,
struct gfs2_log_header_host *head)
{
unsigned int orig_blk = *blk;
int error;
for (;;) {
error = get_log_header(jd, *blk, head);
if (error <= 0)
return error;
if (++*blk == jd->jd_blocks)
*blk = 0;
if (*blk == orig_blk) {
gfs2_consist_inode(GFS2_I(jd->jd_inode));
return -EIO;
}
}
}
/**
* jhead_scan - make sure we've found the head of the log
* @jd: the journal
* @head: this is filled in with the log descriptor of the head
*
* At this point, seg and lh should be either the head of the log or just
* before. Scan forward until we find the head.
*
* Returns: errno
*/
static int jhead_scan(struct gfs2_jdesc *jd, struct gfs2_log_header_host *head)
{
unsigned int blk = head->lh_blkno;
struct gfs2_log_header_host lh;
int error;
for (;;) {
if (++blk == jd->jd_blocks)
blk = 0;
error = get_log_header(jd, blk, &lh);
if (error < 0)
return error;
if (error == 1)
continue;
if (lh.lh_sequence == head->lh_sequence) {
gfs2_consist_inode(GFS2_I(jd->jd_inode));
return -EIO;
}
if (lh.lh_sequence < head->lh_sequence)
break;
*head = lh;
}
return 0;
}
/**
* gfs2_find_jhead - find the head of a log
* @jd: the journal
* @head: the log descriptor for the head of the log is returned here
*
* Do a binary search of a journal and find the valid log entry with the
* highest sequence number. (i.e. the log head)
*
* Returns: errno
*/
int gfs2_find_jhead(struct gfs2_jdesc *jd, struct gfs2_log_header_host *head)
{
struct gfs2_log_header_host lh_1, lh_m;
u32 blk_1, blk_2, blk_m;
int error;
blk_1 = 0;
blk_2 = jd->jd_blocks - 1;
for (;;) {
blk_m = (blk_1 + blk_2) / 2;
error = find_good_lh(jd, &blk_1, &lh_1);
if (error)
return error;
error = find_good_lh(jd, &blk_m, &lh_m);
if (error)
return error;
if (blk_1 == blk_m || blk_m == blk_2)
break;
if (lh_1.lh_sequence <= lh_m.lh_sequence)
blk_1 = blk_m;
else
blk_2 = blk_m;
}
error = jhead_scan(jd, &lh_1);
if (error)
return error;
*head = lh_1;
return error;
}
/**
* foreach_descriptor - go through the active part of the log
* @jd: the journal
* @start: the first log header in the active region
* @end: the last log header (don't process the contents of this entry))
*
* Call a given function once for every log descriptor in the active
* portion of the log.
*
* Returns: errno
*/
static int foreach_descriptor(struct gfs2_jdesc *jd, unsigned int start,
unsigned int end, int pass)
{
struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
struct buffer_head *bh;
struct gfs2_log_descriptor *ld;
int error = 0;
u32 length;
__be64 *ptr;
unsigned int offset = sizeof(struct gfs2_log_descriptor);
offset += sizeof(__be64) - 1;
offset &= ~(sizeof(__be64) - 1);
while (start != end) {
error = gfs2_replay_read_block(jd, start, &bh);
if (error)
return error;
if (gfs2_meta_check(sdp, bh)) {
brelse(bh);
return -EIO;
}
ld = (struct gfs2_log_descriptor *)bh->b_data;
length = be32_to_cpu(ld->ld_length);
if (be32_to_cpu(ld->ld_header.mh_type) == GFS2_METATYPE_LH) {
struct gfs2_log_header_host lh;
error = get_log_header(jd, start, &lh);
if (!error) {
gfs2_replay_incr_blk(sdp, &start);
brelse(bh);
continue;
}
if (error == 1) {
gfs2_consist_inode(GFS2_I(jd->jd_inode));
error = -EIO;
}
brelse(bh);
return error;
} else if (gfs2_metatype_check(sdp, bh, GFS2_METATYPE_LD)) {
brelse(bh);
return -EIO;
}
ptr = (__be64 *)(bh->b_data + offset);
error = lops_scan_elements(jd, start, ld, ptr, pass);
if (error) {
brelse(bh);
return error;
}
while (length--)
gfs2_replay_incr_blk(sdp, &start);
brelse(bh);
}
return 0;
}
/**
* clean_journal - mark a dirty journal as being clean
* @sdp: the filesystem
* @jd: the journal
* @gl: the journal's glock
* @head: the head journal to start from
*
* Returns: errno
*/
static int clean_journal(struct gfs2_jdesc *jd, struct gfs2_log_header_host *head)
{
struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
unsigned int lblock;
struct gfs2_log_header *lh;
u32 hash;
struct buffer_head *bh;
int error;
struct buffer_head bh_map = { .b_state = 0, .b_blocknr = 0 };
lblock = head->lh_blkno;
gfs2_replay_incr_blk(sdp, &lblock);
bh_map.b_size = 1 << ip->i_inode.i_blkbits;
error = gfs2_block_map(&ip->i_inode, lblock, &bh_map, 0);
if (error)
return error;
if (!bh_map.b_blocknr) {
gfs2_consist_inode(ip);
return -EIO;
}
bh = sb_getblk(sdp->sd_vfs, bh_map.b_blocknr);
lock_buffer(bh);
memset(bh->b_data, 0, bh->b_size);
set_buffer_uptodate(bh);
clear_buffer_dirty(bh);
unlock_buffer(bh);
lh = (struct gfs2_log_header *)bh->b_data;
memset(lh, 0, sizeof(struct gfs2_log_header));
lh->lh_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
lh->lh_header.mh_type = cpu_to_be32(GFS2_METATYPE_LH);
lh->lh_header.mh_format = cpu_to_be32(GFS2_FORMAT_LH);
lh->lh_sequence = cpu_to_be64(head->lh_sequence + 1);
lh->lh_flags = cpu_to_be32(GFS2_LOG_HEAD_UNMOUNT);
lh->lh_blkno = cpu_to_be32(lblock);
hash = gfs2_disk_hash((const char *)lh, sizeof(struct gfs2_log_header));
lh->lh_hash = cpu_to_be32(hash);
set_buffer_dirty(bh);
if (sync_dirty_buffer(bh))
gfs2_io_error_bh(sdp, bh);
brelse(bh);
return error;
}
static void gfs2_recovery_done(struct gfs2_sbd *sdp, unsigned int jid,
unsigned int message)
{
char env_jid[20];
char env_status[20];
char *envp[] = { env_jid, env_status, NULL };
struct lm_lockstruct *ls = &sdp->sd_lockstruct;
ls->ls_recover_jid_done = jid;
ls->ls_recover_jid_status = message;
sprintf(env_jid, "JID=%d", jid);
sprintf(env_status, "RECOVERY=%s",
message == LM_RD_SUCCESS ? "Done" : "Failed");
kobject_uevent_env(&sdp->sd_kobj, KOBJ_CHANGE, envp);
}
static int gfs2_recover_get_ref(struct slow_work *work)
{
struct gfs2_jdesc *jd = container_of(work, struct gfs2_jdesc, jd_work);
if (test_and_set_bit(JDF_RECOVERY, &jd->jd_flags))
return -EBUSY;
return 0;
}
static void gfs2_recover_put_ref(struct slow_work *work)
{
struct gfs2_jdesc *jd = container_of(work, struct gfs2_jdesc, jd_work);
clear_bit(JDF_RECOVERY, &jd->jd_flags);
smp_mb__after_clear_bit();
wake_up_bit(&jd->jd_flags, JDF_RECOVERY);
}
static void gfs2_recover_work(struct slow_work *work)
{
struct gfs2_jdesc *jd = container_of(work, struct gfs2_jdesc, jd_work);
struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
struct gfs2_log_header_host head;
struct gfs2_holder j_gh, ji_gh, t_gh;
unsigned long t;
int ro = 0;
unsigned int pass;
int error;
if (jd->jd_jid != sdp->sd_lockstruct.ls_jid) {
fs_info(sdp, "jid=%u: Trying to acquire journal lock...\n",
jd->jd_jid);
/* Acquire the journal lock so we can do recovery */
error = gfs2_glock_nq_num(sdp, jd->jd_jid, &gfs2_journal_glops,
LM_ST_EXCLUSIVE,
LM_FLAG_NOEXP | LM_FLAG_TRY | GL_NOCACHE,
&j_gh);
switch (error) {
case 0:
break;
case GLR_TRYFAILED:
fs_info(sdp, "jid=%u: Busy\n", jd->jd_jid);
error = 0;
default:
goto fail;
};
error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED,
LM_FLAG_NOEXP | GL_NOCACHE, &ji_gh);
if (error)
goto fail_gunlock_j;
} else {
fs_info(sdp, "jid=%u, already locked for use\n", jd->jd_jid);
}
fs_info(sdp, "jid=%u: Looking at journal...\n", jd->jd_jid);
error = gfs2_jdesc_check(jd);
if (error)
goto fail_gunlock_ji;
error = gfs2_find_jhead(jd, &head);
if (error)
goto fail_gunlock_ji;
if (!(head.lh_flags & GFS2_LOG_HEAD_UNMOUNT)) {
fs_info(sdp, "jid=%u: Acquiring the transaction lock...\n",
jd->jd_jid);
t = jiffies;
/* Acquire a shared hold on the transaction lock */
error = gfs2_glock_nq_init(sdp->sd_trans_gl, LM_ST_SHARED,
LM_FLAG_NOEXP | LM_FLAG_PRIORITY |
GL_NOCACHE, &t_gh);
if (error)
goto fail_gunlock_ji;
if (test_bit(SDF_JOURNAL_CHECKED, &sdp->sd_flags)) {
if (!test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))
ro = 1;
} else {
if (sdp->sd_vfs->s_flags & MS_RDONLY) {
/* check if device itself is read-only */
ro = bdev_read_only(sdp->sd_vfs->s_bdev);
if (!ro) {
fs_info(sdp, "recovery required on "
"read-only filesystem.\n");
fs_info(sdp, "write access will be "
"enabled during recovery.\n");
}
}
}
if (ro) {
fs_warn(sdp, "jid=%u: Can't replay: read-only block "
"device\n", jd->jd_jid);
error = -EROFS;
goto fail_gunlock_tr;
}
fs_info(sdp, "jid=%u: Replaying journal...\n", jd->jd_jid);
for (pass = 0; pass < 2; pass++) {
lops_before_scan(jd, &head, pass);
error = foreach_descriptor(jd, head.lh_tail,
head.lh_blkno, pass);
lops_after_scan(jd, error, pass);
if (error)
goto fail_gunlock_tr;
}
error = clean_journal(jd, &head);
if (error)
goto fail_gunlock_tr;
gfs2_glock_dq_uninit(&t_gh);
t = DIV_ROUND_UP(jiffies - t, HZ);
fs_info(sdp, "jid=%u: Journal replayed in %lus\n",
jd->jd_jid, t);
}
if (jd->jd_jid != sdp->sd_lockstruct.ls_jid)
gfs2_glock_dq_uninit(&ji_gh);
gfs2_recovery_done(sdp, jd->jd_jid, LM_RD_SUCCESS);
if (jd->jd_jid != sdp->sd_lockstruct.ls_jid)
gfs2_glock_dq_uninit(&j_gh);
fs_info(sdp, "jid=%u: Done\n", jd->jd_jid);
return;
fail_gunlock_tr:
gfs2_glock_dq_uninit(&t_gh);
fail_gunlock_ji:
if (jd->jd_jid != sdp->sd_lockstruct.ls_jid) {
gfs2_glock_dq_uninit(&ji_gh);
fail_gunlock_j:
gfs2_glock_dq_uninit(&j_gh);
}
fs_info(sdp, "jid=%u: %s\n", jd->jd_jid, (error) ? "Failed" : "Done");
fail:
gfs2_recovery_done(sdp, jd->jd_jid, LM_RD_GAVEUP);
}
struct slow_work_ops gfs2_recover_ops = {
.get_ref = gfs2_recover_get_ref,
.put_ref = gfs2_recover_put_ref,
.execute = gfs2_recover_work,
};
static int gfs2_recovery_wait(void *word)
{
schedule();
return 0;
}
int gfs2_recover_journal(struct gfs2_jdesc *jd)
{
int rv;
rv = slow_work_enqueue(&jd->jd_work);
if (rv)
return rv;
wait_on_bit(&jd->jd_flags, JDF_RECOVERY, gfs2_recovery_wait, TASK_UNINTERRUPTIBLE);
return 0;
}
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