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linux/fs/gfs2/util.c
Bob Peterson 96b1454f2e gfs2: move freeze glock outside the make_fs_rw and _ro functions 
Before this patch, sister functions gfs2_make_fs_rw and gfs2_make_fs_ro locked
(held) the freeze glock by calling gfs2_freeze_lock and gfs2_freeze_unlock.
The problem is, not all the callers of gfs2_make_fs_ro should be doing this.
The three callers of gfs2_make_fs_ro are: remount (gfs2_reconfigure),
signal_our_withdraw, and unmount (gfs2_put_super). But when unmounting the
file system we can get into the following circular lock dependency:

deactivate_super
   down_write(&s->s_umount); <-------------------------------------- s_umount
   deactivate_locked_super
      gfs2_kill_sb
         kill_block_super
            generic_shutdown_super
               gfs2_put_super
                  gfs2_make_fs_ro
                     gfs2_glock_nq_init sd_freeze_gl
                        freeze_go_sync
                           if (freeze glock in SH)
                              freeze_super (vfs)
                                 down_write(&sb->s_umount); <------- s_umount

This patch moves the hold of the freeze glock outside the two sister rw/ro
functions to their callers, but it doesn't request the glock from
gfs2_put_super, thus eliminating the circular dependency.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2020-12-23 00:54:21 +01:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/crc32.h>
#include <linux/gfs2_ondisk.h>
#include <linux/delay.h>
#include <linux/uaccess.h>
#include "gfs2.h"
#include "incore.h"
#include "glock.h"
#include "glops.h"
#include "log.h"
#include "lops.h"
#include "recovery.h"
#include "rgrp.h"
#include "super.h"
#include "util.h"
struct kmem_cache *gfs2_glock_cachep __read_mostly;
struct kmem_cache *gfs2_glock_aspace_cachep __read_mostly;
struct kmem_cache *gfs2_inode_cachep __read_mostly;
struct kmem_cache *gfs2_bufdata_cachep __read_mostly;
struct kmem_cache *gfs2_rgrpd_cachep __read_mostly;
struct kmem_cache *gfs2_quotad_cachep __read_mostly;
struct kmem_cache *gfs2_qadata_cachep __read_mostly;
struct kmem_cache *gfs2_trans_cachep __read_mostly;
mempool_t *gfs2_page_pool __read_mostly;
void gfs2_assert_i(struct gfs2_sbd *sdp)
{
fs_emerg(sdp, "fatal assertion failed\n");
}
/**
* check_journal_clean - Make sure a journal is clean for a spectator mount
* @sdp: The GFS2 superblock
* @jd: The journal descriptor
*
* Returns: 0 if the journal is clean or locked, else an error
*/
int check_journal_clean(struct gfs2_sbd *sdp, struct gfs2_jdesc *jd,
bool verbose)
{
int error;
struct gfs2_holder j_gh;
struct gfs2_log_header_host head;
struct gfs2_inode *ip;
ip = GFS2_I(jd->jd_inode);
error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_NOEXP |
GL_EXACT | GL_NOCACHE, &j_gh);
if (error) {
if (verbose)
fs_err(sdp, "Error %d locking journal for spectator "
"mount.\n", error);
return -EPERM;
}
error = gfs2_jdesc_check(jd);
if (error) {
if (verbose)
fs_err(sdp, "Error checking journal for spectator "
"mount.\n");
goto out_unlock;
}
error = gfs2_find_jhead(jd, &head, false);
if (error) {
if (verbose)
fs_err(sdp, "Error parsing journal for spectator "
"mount.\n");
goto out_unlock;
}
if (!(head.lh_flags & GFS2_LOG_HEAD_UNMOUNT)) {
error = -EPERM;
if (verbose)
fs_err(sdp, "jid=%u: Journal is dirty, so the first "
"mounter must not be a spectator.\n",
jd->jd_jid);
}
out_unlock:
gfs2_glock_dq_uninit(&j_gh);
return error;
}
/**
* gfs2_freeze_lock - hold the freeze glock
* @sdp: the superblock
* @freeze_gh: pointer to the requested holder
* @caller_flags: any additional flags needed by the caller
*/
int gfs2_freeze_lock(struct gfs2_sbd *sdp, struct gfs2_holder *freeze_gh,
int caller_flags)
{
int flags = LM_FLAG_NOEXP | GL_EXACT | caller_flags;
int error;
error = gfs2_glock_nq_init(sdp->sd_freeze_gl, LM_ST_SHARED, flags,
freeze_gh);
if (error && error != GLR_TRYFAILED)
fs_err(sdp, "can't lock the freeze lock: %d\n", error);
return error;
}
void gfs2_freeze_unlock(struct gfs2_holder *freeze_gh)
{
if (gfs2_holder_initialized(freeze_gh))
gfs2_glock_dq_uninit(freeze_gh);
}
static void signal_our_withdraw(struct gfs2_sbd *sdp)
{
struct gfs2_glock *gl = sdp->sd_live_gh.gh_gl;
struct inode *inode = sdp->sd_jdesc->jd_inode;
struct gfs2_inode *ip = GFS2_I(inode);
u64 no_formal_ino = ip->i_no_formal_ino;
int log_write_allowed = test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
int ret = 0;
int tries;
if (test_bit(SDF_NORECOVERY, &sdp->sd_flags))
return;
/* Prevent any glock dq until withdraw recovery is complete */
set_bit(SDF_WITHDRAW_RECOVERY, &sdp->sd_flags);
/*
* Don't tell dlm we're bailing until we have no more buffers in the
* wind. If journal had an IO error, the log code should just purge
* the outstanding buffers rather than submitting new IO. Making the
* file system read-only will flush the journal, etc.
*
* During a normal unmount, gfs2_make_fs_ro calls gfs2_log_shutdown
* which clears SDF_JOURNAL_LIVE. In a withdraw, we must not write
* any UNMOUNT log header, so we can't call gfs2_log_shutdown, and
* therefore we need to clear SDF_JOURNAL_LIVE manually.
*/
clear_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
if (!sb_rdonly(sdp->sd_vfs)) {
struct gfs2_holder freeze_gh;
gfs2_holder_mark_uninitialized(&freeze_gh);
if (sdp->sd_freeze_gl &&
!gfs2_glock_is_locked_by_me(sdp->sd_freeze_gl)) {
ret = gfs2_freeze_lock(sdp, &freeze_gh,
log_write_allowed ? 0 : LM_FLAG_TRY);
if (ret == GLR_TRYFAILED)
ret = 0;
}
if (!ret)
ret = gfs2_make_fs_ro(sdp);
gfs2_freeze_unlock(&freeze_gh);
}
if (sdp->sd_lockstruct.ls_ops->lm_lock == NULL) { /* lock_nolock */
if (!ret)
ret = -EIO;
clear_bit(SDF_WITHDRAW_RECOVERY, &sdp->sd_flags);
goto skip_recovery;
}
/*
* Drop the glock for our journal so another node can recover it.
*/
if (gfs2_holder_initialized(&sdp->sd_journal_gh)) {
gfs2_glock_dq_wait(&sdp->sd_journal_gh);
gfs2_holder_uninit(&sdp->sd_journal_gh);
}
sdp->sd_jinode_gh.gh_flags |= GL_NOCACHE;
gfs2_glock_dq(&sdp->sd_jinode_gh);
if (test_bit(SDF_FS_FROZEN, &sdp->sd_flags)) {
/* Make sure gfs2_unfreeze works if partially-frozen */
flush_work(&sdp->sd_freeze_work);
atomic_set(&sdp->sd_freeze_state, SFS_FROZEN);
thaw_super(sdp->sd_vfs);
} else {
wait_on_bit(&gl->gl_flags, GLF_DEMOTE, TASK_UNINTERRUPTIBLE);
}
/*
* holder_uninit to force glock_put, to force dlm to let go
*/
gfs2_holder_uninit(&sdp->sd_jinode_gh);
/*
* Note: We need to be careful here:
* Our iput of jd_inode will evict it. The evict will dequeue its
* glock, but the glock dq will wait for the withdraw unless we have
* exception code in glock_dq.
*/
iput(inode);
/*
* Wait until the journal inode's glock is freed. This allows try locks
* on other nodes to be successful, otherwise we remain the owner of
* the glock as far as dlm is concerned.
*/
if (gl->gl_ops->go_free) {
set_bit(GLF_FREEING, &gl->gl_flags);
wait_on_bit(&gl->gl_flags, GLF_FREEING, TASK_UNINTERRUPTIBLE);
}
/*
* Dequeue the "live" glock, but keep a reference so it's never freed.
*/
gfs2_glock_hold(gl);
gfs2_glock_dq_wait(&sdp->sd_live_gh);
/*
* We enqueue the "live" glock in EX so that all other nodes
* get a demote request and act on it. We don't really want the
* lock in EX, so we send a "try" lock with 1CB to produce a callback.
*/
fs_warn(sdp, "Requesting recovery of jid %d.\n",
sdp->sd_lockstruct.ls_jid);
gfs2_holder_reinit(LM_ST_EXCLUSIVE, LM_FLAG_TRY_1CB | LM_FLAG_NOEXP,
&sdp->sd_live_gh);
msleep(GL_GLOCK_MAX_HOLD);
/*
* This will likely fail in a cluster, but succeed standalone:
*/
ret = gfs2_glock_nq(&sdp->sd_live_gh);
/*
* If we actually got the "live" lock in EX mode, there are no other
* nodes available to replay our journal. So we try to replay it
* ourselves. We hold the "live" glock to prevent other mounters
* during recovery, then just dequeue it and reacquire it in our
* normal SH mode. Just in case the problem that caused us to
* withdraw prevents us from recovering our journal (e.g. io errors
* and such) we still check if the journal is clean before proceeding
* but we may wait forever until another mounter does the recovery.
*/
if (ret == 0) {
fs_warn(sdp, "No other mounters found. Trying to recover our "
"own journal jid %d.\n", sdp->sd_lockstruct.ls_jid);
if (gfs2_recover_journal(sdp->sd_jdesc, 1))
fs_warn(sdp, "Unable to recover our journal jid %d.\n",
sdp->sd_lockstruct.ls_jid);
gfs2_glock_dq_wait(&sdp->sd_live_gh);
gfs2_holder_reinit(LM_ST_SHARED, LM_FLAG_NOEXP | GL_EXACT,
&sdp->sd_live_gh);
gfs2_glock_nq(&sdp->sd_live_gh);
}
gfs2_glock_queue_put(gl); /* drop the extra reference we acquired */
clear_bit(SDF_WITHDRAW_RECOVERY, &sdp->sd_flags);
/*
* At this point our journal is evicted, so we need to get a new inode
* for it. Once done, we need to call gfs2_find_jhead which
* calls gfs2_map_journal_extents to map it for us again.
*
* Note that we don't really want it to look up a FREE block. The
* GFS2_BLKST_FREE simply overrides a block check in gfs2_inode_lookup
* which would otherwise fail because it requires grabbing an rgrp
* glock, which would fail with -EIO because we're withdrawing.
*/
inode = gfs2_inode_lookup(sdp->sd_vfs, DT_UNKNOWN,
sdp->sd_jdesc->jd_no_addr, no_formal_ino,
GFS2_BLKST_FREE);
if (IS_ERR(inode)) {
fs_warn(sdp, "Reprocessing of jid %d failed with %ld.\n",
sdp->sd_lockstruct.ls_jid, PTR_ERR(inode));
goto skip_recovery;
}
sdp->sd_jdesc->jd_inode = inode;
/*
* Now wait until recovery is complete.
*/
for (tries = 0; tries < 10; tries++) {
ret = check_journal_clean(sdp, sdp->sd_jdesc, false);
if (!ret)
break;
msleep(HZ);
fs_warn(sdp, "Waiting for journal recovery jid %d.\n",
sdp->sd_lockstruct.ls_jid);
}
skip_recovery:
if (!ret)
fs_warn(sdp, "Journal recovery complete for jid %d.\n",
sdp->sd_lockstruct.ls_jid);
else
fs_warn(sdp, "Journal recovery skipped for %d until next "
"mount.\n", sdp->sd_lockstruct.ls_jid);
fs_warn(sdp, "Glock dequeues delayed: %lu\n", sdp->sd_glock_dqs_held);
sdp->sd_glock_dqs_held = 0;
wake_up_bit(&sdp->sd_flags, SDF_WITHDRAW_RECOVERY);
}
void gfs2_lm(struct gfs2_sbd *sdp, const char *fmt, ...)
{
struct va_format vaf;
va_list args;
if (sdp->sd_args.ar_errors == GFS2_ERRORS_WITHDRAW &&
test_bit(SDF_WITHDRAWN, &sdp->sd_flags))
return;
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
fs_err(sdp, "%pV", &vaf);
va_end(args);
}
int gfs2_withdraw(struct gfs2_sbd *sdp)
{
struct lm_lockstruct *ls = &sdp->sd_lockstruct;
const struct lm_lockops *lm = ls->ls_ops;
if (sdp->sd_args.ar_errors == GFS2_ERRORS_WITHDRAW &&
test_and_set_bit(SDF_WITHDRAWN, &sdp->sd_flags)) {
if (!test_bit(SDF_WITHDRAW_IN_PROG, &sdp->sd_flags))
return -1;
wait_on_bit(&sdp->sd_flags, SDF_WITHDRAW_IN_PROG,
TASK_UNINTERRUPTIBLE);
return -1;
}
set_bit(SDF_WITHDRAW_IN_PROG, &sdp->sd_flags);
if (sdp->sd_args.ar_errors == GFS2_ERRORS_WITHDRAW) {
fs_err(sdp, "about to withdraw this file system\n");
BUG_ON(sdp->sd_args.ar_debug);
signal_our_withdraw(sdp);
kobject_uevent(&sdp->sd_kobj, KOBJ_OFFLINE);
if (!strcmp(sdp->sd_lockstruct.ls_ops->lm_proto_name, "lock_dlm"))
wait_for_completion(&sdp->sd_wdack);
if (lm->lm_unmount) {
fs_err(sdp, "telling LM to unmount\n");
lm->lm_unmount(sdp);
}
set_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags);
fs_err(sdp, "File system withdrawn\n");
dump_stack();
clear_bit(SDF_WITHDRAW_IN_PROG, &sdp->sd_flags);
smp_mb__after_atomic();
wake_up_bit(&sdp->sd_flags, SDF_WITHDRAW_IN_PROG);
}
if (sdp->sd_args.ar_errors == GFS2_ERRORS_PANIC)
panic("GFS2: fsid=%s: panic requested\n", sdp->sd_fsname);
return -1;
}
/**
* gfs2_assert_withdraw_i - Cause the machine to withdraw if @assertion is false
*/
void gfs2_assert_withdraw_i(struct gfs2_sbd *sdp, char *assertion,
const char *function, char *file, unsigned int line,
bool delayed)
{
if (gfs2_withdrawn(sdp))
return;
fs_err(sdp,
"fatal: assertion \"%s\" failed\n"
" function = %s, file = %s, line = %u\n",
assertion, function, file, line);
/*
* If errors=panic was specified on mount, it won't help to delay the
* withdraw.
*/
if (sdp->sd_args.ar_errors == GFS2_ERRORS_PANIC)
delayed = false;
if (delayed)
gfs2_withdraw_delayed(sdp);
else
gfs2_withdraw(sdp);
dump_stack();
}
/**
* gfs2_assert_warn_i - Print a message to the console if @assertion is false
*/
void gfs2_assert_warn_i(struct gfs2_sbd *sdp, char *assertion,
const char *function, char *file, unsigned int line)
{
if (time_before(jiffies,
sdp->sd_last_warning +
gfs2_tune_get(sdp, gt_complain_secs) * HZ))
return;
if (sdp->sd_args.ar_errors == GFS2_ERRORS_WITHDRAW)
fs_warn(sdp, "warning: assertion \"%s\" failed at function = %s, file = %s, line = %u\n",
assertion, function, file, line);
if (sdp->sd_args.ar_debug)
BUG();
else
dump_stack();
if (sdp->sd_args.ar_errors == GFS2_ERRORS_PANIC)
panic("GFS2: fsid=%s: warning: assertion \"%s\" failed\n"
"GFS2: fsid=%s: function = %s, file = %s, line = %u\n",
sdp->sd_fsname, assertion,
sdp->sd_fsname, function, file, line);
sdp->sd_last_warning = jiffies;
}
/**
* gfs2_consist_i - Flag a filesystem consistency error and withdraw
*/
void gfs2_consist_i(struct gfs2_sbd *sdp, const char *function,
char *file, unsigned int line)
{
gfs2_lm(sdp,
"fatal: filesystem consistency error - function = %s, file = %s, line = %u\n",
function, file, line);
gfs2_withdraw(sdp);
}
/**
* gfs2_consist_inode_i - Flag an inode consistency error and withdraw
*/
void gfs2_consist_inode_i(struct gfs2_inode *ip,
const char *function, char *file, unsigned int line)
{
struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
gfs2_lm(sdp,
"fatal: filesystem consistency error\n"
" inode = %llu %llu\n"
" function = %s, file = %s, line = %u\n",
(unsigned long long)ip->i_no_formal_ino,
(unsigned long long)ip->i_no_addr,
function, file, line);
gfs2_withdraw(sdp);
}
/**
* gfs2_consist_rgrpd_i - Flag a RG consistency error and withdraw
*/
void gfs2_consist_rgrpd_i(struct gfs2_rgrpd *rgd,
const char *function, char *file, unsigned int line)
{
struct gfs2_sbd *sdp = rgd->rd_sbd;
char fs_id_buf[sizeof(sdp->sd_fsname) + 7];
sprintf(fs_id_buf, "fsid=%s: ", sdp->sd_fsname);
gfs2_rgrp_dump(NULL, rgd, fs_id_buf);
gfs2_lm(sdp,
"fatal: filesystem consistency error\n"
" RG = %llu\n"
" function = %s, file = %s, line = %u\n",
(unsigned long long)rgd->rd_addr,
function, file, line);
gfs2_withdraw(sdp);
}
/**
* gfs2_meta_check_ii - Flag a magic number consistency error and withdraw
* Returns: -1 if this call withdrew the machine,
* -2 if it was already withdrawn
*/
int gfs2_meta_check_ii(struct gfs2_sbd *sdp, struct buffer_head *bh,
const char *type, const char *function, char *file,
unsigned int line)
{
int me;
gfs2_lm(sdp,
"fatal: invalid metadata block\n"
" bh = %llu (%s)\n"
" function = %s, file = %s, line = %u\n",
(unsigned long long)bh->b_blocknr, type,
function, file, line);
me = gfs2_withdraw(sdp);
return (me) ? -1 : -2;
}
/**
* gfs2_metatype_check_ii - Flag a metadata type consistency error and withdraw
* Returns: -1 if this call withdrew the machine,
* -2 if it was already withdrawn
*/
int gfs2_metatype_check_ii(struct gfs2_sbd *sdp, struct buffer_head *bh,
u16 type, u16 t, const char *function,
char *file, unsigned int line)
{
int me;
gfs2_lm(sdp,
"fatal: invalid metadata block\n"
" bh = %llu (type: exp=%u, found=%u)\n"
" function = %s, file = %s, line = %u\n",
(unsigned long long)bh->b_blocknr, type, t,
function, file, line);
me = gfs2_withdraw(sdp);
return (me) ? -1 : -2;
}
/**
* gfs2_io_error_i - Flag an I/O error and withdraw
* Returns: -1 if this call withdrew the machine,
* 0 if it was already withdrawn
*/
int gfs2_io_error_i(struct gfs2_sbd *sdp, const char *function, char *file,
unsigned int line)
{
gfs2_lm(sdp,
"fatal: I/O error\n"
" function = %s, file = %s, line = %u\n",
function, file, line);
return gfs2_withdraw(sdp);
}
/**
* gfs2_io_error_bh_i - Flag a buffer I/O error
* @withdraw: withdraw the filesystem
*/
void gfs2_io_error_bh_i(struct gfs2_sbd *sdp, struct buffer_head *bh,
const char *function, char *file, unsigned int line,
bool withdraw)
{
if (gfs2_withdrawn(sdp))
return;
fs_err(sdp, "fatal: I/O error\n"
" block = %llu\n"
" function = %s, file = %s, line = %u\n",
(unsigned long long)bh->b_blocknr, function, file, line);
if (withdraw)
gfs2_withdraw(sdp);
}
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