linux/fs/gfs2/glops.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
*/
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/gfs2_ondisk.h>
#include <linux/bio.h>
#include <linux/posix_acl.h>
#include <linux/security.h>
#include "gfs2.h"
#include "incore.h"
#include "bmap.h"
#include "glock.h"
#include "glops.h"
#include "inode.h"
#include "log.h"
#include "meta_io.h"
#include "recovery.h"
#include "rgrp.h"
#include "util.h"
#include "trans.h"
#include "dir.h"
#include "lops.h"
struct workqueue_struct *gfs2_freeze_wq;
gfs2: Force withdraw to replay journals and wait for it to finish When a node withdraws from a file system, it often leaves its journal in an incomplete state. This is especially true when the withdraw is caused by io errors writing to the journal. Before this patch, a withdraw would try to write a "shutdown" record to the journal, tell dlm it's done with the file system, and none of the other nodes know about the problem. Later, when the problem is fixed and the withdrawn node is rebooted, it would then discover that its own journal was incomplete, and replay it. However, replaying it at this point is almost guaranteed to introduce corruption because the other nodes are likely to have used affected resource groups that appeared in the journal since the time of the withdraw. Replaying the journal later will overwrite any changes made, and not through any fault of dlm, which was instructed during the withdraw to release those resources. This patch makes file system withdraws seen by the entire cluster. Withdrawing nodes dequeue their journal glock to allow recovery. The remaining nodes check all the journals to see if they are clean or in need of replay. They try to replay dirty journals, but only the journals of withdrawn nodes will be "not busy" and therefore available for replay. Until the journal replay is complete, no i/o related glocks may be given out, to ensure that the replay does not cause the aforementioned corruption: We cannot allow any journal replay to overwrite blocks associated with a glock once it is held. The "live" glock which is now used to signal when a withdraw occurs. When a withdraw occurs, the node signals its withdraw by dequeueing the "live" glock and trying to enqueue it in EX mode, thus forcing the other nodes to all see a demote request, by way of a "1CB" (one callback) try lock. The "live" glock is not granted in EX; the callback is only just used to indicate a withdraw has occurred. Note that all nodes in the cluster must wait for the recovering node to finish replaying the withdrawing node's journal before continuing. To this end, it checks that the journals are clean multiple times in a retry loop. Also note that the withdraw function may be called from a wide variety of situations, and therefore, we need to take extra precautions to make sure pointers are valid before using them in many circumstances. We also need to take care when glocks decide to withdraw, since the withdraw code now uses glocks. Also, before this patch, if a process encountered an error and decided to withdraw, if another process was already withdrawing, the second withdraw would be silently ignored, which set it free to unlock its glocks. That's correct behavior if the original withdrawer encounters further errors down the road. But if secondary waiters don't wait for the journal replay, unlocking glocks will allow other nodes to use them, despite the fact that the journal containing those blocks is being replayed. The replay needs to finish before our glocks are released to other nodes. IOW, secondary withdraws need to wait for the first withdraw to finish. For example, if an rgrp glock is unlocked by a process that didn't wait for the first withdraw, a journal replay could introduce file system corruption by replaying a rgrp block that has already been granted to a different cluster node. Signed-off-by: Bob Peterson <rpeterso@redhat.com>
2020-01-28 19:23:45 +00:00
extern struct workqueue_struct *gfs2_control_wq;
static void gfs2_ail_error(struct gfs2_glock *gl, const struct buffer_head *bh)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
fs_err(sdp,
"AIL buffer %p: blocknr %llu state 0x%08lx mapping %p page "
"state 0x%lx\n",
bh, (unsigned long long)bh->b_blocknr, bh->b_state,
bh->b_folio->mapping, bh->b_folio->flags);
fs_err(sdp, "AIL glock %u:%llu mapping %p\n",
gl->gl_name.ln_type, gl->gl_name.ln_number,
gfs2_glock2aspace(gl));
gfs2_lm(sdp, "AIL error\n");
gfs2_withdraw_delayed(sdp);
}
/**
* __gfs2_ail_flush - remove all buffers for a given lock from the AIL
* @gl: the glock
* @fsync: set when called from fsync (not all buffers will be clean)
* @nr_revokes: Number of buffers to revoke
*
* None of the buffers should be dirty, locked, or pinned.
*/
static void __gfs2_ail_flush(struct gfs2_glock *gl, bool fsync,
unsigned int nr_revokes)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
struct list_head *head = &gl->gl_ail_list;
struct gfs2_bufdata *bd, *tmp;
struct buffer_head *bh;
const unsigned long b_state = (1UL << BH_Dirty)|(1UL << BH_Pinned)|(1UL << BH_Lock);
gfs2_log_lock(sdp);
spin_lock(&sdp->sd_ail_lock);
list_for_each_entry_safe_reverse(bd, tmp, head, bd_ail_gl_list) {
if (nr_revokes == 0)
break;
bh = bd->bd_bh;
if (bh->b_state & b_state) {
if (fsync)
continue;
gfs2_ail_error(gl, bh);
}
gfs2_trans_add_revoke(sdp, bd);
nr_revokes--;
}
GLOCK_BUG_ON(gl, !fsync && atomic_read(&gl->gl_ail_count));
spin_unlock(&sdp->sd_ail_lock);
gfs2_log_unlock(sdp);
if (gfs2_withdrawing(sdp))
gfs2_withdraw(sdp);
}
static int gfs2_ail_empty_gl(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
struct gfs2_trans tr;
unsigned int revokes;
int ret = 0;
revokes = atomic_read(&gl->gl_ail_count);
if (!revokes) {
bool have_revokes;
bool log_in_flight;
/*
* We have nothing on the ail, but there could be revokes on
* the sdp revoke queue, in which case, we still want to flush
* the log and wait for it to finish.
*
* If the sdp revoke list is empty too, we might still have an
* io outstanding for writing revokes, so we should wait for
* it before returning.
*
* If none of these conditions are true, our revokes are all
* flushed and we can return.
*/
gfs2_log_lock(sdp);
have_revokes = !list_empty(&sdp->sd_log_revokes);
log_in_flight = atomic_read(&sdp->sd_log_in_flight);
gfs2_log_unlock(sdp);
if (have_revokes)
goto flush;
if (log_in_flight)
log_flush_wait(sdp);
return 0;
}
memset(&tr, 0, sizeof(tr));
set_bit(TR_ONSTACK, &tr.tr_flags);
ret = __gfs2_trans_begin(&tr, sdp, 0, revokes, _RET_IP_);
if (ret) {
fs_err(sdp, "Transaction error %d: Unable to write revokes.", ret);
goto flush;
}
__gfs2_ail_flush(gl, 0, revokes);
gfs2_trans_end(sdp);
flush:
if (!ret)
gfs2_log_flush(sdp, NULL, GFS2_LOG_HEAD_FLUSH_NORMAL |
GFS2_LFC_AIL_EMPTY_GL);
return ret;
}
void gfs2_ail_flush(struct gfs2_glock *gl, bool fsync)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
unsigned int revokes = atomic_read(&gl->gl_ail_count);
int ret;
if (!revokes)
return;
ret = gfs2_trans_begin(sdp, 0, revokes);
if (ret)
return;
__gfs2_ail_flush(gl, fsync, revokes);
gfs2_trans_end(sdp);
gfs2_log_flush(sdp, NULL, GFS2_LOG_HEAD_FLUSH_NORMAL |
GFS2_LFC_AIL_FLUSH);
}
/**
* gfs2_rgrp_metasync - sync out the metadata of a resource group
* @gl: the glock protecting the resource group
*
*/
static int gfs2_rgrp_metasync(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
struct address_space *metamapping = &sdp->sd_aspace;
struct gfs2_rgrpd *rgd = gfs2_glock2rgrp(gl);
const unsigned bsize = sdp->sd_sb.sb_bsize;
loff_t start = (rgd->rd_addr * bsize) & PAGE_MASK;
loff_t end = PAGE_ALIGN((rgd->rd_addr + rgd->rd_length) * bsize) - 1;
int error;
filemap_fdatawrite_range(metamapping, start, end);
error = filemap_fdatawait_range(metamapping, start, end);
WARN_ON_ONCE(error && !gfs2_withdrawing_or_withdrawn(sdp));
mapping_set_error(metamapping, error);
if (error)
gfs2_io_error(sdp);
return error;
}
/**
* rgrp_go_sync - sync out the metadata for this glock
* @gl: the glock
*
* Called when demoting or unlocking an EX glock. We must flush
* to disk all dirty buffers/pages relating to this glock, and must not
* return to caller to demote/unlock the glock until I/O is complete.
*/
static int rgrp_go_sync(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
gfs2: Rework how rgrp buffer_heads are managed Before this patch, the rgrp code had a serious problem related to how it managed buffer_heads for resource groups. The problem caused file system corruption, especially in cases of journal replay. When an rgrp glock was demoted to transfer ownership to a different cluster node, do_xmote() first calls rgrp_go_sync and then rgrp_go_inval, as expected. When it calls rgrp_go_sync, that called gfs2_rgrp_brelse() that dropped the buffer_head reference count. In most cases, the reference count went to zero, which is right. However, there were other places where the buffers are handled differently. After rgrp_go_sync, do_xmote called rgrp_go_inval which called gfs2_rgrp_brelse a second time, then rgrp_go_inval's call to truncate_inode_pages_range would get rid of the pages in memory, but only if the reference count drops to 0. Unfortunately, gfs2_rgrp_brelse was setting bi->bi_bh = NULL. So when rgrp_go_sync called gfs2_rgrp_brelse, it lost the pointer to the buffer_heads in cases where the reference count was still 1. Therefore, when rgrp_go_inval called gfs2_rgrp_brelse a second time, it failed the check for "if (bi->bi_bh)" and thus failed to call brelse a second time. Because of that, the reference count on those buffers sometimes failed to drop from 1 to 0. And that caused function truncate_inode_pages_range to keep the pages in page cache rather than freeing them. The next time the rgrp glock was acquired, the metadata read of the rgrp buffers re-used the pages in memory, which were now wrong because they were likely modified by the other node who acquired the glock in EX (which is why we demoted the glock). This re-use of the page cache caused corruption because changes made by the other nodes were never seen, so the bitmaps were inaccurate. For some reason, the problem became most apparent when journal replay forced the replay of rgrps in memory, which caused newer rgrp data to be overwritten by the older in-core pages. A big part of the problem was that the rgrp buffer were released in multiple places: The go_unlock function would release them when the glock was released rather than when the glock is demoted, which is clearly wrong because our intent was to cache them until the glock is demoted from SH or EX. This patch attempts to clean up the mess and make one consistent and centralized mechanism for managing the rgrp buffer_heads by implementing several changes: 1. It eliminates the call to gfs2_rgrp_brelse() from rgrp_go_sync. We don't want to release the buffers or zero the pointers when syncing for the reasons stated above. It only makes sense to release them when the glock is actually invalidated (go_inval). And when we do, then we set the bh pointers to NULL. 2. The go_unlock function (which was only used for rgrps) is eliminated, as we've talked about doing many times before. The go_unlock function was called too early in the glock dq process, and should not happen until the glock is invalidated. 3. It also eliminates the call to rgrp_brelse in gfs2_clear_rgrpd. That will now happen automatically when the rgrp glocks are demoted, and shouldn't happen any sooner or later than that. Instead, function gfs2_clear_rgrpd has been modified to demote the rgrp glocks, and therefore, free those pages, before the remaining glocks are culled by gfs2_gl_hash_clear. This prevents the gl_object from hanging around when the glocks are culled. Signed-off-by: Bob Peterson <rpeterso@redhat.com> Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
2019-11-13 17:50:30 +00:00
struct gfs2_rgrpd *rgd = gfs2_glock2rgrp(gl);
int error;
if (!rgd || !test_and_clear_bit(GLF_DIRTY, &gl->gl_flags))
return 0;
GLOCK_BUG_ON(gl, gl->gl_state != LM_ST_EXCLUSIVE);
gfs2_log_flush(sdp, gl, GFS2_LOG_HEAD_FLUSH_NORMAL |
GFS2_LFC_RGRP_GO_SYNC);
error = gfs2_rgrp_metasync(gl);
if (!error)
error = gfs2_ail_empty_gl(gl);
gfs2_free_clones(rgd);
return error;
}
/**
* rgrp_go_inval - invalidate the metadata for this glock
* @gl: the glock
* @flags:
*
* We never used LM_ST_DEFERRED with resource groups, so that we
* should always see the metadata flag set here.
*
*/
static void rgrp_go_inval(struct gfs2_glock *gl, int flags)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
struct address_space *mapping = &sdp->sd_aspace;
struct gfs2_rgrpd *rgd = gfs2_glock2rgrp(gl);
const unsigned bsize = sdp->sd_sb.sb_bsize;
loff_t start, end;
if (!rgd)
return;
start = (rgd->rd_addr * bsize) & PAGE_MASK;
end = PAGE_ALIGN((rgd->rd_addr + rgd->rd_length) * bsize) - 1;
gfs2_rgrp_brelse(rgd);
WARN_ON_ONCE(!(flags & DIO_METADATA));
truncate_inode_pages_range(mapping, start, end);
}
static void gfs2_rgrp_go_dump(struct seq_file *seq, const struct gfs2_glock *gl,
const char *fs_id_buf)
{
struct gfs2_rgrpd *rgd = gl->gl_object;
if (rgd)
gfs2_rgrp_dump(seq, rgd, fs_id_buf);
}
static struct gfs2_inode *gfs2_glock2inode(struct gfs2_glock *gl)
{
struct gfs2_inode *ip;
spin_lock(&gl->gl_lockref.lock);
ip = gl->gl_object;
if (ip)
set_bit(GIF_GLOP_PENDING, &ip->i_flags);
spin_unlock(&gl->gl_lockref.lock);
return ip;
}
struct gfs2_rgrpd *gfs2_glock2rgrp(struct gfs2_glock *gl)
{
struct gfs2_rgrpd *rgd;
spin_lock(&gl->gl_lockref.lock);
rgd = gl->gl_object;
spin_unlock(&gl->gl_lockref.lock);
return rgd;
}
static void gfs2_clear_glop_pending(struct gfs2_inode *ip)
{
if (!ip)
return;
clear_bit_unlock(GIF_GLOP_PENDING, &ip->i_flags);
wake_up_bit(&ip->i_flags, GIF_GLOP_PENDING);
}
/**
* gfs2_inode_metasync - sync out the metadata of an inode
* @gl: the glock protecting the inode
*
*/
int gfs2_inode_metasync(struct gfs2_glock *gl)
{
struct address_space *metamapping = gfs2_glock2aspace(gl);
int error;
filemap_fdatawrite(metamapping);
error = filemap_fdatawait(metamapping);
if (error)
gfs2_io_error(gl->gl_name.ln_sbd);
return error;
}
/**
* inode_go_sync - Sync the dirty metadata of an inode
* @gl: the glock protecting the inode
*
*/
static int inode_go_sync(struct gfs2_glock *gl)
{
struct gfs2_inode *ip = gfs2_glock2inode(gl);
int isreg = ip && S_ISREG(ip->i_inode.i_mode);
struct address_space *metamapping = gfs2_glock2aspace(gl);
int error = 0, ret;
if (isreg) {
if (test_and_clear_bit(GIF_SW_PAGED, &ip->i_flags))
unmap_shared_mapping_range(ip->i_inode.i_mapping, 0, 0);
inode_dio_wait(&ip->i_inode);
}
if (!test_and_clear_bit(GLF_DIRTY, &gl->gl_flags))
goto out;
GLOCK_BUG_ON(gl, gl->gl_state != LM_ST_EXCLUSIVE);
gfs2_log_flush(gl->gl_name.ln_sbd, gl, GFS2_LOG_HEAD_FLUSH_NORMAL |
GFS2_LFC_INODE_GO_SYNC);
filemap_fdatawrite(metamapping);
if (isreg) {
struct address_space *mapping = ip->i_inode.i_mapping;
filemap_fdatawrite(mapping);
error = filemap_fdatawait(mapping);
mapping_set_error(mapping, error);
}
ret = gfs2_inode_metasync(gl);
if (!error)
error = ret;
ret = gfs2_ail_empty_gl(gl);
if (!error)
error = ret;
/*
* Writeback of the data mapping may cause the dirty flag to be set
* so we have to clear it again here.
*/
smp_mb__before_atomic();
clear_bit(GLF_DIRTY, &gl->gl_flags);
out:
gfs2_clear_glop_pending(ip);
return error;
}
/**
* inode_go_inval - prepare a inode glock to be released
* @gl: the glock
* @flags:
*
* Normally we invalidate everything, but if we are moving into
* LM_ST_DEFERRED from LM_ST_SHARED or LM_ST_EXCLUSIVE then we
* can keep hold of the metadata, since it won't have changed.
*
*/
static void inode_go_inval(struct gfs2_glock *gl, int flags)
{
struct gfs2_inode *ip = gfs2_glock2inode(gl);
if (flags & DIO_METADATA) {
struct address_space *mapping = gfs2_glock2aspace(gl);
truncate_inode_pages(mapping, 0);
if (ip) {
gfs2: fix GL_SKIP node_scope problems Before this patch, when a glock was locked, the very first holder on the queue would unlock the lockref and call the go_instantiate glops function (if one existed), unless GL_SKIP was specified. When we introduced the new node-scope concept, we allowed multiple holders to lock glocks in EX mode and share the lock. But node-scope introduced a new problem: if the first holder has GL_SKIP and the next one does NOT, since it is not the first holder on the queue, the go_instantiate op was not called. Eventually the GL_SKIP holder may call the instantiate sub-function (e.g. gfs2_rgrp_bh_get) but there was still a window of time in which another non-GL_SKIP holder assumes the instantiate function had been called by the first holder. In the case of rgrp glocks, this led to a NULL pointer dereference on the buffer_heads. This patch tries to fix the problem by introducing two new glock flags: GLF_INSTANTIATE_NEEDED, which keeps track of when the instantiate function needs to be called to "fill in" or "read in" the object before it is referenced. GLF_INSTANTIATE_IN_PROG which is used to determine when a process is in the process of reading in the object. Whenever a function needs to reference the object, it checks the GLF_INSTANTIATE_NEEDED flag, and if set, it sets GLF_INSTANTIATE_IN_PROG and calls the glops "go_instantiate" function. As before, the gl_lockref spin_lock is unlocked during the IO operation, which may take a relatively long amount of time to complete. While unlocked, if another process determines go_instantiate is still needed, it sees GLF_INSTANTIATE_IN_PROG is set, and waits for the go_instantiate glop operation to be completed. Once GLF_INSTANTIATE_IN_PROG is cleared, it needs to check GLF_INSTANTIATE_NEEDED again because the other process's go_instantiate operation may not have been successful. Functions that previously called the instantiate sub-functions now call directly into gfs2_instantiate so the new bits are managed properly. Signed-off-by: Bob Peterson <rpeterso@redhat.com> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2021-10-06 14:29:18 +00:00
set_bit(GLF_INSTANTIATE_NEEDED, &gl->gl_flags);
forget_all_cached_acls(&ip->i_inode);
security_inode_invalidate_secctx(&ip->i_inode);
gfs2_dir_hash_inval(ip);
}
}
if (ip == GFS2_I(gl->gl_name.ln_sbd->sd_rindex)) {
gfs2_log_flush(gl->gl_name.ln_sbd, NULL,
GFS2_LOG_HEAD_FLUSH_NORMAL |
GFS2_LFC_INODE_GO_INVAL);
gl->gl_name.ln_sbd->sd_rindex_uptodate = 0;
}
if (ip && S_ISREG(ip->i_inode.i_mode))
truncate_inode_pages(ip->i_inode.i_mapping, 0);
gfs2_clear_glop_pending(ip);
}
static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf)
{
struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
const struct gfs2_dinode *str = buf;
struct timespec64 atime, iatime;
u16 height, depth;
umode_t mode = be32_to_cpu(str->di_mode);
struct inode *inode = &ip->i_inode;
bool is_new = inode->i_state & I_NEW;
if (unlikely(ip->i_no_addr != be64_to_cpu(str->di_num.no_addr))) {
gfs2_consist_inode(ip);
return -EIO;
}
if (unlikely(!is_new && inode_wrong_type(inode, mode))) {
gfs2_consist_inode(ip);
return -EIO;
}
ip->i_no_formal_ino = be64_to_cpu(str->di_num.no_formal_ino);
inode->i_mode = mode;
if (is_new) {
inode->i_rdev = 0;
switch (mode & S_IFMT) {
case S_IFBLK:
case S_IFCHR:
inode->i_rdev = MKDEV(be32_to_cpu(str->di_major),
be32_to_cpu(str->di_minor));
break;
}
}
i_uid_write(inode, be32_to_cpu(str->di_uid));
i_gid_write(inode, be32_to_cpu(str->di_gid));
set_nlink(inode, be32_to_cpu(str->di_nlink));
i_size_write(inode, be64_to_cpu(str->di_size));
gfs2_set_inode_blocks(inode, be64_to_cpu(str->di_blocks));
atime.tv_sec = be64_to_cpu(str->di_atime);
atime.tv_nsec = be32_to_cpu(str->di_atime_nsec);
iatime = inode_get_atime(inode);
if (timespec64_compare(&iatime, &atime) < 0)
inode_set_atime_to_ts(inode, atime);
inode_set_mtime(inode, be64_to_cpu(str->di_mtime),
be32_to_cpu(str->di_mtime_nsec));
inode_set_ctime(inode, be64_to_cpu(str->di_ctime),
be32_to_cpu(str->di_ctime_nsec));
ip->i_goal = be64_to_cpu(str->di_goal_meta);
ip->i_generation = be64_to_cpu(str->di_generation);
ip->i_diskflags = be32_to_cpu(str->di_flags);
ip->i_eattr = be64_to_cpu(str->di_eattr);
/* i_diskflags and i_eattr must be set before gfs2_set_inode_flags() */
gfs2_set_inode_flags(inode);
height = be16_to_cpu(str->di_height);
if (unlikely(height > sdp->sd_max_height)) {
gfs2_consist_inode(ip);
return -EIO;
}
ip->i_height = (u8)height;
depth = be16_to_cpu(str->di_depth);
if (unlikely(depth > GFS2_DIR_MAX_DEPTH)) {
gfs2_consist_inode(ip);
return -EIO;
}
ip->i_depth = (u8)depth;
ip->i_entries = be32_to_cpu(str->di_entries);
if (gfs2_is_stuffed(ip) && inode->i_size > gfs2_max_stuffed_size(ip)) {
gfs2_consist_inode(ip);
return -EIO;
}
if (S_ISREG(inode->i_mode))
gfs2_set_aops(inode);
return 0;
}
/**
* gfs2_inode_refresh - Refresh the incore copy of the dinode
* @ip: The GFS2 inode
*
* Returns: errno
*/
int gfs2_inode_refresh(struct gfs2_inode *ip)
{
struct buffer_head *dibh;
int error;
error = gfs2_meta_inode_buffer(ip, &dibh);
if (error)
return error;
error = gfs2_dinode_in(ip, dibh->b_data);
brelse(dibh);
return error;
}
/**
* inode_go_instantiate - read in an inode if necessary
* @gl: The glock
*
* Returns: errno
*/
static int inode_go_instantiate(struct gfs2_glock *gl)
{
struct gfs2_inode *ip = gl->gl_object;
gfs2: fix GL_SKIP node_scope problems Before this patch, when a glock was locked, the very first holder on the queue would unlock the lockref and call the go_instantiate glops function (if one existed), unless GL_SKIP was specified. When we introduced the new node-scope concept, we allowed multiple holders to lock glocks in EX mode and share the lock. But node-scope introduced a new problem: if the first holder has GL_SKIP and the next one does NOT, since it is not the first holder on the queue, the go_instantiate op was not called. Eventually the GL_SKIP holder may call the instantiate sub-function (e.g. gfs2_rgrp_bh_get) but there was still a window of time in which another non-GL_SKIP holder assumes the instantiate function had been called by the first holder. In the case of rgrp glocks, this led to a NULL pointer dereference on the buffer_heads. This patch tries to fix the problem by introducing two new glock flags: GLF_INSTANTIATE_NEEDED, which keeps track of when the instantiate function needs to be called to "fill in" or "read in" the object before it is referenced. GLF_INSTANTIATE_IN_PROG which is used to determine when a process is in the process of reading in the object. Whenever a function needs to reference the object, it checks the GLF_INSTANTIATE_NEEDED flag, and if set, it sets GLF_INSTANTIATE_IN_PROG and calls the glops "go_instantiate" function. As before, the gl_lockref spin_lock is unlocked during the IO operation, which may take a relatively long amount of time to complete. While unlocked, if another process determines go_instantiate is still needed, it sees GLF_INSTANTIATE_IN_PROG is set, and waits for the go_instantiate glop operation to be completed. Once GLF_INSTANTIATE_IN_PROG is cleared, it needs to check GLF_INSTANTIATE_NEEDED again because the other process's go_instantiate operation may not have been successful. Functions that previously called the instantiate sub-functions now call directly into gfs2_instantiate so the new bits are managed properly. Signed-off-by: Bob Peterson <rpeterso@redhat.com> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2021-10-06 14:29:18 +00:00
if (!ip) /* no inode to populate - read it in later */
return 0;
return gfs2_inode_refresh(ip);
}
static int inode_go_held(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
struct gfs2_inode *ip = gl->gl_object;
int error = 0;
if (!ip) /* no inode to populate - read it in later */
return 0;
if (gh->gh_state != LM_ST_DEFERRED)
inode_dio_wait(&ip->i_inode);
if ((ip->i_diskflags & GFS2_DIF_TRUNC_IN_PROG) &&
(gl->gl_state == LM_ST_EXCLUSIVE) &&
(gh->gh_state == LM_ST_EXCLUSIVE))
error = gfs2_truncatei_resume(ip);
return error;
}
/**
* inode_go_dump - print information about an inode
* @seq: The iterator
* @gl: The glock
* @fs_id_buf: file system id (may be empty)
*
*/
static void inode_go_dump(struct seq_file *seq, const struct gfs2_glock *gl,
const char *fs_id_buf)
{
struct gfs2_inode *ip = gl->gl_object;
const struct inode *inode = &ip->i_inode;
if (ip == NULL)
return;
gfs2_print_dbg(seq, "%s I: n:%llu/%llu t:%u f:0x%02lx d:0x%08x s:%llu "
"p:%lu\n", fs_id_buf,
(unsigned long long)ip->i_no_formal_ino,
(unsigned long long)ip->i_no_addr,
IF2DT(inode->i_mode), ip->i_flags,
(unsigned int)ip->i_diskflags,
(unsigned long long)i_size_read(inode),
inode->i_data.nrpages);
}
/**
gfs2: Rework freeze / thaw logic So far, at mount time, gfs2 would take the freeze glock in shared mode and then immediately drop it again, turning it into a cached glock that can be reclaimed at any time. To freeze the filesystem cluster-wide, the node initiating the freeze would take the freeze glock in exclusive mode, which would cause the freeze glock's freeze_go_sync() callback to run on each node. There, gfs2 would freeze the filesystem and schedule gfs2_freeze_func() to run. gfs2_freeze_func() would re-acquire the freeze glock in shared mode, thaw the filesystem, and drop the freeze glock again. The initiating node would keep the freeze glock held in exclusive mode. To thaw the filesystem, the initiating node would drop the freeze glock again, which would allow gfs2_freeze_func() to resume on all nodes, leaving the filesystem in the thawed state. It turns out that in freeze_go_sync(), we cannot reliably and safely freeze the filesystem. This is primarily because the final unmount of a filesystem takes a write lock on the s_umount rw semaphore before calling into gfs2_put_super(), and freeze_go_sync() needs to call freeze_super() which also takes a write lock on the same semaphore, causing a deadlock. We could work around this by trying to take an active reference on the super block first, which would prevent unmount from running at the same time. But that can fail, and freeze_go_sync() isn't actually allowed to fail. To get around this, this patch changes the freeze glock locking scheme as follows: At mount time, each node takes the freeze glock in shared mode. To freeze a filesystem, the initiating node first freezes the filesystem locally and then drops and re-acquires the freeze glock in exclusive mode. All other nodes notice that there is contention on the freeze glock in their go_callback callbacks, and they schedule gfs2_freeze_func() to run. There, they freeze the filesystem locally and drop and re-acquire the freeze glock before re-thawing the filesystem. This is happening outside of the glock state engine, so there, we are allowed to fail. From a cluster point of view, taking and immediately dropping a glock is indistinguishable from taking the glock and only dropping it upon contention, so this new scheme is compatible with the old one. Thanks to Li Dong <lidong@vivo.com> for reporting a locking bug in gfs2_freeze_func() in a previous version of this commit. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2022-11-14 22:34:50 +00:00
* freeze_go_callback - A cluster node is requesting a freeze
* @gl: the glock
gfs2: Rework freeze / thaw logic So far, at mount time, gfs2 would take the freeze glock in shared mode and then immediately drop it again, turning it into a cached glock that can be reclaimed at any time. To freeze the filesystem cluster-wide, the node initiating the freeze would take the freeze glock in exclusive mode, which would cause the freeze glock's freeze_go_sync() callback to run on each node. There, gfs2 would freeze the filesystem and schedule gfs2_freeze_func() to run. gfs2_freeze_func() would re-acquire the freeze glock in shared mode, thaw the filesystem, and drop the freeze glock again. The initiating node would keep the freeze glock held in exclusive mode. To thaw the filesystem, the initiating node would drop the freeze glock again, which would allow gfs2_freeze_func() to resume on all nodes, leaving the filesystem in the thawed state. It turns out that in freeze_go_sync(), we cannot reliably and safely freeze the filesystem. This is primarily because the final unmount of a filesystem takes a write lock on the s_umount rw semaphore before calling into gfs2_put_super(), and freeze_go_sync() needs to call freeze_super() which also takes a write lock on the same semaphore, causing a deadlock. We could work around this by trying to take an active reference on the super block first, which would prevent unmount from running at the same time. But that can fail, and freeze_go_sync() isn't actually allowed to fail. To get around this, this patch changes the freeze glock locking scheme as follows: At mount time, each node takes the freeze glock in shared mode. To freeze a filesystem, the initiating node first freezes the filesystem locally and then drops and re-acquires the freeze glock in exclusive mode. All other nodes notice that there is contention on the freeze glock in their go_callback callbacks, and they schedule gfs2_freeze_func() to run. There, they freeze the filesystem locally and drop and re-acquire the freeze glock before re-thawing the filesystem. This is happening outside of the glock state engine, so there, we are allowed to fail. From a cluster point of view, taking and immediately dropping a glock is indistinguishable from taking the glock and only dropping it upon contention, so this new scheme is compatible with the old one. Thanks to Li Dong <lidong@vivo.com> for reporting a locking bug in gfs2_freeze_func() in a previous version of this commit. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2022-11-14 22:34:50 +00:00
* @remote: true if this came from a different cluster node
*/
gfs2: Rework freeze / thaw logic So far, at mount time, gfs2 would take the freeze glock in shared mode and then immediately drop it again, turning it into a cached glock that can be reclaimed at any time. To freeze the filesystem cluster-wide, the node initiating the freeze would take the freeze glock in exclusive mode, which would cause the freeze glock's freeze_go_sync() callback to run on each node. There, gfs2 would freeze the filesystem and schedule gfs2_freeze_func() to run. gfs2_freeze_func() would re-acquire the freeze glock in shared mode, thaw the filesystem, and drop the freeze glock again. The initiating node would keep the freeze glock held in exclusive mode. To thaw the filesystem, the initiating node would drop the freeze glock again, which would allow gfs2_freeze_func() to resume on all nodes, leaving the filesystem in the thawed state. It turns out that in freeze_go_sync(), we cannot reliably and safely freeze the filesystem. This is primarily because the final unmount of a filesystem takes a write lock on the s_umount rw semaphore before calling into gfs2_put_super(), and freeze_go_sync() needs to call freeze_super() which also takes a write lock on the same semaphore, causing a deadlock. We could work around this by trying to take an active reference on the super block first, which would prevent unmount from running at the same time. But that can fail, and freeze_go_sync() isn't actually allowed to fail. To get around this, this patch changes the freeze glock locking scheme as follows: At mount time, each node takes the freeze glock in shared mode. To freeze a filesystem, the initiating node first freezes the filesystem locally and then drops and re-acquires the freeze glock in exclusive mode. All other nodes notice that there is contention on the freeze glock in their go_callback callbacks, and they schedule gfs2_freeze_func() to run. There, they freeze the filesystem locally and drop and re-acquire the freeze glock before re-thawing the filesystem. This is happening outside of the glock state engine, so there, we are allowed to fail. From a cluster point of view, taking and immediately dropping a glock is indistinguishable from taking the glock and only dropping it upon contention, so this new scheme is compatible with the old one. Thanks to Li Dong <lidong@vivo.com> for reporting a locking bug in gfs2_freeze_func() in a previous version of this commit. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2022-11-14 22:34:50 +00:00
static void freeze_go_callback(struct gfs2_glock *gl, bool remote)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
gfs2: Rework freeze / thaw logic So far, at mount time, gfs2 would take the freeze glock in shared mode and then immediately drop it again, turning it into a cached glock that can be reclaimed at any time. To freeze the filesystem cluster-wide, the node initiating the freeze would take the freeze glock in exclusive mode, which would cause the freeze glock's freeze_go_sync() callback to run on each node. There, gfs2 would freeze the filesystem and schedule gfs2_freeze_func() to run. gfs2_freeze_func() would re-acquire the freeze glock in shared mode, thaw the filesystem, and drop the freeze glock again. The initiating node would keep the freeze glock held in exclusive mode. To thaw the filesystem, the initiating node would drop the freeze glock again, which would allow gfs2_freeze_func() to resume on all nodes, leaving the filesystem in the thawed state. It turns out that in freeze_go_sync(), we cannot reliably and safely freeze the filesystem. This is primarily because the final unmount of a filesystem takes a write lock on the s_umount rw semaphore before calling into gfs2_put_super(), and freeze_go_sync() needs to call freeze_super() which also takes a write lock on the same semaphore, causing a deadlock. We could work around this by trying to take an active reference on the super block first, which would prevent unmount from running at the same time. But that can fail, and freeze_go_sync() isn't actually allowed to fail. To get around this, this patch changes the freeze glock locking scheme as follows: At mount time, each node takes the freeze glock in shared mode. To freeze a filesystem, the initiating node first freezes the filesystem locally and then drops and re-acquires the freeze glock in exclusive mode. All other nodes notice that there is contention on the freeze glock in their go_callback callbacks, and they schedule gfs2_freeze_func() to run. There, they freeze the filesystem locally and drop and re-acquire the freeze glock before re-thawing the filesystem. This is happening outside of the glock state engine, so there, we are allowed to fail. From a cluster point of view, taking and immediately dropping a glock is indistinguishable from taking the glock and only dropping it upon contention, so this new scheme is compatible with the old one. Thanks to Li Dong <lidong@vivo.com> for reporting a locking bug in gfs2_freeze_func() in a previous version of this commit. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2022-11-14 22:34:50 +00:00
struct super_block *sb = sdp->sd_vfs;
if (!remote ||
(gl->gl_state != LM_ST_SHARED &&
gl->gl_state != LM_ST_UNLOCKED) ||
gfs2: Rework freeze / thaw logic So far, at mount time, gfs2 would take the freeze glock in shared mode and then immediately drop it again, turning it into a cached glock that can be reclaimed at any time. To freeze the filesystem cluster-wide, the node initiating the freeze would take the freeze glock in exclusive mode, which would cause the freeze glock's freeze_go_sync() callback to run on each node. There, gfs2 would freeze the filesystem and schedule gfs2_freeze_func() to run. gfs2_freeze_func() would re-acquire the freeze glock in shared mode, thaw the filesystem, and drop the freeze glock again. The initiating node would keep the freeze glock held in exclusive mode. To thaw the filesystem, the initiating node would drop the freeze glock again, which would allow gfs2_freeze_func() to resume on all nodes, leaving the filesystem in the thawed state. It turns out that in freeze_go_sync(), we cannot reliably and safely freeze the filesystem. This is primarily because the final unmount of a filesystem takes a write lock on the s_umount rw semaphore before calling into gfs2_put_super(), and freeze_go_sync() needs to call freeze_super() which also takes a write lock on the same semaphore, causing a deadlock. We could work around this by trying to take an active reference on the super block first, which would prevent unmount from running at the same time. But that can fail, and freeze_go_sync() isn't actually allowed to fail. To get around this, this patch changes the freeze glock locking scheme as follows: At mount time, each node takes the freeze glock in shared mode. To freeze a filesystem, the initiating node first freezes the filesystem locally and then drops and re-acquires the freeze glock in exclusive mode. All other nodes notice that there is contention on the freeze glock in their go_callback callbacks, and they schedule gfs2_freeze_func() to run. There, they freeze the filesystem locally and drop and re-acquire the freeze glock before re-thawing the filesystem. This is happening outside of the glock state engine, so there, we are allowed to fail. From a cluster point of view, taking and immediately dropping a glock is indistinguishable from taking the glock and only dropping it upon contention, so this new scheme is compatible with the old one. Thanks to Li Dong <lidong@vivo.com> for reporting a locking bug in gfs2_freeze_func() in a previous version of this commit. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2022-11-14 22:34:50 +00:00
gl->gl_demote_state != LM_ST_UNLOCKED)
return;
/*
gfs2: Rework freeze / thaw logic So far, at mount time, gfs2 would take the freeze glock in shared mode and then immediately drop it again, turning it into a cached glock that can be reclaimed at any time. To freeze the filesystem cluster-wide, the node initiating the freeze would take the freeze glock in exclusive mode, which would cause the freeze glock's freeze_go_sync() callback to run on each node. There, gfs2 would freeze the filesystem and schedule gfs2_freeze_func() to run. gfs2_freeze_func() would re-acquire the freeze glock in shared mode, thaw the filesystem, and drop the freeze glock again. The initiating node would keep the freeze glock held in exclusive mode. To thaw the filesystem, the initiating node would drop the freeze glock again, which would allow gfs2_freeze_func() to resume on all nodes, leaving the filesystem in the thawed state. It turns out that in freeze_go_sync(), we cannot reliably and safely freeze the filesystem. This is primarily because the final unmount of a filesystem takes a write lock on the s_umount rw semaphore before calling into gfs2_put_super(), and freeze_go_sync() needs to call freeze_super() which also takes a write lock on the same semaphore, causing a deadlock. We could work around this by trying to take an active reference on the super block first, which would prevent unmount from running at the same time. But that can fail, and freeze_go_sync() isn't actually allowed to fail. To get around this, this patch changes the freeze glock locking scheme as follows: At mount time, each node takes the freeze glock in shared mode. To freeze a filesystem, the initiating node first freezes the filesystem locally and then drops and re-acquires the freeze glock in exclusive mode. All other nodes notice that there is contention on the freeze glock in their go_callback callbacks, and they schedule gfs2_freeze_func() to run. There, they freeze the filesystem locally and drop and re-acquire the freeze glock before re-thawing the filesystem. This is happening outside of the glock state engine, so there, we are allowed to fail. From a cluster point of view, taking and immediately dropping a glock is indistinguishable from taking the glock and only dropping it upon contention, so this new scheme is compatible with the old one. Thanks to Li Dong <lidong@vivo.com> for reporting a locking bug in gfs2_freeze_func() in a previous version of this commit. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2022-11-14 22:34:50 +00:00
* Try to get an active super block reference to prevent racing with
* unmount (see super_trylock_shared()). But note that unmount isn't
* the only place where a write lock on s_umount is taken, and we can
* fail here because of things like remount as well.
*/
gfs2: Rework freeze / thaw logic So far, at mount time, gfs2 would take the freeze glock in shared mode and then immediately drop it again, turning it into a cached glock that can be reclaimed at any time. To freeze the filesystem cluster-wide, the node initiating the freeze would take the freeze glock in exclusive mode, which would cause the freeze glock's freeze_go_sync() callback to run on each node. There, gfs2 would freeze the filesystem and schedule gfs2_freeze_func() to run. gfs2_freeze_func() would re-acquire the freeze glock in shared mode, thaw the filesystem, and drop the freeze glock again. The initiating node would keep the freeze glock held in exclusive mode. To thaw the filesystem, the initiating node would drop the freeze glock again, which would allow gfs2_freeze_func() to resume on all nodes, leaving the filesystem in the thawed state. It turns out that in freeze_go_sync(), we cannot reliably and safely freeze the filesystem. This is primarily because the final unmount of a filesystem takes a write lock on the s_umount rw semaphore before calling into gfs2_put_super(), and freeze_go_sync() needs to call freeze_super() which also takes a write lock on the same semaphore, causing a deadlock. We could work around this by trying to take an active reference on the super block first, which would prevent unmount from running at the same time. But that can fail, and freeze_go_sync() isn't actually allowed to fail. To get around this, this patch changes the freeze glock locking scheme as follows: At mount time, each node takes the freeze glock in shared mode. To freeze a filesystem, the initiating node first freezes the filesystem locally and then drops and re-acquires the freeze glock in exclusive mode. All other nodes notice that there is contention on the freeze glock in their go_callback callbacks, and they schedule gfs2_freeze_func() to run. There, they freeze the filesystem locally and drop and re-acquire the freeze glock before re-thawing the filesystem. This is happening outside of the glock state engine, so there, we are allowed to fail. From a cluster point of view, taking and immediately dropping a glock is indistinguishable from taking the glock and only dropping it upon contention, so this new scheme is compatible with the old one. Thanks to Li Dong <lidong@vivo.com> for reporting a locking bug in gfs2_freeze_func() in a previous version of this commit. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2022-11-14 22:34:50 +00:00
if (down_read_trylock(&sb->s_umount)) {
atomic_inc(&sb->s_active);
up_read(&sb->s_umount);
if (!queue_work(gfs2_freeze_wq, &sdp->sd_freeze_work))
deactivate_super(sb);
}
}
/**
GFS2: remove transaction glock GFS2 has a transaction glock, which must be grabbed for every transaction, whose purpose is to deal with freezing the filesystem. Aside from this involving a large amount of locking, it is very easy to make the current fsfreeze code hang on unfreezing. This patch rewrites how gfs2 handles freezing the filesystem. The transaction glock is removed. In it's place is a freeze glock, which is cached (but not held) in a shared state by every node in the cluster when the filesystem is mounted. This lock only needs to be grabbed on freezing, and actions which need to be safe from freezing, like recovery. When a node wants to freeze the filesystem, it grabs this glock exclusively. When the freeze glock state changes on the nodes (either from shared to unlocked, or shared to exclusive), the filesystem does a special log flush. gfs2_log_flush() does all the work for flushing out the and shutting down the incore log, and then it tries to grab the freeze glock in a shared state again. Since the filesystem is stuck in gfs2_log_flush, no new transaction can start, and nothing can be written to disk. Unfreezing the filesytem simply involes dropping the freeze glock, allowing gfs2_log_flush() to grab and then release the shared lock, so it is cached for next time. However, in order for the unfreezing ioctl to occur, gfs2 needs to get a shared lock on the filesystem root directory inode to check permissions. If that glock has already been grabbed exclusively, fsfreeze will be unable to get the shared lock and unfreeze the filesystem. In order to allow the unfreeze, this patch makes gfs2 grab a shared lock on the filesystem root directory during the freeze, and hold it until it unfreezes the filesystem. The functions which need to grab a shared lock in order to allow the unfreeze ioctl to be issued now use the lock grabbed by the freeze code instead. The freeze and unfreeze code take care to make sure that this shared lock will not be dropped while another process is using it. Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2014-05-02 03:26:55 +00:00
* freeze_go_xmote_bh - After promoting/demoting the freeze glock
* @gl: the glock
*/
static int freeze_go_xmote_bh(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
struct gfs2_inode *ip = GFS2_I(sdp->sd_jdesc->jd_inode);
struct gfs2_glock *j_gl = ip->i_gl;
struct gfs2_log_header_host head;
int error;
if (test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags)) {
j_gl->gl_ops->go_inval(j_gl, DIO_METADATA);
error = gfs2_find_jhead(sdp->sd_jdesc, &head, false);
if (gfs2_assert_withdraw_delayed(sdp, !error))
return error;
if (gfs2_assert_withdraw_delayed(sdp, head.lh_flags &
GFS2_LOG_HEAD_UNMOUNT))
return -EIO;
sdp->sd_log_sequence = head.lh_sequence + 1;
gfs2_log_pointers_init(sdp, head.lh_blkno);
}
return 0;
}
/**
* iopen_go_callback - schedule the dcache entry for the inode to be deleted
* @gl: the glock
* @remote: true if this came from a different cluster node
*
* gl_lockref.lock lock is held while calling this
*/
static void iopen_go_callback(struct gfs2_glock *gl, bool remote)
{
struct gfs2_inode *ip = gl->gl_object;
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
if (!remote || sb_rdonly(sdp->sd_vfs) ||
test_bit(SDF_KILL, &sdp->sd_flags))
return;
if (gl->gl_demote_state == LM_ST_UNLOCKED &&
gl->gl_state == LM_ST_SHARED && ip) {
gl->gl_lockref.count++;
if (!gfs2_queue_try_to_evict(gl))
gl->gl_lockref.count--;
}
}
gfs2: Force withdraw to replay journals and wait for it to finish When a node withdraws from a file system, it often leaves its journal in an incomplete state. This is especially true when the withdraw is caused by io errors writing to the journal. Before this patch, a withdraw would try to write a "shutdown" record to the journal, tell dlm it's done with the file system, and none of the other nodes know about the problem. Later, when the problem is fixed and the withdrawn node is rebooted, it would then discover that its own journal was incomplete, and replay it. However, replaying it at this point is almost guaranteed to introduce corruption because the other nodes are likely to have used affected resource groups that appeared in the journal since the time of the withdraw. Replaying the journal later will overwrite any changes made, and not through any fault of dlm, which was instructed during the withdraw to release those resources. This patch makes file system withdraws seen by the entire cluster. Withdrawing nodes dequeue their journal glock to allow recovery. The remaining nodes check all the journals to see if they are clean or in need of replay. They try to replay dirty journals, but only the journals of withdrawn nodes will be "not busy" and therefore available for replay. Until the journal replay is complete, no i/o related glocks may be given out, to ensure that the replay does not cause the aforementioned corruption: We cannot allow any journal replay to overwrite blocks associated with a glock once it is held. The "live" glock which is now used to signal when a withdraw occurs. When a withdraw occurs, the node signals its withdraw by dequeueing the "live" glock and trying to enqueue it in EX mode, thus forcing the other nodes to all see a demote request, by way of a "1CB" (one callback) try lock. The "live" glock is not granted in EX; the callback is only just used to indicate a withdraw has occurred. Note that all nodes in the cluster must wait for the recovering node to finish replaying the withdrawing node's journal before continuing. To this end, it checks that the journals are clean multiple times in a retry loop. Also note that the withdraw function may be called from a wide variety of situations, and therefore, we need to take extra precautions to make sure pointers are valid before using them in many circumstances. We also need to take care when glocks decide to withdraw, since the withdraw code now uses glocks. Also, before this patch, if a process encountered an error and decided to withdraw, if another process was already withdrawing, the second withdraw would be silently ignored, which set it free to unlock its glocks. That's correct behavior if the original withdrawer encounters further errors down the road. But if secondary waiters don't wait for the journal replay, unlocking glocks will allow other nodes to use them, despite the fact that the journal containing those blocks is being replayed. The replay needs to finish before our glocks are released to other nodes. IOW, secondary withdraws need to wait for the first withdraw to finish. For example, if an rgrp glock is unlocked by a process that didn't wait for the first withdraw, a journal replay could introduce file system corruption by replaying a rgrp block that has already been granted to a different cluster node. Signed-off-by: Bob Peterson <rpeterso@redhat.com>
2020-01-28 19:23:45 +00:00
/**
* inode_go_unlocked - wake up anyone waiting for dlm's unlock ast
* @gl: glock being unlocked
gfs2: Force withdraw to replay journals and wait for it to finish When a node withdraws from a file system, it often leaves its journal in an incomplete state. This is especially true when the withdraw is caused by io errors writing to the journal. Before this patch, a withdraw would try to write a "shutdown" record to the journal, tell dlm it's done with the file system, and none of the other nodes know about the problem. Later, when the problem is fixed and the withdrawn node is rebooted, it would then discover that its own journal was incomplete, and replay it. However, replaying it at this point is almost guaranteed to introduce corruption because the other nodes are likely to have used affected resource groups that appeared in the journal since the time of the withdraw. Replaying the journal later will overwrite any changes made, and not through any fault of dlm, which was instructed during the withdraw to release those resources. This patch makes file system withdraws seen by the entire cluster. Withdrawing nodes dequeue their journal glock to allow recovery. The remaining nodes check all the journals to see if they are clean or in need of replay. They try to replay dirty journals, but only the journals of withdrawn nodes will be "not busy" and therefore available for replay. Until the journal replay is complete, no i/o related glocks may be given out, to ensure that the replay does not cause the aforementioned corruption: We cannot allow any journal replay to overwrite blocks associated with a glock once it is held. The "live" glock which is now used to signal when a withdraw occurs. When a withdraw occurs, the node signals its withdraw by dequeueing the "live" glock and trying to enqueue it in EX mode, thus forcing the other nodes to all see a demote request, by way of a "1CB" (one callback) try lock. The "live" glock is not granted in EX; the callback is only just used to indicate a withdraw has occurred. Note that all nodes in the cluster must wait for the recovering node to finish replaying the withdrawing node's journal before continuing. To this end, it checks that the journals are clean multiple times in a retry loop. Also note that the withdraw function may be called from a wide variety of situations, and therefore, we need to take extra precautions to make sure pointers are valid before using them in many circumstances. We also need to take care when glocks decide to withdraw, since the withdraw code now uses glocks. Also, before this patch, if a process encountered an error and decided to withdraw, if another process was already withdrawing, the second withdraw would be silently ignored, which set it free to unlock its glocks. That's correct behavior if the original withdrawer encounters further errors down the road. But if secondary waiters don't wait for the journal replay, unlocking glocks will allow other nodes to use them, despite the fact that the journal containing those blocks is being replayed. The replay needs to finish before our glocks are released to other nodes. IOW, secondary withdraws need to wait for the first withdraw to finish. For example, if an rgrp glock is unlocked by a process that didn't wait for the first withdraw, a journal replay could introduce file system corruption by replaying a rgrp block that has already been granted to a different cluster node. Signed-off-by: Bob Peterson <rpeterso@redhat.com>
2020-01-28 19:23:45 +00:00
*
* For now, this is only used for the journal inode glock. In withdraw
* situations, we need to wait for the glock to be unlocked so that we know
gfs2: Force withdraw to replay journals and wait for it to finish When a node withdraws from a file system, it often leaves its journal in an incomplete state. This is especially true when the withdraw is caused by io errors writing to the journal. Before this patch, a withdraw would try to write a "shutdown" record to the journal, tell dlm it's done with the file system, and none of the other nodes know about the problem. Later, when the problem is fixed and the withdrawn node is rebooted, it would then discover that its own journal was incomplete, and replay it. However, replaying it at this point is almost guaranteed to introduce corruption because the other nodes are likely to have used affected resource groups that appeared in the journal since the time of the withdraw. Replaying the journal later will overwrite any changes made, and not through any fault of dlm, which was instructed during the withdraw to release those resources. This patch makes file system withdraws seen by the entire cluster. Withdrawing nodes dequeue their journal glock to allow recovery. The remaining nodes check all the journals to see if they are clean or in need of replay. They try to replay dirty journals, but only the journals of withdrawn nodes will be "not busy" and therefore available for replay. Until the journal replay is complete, no i/o related glocks may be given out, to ensure that the replay does not cause the aforementioned corruption: We cannot allow any journal replay to overwrite blocks associated with a glock once it is held. The "live" glock which is now used to signal when a withdraw occurs. When a withdraw occurs, the node signals its withdraw by dequeueing the "live" glock and trying to enqueue it in EX mode, thus forcing the other nodes to all see a demote request, by way of a "1CB" (one callback) try lock. The "live" glock is not granted in EX; the callback is only just used to indicate a withdraw has occurred. Note that all nodes in the cluster must wait for the recovering node to finish replaying the withdrawing node's journal before continuing. To this end, it checks that the journals are clean multiple times in a retry loop. Also note that the withdraw function may be called from a wide variety of situations, and therefore, we need to take extra precautions to make sure pointers are valid before using them in many circumstances. We also need to take care when glocks decide to withdraw, since the withdraw code now uses glocks. Also, before this patch, if a process encountered an error and decided to withdraw, if another process was already withdrawing, the second withdraw would be silently ignored, which set it free to unlock its glocks. That's correct behavior if the original withdrawer encounters further errors down the road. But if secondary waiters don't wait for the journal replay, unlocking glocks will allow other nodes to use them, despite the fact that the journal containing those blocks is being replayed. The replay needs to finish before our glocks are released to other nodes. IOW, secondary withdraws need to wait for the first withdraw to finish. For example, if an rgrp glock is unlocked by a process that didn't wait for the first withdraw, a journal replay could introduce file system corruption by replaying a rgrp block that has already been granted to a different cluster node. Signed-off-by: Bob Peterson <rpeterso@redhat.com>
2020-01-28 19:23:45 +00:00
* other nodes may proceed with recovery / journal replay.
*/
static void inode_go_unlocked(struct gfs2_glock *gl)
gfs2: Force withdraw to replay journals and wait for it to finish When a node withdraws from a file system, it often leaves its journal in an incomplete state. This is especially true when the withdraw is caused by io errors writing to the journal. Before this patch, a withdraw would try to write a "shutdown" record to the journal, tell dlm it's done with the file system, and none of the other nodes know about the problem. Later, when the problem is fixed and the withdrawn node is rebooted, it would then discover that its own journal was incomplete, and replay it. However, replaying it at this point is almost guaranteed to introduce corruption because the other nodes are likely to have used affected resource groups that appeared in the journal since the time of the withdraw. Replaying the journal later will overwrite any changes made, and not through any fault of dlm, which was instructed during the withdraw to release those resources. This patch makes file system withdraws seen by the entire cluster. Withdrawing nodes dequeue their journal glock to allow recovery. The remaining nodes check all the journals to see if they are clean or in need of replay. They try to replay dirty journals, but only the journals of withdrawn nodes will be "not busy" and therefore available for replay. Until the journal replay is complete, no i/o related glocks may be given out, to ensure that the replay does not cause the aforementioned corruption: We cannot allow any journal replay to overwrite blocks associated with a glock once it is held. The "live" glock which is now used to signal when a withdraw occurs. When a withdraw occurs, the node signals its withdraw by dequeueing the "live" glock and trying to enqueue it in EX mode, thus forcing the other nodes to all see a demote request, by way of a "1CB" (one callback) try lock. The "live" glock is not granted in EX; the callback is only just used to indicate a withdraw has occurred. Note that all nodes in the cluster must wait for the recovering node to finish replaying the withdrawing node's journal before continuing. To this end, it checks that the journals are clean multiple times in a retry loop. Also note that the withdraw function may be called from a wide variety of situations, and therefore, we need to take extra precautions to make sure pointers are valid before using them in many circumstances. We also need to take care when glocks decide to withdraw, since the withdraw code now uses glocks. Also, before this patch, if a process encountered an error and decided to withdraw, if another process was already withdrawing, the second withdraw would be silently ignored, which set it free to unlock its glocks. That's correct behavior if the original withdrawer encounters further errors down the road. But if secondary waiters don't wait for the journal replay, unlocking glocks will allow other nodes to use them, despite the fact that the journal containing those blocks is being replayed. The replay needs to finish before our glocks are released to other nodes. IOW, secondary withdraws need to wait for the first withdraw to finish. For example, if an rgrp glock is unlocked by a process that didn't wait for the first withdraw, a journal replay could introduce file system corruption by replaying a rgrp block that has already been granted to a different cluster node. Signed-off-by: Bob Peterson <rpeterso@redhat.com>
2020-01-28 19:23:45 +00:00
{
/* Note that we cannot reference gl_object because it's already set
* to NULL by this point in its lifecycle. */
if (!test_bit(GLF_UNLOCKED, &gl->gl_flags))
gfs2: Force withdraw to replay journals and wait for it to finish When a node withdraws from a file system, it often leaves its journal in an incomplete state. This is especially true when the withdraw is caused by io errors writing to the journal. Before this patch, a withdraw would try to write a "shutdown" record to the journal, tell dlm it's done with the file system, and none of the other nodes know about the problem. Later, when the problem is fixed and the withdrawn node is rebooted, it would then discover that its own journal was incomplete, and replay it. However, replaying it at this point is almost guaranteed to introduce corruption because the other nodes are likely to have used affected resource groups that appeared in the journal since the time of the withdraw. Replaying the journal later will overwrite any changes made, and not through any fault of dlm, which was instructed during the withdraw to release those resources. This patch makes file system withdraws seen by the entire cluster. Withdrawing nodes dequeue their journal glock to allow recovery. The remaining nodes check all the journals to see if they are clean or in need of replay. They try to replay dirty journals, but only the journals of withdrawn nodes will be "not busy" and therefore available for replay. Until the journal replay is complete, no i/o related glocks may be given out, to ensure that the replay does not cause the aforementioned corruption: We cannot allow any journal replay to overwrite blocks associated with a glock once it is held. The "live" glock which is now used to signal when a withdraw occurs. When a withdraw occurs, the node signals its withdraw by dequeueing the "live" glock and trying to enqueue it in EX mode, thus forcing the other nodes to all see a demote request, by way of a "1CB" (one callback) try lock. The "live" glock is not granted in EX; the callback is only just used to indicate a withdraw has occurred. Note that all nodes in the cluster must wait for the recovering node to finish replaying the withdrawing node's journal before continuing. To this end, it checks that the journals are clean multiple times in a retry loop. Also note that the withdraw function may be called from a wide variety of situations, and therefore, we need to take extra precautions to make sure pointers are valid before using them in many circumstances. We also need to take care when glocks decide to withdraw, since the withdraw code now uses glocks. Also, before this patch, if a process encountered an error and decided to withdraw, if another process was already withdrawing, the second withdraw would be silently ignored, which set it free to unlock its glocks. That's correct behavior if the original withdrawer encounters further errors down the road. But if secondary waiters don't wait for the journal replay, unlocking glocks will allow other nodes to use them, despite the fact that the journal containing those blocks is being replayed. The replay needs to finish before our glocks are released to other nodes. IOW, secondary withdraws need to wait for the first withdraw to finish. For example, if an rgrp glock is unlocked by a process that didn't wait for the first withdraw, a journal replay could introduce file system corruption by replaying a rgrp block that has already been granted to a different cluster node. Signed-off-by: Bob Peterson <rpeterso@redhat.com>
2020-01-28 19:23:45 +00:00
return;
clear_bit_unlock(GLF_UNLOCKED, &gl->gl_flags);
wake_up_bit(&gl->gl_flags, GLF_UNLOCKED);
gfs2: Force withdraw to replay journals and wait for it to finish When a node withdraws from a file system, it often leaves its journal in an incomplete state. This is especially true when the withdraw is caused by io errors writing to the journal. Before this patch, a withdraw would try to write a "shutdown" record to the journal, tell dlm it's done with the file system, and none of the other nodes know about the problem. Later, when the problem is fixed and the withdrawn node is rebooted, it would then discover that its own journal was incomplete, and replay it. However, replaying it at this point is almost guaranteed to introduce corruption because the other nodes are likely to have used affected resource groups that appeared in the journal since the time of the withdraw. Replaying the journal later will overwrite any changes made, and not through any fault of dlm, which was instructed during the withdraw to release those resources. This patch makes file system withdraws seen by the entire cluster. Withdrawing nodes dequeue their journal glock to allow recovery. The remaining nodes check all the journals to see if they are clean or in need of replay. They try to replay dirty journals, but only the journals of withdrawn nodes will be "not busy" and therefore available for replay. Until the journal replay is complete, no i/o related glocks may be given out, to ensure that the replay does not cause the aforementioned corruption: We cannot allow any journal replay to overwrite blocks associated with a glock once it is held. The "live" glock which is now used to signal when a withdraw occurs. When a withdraw occurs, the node signals its withdraw by dequeueing the "live" glock and trying to enqueue it in EX mode, thus forcing the other nodes to all see a demote request, by way of a "1CB" (one callback) try lock. The "live" glock is not granted in EX; the callback is only just used to indicate a withdraw has occurred. Note that all nodes in the cluster must wait for the recovering node to finish replaying the withdrawing node's journal before continuing. To this end, it checks that the journals are clean multiple times in a retry loop. Also note that the withdraw function may be called from a wide variety of situations, and therefore, we need to take extra precautions to make sure pointers are valid before using them in many circumstances. We also need to take care when glocks decide to withdraw, since the withdraw code now uses glocks. Also, before this patch, if a process encountered an error and decided to withdraw, if another process was already withdrawing, the second withdraw would be silently ignored, which set it free to unlock its glocks. That's correct behavior if the original withdrawer encounters further errors down the road. But if secondary waiters don't wait for the journal replay, unlocking glocks will allow other nodes to use them, despite the fact that the journal containing those blocks is being replayed. The replay needs to finish before our glocks are released to other nodes. IOW, secondary withdraws need to wait for the first withdraw to finish. For example, if an rgrp glock is unlocked by a process that didn't wait for the first withdraw, a journal replay could introduce file system corruption by replaying a rgrp block that has already been granted to a different cluster node. Signed-off-by: Bob Peterson <rpeterso@redhat.com>
2020-01-28 19:23:45 +00:00
}
/**
* nondisk_go_callback - used to signal when a node did a withdraw
* @gl: the nondisk glock
* @remote: true if this came from a different cluster node
*
*/
static void nondisk_go_callback(struct gfs2_glock *gl, bool remote)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
/* Ignore the callback unless it's from another node, and it's the
live lock. */
if (!remote || gl->gl_name.ln_number != GFS2_LIVE_LOCK)
return;
/* First order of business is to cancel the demote request. We don't
* really want to demote a nondisk glock. At best it's just to inform
* us of another node's withdraw. We'll keep it in SH mode. */
clear_bit(GLF_DEMOTE, &gl->gl_flags);
clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
/* Ignore the unlock if we're withdrawn, unmounting, or in recovery. */
if (test_bit(SDF_NORECOVERY, &sdp->sd_flags) ||
test_bit(SDF_WITHDRAWN, &sdp->sd_flags) ||
test_bit(SDF_REMOTE_WITHDRAW, &sdp->sd_flags))
return;
/* We only care when a node wants us to unlock, because that means
* they want a journal recovered. */
if (gl->gl_demote_state != LM_ST_UNLOCKED)
return;
if (sdp->sd_args.ar_spectator) {
fs_warn(sdp, "Spectator node cannot recover journals.\n");
return;
}
fs_warn(sdp, "Some node has withdrawn; checking for recovery.\n");
set_bit(SDF_REMOTE_WITHDRAW, &sdp->sd_flags);
/*
* We can't call remote_withdraw directly here or gfs2_recover_journal
* because this is called from the glock unlock function and the
* remote_withdraw needs to enqueue and dequeue the same "live" glock
* we were called from. So we queue it to the control work queue in
* lock_dlm.
*/
queue_delayed_work(gfs2_control_wq, &sdp->sd_control_work, 0);
}
const struct gfs2_glock_operations gfs2_meta_glops = {
.go_type = LM_TYPE_META,
.go_flags = GLOF_NONDISK,
};
const struct gfs2_glock_operations gfs2_inode_glops = {
.go_sync = inode_go_sync,
.go_inval = inode_go_inval,
.go_instantiate = inode_go_instantiate,
.go_held = inode_go_held,
.go_dump = inode_go_dump,
.go_type = LM_TYPE_INODE,
.go_flags = GLOF_ASPACE | GLOF_LVB,
.go_unlocked = inode_go_unlocked,
};
const struct gfs2_glock_operations gfs2_rgrp_glops = {
.go_sync = rgrp_go_sync,
.go_inval = rgrp_go_inval,
.go_instantiate = gfs2_rgrp_go_instantiate,
.go_dump = gfs2_rgrp_go_dump,
.go_type = LM_TYPE_RGRP,
.go_flags = GLOF_LVB,
};
GFS2: remove transaction glock GFS2 has a transaction glock, which must be grabbed for every transaction, whose purpose is to deal with freezing the filesystem. Aside from this involving a large amount of locking, it is very easy to make the current fsfreeze code hang on unfreezing. This patch rewrites how gfs2 handles freezing the filesystem. The transaction glock is removed. In it's place is a freeze glock, which is cached (but not held) in a shared state by every node in the cluster when the filesystem is mounted. This lock only needs to be grabbed on freezing, and actions which need to be safe from freezing, like recovery. When a node wants to freeze the filesystem, it grabs this glock exclusively. When the freeze glock state changes on the nodes (either from shared to unlocked, or shared to exclusive), the filesystem does a special log flush. gfs2_log_flush() does all the work for flushing out the and shutting down the incore log, and then it tries to grab the freeze glock in a shared state again. Since the filesystem is stuck in gfs2_log_flush, no new transaction can start, and nothing can be written to disk. Unfreezing the filesytem simply involes dropping the freeze glock, allowing gfs2_log_flush() to grab and then release the shared lock, so it is cached for next time. However, in order for the unfreezing ioctl to occur, gfs2 needs to get a shared lock on the filesystem root directory inode to check permissions. If that glock has already been grabbed exclusively, fsfreeze will be unable to get the shared lock and unfreeze the filesystem. In order to allow the unfreeze, this patch makes gfs2 grab a shared lock on the filesystem root directory during the freeze, and hold it until it unfreezes the filesystem. The functions which need to grab a shared lock in order to allow the unfreeze ioctl to be issued now use the lock grabbed by the freeze code instead. The freeze and unfreeze code take care to make sure that this shared lock will not be dropped while another process is using it. Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2014-05-02 03:26:55 +00:00
const struct gfs2_glock_operations gfs2_freeze_glops = {
.go_xmote_bh = freeze_go_xmote_bh,
gfs2: Rework freeze / thaw logic So far, at mount time, gfs2 would take the freeze glock in shared mode and then immediately drop it again, turning it into a cached glock that can be reclaimed at any time. To freeze the filesystem cluster-wide, the node initiating the freeze would take the freeze glock in exclusive mode, which would cause the freeze glock's freeze_go_sync() callback to run on each node. There, gfs2 would freeze the filesystem and schedule gfs2_freeze_func() to run. gfs2_freeze_func() would re-acquire the freeze glock in shared mode, thaw the filesystem, and drop the freeze glock again. The initiating node would keep the freeze glock held in exclusive mode. To thaw the filesystem, the initiating node would drop the freeze glock again, which would allow gfs2_freeze_func() to resume on all nodes, leaving the filesystem in the thawed state. It turns out that in freeze_go_sync(), we cannot reliably and safely freeze the filesystem. This is primarily because the final unmount of a filesystem takes a write lock on the s_umount rw semaphore before calling into gfs2_put_super(), and freeze_go_sync() needs to call freeze_super() which also takes a write lock on the same semaphore, causing a deadlock. We could work around this by trying to take an active reference on the super block first, which would prevent unmount from running at the same time. But that can fail, and freeze_go_sync() isn't actually allowed to fail. To get around this, this patch changes the freeze glock locking scheme as follows: At mount time, each node takes the freeze glock in shared mode. To freeze a filesystem, the initiating node first freezes the filesystem locally and then drops and re-acquires the freeze glock in exclusive mode. All other nodes notice that there is contention on the freeze glock in their go_callback callbacks, and they schedule gfs2_freeze_func() to run. There, they freeze the filesystem locally and drop and re-acquire the freeze glock before re-thawing the filesystem. This is happening outside of the glock state engine, so there, we are allowed to fail. From a cluster point of view, taking and immediately dropping a glock is indistinguishable from taking the glock and only dropping it upon contention, so this new scheme is compatible with the old one. Thanks to Li Dong <lidong@vivo.com> for reporting a locking bug in gfs2_freeze_func() in a previous version of this commit. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2022-11-14 22:34:50 +00:00
.go_callback = freeze_go_callback,
.go_type = LM_TYPE_NONDISK,
.go_flags = GLOF_NONDISK,
};
const struct gfs2_glock_operations gfs2_iopen_glops = {
.go_type = LM_TYPE_IOPEN,
.go_callback = iopen_go_callback,
.go_dump = inode_go_dump,
.go_flags = GLOF_NONDISK,
gfs2: set lockdep subclass for iopen glocks This patch introduce a new globs attribute to define the subclass of the glock lockref spinlock. This avoid the following lockdep warning, which occurs when we lock an inode lock while an iopen lock is held: ============================================ WARNING: possible recursive locking detected 5.10.0-rc3+ #4990 Not tainted -------------------------------------------- kworker/0:1/12 is trying to acquire lock: ffff9067d45672d8 (&gl->gl_lockref.lock){+.+.}-{3:3}, at: lockref_get+0x9/0x20 but task is already holding lock: ffff9067da308588 (&gl->gl_lockref.lock){+.+.}-{3:3}, at: delete_work_func+0x164/0x260 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&gl->gl_lockref.lock); lock(&gl->gl_lockref.lock); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by kworker/0:1/12: #0: ffff9067c1bfdd38 ((wq_completion)delete_workqueue){+.+.}-{0:0}, at: process_one_work+0x1b7/0x540 #1: ffffac594006be70 ((work_completion)(&(&gl->gl_delete)->work)){+.+.}-{0:0}, at: process_one_work+0x1b7/0x540 #2: ffff9067da308588 (&gl->gl_lockref.lock){+.+.}-{3:3}, at: delete_work_func+0x164/0x260 stack backtrace: CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.10.0-rc3+ #4990 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014 Workqueue: delete_workqueue delete_work_func Call Trace: dump_stack+0x8b/0xb0 __lock_acquire.cold+0x19e/0x2e3 lock_acquire+0x150/0x410 ? lockref_get+0x9/0x20 _raw_spin_lock+0x27/0x40 ? lockref_get+0x9/0x20 lockref_get+0x9/0x20 delete_work_func+0x188/0x260 process_one_work+0x237/0x540 worker_thread+0x4d/0x3b0 ? process_one_work+0x540/0x540 kthread+0x127/0x140 ? __kthread_bind_mask+0x60/0x60 ret_from_fork+0x22/0x30 Suggested-by: Andreas Gruenbacher <agruenba@redhat.com> Signed-off-by: Alexander Aring <aahringo@redhat.com> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2020-11-23 15:53:35 +00:00
.go_subclass = 1,
};
const struct gfs2_glock_operations gfs2_flock_glops = {
.go_type = LM_TYPE_FLOCK,
.go_flags = GLOF_NONDISK,
};
const struct gfs2_glock_operations gfs2_nondisk_glops = {
.go_type = LM_TYPE_NONDISK,
.go_flags = GLOF_NONDISK,
gfs2: Force withdraw to replay journals and wait for it to finish When a node withdraws from a file system, it often leaves its journal in an incomplete state. This is especially true when the withdraw is caused by io errors writing to the journal. Before this patch, a withdraw would try to write a "shutdown" record to the journal, tell dlm it's done with the file system, and none of the other nodes know about the problem. Later, when the problem is fixed and the withdrawn node is rebooted, it would then discover that its own journal was incomplete, and replay it. However, replaying it at this point is almost guaranteed to introduce corruption because the other nodes are likely to have used affected resource groups that appeared in the journal since the time of the withdraw. Replaying the journal later will overwrite any changes made, and not through any fault of dlm, which was instructed during the withdraw to release those resources. This patch makes file system withdraws seen by the entire cluster. Withdrawing nodes dequeue their journal glock to allow recovery. The remaining nodes check all the journals to see if they are clean or in need of replay. They try to replay dirty journals, but only the journals of withdrawn nodes will be "not busy" and therefore available for replay. Until the journal replay is complete, no i/o related glocks may be given out, to ensure that the replay does not cause the aforementioned corruption: We cannot allow any journal replay to overwrite blocks associated with a glock once it is held. The "live" glock which is now used to signal when a withdraw occurs. When a withdraw occurs, the node signals its withdraw by dequeueing the "live" glock and trying to enqueue it in EX mode, thus forcing the other nodes to all see a demote request, by way of a "1CB" (one callback) try lock. The "live" glock is not granted in EX; the callback is only just used to indicate a withdraw has occurred. Note that all nodes in the cluster must wait for the recovering node to finish replaying the withdrawing node's journal before continuing. To this end, it checks that the journals are clean multiple times in a retry loop. Also note that the withdraw function may be called from a wide variety of situations, and therefore, we need to take extra precautions to make sure pointers are valid before using them in many circumstances. We also need to take care when glocks decide to withdraw, since the withdraw code now uses glocks. Also, before this patch, if a process encountered an error and decided to withdraw, if another process was already withdrawing, the second withdraw would be silently ignored, which set it free to unlock its glocks. That's correct behavior if the original withdrawer encounters further errors down the road. But if secondary waiters don't wait for the journal replay, unlocking glocks will allow other nodes to use them, despite the fact that the journal containing those blocks is being replayed. The replay needs to finish before our glocks are released to other nodes. IOW, secondary withdraws need to wait for the first withdraw to finish. For example, if an rgrp glock is unlocked by a process that didn't wait for the first withdraw, a journal replay could introduce file system corruption by replaying a rgrp block that has already been granted to a different cluster node. Signed-off-by: Bob Peterson <rpeterso@redhat.com>
2020-01-28 19:23:45 +00:00
.go_callback = nondisk_go_callback,
};
const struct gfs2_glock_operations gfs2_quota_glops = {
.go_type = LM_TYPE_QUOTA,
.go_flags = GLOF_LVB | GLOF_NONDISK,
};
const struct gfs2_glock_operations gfs2_journal_glops = {
.go_type = LM_TYPE_JOURNAL,
.go_flags = GLOF_NONDISK,
};
const struct gfs2_glock_operations *gfs2_glops_list[] = {
[LM_TYPE_META] = &gfs2_meta_glops,
[LM_TYPE_INODE] = &gfs2_inode_glops,
[LM_TYPE_RGRP] = &gfs2_rgrp_glops,
[LM_TYPE_IOPEN] = &gfs2_iopen_glops,
[LM_TYPE_FLOCK] = &gfs2_flock_glops,
[LM_TYPE_NONDISK] = &gfs2_nondisk_glops,
[LM_TYPE_QUOTA] = &gfs2_quota_glops,
[LM_TYPE_JOURNAL] = &gfs2_journal_glops,
};