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alistair23-linux/fs/gfs2/glops.c
Benjamin Marzinski 24972557b1 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>
2014-05-14 10:04:34 +01:00

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/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU General Public License version 2.
*/
#include <linux/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 "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"
static void gfs2_ail_error(struct gfs2_glock *gl, const struct buffer_head *bh)
{
fs_err(gl->gl_sbd, "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_page->mapping, bh->b_page->flags);
fs_err(gl->gl_sbd, "AIL glock %u:%llu mapping %p\n",
gl->gl_name.ln_type, gl->gl_name.ln_number,
gfs2_glock2aspace(gl));
gfs2_lm_withdraw(gl->gl_sbd, "AIL error\n");
}
/**
* __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)
*
* 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_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);
}
static void gfs2_ail_empty_gl(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_sbd;
struct gfs2_trans tr;
memset(&tr, 0, sizeof(tr));
INIT_LIST_HEAD(&tr.tr_buf);
INIT_LIST_HEAD(&tr.tr_databuf);
tr.tr_revokes = atomic_read(&gl->gl_ail_count);
if (!tr.tr_revokes)
return;
/* A shortened, inline version of gfs2_trans_begin()
* tr->alloced is not set since the transaction structure is
* on the stack */
tr.tr_reserved = 1 + gfs2_struct2blk(sdp, tr.tr_revokes, sizeof(u64));
tr.tr_ip = (unsigned long)__builtin_return_address(0);
sb_start_intwrite(sdp->sd_vfs);
if (gfs2_log_reserve(sdp, tr.tr_reserved) < 0) {
sb_end_intwrite(sdp->sd_vfs);
return;
}
WARN_ON_ONCE(current->journal_info);
current->journal_info = &tr;
__gfs2_ail_flush(gl, 0, tr.tr_revokes);
gfs2_trans_end(sdp);
gfs2_log_flush(sdp, NULL, NORMAL_FLUSH);
}
void gfs2_ail_flush(struct gfs2_glock *gl, bool fsync)
{
struct gfs2_sbd *sdp = gl->gl_sbd;
unsigned int revokes = atomic_read(&gl->gl_ail_count);
unsigned int max_revokes = (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_log_descriptor)) / sizeof(u64);
int ret;
if (!revokes)
return;
while (revokes > max_revokes)
max_revokes += (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_meta_header)) / sizeof(u64);
ret = gfs2_trans_begin(sdp, 0, max_revokes);
if (ret)
return;
__gfs2_ail_flush(gl, fsync, max_revokes);
gfs2_trans_end(sdp);
gfs2_log_flush(sdp, NULL, NORMAL_FLUSH);
}
/**
* 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
* not return to caller to demote/unlock the glock until I/O is complete.
*/
static void rgrp_go_sync(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_sbd;
struct address_space *mapping = &sdp->sd_aspace;
struct gfs2_rgrpd *rgd;
int error;
if (!test_and_clear_bit(GLF_DIRTY, &gl->gl_flags))
return;
GLOCK_BUG_ON(gl, gl->gl_state != LM_ST_EXCLUSIVE);
gfs2_log_flush(sdp, gl, NORMAL_FLUSH);
filemap_fdatawrite_range(mapping, gl->gl_vm.start, gl->gl_vm.end);
error = filemap_fdatawait_range(mapping, gl->gl_vm.start, gl->gl_vm.end);
mapping_set_error(mapping, error);
gfs2_ail_empty_gl(gl);
spin_lock(&gl->gl_spin);
rgd = gl->gl_object;
if (rgd)
gfs2_free_clones(rgd);
spin_unlock(&gl->gl_spin);
}
/**
* 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_sbd;
struct address_space *mapping = &sdp->sd_aspace;
WARN_ON_ONCE(!(flags & DIO_METADATA));
gfs2_assert_withdraw(sdp, !atomic_read(&gl->gl_ail_count));
truncate_inode_pages_range(mapping, gl->gl_vm.start, gl->gl_vm.end);
if (gl->gl_object) {
struct gfs2_rgrpd *rgd = (struct gfs2_rgrpd *)gl->gl_object;
rgd->rd_flags &= ~GFS2_RDF_UPTODATE;
}
}
/**
* inode_go_sync - Sync the dirty data and/or metadata for an inode glock
* @gl: the glock protecting the inode
*
*/
static void inode_go_sync(struct gfs2_glock *gl)
{
struct gfs2_inode *ip = gl->gl_object;
struct address_space *metamapping = gfs2_glock2aspace(gl);
int error;
if (ip && !S_ISREG(ip->i_inode.i_mode))
ip = NULL;
if (ip) {
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))
return;
GLOCK_BUG_ON(gl, gl->gl_state != LM_ST_EXCLUSIVE);
gfs2_log_flush(gl->gl_sbd, gl, NORMAL_FLUSH);
filemap_fdatawrite(metamapping);
if (ip) {
struct address_space *mapping = ip->i_inode.i_mapping;
filemap_fdatawrite(mapping);
error = filemap_fdatawait(mapping);
mapping_set_error(mapping, error);
}
error = filemap_fdatawait(metamapping);
mapping_set_error(metamapping, error);
gfs2_ail_empty_gl(gl);
/*
* Writeback of the data mapping may cause the dirty flag to be set
* so we have to clear it again here.
*/
smp_mb__before_clear_bit();
clear_bit(GLF_DIRTY, &gl->gl_flags);
}
/**
* inode_go_inval - prepare a inode glock to be released
* @gl: the glock
* @flags:
*
* Normally we invlidate 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 = gl->gl_object;
gfs2_assert_withdraw(gl->gl_sbd, !atomic_read(&gl->gl_ail_count));
if (flags & DIO_METADATA) {
struct address_space *mapping = gfs2_glock2aspace(gl);
truncate_inode_pages(mapping, 0);
if (ip) {
set_bit(GIF_INVALID, &ip->i_flags);
forget_all_cached_acls(&ip->i_inode);
gfs2_dir_hash_inval(ip);
}
}
if (ip == GFS2_I(gl->gl_sbd->sd_rindex)) {
gfs2_log_flush(gl->gl_sbd, NULL, NORMAL_FLUSH);
gl->gl_sbd->sd_rindex_uptodate = 0;
}
if (ip && S_ISREG(ip->i_inode.i_mode))
truncate_inode_pages(ip->i_inode.i_mapping, 0);
}
/**
* inode_go_demote_ok - Check to see if it's ok to unlock an inode glock
* @gl: the glock
*
* Returns: 1 if it's ok
*/
static int inode_go_demote_ok(const struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_sbd;
struct gfs2_holder *gh;
if (sdp->sd_jindex == gl->gl_object || sdp->sd_rindex == gl->gl_object)
return 0;
if (!list_empty(&gl->gl_holders)) {
gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
if (gh->gh_list.next != &gl->gl_holders)
return 0;
}
return 1;
}
/**
* gfs2_set_nlink - Set the inode's link count based on on-disk info
* @inode: The inode in question
* @nlink: The link count
*
* If the link count has hit zero, it must never be raised, whatever the
* on-disk inode might say. When new struct inodes are created the link
* count is set to 1, so that we can safely use this test even when reading
* in on disk information for the first time.
*/
static void gfs2_set_nlink(struct inode *inode, u32 nlink)
{
/*
* We will need to review setting the nlink count here in the
* light of the forthcoming ro bind mount work. This is a reminder
* to do that.
*/
if ((inode->i_nlink != nlink) && (inode->i_nlink != 0)) {
if (nlink == 0)
clear_nlink(inode);
else
set_nlink(inode, nlink);
}
}
static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf)
{
const struct gfs2_dinode *str = buf;
struct timespec atime;
u16 height, depth;
if (unlikely(ip->i_no_addr != be64_to_cpu(str->di_num.no_addr)))
goto corrupt;
ip->i_no_formal_ino = be64_to_cpu(str->di_num.no_formal_ino);
ip->i_inode.i_mode = be32_to_cpu(str->di_mode);
ip->i_inode.i_rdev = 0;
switch (ip->i_inode.i_mode & S_IFMT) {
case S_IFBLK:
case S_IFCHR:
ip->i_inode.i_rdev = MKDEV(be32_to_cpu(str->di_major),
be32_to_cpu(str->di_minor));
break;
};
i_uid_write(&ip->i_inode, be32_to_cpu(str->di_uid));
i_gid_write(&ip->i_inode, be32_to_cpu(str->di_gid));
gfs2_set_nlink(&ip->i_inode, be32_to_cpu(str->di_nlink));
i_size_write(&ip->i_inode, be64_to_cpu(str->di_size));
gfs2_set_inode_blocks(&ip->i_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);
if (timespec_compare(&ip->i_inode.i_atime, &atime) < 0)
ip->i_inode.i_atime = atime;
ip->i_inode.i_mtime.tv_sec = be64_to_cpu(str->di_mtime);
ip->i_inode.i_mtime.tv_nsec = be32_to_cpu(str->di_mtime_nsec);
ip->i_inode.i_ctime.tv_sec = be64_to_cpu(str->di_ctime);
ip->i_inode.i_ctime.tv_nsec = 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(&ip->i_inode);
height = be16_to_cpu(str->di_height);
if (unlikely(height > GFS2_MAX_META_HEIGHT))
goto corrupt;
ip->i_height = (u8)height;
depth = be16_to_cpu(str->di_depth);
if (unlikely(depth > GFS2_DIR_MAX_DEPTH))
goto corrupt;
ip->i_depth = (u8)depth;
ip->i_entries = be32_to_cpu(str->di_entries);
if (S_ISREG(ip->i_inode.i_mode))
gfs2_set_aops(&ip->i_inode);
return 0;
corrupt:
gfs2_consist_inode(ip);
return -EIO;
}
/**
* 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);
clear_bit(GIF_INVALID, &ip->i_flags);
return error;
}
/**
* inode_go_lock - operation done after an inode lock is locked by a process
* @gl: the glock
* @flags:
*
* Returns: errno
*/
static int inode_go_lock(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
struct gfs2_sbd *sdp = gl->gl_sbd;
struct gfs2_inode *ip = gl->gl_object;
int error = 0;
if (!ip || (gh->gh_flags & GL_SKIP))
return 0;
if (test_bit(GIF_INVALID, &ip->i_flags)) {
error = gfs2_inode_refresh(ip);
if (error)
return error;
}
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)) {
spin_lock(&sdp->sd_trunc_lock);
if (list_empty(&ip->i_trunc_list))
list_add(&sdp->sd_trunc_list, &ip->i_trunc_list);
spin_unlock(&sdp->sd_trunc_lock);
wake_up(&sdp->sd_quota_wait);
return 1;
}
return error;
}
/**
* inode_go_dump - print information about an inode
* @seq: The iterator
* @ip: the inode
*
*/
static void inode_go_dump(struct seq_file *seq, const struct gfs2_glock *gl)
{
const struct gfs2_inode *ip = gl->gl_object;
if (ip == NULL)
return;
gfs2_print_dbg(seq, " I: n:%llu/%llu t:%u f:0x%02lx d:0x%08x s:%llu\n",
(unsigned long long)ip->i_no_formal_ino,
(unsigned long long)ip->i_no_addr,
IF2DT(ip->i_inode.i_mode), ip->i_flags,
(unsigned int)ip->i_diskflags,
(unsigned long long)i_size_read(&ip->i_inode));
}
/**
* freeze_go_sync - promote/demote the freeze glock
* @gl: the glock
* @state: the requested state
* @flags:
*
*/
static void freeze_go_sync(struct gfs2_glock *gl)
{
struct gfs2_sbd *sdp = gl->gl_sbd;
DEFINE_WAIT(wait);
if (gl->gl_state == LM_ST_SHARED &&
test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags)) {
atomic_set(&sdp->sd_log_freeze, 1);
wake_up(&sdp->sd_logd_waitq);
do {
prepare_to_wait(&sdp->sd_log_frozen_wait, &wait,
TASK_UNINTERRUPTIBLE);
if (atomic_read(&sdp->sd_log_freeze))
io_schedule();
} while(atomic_read(&sdp->sd_log_freeze));
finish_wait(&sdp->sd_log_frozen_wait, &wait);
}
}
/**
* 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_holder *gh)
{
struct gfs2_sbd *sdp = gl->gl_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);
if (error)
gfs2_consist(sdp);
if (!(head.lh_flags & GFS2_LOG_HEAD_UNMOUNT))
gfs2_consist(sdp);
/* Initialize some head of the log stuff */
if (!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)) {
sdp->sd_log_sequence = head.lh_sequence + 1;
gfs2_log_pointers_init(sdp, head.lh_blkno);
}
}
return 0;
}
/**
* trans_go_demote_ok
* @gl: the glock
*
* Always returns 0
*/
static int freeze_go_demote_ok(const struct gfs2_glock *gl)
{
return 0;
}
/**
* iopen_go_callback - schedule the dcache entry for the inode to be deleted
* @gl: the glock
*
* gl_spin lock is held while calling this
*/
static void iopen_go_callback(struct gfs2_glock *gl, bool remote)
{
struct gfs2_inode *ip = (struct gfs2_inode *)gl->gl_object;
struct gfs2_sbd *sdp = gl->gl_sbd;
if (!remote || (sdp->sd_vfs->s_flags & MS_RDONLY))
return;
if (gl->gl_demote_state == LM_ST_UNLOCKED &&
gl->gl_state == LM_ST_SHARED && ip) {
gl->gl_lockref.count++;
if (queue_work(gfs2_delete_workqueue, &gl->gl_delete) == 0)
gl->gl_lockref.count--;
}
}
const struct gfs2_glock_operations gfs2_meta_glops = {
.go_type = LM_TYPE_META,
};
const struct gfs2_glock_operations gfs2_inode_glops = {
.go_sync = inode_go_sync,
.go_inval = inode_go_inval,
.go_demote_ok = inode_go_demote_ok,
.go_lock = inode_go_lock,
.go_dump = inode_go_dump,
.go_type = LM_TYPE_INODE,
.go_flags = GLOF_ASPACE,
};
const struct gfs2_glock_operations gfs2_rgrp_glops = {
.go_sync = rgrp_go_sync,
.go_inval = rgrp_go_inval,
.go_lock = gfs2_rgrp_go_lock,
.go_unlock = gfs2_rgrp_go_unlock,
.go_dump = gfs2_rgrp_dump,
.go_type = LM_TYPE_RGRP,
.go_flags = GLOF_LVB,
};
const struct gfs2_glock_operations gfs2_freeze_glops = {
.go_sync = freeze_go_sync,
.go_xmote_bh = freeze_go_xmote_bh,
.go_demote_ok = freeze_go_demote_ok,
.go_type = LM_TYPE_NONDISK,
};
const struct gfs2_glock_operations gfs2_iopen_glops = {
.go_type = LM_TYPE_IOPEN,
.go_callback = iopen_go_callback,
};
const struct gfs2_glock_operations gfs2_flock_glops = {
.go_type = LM_TYPE_FLOCK,
};
const struct gfs2_glock_operations gfs2_nondisk_glops = {
.go_type = LM_TYPE_NONDISK,
};
const struct gfs2_glock_operations gfs2_quota_glops = {
.go_type = LM_TYPE_QUOTA,
.go_flags = GLOF_LVB,
};
const struct gfs2_glock_operations gfs2_journal_glops = {
.go_type = LM_TYPE_JOURNAL,
};
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,
};
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