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![Benjamin Marzinski](/assets/img/avatar_default.png)
The current gfs2 freezing code is considerably more complicated than it should be because it doesn't use the vfs freezing code on any node except the one that begins the freeze. This is because it needs to acquire a cluster glock before calling the vfs code to prevent a deadlock, and without the new freeze_super and thaw_super hooks, that was impossible. To deal with the issue, gfs2 had to do some hacky locking tricks to make sure that a frozen node couldn't be holding on a lock it needed to do the unfreeze ioctl. This patch makes use of the new hooks to simply the gfs2 locking code. Now, all the nodes in the cluster freeze and thaw in exactly the same way. Every node in the cluster caches the freeze glock in the shared state. The new freeze_super hook allows the freezing node to grab this freeze glock in the exclusive state without first calling the vfs freeze_super function. All the nodes in the cluster see this lock change, and call the vfs freeze_super function. The vfs locking code guarantees that the nodes can't get stuck holding the glocks necessary to unfreeze the system. To unfreeze, the freezing node uses the new thaw_super hook to drop the freeze glock. Again, all the nodes notice this, reacquire the glock in shared mode and call the vfs thaw_super function. Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
279 lines
7.2 KiB
C
279 lines
7.2 KiB
C
/*
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* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
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* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the GNU General Public License version 2.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/completion.h>
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#include <linux/buffer_head.h>
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#include <linux/kallsyms.h>
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#include <linux/gfs2_ondisk.h>
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#include "gfs2.h"
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#include "incore.h"
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#include "glock.h"
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#include "inode.h"
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#include "log.h"
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#include "lops.h"
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#include "meta_io.h"
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#include "trans.h"
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#include "util.h"
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#include "trace_gfs2.h"
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int gfs2_trans_begin(struct gfs2_sbd *sdp, unsigned int blocks,
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unsigned int revokes)
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{
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struct gfs2_trans *tr;
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int error;
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BUG_ON(current->journal_info);
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BUG_ON(blocks == 0 && revokes == 0);
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if (!test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))
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return -EROFS;
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tr = kzalloc(sizeof(struct gfs2_trans), GFP_NOFS);
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if (!tr)
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return -ENOMEM;
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tr->tr_ip = _RET_IP_;
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tr->tr_blocks = blocks;
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tr->tr_revokes = revokes;
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tr->tr_reserved = 1;
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tr->tr_alloced = 1;
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if (blocks)
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tr->tr_reserved += 6 + blocks;
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if (revokes)
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tr->tr_reserved += gfs2_struct2blk(sdp, revokes,
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sizeof(u64));
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INIT_LIST_HEAD(&tr->tr_databuf);
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INIT_LIST_HEAD(&tr->tr_buf);
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sb_start_intwrite(sdp->sd_vfs);
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error = gfs2_log_reserve(sdp, tr->tr_reserved);
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if (error)
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goto fail;
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current->journal_info = tr;
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return 0;
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fail:
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sb_end_intwrite(sdp->sd_vfs);
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kfree(tr);
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return error;
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}
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static void gfs2_print_trans(const struct gfs2_trans *tr)
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{
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pr_warn("Transaction created at: %pSR\n", (void *)tr->tr_ip);
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pr_warn("blocks=%u revokes=%u reserved=%u touched=%u\n",
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tr->tr_blocks, tr->tr_revokes, tr->tr_reserved, tr->tr_touched);
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pr_warn("Buf %u/%u Databuf %u/%u Revoke %u/%u\n",
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tr->tr_num_buf_new, tr->tr_num_buf_rm,
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tr->tr_num_databuf_new, tr->tr_num_databuf_rm,
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tr->tr_num_revoke, tr->tr_num_revoke_rm);
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}
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void gfs2_trans_end(struct gfs2_sbd *sdp)
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{
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struct gfs2_trans *tr = current->journal_info;
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s64 nbuf;
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int alloced = tr->tr_alloced;
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BUG_ON(!tr);
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current->journal_info = NULL;
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if (!tr->tr_touched) {
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gfs2_log_release(sdp, tr->tr_reserved);
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if (alloced) {
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kfree(tr);
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sb_end_intwrite(sdp->sd_vfs);
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}
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return;
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}
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nbuf = tr->tr_num_buf_new + tr->tr_num_databuf_new;
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nbuf -= tr->tr_num_buf_rm;
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nbuf -= tr->tr_num_databuf_rm;
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if (gfs2_assert_withdraw(sdp, (nbuf <= tr->tr_blocks) &&
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(tr->tr_num_revoke <= tr->tr_revokes)))
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gfs2_print_trans(tr);
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gfs2_log_commit(sdp, tr);
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if (alloced && !tr->tr_attached)
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kfree(tr);
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up_read(&sdp->sd_log_flush_lock);
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if (sdp->sd_vfs->s_flags & MS_SYNCHRONOUS)
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gfs2_log_flush(sdp, NULL, NORMAL_FLUSH);
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if (alloced)
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sb_end_intwrite(sdp->sd_vfs);
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}
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static struct gfs2_bufdata *gfs2_alloc_bufdata(struct gfs2_glock *gl,
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struct buffer_head *bh,
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const struct gfs2_log_operations *lops)
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{
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struct gfs2_bufdata *bd;
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bd = kmem_cache_zalloc(gfs2_bufdata_cachep, GFP_NOFS | __GFP_NOFAIL);
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bd->bd_bh = bh;
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bd->bd_gl = gl;
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bd->bd_ops = lops;
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INIT_LIST_HEAD(&bd->bd_list);
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bh->b_private = bd;
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return bd;
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}
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/**
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* gfs2_trans_add_data - Add a databuf to the transaction.
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* @gl: The inode glock associated with the buffer
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* @bh: The buffer to add
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*
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* This is used in two distinct cases:
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* i) In ordered write mode
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* We put the data buffer on a list so that we can ensure that its
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* synced to disk at the right time
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* ii) In journaled data mode
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* We need to journal the data block in the same way as metadata in
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* the functions above. The difference is that here we have a tag
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* which is two __be64's being the block number (as per meta data)
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* and a flag which says whether the data block needs escaping or
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* not. This means we need a new log entry for each 251 or so data
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* blocks, which isn't an enormous overhead but twice as much as
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* for normal metadata blocks.
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*/
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void gfs2_trans_add_data(struct gfs2_glock *gl, struct buffer_head *bh)
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{
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struct gfs2_trans *tr = current->journal_info;
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struct gfs2_sbd *sdp = gl->gl_sbd;
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struct address_space *mapping = bh->b_page->mapping;
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struct gfs2_inode *ip = GFS2_I(mapping->host);
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struct gfs2_bufdata *bd;
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if (!gfs2_is_jdata(ip)) {
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gfs2_ordered_add_inode(ip);
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return;
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}
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lock_buffer(bh);
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gfs2_log_lock(sdp);
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bd = bh->b_private;
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if (bd == NULL) {
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gfs2_log_unlock(sdp);
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unlock_buffer(bh);
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if (bh->b_private == NULL)
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bd = gfs2_alloc_bufdata(gl, bh, &gfs2_databuf_lops);
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lock_buffer(bh);
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gfs2_log_lock(sdp);
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}
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gfs2_assert(sdp, bd->bd_gl == gl);
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tr->tr_touched = 1;
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if (list_empty(&bd->bd_list)) {
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set_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags);
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set_bit(GLF_DIRTY, &bd->bd_gl->gl_flags);
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gfs2_pin(sdp, bd->bd_bh);
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tr->tr_num_databuf_new++;
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list_add_tail(&bd->bd_list, &tr->tr_databuf);
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}
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gfs2_log_unlock(sdp);
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unlock_buffer(bh);
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}
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static void meta_lo_add(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd)
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{
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struct gfs2_meta_header *mh;
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struct gfs2_trans *tr;
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enum gfs2_freeze_state state = atomic_read(&sdp->sd_freeze_state);
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tr = current->journal_info;
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tr->tr_touched = 1;
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if (!list_empty(&bd->bd_list))
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return;
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set_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags);
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set_bit(GLF_DIRTY, &bd->bd_gl->gl_flags);
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mh = (struct gfs2_meta_header *)bd->bd_bh->b_data;
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if (unlikely(mh->mh_magic != cpu_to_be32(GFS2_MAGIC))) {
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pr_err("Attempting to add uninitialised block to journal (inplace block=%lld)\n",
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(unsigned long long)bd->bd_bh->b_blocknr);
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BUG();
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}
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if (unlikely(state == SFS_FROZEN)) {
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printk(KERN_INFO "GFS2:adding buf while frozen\n");
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gfs2_assert_withdraw(sdp, 0);
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}
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gfs2_pin(sdp, bd->bd_bh);
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mh->__pad0 = cpu_to_be64(0);
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mh->mh_jid = cpu_to_be32(sdp->sd_jdesc->jd_jid);
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list_add(&bd->bd_list, &tr->tr_buf);
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tr->tr_num_buf_new++;
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}
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void gfs2_trans_add_meta(struct gfs2_glock *gl, struct buffer_head *bh)
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{
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struct gfs2_sbd *sdp = gl->gl_sbd;
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struct gfs2_bufdata *bd;
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lock_buffer(bh);
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gfs2_log_lock(sdp);
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bd = bh->b_private;
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if (bd == NULL) {
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gfs2_log_unlock(sdp);
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unlock_buffer(bh);
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lock_page(bh->b_page);
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if (bh->b_private == NULL)
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bd = gfs2_alloc_bufdata(gl, bh, &gfs2_buf_lops);
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unlock_page(bh->b_page);
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lock_buffer(bh);
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gfs2_log_lock(sdp);
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}
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gfs2_assert(sdp, bd->bd_gl == gl);
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meta_lo_add(sdp, bd);
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gfs2_log_unlock(sdp);
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unlock_buffer(bh);
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}
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void gfs2_trans_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd)
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{
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struct gfs2_trans *tr = current->journal_info;
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BUG_ON(!list_empty(&bd->bd_list));
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gfs2_add_revoke(sdp, bd);
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tr->tr_touched = 1;
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tr->tr_num_revoke++;
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}
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void gfs2_trans_add_unrevoke(struct gfs2_sbd *sdp, u64 blkno, unsigned int len)
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{
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struct gfs2_bufdata *bd, *tmp;
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struct gfs2_trans *tr = current->journal_info;
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unsigned int n = len;
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gfs2_log_lock(sdp);
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list_for_each_entry_safe(bd, tmp, &sdp->sd_log_le_revoke, bd_list) {
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if ((bd->bd_blkno >= blkno) && (bd->bd_blkno < (blkno + len))) {
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list_del_init(&bd->bd_list);
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gfs2_assert_withdraw(sdp, sdp->sd_log_num_revoke);
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sdp->sd_log_num_revoke--;
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kmem_cache_free(gfs2_bufdata_cachep, bd);
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tr->tr_num_revoke_rm++;
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if (--n == 0)
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break;
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}
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}
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gfs2_log_unlock(sdp);
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}
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