Staging: pohmelfs: distributed locking and cache coherency protocol.
POHMELFS utilizes writeback cache, which is built on top of MO(E)SI-like coherency protocol. This patch includes its implementation and cache object processing helpers (like allocation and completion callbacks). POHMELFS uses scalable cached read/write locking. No additional requests are performed if lock is granted to the filesystem. The same protocol is used by the server to on-demand flushing of the client's cache (for example when server wants to update local data). Signed-off-by: Evgeniy Polyakov <zbr@ioremap.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Evgeniy Polyakov
Greg Kroah-Hartman
Родитель
b3f08cad3d
Коммит
ac7036c131
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/*
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* 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/module.h>
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#include <linux/backing-dev.h>
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#include <linux/fs.h>
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#include <linux/fsnotify.h>
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#include <linux/slab.h>
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#include <linux/mempool.h>
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#include "netfs.h"
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static int pohmelfs_send_lock_trans(struct pohmelfs_inode *pi,
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u64 id, u64 start, u32 size, int type)
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{
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struct inode *inode = &pi->vfs_inode;
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struct pohmelfs_sb *psb = POHMELFS_SB(inode->i_sb);
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struct netfs_trans *t;
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struct netfs_cmd *cmd;
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int path_len, err;
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void *data;
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struct netfs_lock *l;
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int isize = (type & POHMELFS_LOCK_GRAB) ? 0 : sizeof(struct netfs_inode_info);
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err = pohmelfs_path_length(pi);
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if (err < 0)
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goto err_out_exit;
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path_len = err;
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err = -ENOMEM;
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t = netfs_trans_alloc(psb, path_len + sizeof(struct netfs_lock) + isize, 0, 0);
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if (!t)
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goto err_out_exit;
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cmd = netfs_trans_current(t);
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data = cmd + 1;
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err = pohmelfs_construct_path_string(pi, data, path_len);
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if (err < 0)
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goto err_out_free;
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path_len = err;
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l = data + path_len;
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l->start = start;
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l->size = size;
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l->type = type;
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l->ino = pi->ino;
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cmd->cmd = NETFS_LOCK;
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cmd->start = 0;
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cmd->id = id;
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cmd->size = sizeof(struct netfs_lock) + path_len + isize;
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cmd->ext = path_len;
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cmd->csize = 0;
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netfs_convert_cmd(cmd);
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netfs_convert_lock(l);
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if (isize) {
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struct netfs_inode_info *info = (struct netfs_inode_info *)(l + 1);
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info->mode = inode->i_mode;
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info->nlink = inode->i_nlink;
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info->uid = inode->i_uid;
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info->gid = inode->i_gid;
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info->blocks = inode->i_blocks;
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info->rdev = inode->i_rdev;
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info->size = inode->i_size;
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info->version = inode->i_version;
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netfs_convert_inode_info(info);
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}
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netfs_trans_update(cmd, t, path_len + sizeof(struct netfs_lock) + isize);
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return netfs_trans_finish(t, psb);
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err_out_free:
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netfs_trans_free(t);
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err_out_exit:
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printk("%s: err: %d.\n", __func__, err);
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return err;
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}
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int pohmelfs_data_lock(struct pohmelfs_inode *pi, u64 start, u32 size, int type)
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{
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struct pohmelfs_sb *psb = POHMELFS_SB(pi->vfs_inode.i_sb);
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struct pohmelfs_mcache *m;
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int err = -ENOMEM;
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struct iattr iattr;
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struct inode *inode = &pi->vfs_inode;
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dprintk("%s: %p: ino: %llu, start: %llu, size: %u, "
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"type: %d, locked as: %d, owned: %d.\n",
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__func__, &pi->vfs_inode, pi->ino,
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start, size, type, pi->lock_type,
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!!test_bit(NETFS_INODE_OWNED, &pi->state));
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if (!pohmelfs_need_lock(pi, type))
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return 0;
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m = pohmelfs_mcache_alloc(psb, start, size, NULL);
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if (IS_ERR(m))
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return PTR_ERR(m);
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err = pohmelfs_send_lock_trans(pi, m->gen, start, size,
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type | POHMELFS_LOCK_GRAB);
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if (err)
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goto err_out_put;
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err = wait_for_completion_timeout(&m->complete, psb->mcache_timeout);
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if (err)
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err = m->err;
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else
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err = -ETIMEDOUT;
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if (err) {
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printk("%s: %p: ino: %llu, mgen: %llu, start: %llu, size: %u, err: %d.\n",
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__func__, &pi->vfs_inode, pi->ino, m->gen, start, size, err);
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}
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if (err && (err != -ENOENT))
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goto err_out_put;
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if (!err) {
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netfs_convert_inode_info(&m->info);
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iattr.ia_valid = ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_SIZE | ATTR_ATIME;
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iattr.ia_mode = m->info.mode;
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iattr.ia_uid = m->info.uid;
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iattr.ia_gid = m->info.gid;
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iattr.ia_size = m->info.size;
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iattr.ia_atime = CURRENT_TIME;
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dprintk("%s: %p: ino: %llu, mgen: %llu, start: %llu, isize: %llu -> %llu.\n",
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__func__, &pi->vfs_inode, pi->ino, m->gen, start, inode->i_size, m->info.size);
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err = pohmelfs_setattr_raw(inode, &iattr);
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if (!err) {
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struct dentry *dentry = d_find_alias(inode);
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if (dentry) {
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fsnotify_change(dentry, iattr.ia_valid);
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dput(dentry);
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}
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}
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}
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pi->lock_type = type;
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set_bit(NETFS_INODE_OWNED, &pi->state);
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pohmelfs_mcache_put(psb, m);
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return 0;
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err_out_put:
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pohmelfs_mcache_put(psb, m);
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return err;
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}
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int pohmelfs_data_unlock(struct pohmelfs_inode *pi, u64 start, u32 size, int type)
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{
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dprintk("%s: %p: ino: %llu, start: %llu, size: %u, type: %d.\n",
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__func__, &pi->vfs_inode, pi->ino, start, size, type);
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pi->lock_type = 0;
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clear_bit(NETFS_INODE_REMOTE_DIR_SYNCED, &pi->state);
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clear_bit(NETFS_INODE_OWNED, &pi->state);
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return pohmelfs_send_lock_trans(pi, pi->ino, start, size, type);
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}
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@ -0,0 +1,171 @@
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/*
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* 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/mempool.h>
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#include "netfs.h"
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static struct kmem_cache *pohmelfs_mcache_cache;
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static mempool_t *pohmelfs_mcache_pool;
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static inline int pohmelfs_mcache_cmp(u64 gen, u64 new)
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{
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if (gen < new)
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return 1;
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if (gen > new)
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return -1;
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return 0;
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}
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struct pohmelfs_mcache *pohmelfs_mcache_search(struct pohmelfs_sb *psb, u64 gen)
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{
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struct rb_root *root = &psb->mcache_root;
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struct rb_node *n = root->rb_node;
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struct pohmelfs_mcache *tmp, *ret = NULL;
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int cmp;
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while (n) {
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tmp = rb_entry(n, struct pohmelfs_mcache, mcache_entry);
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cmp = pohmelfs_mcache_cmp(tmp->gen, gen);
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if (cmp < 0)
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n = n->rb_left;
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else if (cmp > 0)
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n = n->rb_right;
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else {
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ret = tmp;
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pohmelfs_mcache_get(ret);
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break;
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}
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}
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return ret;
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}
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static int pohmelfs_mcache_insert(struct pohmelfs_sb *psb, struct pohmelfs_mcache *m)
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{
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struct rb_root *root = &psb->mcache_root;
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struct rb_node **n = &root->rb_node, *parent = NULL;
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struct pohmelfs_mcache *ret = NULL, *tmp;
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int cmp;
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while (*n) {
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parent = *n;
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tmp = rb_entry(parent, struct pohmelfs_mcache, mcache_entry);
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cmp = pohmelfs_mcache_cmp(tmp->gen, m->gen);
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if (cmp < 0)
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n = &parent->rb_left;
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else if (cmp > 0)
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n = &parent->rb_right;
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else {
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ret = tmp;
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break;
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}
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}
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if (ret)
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return -EEXIST;
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rb_link_node(&m->mcache_entry, parent, n);
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rb_insert_color(&m->mcache_entry, root);
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return 0;
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}
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static int pohmelfs_mcache_remove(struct pohmelfs_sb *psb, struct pohmelfs_mcache *m)
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{
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if (m && m->mcache_entry.rb_parent_color) {
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rb_erase(&m->mcache_entry, &psb->mcache_root);
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m->mcache_entry.rb_parent_color = 0;
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return 1;
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}
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return 0;
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}
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void pohmelfs_mcache_remove_locked(struct pohmelfs_sb *psb, struct pohmelfs_mcache *m)
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{
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mutex_lock(&psb->mcache_lock);
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pohmelfs_mcache_remove(psb, m);
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mutex_unlock(&psb->mcache_lock);
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}
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struct pohmelfs_mcache *pohmelfs_mcache_alloc(struct pohmelfs_sb *psb, u64 start,
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unsigned int size, void *data)
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{
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struct pohmelfs_mcache *m;
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int err = -ENOMEM;
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m = mempool_alloc(pohmelfs_mcache_pool, GFP_KERNEL);
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if (!m)
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goto err_out_exit;
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init_completion(&m->complete);
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m->err = 0;
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atomic_set(&m->refcnt, 1);
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m->data = data;
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m->start = start;
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m->size = size;
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m->gen = atomic_long_inc_return(&psb->mcache_gen);
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mutex_lock(&psb->mcache_lock);
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err = pohmelfs_mcache_insert(psb, m);
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mutex_unlock(&psb->mcache_lock);
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if (err)
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goto err_out_free;
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return m;
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err_out_free:
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mempool_free(m, pohmelfs_mcache_pool);
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err_out_exit:
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return ERR_PTR(err);
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}
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void pohmelfs_mcache_free(struct pohmelfs_sb *psb, struct pohmelfs_mcache *m)
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{
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pohmelfs_mcache_remove_locked(psb, m);
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mempool_free(m, pohmelfs_mcache_pool);
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}
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int __init pohmelfs_mcache_init(void)
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{
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pohmelfs_mcache_cache = kmem_cache_create("pohmelfs_mcache_cache",
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sizeof(struct pohmelfs_mcache),
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0, (SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD), NULL);
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if (!pohmelfs_mcache_cache)
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goto err_out_exit;
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pohmelfs_mcache_pool = mempool_create_slab_pool(256, pohmelfs_mcache_cache);
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if (!pohmelfs_mcache_pool)
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goto err_out_free;
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return 0;
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err_out_free:
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kmem_cache_destroy(pohmelfs_mcache_cache);
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err_out_exit:
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return -ENOMEM;
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}
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void pohmelfs_mcache_exit(void)
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{
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mempool_destroy(pohmelfs_mcache_pool);
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kmem_cache_destroy(pohmelfs_mcache_cache);
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}
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