[PATCH] OCFS2: The Second Oracle Cluster Filesystem

dlmfs: A minimal dlm userspace interface implemented via a virtual
file system.
Most of the OCFS2 tools make use of this to take cluster locks when
doing operations on the file system.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Kurt Hackel <kurt.hackel@oracle.com>

1 files changed, 640 insertions, 0 deletions

diff --git a/fs/ocfs2/dlm/dlmfs.c b/fs/ocfs2/dlm/dlmfs.c
new file mode 100644
index 000000000000..dd2d24dc25e0
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmfs.c
@@ -0,0 +1,640 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * dlmfs.c
+ *
+ * Code which implements the kernel side of a minimal userspace
+ * interface to our DLM. This file handles the virtual file system
+ * used for communication with userspace. Credit should go to ramfs,
+ * which was a template for the fs side of this module.
+ *
+ * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+/* Simple VFS hooks based on: */
+/*
+ * Resizable simple ram filesystem for Linux.
+ *
+ * Copyright (C) 2000 Linus Torvalds.
+ *               2000 Transmeta Corp.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/smp_lock.h>
+#include <linux/backing-dev.h>
+
+#include <asm/uaccess.h>
+
+
+#include "cluster/nodemanager.h"
+#include "cluster/heartbeat.h"
+#include "cluster/tcp.h"
+
+#include "dlmapi.h"
+
+#include "userdlm.h"
+
+#include "dlmfsver.h"
+
+#define MLOG_MASK_PREFIX ML_DLMFS
+#include "cluster/masklog.h"
+
+static struct super_operations dlmfs_ops;
+static struct file_operations dlmfs_file_operations;
+static struct inode_operations dlmfs_dir_inode_operations;
+static struct inode_operations dlmfs_root_inode_operations;
+static struct inode_operations dlmfs_file_inode_operations;
+static kmem_cache_t *dlmfs_inode_cache;
+
+struct workqueue_struct *user_dlm_worker;
+
+/*
+ * decodes a set of open flags into a valid lock level and a set of flags.
+ * returns < 0 if we have invalid flags
+ * flags which mean something to us:
+ * O_RDONLY -> PRMODE level
+ * O_WRONLY -> EXMODE level
+ *
+ * O_NONBLOCK -> LKM_NOQUEUE
+ */
+static int dlmfs_decode_open_flags(int open_flags,
+                                   int *level,
+                                   int *flags)
+{
+        if (open_flags & (O_WRONLY|O_RDWR))
+                *level = LKM_EXMODE;
+        else
+                *level = LKM_PRMODE;
+
+        *flags = 0;
+        if (open_flags & O_NONBLOCK)
+                *flags |= LKM_NOQUEUE;
+
+        return 0;
+}
+
+static int dlmfs_file_open(struct inode *inode,
+                           struct file *file)
+{
+        int status, level, flags;
+        struct dlmfs_filp_private *fp = NULL;
+        struct dlmfs_inode_private *ip;
+
+        if (S_ISDIR(inode->i_mode))
+                BUG();
+
+        mlog(0, "open called on inode %lu, flags 0x%x\n", inode->i_ino,
+                file->f_flags);
+
+        status = dlmfs_decode_open_flags(file->f_flags, &level, &flags);
+        if (status < 0)
+                goto bail;
+
+        /* We don't want to honor O_APPEND at read/write time as it
+         * doesn't make sense for LVB writes. */
+        file->f_flags &= ~O_APPEND;
+
+        fp = kmalloc(sizeof(*fp), GFP_KERNEL);
+        if (!fp) {
+                status = -ENOMEM;
+                goto bail;
+        }
+        fp->fp_lock_level = level;
+
+        ip = DLMFS_I(inode);
+
+        status = user_dlm_cluster_lock(&ip->ip_lockres, level, flags);
+        if (status < 0) {
+                /* this is a strange error to return here but I want
+                 * to be able userspace to be able to distinguish a
+                 * valid lock request from one that simply couldn't be
+                 * granted. */
+                if (flags & LKM_NOQUEUE && status == -EAGAIN)
+                        status = -ETXTBSY;
+                kfree(fp);
+                goto bail;
+        }
+
+        file->private_data = fp;
+bail:
+        return status;
+}
+
+static int dlmfs_file_release(struct inode *inode,
+                              struct file *file)
+{
+        int level, status;
+        struct dlmfs_inode_private *ip = DLMFS_I(inode);
+        struct dlmfs_filp_private *fp =
+                (struct dlmfs_filp_private *) file->private_data;
+
+        if (S_ISDIR(inode->i_mode))
+                BUG();
+
+        mlog(0, "close called on inode %lu\n", inode->i_ino);
+
+        status = 0;
+        if (fp) {
+                level = fp->fp_lock_level;
+                if (level != LKM_IVMODE)
+                        user_dlm_cluster_unlock(&ip->ip_lockres, level);
+
+                kfree(fp);
+                file->private_data = NULL;
+        }
+
+        return 0;
+}
+
+static ssize_t dlmfs_file_read(struct file *filp,
+                               char __user *buf,
+                               size_t count,
+                               loff_t *ppos)
+{
+        int bytes_left;
+        ssize_t readlen;
+        char *lvb_buf;
+        struct inode *inode = filp->f_dentry->d_inode;
+
+        mlog(0, "inode %lu, count = %zu, *ppos = %llu\n",
+                inode->i_ino, count, *ppos);
+
+        if (*ppos >= i_size_read(inode))
+                return 0;
+
+        if (!count)
+                return 0;
+
+        if (!access_ok(VERIFY_WRITE, buf, count))
+                return -EFAULT;
+
+        /* don't read past the lvb */
+        if ((count + *ppos) > i_size_read(inode))
+                readlen = i_size_read(inode) - *ppos;
+        else
+                readlen = count - *ppos;
+
+        lvb_buf = kmalloc(readlen, GFP_KERNEL);
+        if (!lvb_buf)
+                return -ENOMEM;
+
+        user_dlm_read_lvb(inode, lvb_buf, readlen);
+        bytes_left = __copy_to_user(buf, lvb_buf, readlen);
+        readlen -= bytes_left;
+
+        kfree(lvb_buf);
+
+        *ppos = *ppos + readlen;
+
+        mlog(0, "read %zd bytes\n", readlen);
+        return readlen;
+}
+
+static ssize_t dlmfs_file_write(struct file *filp,
+                                const char __user *buf,
+                                size_t count,
+                                loff_t *ppos)
+{
+        int bytes_left;
+        ssize_t writelen;
+        char *lvb_buf;
+        struct inode *inode = filp->f_dentry->d_inode;
+
+        mlog(0, "inode %lu, count = %zu, *ppos = %llu\n",
+                inode->i_ino, count, *ppos);
+
+        if (*ppos >= i_size_read(inode))
+                return -ENOSPC;
+
+        if (!count)
+                return 0;
+
+        if (!access_ok(VERIFY_READ, buf, count))
+                return -EFAULT;
+
+        /* don't write past the lvb */
+        if ((count + *ppos) > i_size_read(inode))
+                writelen = i_size_read(inode) - *ppos;
+        else
+                writelen = count - *ppos;
+
+        lvb_buf = kmalloc(writelen, GFP_KERNEL);
+        if (!lvb_buf)
+                return -ENOMEM;
+
+        bytes_left = copy_from_user(lvb_buf, buf, writelen);
+        writelen -= bytes_left;
+        if (writelen)
+                user_dlm_write_lvb(inode, lvb_buf, writelen);
+
+        kfree(lvb_buf);
+
+        *ppos = *ppos + writelen;
+        mlog(0, "wrote %zd bytes\n", writelen);
+        return writelen;
+}
+
+static void dlmfs_init_once(void *foo,
+                            kmem_cache_t *cachep,
+                            unsigned long flags)
+{
+        struct dlmfs_inode_private *ip =
+                (struct dlmfs_inode_private *) foo;
+
+        if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
+            SLAB_CTOR_CONSTRUCTOR) {
+                ip->ip_dlm = NULL;
+                ip->ip_parent = NULL;
+
+                inode_init_once(&ip->ip_vfs_inode);
+        }
+}
+
+static struct inode *dlmfs_alloc_inode(struct super_block *sb)
+{
+        struct dlmfs_inode_private *ip;
+
+        ip = kmem_cache_alloc(dlmfs_inode_cache, SLAB_NOFS);
+        if (!ip)
+                return NULL;
+
+        return &ip->ip_vfs_inode;
+}
+
+static void dlmfs_destroy_inode(struct inode *inode)
+{
+        kmem_cache_free(dlmfs_inode_cache, DLMFS_I(inode));
+}
+
+static void dlmfs_clear_inode(struct inode *inode)
+{
+        int status;
+        struct dlmfs_inode_private *ip;
+
+        if (!inode)
+                return;
+
+        mlog(0, "inode %lu\n", inode->i_ino);
+
+        ip = DLMFS_I(inode);
+
+        if (S_ISREG(inode->i_mode)) {
+                status = user_dlm_destroy_lock(&ip->ip_lockres);
+                if (status < 0)
+                        mlog_errno(status);
+                iput(ip->ip_parent);
+                goto clear_fields;
+        }
+
+        mlog(0, "we're a directory, ip->ip_dlm = 0x%p\n", ip->ip_dlm);
+        /* we must be a directory. If required, lets unregister the
+         * dlm context now. */
+        if (ip->ip_dlm)
+                user_dlm_unregister_context(ip->ip_dlm);
+clear_fields:
+        ip->ip_parent = NULL;
+        ip->ip_dlm = NULL;
+}
+
+static struct backing_dev_info dlmfs_backing_dev_info = {
+        .ra_pages       = 0,    /* No readahead */
+        .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
+};
+
+static struct inode *dlmfs_get_root_inode(struct super_block *sb)
+{
+        struct inode *inode = new_inode(sb);
+        int mode = S_IFDIR | 0755;
+        struct dlmfs_inode_private *ip;
+
+        if (inode) {
+                ip = DLMFS_I(inode);
+
+                inode->i_mode = mode;
+                inode->i_uid = current->fsuid;
+                inode->i_gid = current->fsgid;
+                inode->i_blksize = PAGE_CACHE_SIZE;
+                inode->i_blocks = 0;
+                inode->i_mapping->backing_dev_info = &dlmfs_backing_dev_info;
+                inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+                inode->i_nlink++;
+
+                inode->i_fop = &simple_dir_operations;
+                inode->i_op = &dlmfs_root_inode_operations;
+        }
+
+        return inode;
+}
+
+static struct inode *dlmfs_get_inode(struct inode *parent,
+                                     struct dentry *dentry,
+                                     int mode)
+{
+        struct super_block *sb = parent->i_sb;
+        struct inode * inode = new_inode(sb);
+        struct dlmfs_inode_private *ip;
+
+        if (!inode)
+                return NULL;
+
+        inode->i_mode = mode;
+        inode->i_uid = current->fsuid;
+        inode->i_gid = current->fsgid;
+        inode->i_blksize = PAGE_CACHE_SIZE;
+        inode->i_blocks = 0;
+        inode->i_mapping->backing_dev_info = &dlmfs_backing_dev_info;
+        inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+
+        ip = DLMFS_I(inode);
+        ip->ip_dlm = DLMFS_I(parent)->ip_dlm;
+
+        switch (mode & S_IFMT) {
+        default:
+                /* for now we don't support anything other than
+                 * directories and regular files. */
+                BUG();
+                break;
+        case S_IFREG:
+                inode->i_op = &dlmfs_file_inode_operations;
+                inode->i_fop = &dlmfs_file_operations;
+
+                i_size_write(inode,  DLM_LVB_LEN);
+
+                user_dlm_lock_res_init(&ip->ip_lockres, dentry);
+
+                /* released at clear_inode time, this insures that we
+                 * get to drop the dlm reference on each lock *before*
+                 * we call the unregister code for releasing parent
+                 * directories. */
+                ip->ip_parent = igrab(parent);
+                BUG_ON(!ip->ip_parent);
+                break;
+        case S_IFDIR:
+                inode->i_op = &dlmfs_dir_inode_operations;
+                inode->i_fop = &simple_dir_operations;
+
+                /* directory inodes start off with i_nlink ==
+                 * 2 (for "." entry) */
+                inode->i_nlink++;
+                break;
+        }
+
+        if (parent->i_mode & S_ISGID) {
+                inode->i_gid = parent->i_gid;
+                if (S_ISDIR(mode))
+                        inode->i_mode |= S_ISGID;
+        }
+
+        return inode;
+}
+
+/*
+ * File creation. Allocate an inode, and we're done..
+ */
+/* SMP-safe */
+static int dlmfs_mkdir(struct inode * dir,
+                       struct dentry * dentry,
+                       int mode)
+{
+        int status;
+        struct inode *inode = NULL;
+        struct qstr *domain = &dentry->d_name;
+        struct dlmfs_inode_private *ip;
+        struct dlm_ctxt *dlm;
+
+        mlog(0, "mkdir %.*s\n", domain->len, domain->name);
+
+        /* verify that we have a proper domain */
+        if (domain->len >= O2NM_MAX_NAME_LEN) {
+                status = -EINVAL;
+                mlog(ML_ERROR, "invalid domain name for directory.\n");
+                goto bail;
+        }
+
+        inode = dlmfs_get_inode(dir, dentry, mode | S_IFDIR);
+        if (!inode) {
+                status = -ENOMEM;
+                mlog_errno(status);
+                goto bail;
+        }
+
+        ip = DLMFS_I(inode);
+
+        dlm = user_dlm_register_context(domain);
+        if (IS_ERR(dlm)) {
+                status = PTR_ERR(dlm);
+                mlog(ML_ERROR, "Error %d could not register domain \"%.*s\"\n",
+                     status, domain->len, domain->name);
+                goto bail;
+        }
+        ip->ip_dlm = dlm;
+
+        dir->i_nlink++;
+        d_instantiate(dentry, inode);
+        dget(dentry);   /* Extra count - pin the dentry in core */
+
+        status = 0;
+bail:
+        if (status < 0)
+                iput(inode);
+        return status;
+}
+
+static int dlmfs_create(struct inode *dir,
+                        struct dentry *dentry,
+                        int mode,
+                        struct nameidata *nd)
+{
+        int status = 0;
+        struct inode *inode;
+        struct qstr *name = &dentry->d_name;
+
+        mlog(0, "create %.*s\n", name->len, name->name);
+
+        /* verify name is valid and doesn't contain any dlm reserved
+         * characters */
+        if (name->len >= USER_DLM_LOCK_ID_MAX_LEN ||
+            name->name[0] == '$') {
+                status = -EINVAL;
+                mlog(ML_ERROR, "invalid lock name, %.*s\n", name->len,
+                     name->name);
+                goto bail;
+        }
+
+        inode = dlmfs_get_inode(dir, dentry, mode | S_IFREG);
+        if (!inode) {
+                status = -ENOMEM;
+                mlog_errno(status);
+                goto bail;
+        }
+
+        d_instantiate(dentry, inode);
+        dget(dentry);   /* Extra count - pin the dentry in core */
+bail:
+        return status;
+}
+
+static int dlmfs_unlink(struct inode *dir,
+                        struct dentry *dentry)
+{
+        int status;
+        struct inode *inode = dentry->d_inode;
+
+        mlog(0, "unlink inode %lu\n", inode->i_ino);
+
+        /* if there are no current holders, or none that are waiting
+         * to acquire a lock, this basically destroys our lockres. */
+        status = user_dlm_destroy_lock(&DLMFS_I(inode)->ip_lockres);
+        if (status < 0) {
+                mlog(ML_ERROR, "unlink %.*s, error %d from destroy\n",
+                     dentry->d_name.len, dentry->d_name.name, status);
+                goto bail;
+        }
+        status = simple_unlink(dir, dentry);
+bail:
+        return status;
+}
+
+static int dlmfs_fill_super(struct super_block * sb,
+                            void * data,
+                            int silent)
+{
+        struct inode * inode;
+        struct dentry * root;
+
+        sb->s_maxbytes = MAX_LFS_FILESIZE;
+        sb->s_blocksize = PAGE_CACHE_SIZE;
+        sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+        sb->s_magic = DLMFS_MAGIC;
+        sb->s_op = &dlmfs_ops;
+        inode = dlmfs_get_root_inode(sb);
+        if (!inode)
+                return -ENOMEM;
+
+        root = d_alloc_root(inode);
+        if (!root) {
+                iput(inode);
+                return -ENOMEM;
+        }
+        sb->s_root = root;
+        return 0;
+}
+
+static struct file_operations dlmfs_file_operations = {
+        .open           = dlmfs_file_open,
+        .release        = dlmfs_file_release,
+        .read           = dlmfs_file_read,
+        .write          = dlmfs_file_write,
+};
+
+static struct inode_operations dlmfs_dir_inode_operations = {
+        .create         = dlmfs_create,
+        .lookup         = simple_lookup,
+        .unlink         = dlmfs_unlink,
+};
+
+/* this way we can restrict mkdir to only the toplevel of the fs. */
+static struct inode_operations dlmfs_root_inode_operations = {
+        .lookup         = simple_lookup,
+        .mkdir          = dlmfs_mkdir,
+        .rmdir          = simple_rmdir,
+};
+
+static struct super_operations dlmfs_ops = {
+        .statfs         = simple_statfs,
+        .alloc_inode    = dlmfs_alloc_inode,
+        .destroy_inode  = dlmfs_destroy_inode,
+        .clear_inode    = dlmfs_clear_inode,
+        .drop_inode     = generic_delete_inode,
+};
+
+static struct inode_operations dlmfs_file_inode_operations = {
+        .getattr        = simple_getattr,
+};
+
+static struct super_block *dlmfs_get_sb(struct file_system_type *fs_type,
+        int flags, const char *dev_name, void *data)
+{
+        return get_sb_nodev(fs_type, flags, data, dlmfs_fill_super);
+}
+
+static struct file_system_type dlmfs_fs_type = {
+        .owner          = THIS_MODULE,
+        .name           = "ocfs2_dlmfs",
+        .get_sb         = dlmfs_get_sb,
+        .kill_sb        = kill_litter_super,
+};
+
+static int __init init_dlmfs_fs(void)
+{
+        int status;
+        int cleanup_inode = 0, cleanup_worker = 0;
+
+        dlmfs_print_version();
+
+        dlmfs_inode_cache = kmem_cache_create("dlmfs_inode_cache",
+                                sizeof(struct dlmfs_inode_private),
+                                0, SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT,
+                                dlmfs_init_once, NULL);
+        if (!dlmfs_inode_cache)
+                return -ENOMEM;
+        cleanup_inode = 1;
+
+        user_dlm_worker = create_singlethread_workqueue("user_dlm");
+        if (!user_dlm_worker) {
+                status = -ENOMEM;
+                goto bail;
+        }
+        cleanup_worker = 1;
+
+        status = register_filesystem(&dlmfs_fs_type);
+bail:
+        if (status) {
+                if (cleanup_inode)
+                        kmem_cache_destroy(dlmfs_inode_cache);
+                if (cleanup_worker)
+                        destroy_workqueue(user_dlm_worker);
+        } else
+                printk("OCFS2 User DLM kernel interface loaded\n");
+        return status;
+}
+
+static void __exit exit_dlmfs_fs(void)
+{
+        unregister_filesystem(&dlmfs_fs_type);
+
+        flush_workqueue(user_dlm_worker);
+        destroy_workqueue(user_dlm_worker);
+
+        if (kmem_cache_destroy(dlmfs_inode_cache))
+                printk(KERN_INFO "dlmfs_inode_cache: not all structures "
+                       "were freed\n");
+}
+
+MODULE_AUTHOR("Oracle");
+MODULE_LICENSE("GPL");
+
+module_init(init_dlmfs_fs)
+module_exit(exit_dlmfs_fs)