// SPDX-License-Identifier: GPL-2.0-or-later /* -*- 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. */ /* Simple VFS hooks based on: */ /* * Resizable simple ram filesystem for Linux. * * Copyright (C) 2000 Linus Torvalds. * 2000 Transmeta Corp. */ #include #include #include #include #include #include #include #include #include #include #include #include "../stackglue.h" #include "userdlm.h" #define MLOG_MASK_PREFIX ML_DLMFS #include "../cluster/masklog.h" static const struct super_operations dlmfs_ops; static const struct file_operations dlmfs_file_operations; static const struct inode_operations dlmfs_dir_inode_operations; static const struct inode_operations dlmfs_root_inode_operations; static const struct inode_operations dlmfs_file_inode_operations; static struct kmem_cache *dlmfs_inode_cache; struct workqueue_struct *user_dlm_worker; /* * These are the ABI capabilities of dlmfs. * * Over time, dlmfs has added some features that were not part of the * initial ABI. Unfortunately, some of these features are not detectable * via standard usage. For example, Linux's default poll always returns * EPOLLIN, so there is no way for a caller of poll(2) to know when dlmfs * added poll support. Instead, we provide this list of new capabilities. * * Capabilities is a read-only attribute. We do it as a module parameter * so we can discover it whether dlmfs is built in, loaded, or even not * loaded. * * The ABI features are local to this machine's dlmfs mount. This is * distinct from the locking protocol, which is concerned with inter-node * interaction. * * Capabilities: * - bast : EPOLLIN against the file descriptor of a held lock * signifies a bast fired on the lock. */ #define DLMFS_CAPABILITIES "bast stackglue" static int param_set_dlmfs_capabilities(const char *val, const struct kernel_param *kp) { printk(KERN_ERR "%s: readonly parameter\n", kp->name); return -EINVAL; } static int param_get_dlmfs_capabilities(char *buffer, const struct kernel_param *kp) { return strlcpy(buffer, DLMFS_CAPABILITIES, strlen(DLMFS_CAPABILITIES) + 1); } module_param_call(capabilities, param_set_dlmfs_capabilities, param_get_dlmfs_capabilities, NULL, 0444); MODULE_PARM_DESC(capabilities, DLMFS_CAPABILITIES); /* * 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 -> NOQUEUE */ static int dlmfs_decode_open_flags(int open_flags, int *level, int *flags) { if (open_flags & (O_WRONLY|O_RDWR)) *level = DLM_LOCK_EX; else *level = DLM_LOCK_PR; *flags = 0; if (open_flags & O_NONBLOCK) *flags |= DLM_LKF_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_NOFS); 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 & DLM_LKF_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; struct dlmfs_inode_private *ip = DLMFS_I(inode); struct dlmfs_filp_private *fp = file->private_data; if (S_ISDIR(inode->i_mode)) BUG(); mlog(0, "close called on inode %lu\n", inode->i_ino); if (fp) { level = fp->fp_lock_level; if (level != DLM_LOCK_IV) user_dlm_cluster_unlock(&ip->ip_lockres, level); kfree(fp); file->private_data = NULL; } return 0; } /* * We do ->setattr() just to override size changes. Our size is the size * of the LVB and nothing else. */ static int dlmfs_file_setattr(struct dentry *dentry, struct iattr *attr) { int error; struct inode *inode = d_inode(dentry); attr->ia_valid &= ~ATTR_SIZE; error = setattr_prepare(&init_user_ns, dentry, attr); if (error) return error; setattr_copy(&init_user_ns, inode, attr); mark_inode_dirty(inode); return 0; } static __poll_t dlmfs_file_poll(struct file *file, poll_table *wait) { __poll_t event = 0; struct inode *inode = file_inode(file); struct dlmfs_inode_private *ip = DLMFS_I(inode); poll_wait(file, &ip->ip_lockres.l_event, wait); spin_lock(&ip->ip_lockres.l_lock); if (ip->ip_lockres.l_flags & USER_LOCK_BLOCKED) event = EPOLLIN | EPOLLRDNORM; spin_unlock(&ip->ip_lockres.l_lock); return event; } static ssize_t dlmfs_file_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { char lvb[DLM_LVB_LEN]; if (!user_dlm_read_lvb(file_inode(file), lvb)) return 0; return simple_read_from_buffer(buf, count, ppos, lvb, sizeof(lvb)); } static ssize_t dlmfs_file_write(struct file *filp, const char __user *buf, size_t count, loff_t *ppos) { char lvb_buf[DLM_LVB_LEN]; int bytes_left; struct inode *inode = file_inode(filp); mlog(0, "inode %lu, count = %zu, *ppos = %llu\n", inode->i_ino, count, *ppos); if (*ppos >= DLM_LVB_LEN) return -ENOSPC; /* don't write past the lvb */ if (count > DLM_LVB_LEN - *ppos) count = DLM_LVB_LEN - *ppos; if (!count) return 0; bytes_left = copy_from_user(lvb_buf, buf, count); count -= bytes_left; if (count) user_dlm_write_lvb(inode, lvb_buf, count); *ppos = *ppos + count; mlog(0, "wrote %zu bytes\n", count); return count; } static void dlmfs_init_once(void *foo) { struct dlmfs_inode_private *ip = (struct dlmfs_inode_private *) foo; ip->ip_conn = 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, GFP_NOFS); if (!ip) return NULL; return &ip->ip_vfs_inode; } static void dlmfs_free_inode(struct inode *inode) { kmem_cache_free(dlmfs_inode_cache, DLMFS_I(inode)); } static void dlmfs_evict_inode(struct inode *inode) { int status; struct dlmfs_inode_private *ip; clear_inode(inode); 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_conn = 0x%p\n", ip->ip_conn); /* we must be a directory. If required, lets unregister the * dlm context now. */ if (ip->ip_conn) user_dlm_unregister(ip->ip_conn); clear_fields: ip->ip_parent = NULL; ip->ip_conn = NULL; } static struct inode *dlmfs_get_root_inode(struct super_block *sb) { struct inode *inode = new_inode(sb); umode_t mode = S_IFDIR | 0755; if (inode) { inode->i_ino = get_next_ino(); inode_init_owner(&init_user_ns, inode, NULL, mode); inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); inc_nlink(inode); 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, umode_t 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_ino = get_next_ino(); inode_init_owner(&init_user_ns, inode, parent, mode); inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); ip = DLMFS_I(inode); ip->ip_conn = DLMFS_I(parent)->ip_conn; 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) */ inc_nlink(inode); break; } return inode; } /* * File creation. Allocate an inode, and we're done.. */ /* SMP-safe */ static int dlmfs_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode) { int status; struct inode *inode = NULL; const struct qstr *domain = &dentry->d_name; struct dlmfs_inode_private *ip; struct ocfs2_cluster_connection *conn; mlog(0, "mkdir %.*s\n", domain->len, domain->name); /* verify that we have a proper domain */ if (domain->len >= GROUP_NAME_MAX) { 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); conn = user_dlm_register(domain); if (IS_ERR(conn)) { status = PTR_ERR(conn); mlog(ML_ERROR, "Error %d could not register domain \"%.*s\"\n", status, domain->len, domain->name); goto bail; } ip->ip_conn = conn; inc_nlink(dir); 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, umode_t mode, bool excl) { int status = 0; struct inode *inode; const 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 = d_inode(dentry); 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 %pd, error %d from destroy\n", dentry, status); goto bail; } status = simple_unlink(dir, dentry); bail: return status; } static int dlmfs_fill_super(struct super_block * sb, void * data, int silent) { sb->s_maxbytes = MAX_LFS_FILESIZE; sb->s_blocksize = PAGE_SIZE; sb->s_blocksize_bits = PAGE_SHIFT; sb->s_magic = DLMFS_MAGIC; sb->s_op = &dlmfs_ops; sb->s_root = d_make_root(dlmfs_get_root_inode(sb)); if (!sb->s_root) return -ENOMEM; return 0; } static const struct file_operations dlmfs_file_operations = { .open = dlmfs_file_open, .release = dlmfs_file_release, .poll = dlmfs_file_poll, .read = dlmfs_file_read, .write = dlmfs_file_write, .llseek = default_llseek, }; static const 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 const struct inode_operations dlmfs_root_inode_operations = { .lookup = simple_lookup, .mkdir = dlmfs_mkdir, .rmdir = simple_rmdir, }; static const struct super_operations dlmfs_ops = { .statfs = simple_statfs, .alloc_inode = dlmfs_alloc_inode, .free_inode = dlmfs_free_inode, .evict_inode = dlmfs_evict_inode, .drop_inode = generic_delete_inode, }; static const struct inode_operations dlmfs_file_inode_operations = { .getattr = simple_getattr, .setattr = dlmfs_file_setattr, }; static struct dentry *dlmfs_mount(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { return mount_nodev(fs_type, flags, data, dlmfs_fill_super); } static struct file_system_type dlmfs_fs_type = { .owner = THIS_MODULE, .name = "ocfs2_dlmfs", .mount = dlmfs_mount, .kill_sb = kill_litter_super, }; MODULE_ALIAS_FS("ocfs2_dlmfs"); static int __init init_dlmfs_fs(void) { int status; int cleanup_inode = 0, cleanup_worker = 0; dlmfs_inode_cache = kmem_cache_create("dlmfs_inode_cache", sizeof(struct dlmfs_inode_private), 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT| SLAB_MEM_SPREAD|SLAB_ACCOUNT), dlmfs_init_once); if (!dlmfs_inode_cache) { status = -ENOMEM; goto bail; } cleanup_inode = 1; user_dlm_worker = alloc_workqueue("user_dlm", WQ_MEM_RECLAIM, 0); if (!user_dlm_worker) { status = -ENOMEM; goto bail; } cleanup_worker = 1; user_dlm_set_locking_protocol(); 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); destroy_workqueue(user_dlm_worker); /* * Make sure all delayed rcu free inodes are flushed before we * destroy cache. */ rcu_barrier(); kmem_cache_destroy(dlmfs_inode_cache); } MODULE_AUTHOR("Oracle"); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("OCFS2 DLM-Filesystem"); module_init(init_dlmfs_fs) module_exit(exit_dlmfs_fs)