/* * VFS-related code for RelayFS, a high-speed data relay filesystem. * * Copyright (C) 2003-2005 - Tom Zanussi , IBM Corp * Copyright (C) 2003-2005 - Karim Yaghmour * * Based on ramfs, Copyright (C) 2002 - Linus Torvalds * * This file is released under the GPL. */ #include #include #include #include #include #include #include #include #include #include #include "relay.h" #include "buffers.h" #define RELAYFS_MAGIC 0xF0B4A981 static struct vfsmount * relayfs_mount; static int relayfs_mount_count; static struct backing_dev_info relayfs_backing_dev_info = { .ra_pages = 0, /* No readahead */ .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, }; static struct inode *relayfs_get_inode(struct super_block *sb, int mode, struct file_operations *fops, void *data) { struct inode *inode; inode = new_inode(sb); if (!inode) return NULL; inode->i_mode = mode; inode->i_uid = 0; inode->i_gid = 0; inode->i_blksize = PAGE_CACHE_SIZE; inode->i_blocks = 0; inode->i_mapping->backing_dev_info = &relayfs_backing_dev_info; inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; switch (mode & S_IFMT) { case S_IFREG: inode->i_fop = fops; if (data) inode->u.generic_ip = data; break; case S_IFDIR: inode->i_op = &simple_dir_inode_operations; inode->i_fop = &simple_dir_operations; /* directory inodes start off with i_nlink == 2 (for "." entry) */ inode->i_nlink++; break; default: break; } return inode; } /** * relayfs_create_entry - create a relayfs directory or file * @name: the name of the file to create * @parent: parent directory * @mode: mode * @fops: file operations to use for the file * @data: user-associated data for this file * * Returns the new dentry, NULL on failure * * Creates a file or directory with the specifed permissions. */ static struct dentry *relayfs_create_entry(const char *name, struct dentry *parent, int mode, struct file_operations *fops, void *data) { struct dentry *d; struct inode *inode; int error = 0; BUG_ON(!name || !(S_ISREG(mode) || S_ISDIR(mode))); error = simple_pin_fs("relayfs", &relayfs_mount, &relayfs_mount_count); if (error) { printk(KERN_ERR "Couldn't mount relayfs: errcode %d\n", error); return NULL; } if (!parent && relayfs_mount && relayfs_mount->mnt_sb) parent = relayfs_mount->mnt_sb->s_root; if (!parent) { simple_release_fs(&relayfs_mount, &relayfs_mount_count); return NULL; } parent = dget(parent); down(&parent->d_inode->i_sem); d = lookup_one_len(name, parent, strlen(name)); if (IS_ERR(d)) { d = NULL; goto release_mount; } if (d->d_inode) { d = NULL; goto release_mount; } inode = relayfs_get_inode(parent->d_inode->i_sb, mode, fops, data); if (!inode) { d = NULL; goto release_mount; } d_instantiate(d, inode); dget(d); /* Extra count - pin the dentry in core */ if (S_ISDIR(mode)) parent->d_inode->i_nlink++; goto exit; release_mount: simple_release_fs(&relayfs_mount, &relayfs_mount_count); exit: up(&parent->d_inode->i_sem); dput(parent); return d; } /** * relayfs_create_file - create a file in the relay filesystem * @name: the name of the file to create * @parent: parent directory * @mode: mode, if not specied the default perms are used * @fops: file operations to use for the file * @data: user-associated data for this file * * Returns file dentry if successful, NULL otherwise. * * The file will be created user r on behalf of current user. */ struct dentry *relayfs_create_file(const char *name, struct dentry *parent, int mode, struct file_operations *fops, void *data) { BUG_ON(!fops); if (!mode) mode = S_IRUSR; mode = (mode & S_IALLUGO) | S_IFREG; return relayfs_create_entry(name, parent, mode, fops, data); } /** * relayfs_create_dir - create a directory in the relay filesystem * @name: the name of the directory to create * @parent: parent directory, NULL if parent should be fs root * * Returns directory dentry if successful, NULL otherwise. * * The directory will be created world rwx on behalf of current user. */ struct dentry *relayfs_create_dir(const char *name, struct dentry *parent) { int mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; return relayfs_create_entry(name, parent, mode, NULL, NULL); } /** * relayfs_remove - remove a file or directory in the relay filesystem * @dentry: file or directory dentry * * Returns 0 if successful, negative otherwise. */ int relayfs_remove(struct dentry *dentry) { struct dentry *parent; int error = 0; if (!dentry) return -EINVAL; parent = dentry->d_parent; if (!parent) return -EINVAL; parent = dget(parent); down(&parent->d_inode->i_sem); if (dentry->d_inode) { if (S_ISDIR(dentry->d_inode->i_mode)) error = simple_rmdir(parent->d_inode, dentry); else error = simple_unlink(parent->d_inode, dentry); if (!error) d_delete(dentry); } if (!error) dput(dentry); up(&parent->d_inode->i_sem); dput(parent); if (!error) simple_release_fs(&relayfs_mount, &relayfs_mount_count); return error; } /** * relayfs_remove_file - remove a file from relay filesystem * @dentry: directory dentry * * Returns 0 if successful, negative otherwise. */ int relayfs_remove_file(struct dentry *dentry) { return relayfs_remove(dentry); } /** * relayfs_remove_dir - remove a directory in the relay filesystem * @dentry: directory dentry * * Returns 0 if successful, negative otherwise. */ int relayfs_remove_dir(struct dentry *dentry) { return relayfs_remove(dentry); } /** * relay_file_open - open file op for relay files * @inode: the inode * @filp: the file * * Increments the channel buffer refcount. */ static int relay_file_open(struct inode *inode, struct file *filp) { struct rchan_buf *buf = inode->u.generic_ip; kref_get(&buf->kref); filp->private_data = buf; return 0; } /** * relay_file_mmap - mmap file op for relay files * @filp: the file * @vma: the vma describing what to map * * Calls upon relay_mmap_buf to map the file into user space. */ static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma) { struct rchan_buf *buf = filp->private_data; return relay_mmap_buf(buf, vma); } /** * relay_file_poll - poll file op for relay files * @filp: the file * @wait: poll table * * Poll implemention. */ static unsigned int relay_file_poll(struct file *filp, poll_table *wait) { unsigned int mask = 0; struct rchan_buf *buf = filp->private_data; if (buf->finalized) return POLLERR; if (filp->f_mode & FMODE_READ) { poll_wait(filp, &buf->read_wait, wait); if (!relay_buf_empty(buf)) mask |= POLLIN | POLLRDNORM; } return mask; } /** * relay_file_release - release file op for relay files * @inode: the inode * @filp: the file * * Decrements the channel refcount, as the filesystem is * no longer using it. */ static int relay_file_release(struct inode *inode, struct file *filp) { struct rchan_buf *buf = filp->private_data; kref_put(&buf->kref, relay_remove_buf); return 0; } /** * relay_file_read_consume - update the consumed count for the buffer */ static void relay_file_read_consume(struct rchan_buf *buf, size_t read_pos, size_t bytes_consumed) { size_t subbuf_size = buf->chan->subbuf_size; size_t n_subbufs = buf->chan->n_subbufs; size_t read_subbuf; if (buf->bytes_consumed + bytes_consumed > subbuf_size) { relay_subbufs_consumed(buf->chan, buf->cpu, 1); buf->bytes_consumed = 0; } buf->bytes_consumed += bytes_consumed; read_subbuf = read_pos / buf->chan->subbuf_size; if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) { if ((read_subbuf == buf->subbufs_produced % n_subbufs) && (buf->offset == subbuf_size)) return; relay_subbufs_consumed(buf->chan, buf->cpu, 1); buf->bytes_consumed = 0; } } /** * relay_file_read_avail - boolean, are there unconsumed bytes available? */ static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos) { size_t bytes_produced, bytes_consumed, write_offset; size_t subbuf_size = buf->chan->subbuf_size; size_t n_subbufs = buf->chan->n_subbufs; size_t produced = buf->subbufs_produced % n_subbufs; size_t consumed = buf->subbufs_consumed % n_subbufs; write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; if (consumed > produced) { if ((produced > n_subbufs) && (produced + n_subbufs - consumed <= n_subbufs)) produced += n_subbufs; } else if (consumed == produced) { if (buf->offset > subbuf_size) { produced += n_subbufs; if (buf->subbufs_produced == buf->subbufs_consumed) consumed += n_subbufs; } } if (buf->offset > subbuf_size) bytes_produced = (produced - 1) * subbuf_size + write_offset; else bytes_produced = produced * subbuf_size + write_offset; bytes_consumed = consumed * subbuf_size + buf->bytes_consumed; if (bytes_produced == bytes_consumed) return 0; relay_file_read_consume(buf, read_pos, 0); return 1; } /** * relay_file_read_subbuf_avail - return bytes available in sub-buffer */ static size_t relay_file_read_subbuf_avail(size_t read_pos, struct rchan_buf *buf) { size_t padding, avail = 0; size_t read_subbuf, read_offset, write_subbuf, write_offset; size_t subbuf_size = buf->chan->subbuf_size; write_subbuf = (buf->data - buf->start) / subbuf_size; write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; read_subbuf = read_pos / subbuf_size; read_offset = read_pos % subbuf_size; padding = buf->padding[read_subbuf]; if (read_subbuf == write_subbuf) { if (read_offset + padding < write_offset) avail = write_offset - (read_offset + padding); } else avail = (subbuf_size - padding) - read_offset; return avail; } /** * relay_file_read_start_pos - find the first available byte to read * * If the read_pos is in the middle of padding, return the * position of the first actually available byte, otherwise * return the original value. */ static size_t relay_file_read_start_pos(size_t read_pos, struct rchan_buf *buf) { size_t read_subbuf, padding, padding_start, padding_end; size_t subbuf_size = buf->chan->subbuf_size; size_t n_subbufs = buf->chan->n_subbufs; read_subbuf = read_pos / subbuf_size; padding = buf->padding[read_subbuf]; padding_start = (read_subbuf + 1) * subbuf_size - padding; padding_end = (read_subbuf + 1) * subbuf_size; if (read_pos >= padding_start && read_pos < padding_end) { read_subbuf = (read_subbuf + 1) % n_subbufs; read_pos = read_subbuf * subbuf_size; } return read_pos; } /** * relay_file_read_end_pos - return the new read position */ static size_t relay_file_read_end_pos(struct rchan_buf *buf, size_t read_pos, size_t count) { size_t read_subbuf, padding, end_pos; size_t subbuf_size = buf->chan->subbuf_size; size_t n_subbufs = buf->chan->n_subbufs; read_subbuf = read_pos / subbuf_size; padding = buf->padding[read_subbuf]; if (read_pos % subbuf_size + count + padding == subbuf_size) end_pos = (read_subbuf + 1) * subbuf_size; else end_pos = read_pos + count; if (end_pos >= subbuf_size * n_subbufs) end_pos = 0; return end_pos; } /** * relay_file_read - read file op for relay files * @filp: the file * @buffer: the userspace buffer * @count: number of bytes to read * @ppos: position to read from * * Reads count bytes or the number of bytes available in the * current sub-buffer being read, whichever is smaller. */ static ssize_t relay_file_read(struct file *filp, char __user *buffer, size_t count, loff_t *ppos) { struct rchan_buf *buf = filp->private_data; struct inode *inode = filp->f_dentry->d_inode; size_t read_start, avail; ssize_t ret = 0; void *from; down(&inode->i_sem); if(!relay_file_read_avail(buf, *ppos)) goto out; read_start = relay_file_read_start_pos(*ppos, buf); avail = relay_file_read_subbuf_avail(read_start, buf); if (!avail) goto out; from = buf->start + read_start; ret = count = min(count, avail); if (copy_to_user(buffer, from, count)) { ret = -EFAULT; goto out; } relay_file_read_consume(buf, read_start, count); *ppos = relay_file_read_end_pos(buf, read_start, count); out: up(&inode->i_sem); return ret; } struct file_operations relay_file_operations = { .open = relay_file_open, .poll = relay_file_poll, .mmap = relay_file_mmap, .read = relay_file_read, .llseek = no_llseek, .release = relay_file_release, }; static struct super_operations relayfs_ops = { .statfs = simple_statfs, .drop_inode = generic_delete_inode, }; static int relayfs_fill_super(struct super_block * sb, void * data, int silent) { struct inode *inode; struct dentry *root; int mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; sb->s_blocksize = PAGE_CACHE_SIZE; sb->s_blocksize_bits = PAGE_CACHE_SHIFT; sb->s_magic = RELAYFS_MAGIC; sb->s_op = &relayfs_ops; inode = relayfs_get_inode(sb, mode, NULL, NULL); if (!inode) return -ENOMEM; root = d_alloc_root(inode); if (!root) { iput(inode); return -ENOMEM; } sb->s_root = root; return 0; } static struct super_block * relayfs_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { return get_sb_single(fs_type, flags, data, relayfs_fill_super); } static struct file_system_type relayfs_fs_type = { .owner = THIS_MODULE, .name = "relayfs", .get_sb = relayfs_get_sb, .kill_sb = kill_litter_super, }; static int __init init_relayfs_fs(void) { return register_filesystem(&relayfs_fs_type); } static void __exit exit_relayfs_fs(void) { unregister_filesystem(&relayfs_fs_type); } module_init(init_relayfs_fs) module_exit(exit_relayfs_fs) EXPORT_SYMBOL_GPL(relay_file_operations); EXPORT_SYMBOL_GPL(relayfs_create_dir); EXPORT_SYMBOL_GPL(relayfs_remove_dir); EXPORT_SYMBOL_GPL(relayfs_create_file); EXPORT_SYMBOL_GPL(relayfs_remove_file); MODULE_AUTHOR("Tom Zanussi and Karim Yaghmour "); MODULE_DESCRIPTION("Relay Filesystem"); MODULE_LICENSE("GPL");