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* arch/s390/hypfs/inode.c
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* Hypervisor filesystem for Linux on s390.
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* Copyright IBM Corp. 2006, 2008
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* Author(s): Michael Holzheu <holzheu@de.ibm.com>
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#define KMSG_COMPONENT "hypfs"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/namei.h>
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#include <linux/vfs.h>
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#include <linux/slab.h>
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#include <linux/pagemap.h>
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#include <linux/time.h>
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#include <linux/parser.h>
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#include <linux/sysfs.h>
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#include <linux/module.h>
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#include <linux/seq_file.h>
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#include <linux/mount.h>
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#include <asm/ebcdic.h>
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#define HYPFS_MAGIC 0x687970 /* ASCII 'hyp' */
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#define TMP_SIZE 64 /* size of temporary buffers */
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static struct dentry *hypfs_create_update_file(struct super_block *sb,
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struct hypfs_sb_info {
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uid_t uid; /* uid used for files and dirs */
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gid_t gid; /* gid used for files and dirs */
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struct dentry *update_file; /* file to trigger update */
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time_t last_update; /* last update time in secs since 1970 */
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struct mutex lock; /* lock to protect update process */
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static const struct file_operations hypfs_file_ops;
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static struct file_system_type hypfs_type;
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static const struct super_operations hypfs_s_ops;
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/* start of list of all dentries, which have to be deleted on update */
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static struct dentry *hypfs_last_dentry;
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static void hypfs_update_update(struct super_block *sb)
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struct hypfs_sb_info *sb_info = sb->s_fs_info;
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struct inode *inode = sb_info->update_file->d_inode;
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sb_info->last_update = get_seconds();
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inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
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/* directory tree removal functions */
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static void hypfs_add_dentry(struct dentry *dentry)
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dentry->d_fsdata = hypfs_last_dentry;
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hypfs_last_dentry = dentry;
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static inline int hypfs_positive(struct dentry *dentry)
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return dentry->d_inode && !d_unhashed(dentry);
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static void hypfs_remove(struct dentry *dentry)
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struct dentry *parent;
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parent = dentry->d_parent;
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if (!parent || !parent->d_inode)
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mutex_lock(&parent->d_inode->i_mutex);
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if (hypfs_positive(dentry)) {
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if (S_ISDIR(dentry->d_inode->i_mode))
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simple_rmdir(parent->d_inode, dentry);
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simple_unlink(parent->d_inode, dentry);
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mutex_unlock(&parent->d_inode->i_mutex);
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static void hypfs_delete_tree(struct dentry *root)
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while (hypfs_last_dentry) {
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struct dentry *next_dentry;
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next_dentry = hypfs_last_dentry->d_fsdata;
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hypfs_remove(hypfs_last_dentry);
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hypfs_last_dentry = next_dentry;
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static struct inode *hypfs_make_inode(struct super_block *sb, int mode)
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struct inode *ret = new_inode(sb);
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struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
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ret->i_uid = hypfs_info->uid;
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ret->i_gid = hypfs_info->gid;
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ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
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static void hypfs_evict_inode(struct inode *inode)
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end_writeback(inode);
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kfree(inode->i_private);
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static int hypfs_open(struct inode *inode, struct file *filp)
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char *data = filp->f_path.dentry->d_inode->i_private;
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struct hypfs_sb_info *fs_info;
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if (filp->f_mode & FMODE_WRITE) {
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if (!(inode->i_mode & S_IWUGO))
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if (filp->f_mode & FMODE_READ) {
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if (!(inode->i_mode & S_IRUGO))
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fs_info = inode->i_sb->s_fs_info;
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mutex_lock(&fs_info->lock);
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filp->private_data = kstrdup(data, GFP_KERNEL);
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if (!filp->private_data) {
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mutex_unlock(&fs_info->lock);
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mutex_unlock(&fs_info->lock);
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return nonseekable_open(inode, filp);
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static ssize_t hypfs_aio_read(struct kiocb *iocb, const struct iovec *iov,
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unsigned long nr_segs, loff_t offset)
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struct file *filp = iocb->ki_filp;
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char __user *buf = iov[0].iov_base;
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size_t count = iov[0].iov_len;
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data = filp->private_data;
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ret = simple_read_from_buffer(buf, count, &offset, data, strlen(data));
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static ssize_t hypfs_aio_write(struct kiocb *iocb, const struct iovec *iov,
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unsigned long nr_segs, loff_t offset)
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struct super_block *sb;
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struct hypfs_sb_info *fs_info;
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size_t count = iov_length(iov, nr_segs);
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sb = iocb->ki_filp->f_path.dentry->d_inode->i_sb;
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fs_info = sb->s_fs_info;
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* Currently we only allow one update per second for two reasons:
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* 1. diag 204 is VERY expensive
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* 2. If several processes do updates in parallel and then read the
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* hypfs data, the likelihood of collisions is reduced, if we restrict
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* the minimum update interval. A collision occurs, if during the
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* data gathering of one process another process triggers an update
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* If the first process wants to ensure consistent data, it has
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* to restart data collection in this case.
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mutex_lock(&fs_info->lock);
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if (fs_info->last_update == get_seconds()) {
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hypfs_delete_tree(sb->s_root);
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rc = hypfs_vm_create_files(sb, sb->s_root);
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rc = hypfs_diag_create_files(sb, sb->s_root);
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pr_err("Updating the hypfs tree failed\n");
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hypfs_delete_tree(sb->s_root);
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hypfs_update_update(sb);
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mutex_unlock(&fs_info->lock);
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static int hypfs_release(struct inode *inode, struct file *filp)
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kfree(filp->private_data);
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enum { opt_uid, opt_gid, opt_err };
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static const match_table_t hypfs_tokens = {
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static int hypfs_parse_options(char *options, struct super_block *sb)
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substring_t args[MAX_OPT_ARGS];
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while ((str = strsep(&options, ",")) != NULL) {
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struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
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token = match_token(str, hypfs_tokens, args);
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if (match_int(&args[0], &option))
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hypfs_info->uid = option;
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if (match_int(&args[0], &option))
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hypfs_info->gid = option;
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pr_err("%s is not a valid mount option\n", str);
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static int hypfs_show_options(struct seq_file *s, struct vfsmount *mnt)
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struct hypfs_sb_info *hypfs_info = mnt->mnt_sb->s_fs_info;
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seq_printf(s, ",uid=%u", hypfs_info->uid);
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seq_printf(s, ",gid=%u", hypfs_info->gid);
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static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
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struct inode *root_inode;
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struct dentry *root_dentry;
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struct hypfs_sb_info *sbi;
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sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
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mutex_init(&sbi->lock);
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sbi->uid = current_uid();
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sbi->gid = current_gid();
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sb->s_blocksize = PAGE_CACHE_SIZE;
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sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
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sb->s_magic = HYPFS_MAGIC;
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sb->s_op = &hypfs_s_ops;
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if (hypfs_parse_options(data, sb))
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root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
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root_inode->i_op = &simple_dir_inode_operations;
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root_inode->i_fop = &simple_dir_operations;
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sb->s_root = root_dentry = d_alloc_root(root_inode);
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rc = hypfs_vm_create_files(sb, root_dentry);
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rc = hypfs_diag_create_files(sb, root_dentry);
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sbi->update_file = hypfs_create_update_file(sb, root_dentry);
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if (IS_ERR(sbi->update_file))
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return PTR_ERR(sbi->update_file);
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hypfs_update_update(sb);
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pr_info("Hypervisor filesystem mounted\n");
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static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
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const char *devname, void *data)
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return mount_single(fst, flags, data, hypfs_fill_super);
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static void hypfs_kill_super(struct super_block *sb)
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struct hypfs_sb_info *sb_info = sb->s_fs_info;
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hypfs_delete_tree(sb->s_root);
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if (sb_info->update_file)
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hypfs_remove(sb_info->update_file);
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kfree(sb->s_fs_info);
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sb->s_fs_info = NULL;
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kill_litter_super(sb);
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static struct dentry *hypfs_create_file(struct super_block *sb,
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struct dentry *parent, const char *name,
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char *data, mode_t mode)
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struct dentry *dentry;
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mutex_lock(&parent->d_inode->i_mutex);
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dentry = lookup_one_len(name, parent, strlen(name));
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if (IS_ERR(dentry)) {
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dentry = ERR_PTR(-ENOMEM);
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inode = hypfs_make_inode(sb, mode);
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dentry = ERR_PTR(-ENOMEM);
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if (mode & S_IFREG) {
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inode->i_fop = &hypfs_file_ops;
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inode->i_size = strlen(data);
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} else if (mode & S_IFDIR) {
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inode->i_op = &simple_dir_inode_operations;
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inode->i_fop = &simple_dir_operations;
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inc_nlink(parent->d_inode);
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inode->i_private = data;
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d_instantiate(dentry, inode);
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mutex_unlock(&parent->d_inode->i_mutex);
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struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
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struct dentry *dentry;
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dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
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hypfs_add_dentry(dentry);
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static struct dentry *hypfs_create_update_file(struct super_block *sb,
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struct dentry *dentry;
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dentry = hypfs_create_file(sb, dir, "update", NULL,
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S_IFREG | UPDATE_FILE_MODE);
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* We do not put the update file on the 'delete' list with
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* hypfs_add_dentry(), since it should not be removed when the tree
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struct dentry *hypfs_create_u64(struct super_block *sb, struct dentry *dir,
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const char *name, __u64 value)
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struct dentry *dentry;
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snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
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buffer = kstrdup(tmp, GFP_KERNEL);
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return ERR_PTR(-ENOMEM);
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hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
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if (IS_ERR(dentry)) {
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return ERR_PTR(-ENOMEM);
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hypfs_add_dentry(dentry);
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struct dentry *hypfs_create_str(struct super_block *sb, struct dentry *dir,
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const char *name, char *string)
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struct dentry *dentry;
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buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
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return ERR_PTR(-ENOMEM);
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sprintf(buffer, "%s\n", string);
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hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
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if (IS_ERR(dentry)) {
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return ERR_PTR(-ENOMEM);
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hypfs_add_dentry(dentry);
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static const struct file_operations hypfs_file_ops = {
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.release = hypfs_release,
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.read = do_sync_read,
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.write = do_sync_write,
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.aio_read = hypfs_aio_read,
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.aio_write = hypfs_aio_write,
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static struct file_system_type hypfs_type = {
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.owner = THIS_MODULE,
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.name = "s390_hypfs",
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.mount = hypfs_mount,
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.kill_sb = hypfs_kill_super
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static const struct super_operations hypfs_s_ops = {
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.statfs = simple_statfs,
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.evict_inode = hypfs_evict_inode,
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.show_options = hypfs_show_options,
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static struct kobject *s390_kobj;
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static int __init hypfs_init(void)
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rc = hypfs_dbfs_init();
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if (hypfs_diag_init()) {
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if (hypfs_vm_init()) {
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goto fail_hypfs_diag_exit;
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s390_kobj = kobject_create_and_add("s390", hypervisor_kobj);
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goto fail_hypfs_vm_exit;
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rc = register_filesystem(&hypfs_type);
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goto fail_filesystem;
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kobject_put(s390_kobj);
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fail_hypfs_diag_exit:
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pr_err("Initialization of hypfs failed with rc=%i\n", rc);
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static void __exit hypfs_exit(void)
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unregister_filesystem(&hypfs_type);
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kobject_put(s390_kobj);
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module_init(hypfs_init)
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module_exit(hypfs_exit)
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
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MODULE_DESCRIPTION("s390 Hypervisor Filesystem");