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linux/fs/unionfs/union.h

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/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef _UNION_H_
#define _UNION_H_
#include <linux/dcache.h>
#include <linux/file.h>
#include <linux/list.h>
#include <linux/fs.h>
#include <linux/aio.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/page-flags.h>
#include <linux/pagemap.h>
#include <linux/poll.h>
#include <linux/security.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/statfs.h>
#include <linux/string.h>
#include <linux/vmalloc.h>
#include <linux/writeback.h>
#include <linux/buffer_head.h>
#include <linux/xattr.h>
#include <linux/fs_stack.h>
#include <linux/magic.h>
#include <linux/log2.h>
#include <linux/poison.h>
#include <linux/mman.h>
#include <linux/backing-dev.h>
#include <linux/splice.h>
#include <linux/sched.h>
#include <linux/union_fs.h>
/* the file system name */
#define UNIONFS_NAME "unionfs"
/* unionfs root inode number */
#define UNIONFS_ROOT_INO 1
/* number of times we try to get a unique temporary file name */
#define GET_TMPNAM_MAX_RETRY 5
/* maximum number of branches we support, to avoid memory blowup */
#define UNIONFS_MAX_BRANCHES 128
/* minimum time (seconds) required for time-based cache-coherency */
#define UNIONFS_MIN_CC_TIME 3
/* Operations vectors defined in specific files. */
extern struct file_operations unionfs_main_fops;
extern struct file_operations unionfs_dir_fops;
extern struct inode_operations unionfs_main_iops;
extern struct inode_operations unionfs_dir_iops;
extern struct inode_operations unionfs_symlink_iops;
extern struct super_operations unionfs_sops;
extern struct dentry_operations unionfs_dops;
extern struct address_space_operations unionfs_aops, unionfs_dummy_aops;
extern struct vm_operations_struct unionfs_vm_ops;
/* How long should an entry be allowed to persist */
#define RDCACHE_JIFFIES (5*HZ)
/* compatibility with Real-Time patches */
#ifdef CONFIG_PREEMPT_RT
# define unionfs_rw_semaphore compat_rw_semaphore
#else /* not CONFIG_PREEMPT_RT */
# define unionfs_rw_semaphore rw_semaphore
#endif /* not CONFIG_PREEMPT_RT */
/* file private data. */
struct unionfs_file_info {
int bstart;
int bend;
atomic_t generation;
struct unionfs_dir_state *rdstate;
struct file **lower_files;
int *saved_branch_ids; /* IDs of branches when file was opened */
const struct vm_operations_struct *lower_vm_ops;
bool wrote_to_file; /* for delayed copyup */
};
/* unionfs inode data in memory */
struct unionfs_inode_info {
int bstart;
int bend;
atomic_t generation;
/* Stuff for readdir over NFS. */
spinlock_t rdlock;
struct list_head readdircache;
int rdcount;
int hashsize;
int cookie;
/* The lower inodes */
struct inode **lower_inodes;
struct inode vfs_inode;
};
/* unionfs dentry data in memory */
struct unionfs_dentry_info {
/*
* The semaphore is used to lock the dentry as soon as we get into a
* unionfs function from the VFS. Our lock ordering is that children
* go before their parents.
*/
struct mutex lock;
int bstart;
int bend;
int bopaque;
int bcount;
atomic_t generation;
struct path *lower_paths;
};
/* These are the pointers to our various objects. */
struct unionfs_data {
struct super_block *sb; /* lower super_block */
atomic_t open_files; /* number of open files on branch */
int branchperms;
int branch_id; /* unique branch ID at re/mount time */
};
/* unionfs super-block data in memory */
struct unionfs_sb_info {
int bend;
atomic_t generation;
/*
* This rwsem is used to make sure that a branch management
* operation...
* 1) will not begin before all currently in-flight operations
* complete.
* 2) any new operations do not execute until the currently
* running branch management operation completes.
*
* The write_lock_owner records the PID of the task which grabbed
* the rw_sem for writing. If the same task also tries to grab the
* read lock, we allow it. This prevents a self-deadlock when
* branch-management is used on a pivot_root'ed union, because we
* have to ->lookup paths which belong to the same union.
*/
struct unionfs_rw_semaphore rwsem;
pid_t write_lock_owner; /* PID of rw_sem owner (write lock) */
int high_branch_id; /* last unique branch ID given */
char *dev_name; /* to identify different unions in pr_debug */
struct unionfs_data *data;
};
/*
* structure for making the linked list of entries by readdir on left branch
* to compare with entries on right branch
*/
struct filldir_node {
struct list_head file_list; /* list for directory entries */
char *name; /* name entry */
int hash; /* name hash */
int namelen; /* name len since name is not 0 terminated */
/*
* we can check for duplicate whiteouts and files in the same branch
* in order to return -EIO.
*/
int bindex;
/* is this a whiteout entry? */
int whiteout;
/* Inline name, so we don't need to separately kmalloc small ones */
char iname[DNAME_INLINE_LEN];
};
/* Directory hash table. */
struct unionfs_dir_state {
unsigned int cookie; /* the cookie, based off of rdversion */
unsigned int offset; /* The entry we have returned. */
int bindex;
loff_t dirpos; /* offset within the lower level directory */
int size; /* How big is the hash table? */
int hashentries; /* How many entries have been inserted? */
unsigned long access;
/* This cache list is used when the inode keeps us around. */
struct list_head cache;
struct list_head list[0];
};
/* externs needed for fanout.h or sioq.h */
extern int unionfs_get_nlinks(const struct inode *inode);
extern void unionfs_copy_attr_times(struct inode *upper);
extern void unionfs_copy_attr_all(struct inode *dest, const struct inode *src);
/* include miscellaneous macros */
#include "fanout.h"
#include "sioq.h"
/* externs for cache creation/deletion routines */
extern void unionfs_destroy_filldir_cache(void);
extern int unionfs_init_filldir_cache(void);
extern int unionfs_init_inode_cache(void);
extern void unionfs_destroy_inode_cache(void);
extern int unionfs_init_dentry_cache(void);
extern void unionfs_destroy_dentry_cache(void);
/* Initialize and free readdir-specific state. */
extern int init_rdstate(struct file *file);
extern struct unionfs_dir_state *alloc_rdstate(struct inode *inode,
int bindex);
extern struct unionfs_dir_state *find_rdstate(struct inode *inode,
loff_t fpos);
extern void free_rdstate(struct unionfs_dir_state *state);
extern int add_filldir_node(struct unionfs_dir_state *rdstate,
const char *name, int namelen, int bindex,
int whiteout);
extern struct filldir_node *find_filldir_node(struct unionfs_dir_state *rdstate,
const char *name, int namelen,
int is_whiteout);
extern struct dentry **alloc_new_dentries(int objs);
extern struct unionfs_data *alloc_new_data(int objs);
/* We can only use 32-bits of offset for rdstate --- blech! */
#define DIREOF (0xfffff)
#define RDOFFBITS 20 /* This is the number of bits in DIREOF. */
#define MAXRDCOOKIE (0xfff)
/* Turn an rdstate into an offset. */
static inline off_t rdstate2offset(struct unionfs_dir_state *buf)
{
off_t tmp;
tmp = ((buf->cookie & MAXRDCOOKIE) << RDOFFBITS)
| (buf->offset & DIREOF);
return tmp;
}
/* Macros for locking a super_block. */
enum unionfs_super_lock_class {
UNIONFS_SMUTEX_NORMAL,
UNIONFS_SMUTEX_PARENT, /* when locking on behalf of file */
UNIONFS_SMUTEX_CHILD, /* when locking on behalf of dentry */
};
static inline void unionfs_read_lock(struct super_block *sb, int subclass)
{
if (UNIONFS_SB(sb)->write_lock_owner &&
UNIONFS_SB(sb)->write_lock_owner == current->pid)
return;
down_read_nested(&UNIONFS_SB(sb)->rwsem, subclass);
}
static inline void unionfs_read_unlock(struct super_block *sb)
{
if (UNIONFS_SB(sb)->write_lock_owner &&
UNIONFS_SB(sb)->write_lock_owner == current->pid)
return;
up_read(&UNIONFS_SB(sb)->rwsem);
}
static inline void unionfs_write_lock(struct super_block *sb)
{
down_write(&UNIONFS_SB(sb)->rwsem);
UNIONFS_SB(sb)->write_lock_owner = current->pid;
}
static inline void unionfs_write_unlock(struct super_block *sb)
{
up_write(&UNIONFS_SB(sb)->rwsem);
UNIONFS_SB(sb)->write_lock_owner = 0;
}
static inline void unionfs_double_lock_dentry(struct dentry *d1,
struct dentry *d2)
{
BUG_ON(d1 == d2);
if (d1 < d2) {
unionfs_lock_dentry(d1, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(d2, UNIONFS_DMUTEX_CHILD);
} else {
unionfs_lock_dentry(d2, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(d1, UNIONFS_DMUTEX_CHILD);
}
}
static inline void unionfs_double_unlock_dentry(struct dentry *d1,
struct dentry *d2)
{
BUG_ON(d1 == d2);
if (d1 < d2) { /* unlock in reverse order than double_lock_dentry */
unionfs_unlock_dentry(d1);
unionfs_unlock_dentry(d2);
} else {
unionfs_unlock_dentry(d2);
unionfs_unlock_dentry(d1);
}
}
static inline void unionfs_double_lock_parents(struct dentry *p1,
struct dentry *p2)
{
if (p1 == p2) {
unionfs_lock_dentry(p1, UNIONFS_DMUTEX_REVAL_PARENT);
return;
}
if (p1 < p2) {
unionfs_lock_dentry(p1, UNIONFS_DMUTEX_REVAL_PARENT);
unionfs_lock_dentry(p2, UNIONFS_DMUTEX_REVAL_CHILD);
} else {
unionfs_lock_dentry(p2, UNIONFS_DMUTEX_REVAL_PARENT);
unionfs_lock_dentry(p1, UNIONFS_DMUTEX_REVAL_CHILD);
}
}
static inline void unionfs_double_unlock_parents(struct dentry *p1,
struct dentry *p2)
{
if (p1 == p2) {
unionfs_unlock_dentry(p1);
return;
}
if (p1 < p2) { /* unlock in reverse order of double_lock_parents */
unionfs_unlock_dentry(p1);
unionfs_unlock_dentry(p2);
} else {
unionfs_unlock_dentry(p2);
unionfs_unlock_dentry(p1);
}
}
extern int new_dentry_private_data(struct dentry *dentry, int subclass);
extern int realloc_dentry_private_data(struct dentry *dentry);
extern void free_dentry_private_data(struct dentry *dentry);
extern void update_bstart(struct dentry *dentry);
/*
* EXTERNALS:
*/
/* replicates the directory structure up to given dentry in given branch */
extern struct dentry *create_parents(struct inode *dir, struct dentry *dentry,
const char *name, int bindex);
/* partial lookup */
extern int unionfs_partial_lookup(struct dentry *dentry,
struct dentry *parent);
extern struct dentry *unionfs_lookup_full(struct dentry *dentry,
struct dentry *parent,
int lookupmode);
/* copies a file from dbstart to newbindex branch */
extern int copyup_file(struct inode *dir, struct file *file, int bstart,
int newbindex, loff_t size);
extern int copyup_named_file(struct inode *dir, struct file *file,
char *name, int bstart, int new_bindex,
loff_t len);
/* copies a dentry from dbstart to newbindex branch */
extern int copyup_dentry(struct inode *dir, struct dentry *dentry,
int bstart, int new_bindex, const char *name,
int namelen, struct file **copyup_file, loff_t len);
/* helper functions for post-copyup actions */
extern void unionfs_postcopyup_setmnt(struct dentry *dentry);
extern void unionfs_postcopyup_release(struct dentry *dentry);
/* Is this directory empty: 0 if it is empty, -ENOTEMPTY if not. */
extern int check_empty(struct dentry *dentry, struct dentry *parent,
struct unionfs_dir_state **namelist);
/* whiteout and opaque directory helpers */
extern char *alloc_whname(const char *name, int len);
extern bool is_whiteout_name(char **namep, int *namelenp);
extern bool is_validname(const char *name);
extern struct dentry *lookup_whiteout(const char *name,
struct dentry *lower_parent);
extern struct dentry *find_first_whiteout(struct dentry *dentry);
extern int unlink_whiteout(struct dentry *wh_dentry);
extern int check_unlink_whiteout(struct dentry *dentry,
struct dentry *lower_dentry, int bindex);
extern int create_whiteout(struct dentry *dentry, int start);
extern int delete_whiteouts(struct dentry *dentry, int bindex,
struct unionfs_dir_state *namelist);
extern int is_opaque_dir(struct dentry *dentry, int bindex);
extern int make_dir_opaque(struct dentry *dir, int bindex);
extern void unionfs_set_max_namelen(long *namelen);
extern void unionfs_reinterpose(struct dentry *this_dentry);
extern struct super_block *unionfs_duplicate_super(struct super_block *sb);
/* Locking functions. */
extern int unionfs_setlk(struct file *file, int cmd, struct file_lock *fl);
extern int unionfs_getlk(struct file *file, struct file_lock *fl);
/* Common file operations. */
extern int unionfs_file_revalidate(struct file *file, struct dentry *parent,
bool willwrite);
extern int unionfs_open(struct inode *inode, struct file *file);
extern int unionfs_file_release(struct inode *inode, struct file *file);
extern int unionfs_flush(struct file *file, fl_owner_t id);
extern long unionfs_ioctl(struct file *file, unsigned int cmd,
unsigned long arg);
extern int unionfs_fsync(struct file *file, loff_t start, loff_t end,
int datasync);
extern int unionfs_fasync(int fd, struct file *file, int flag);
/* Inode operations */
extern struct inode *unionfs_iget(struct super_block *sb, unsigned long ino);
extern int unionfs_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry);
extern int unionfs_unlink(struct inode *dir, struct dentry *dentry);
extern int unionfs_rmdir(struct inode *dir, struct dentry *dentry);
extern bool __unionfs_d_revalidate(struct dentry *dentry,
struct dentry *parent, bool willwrite,
unsigned int flags);
extern bool is_negative_lower(const struct dentry *dentry);
extern bool is_newer_lower(const struct dentry *dentry);
extern void purge_sb_data(struct super_block *sb);
/* The values for unionfs_interpose's flag. */
#define INTERPOSE_DEFAULT 0
#define INTERPOSE_LOOKUP 1
#define INTERPOSE_REVAL 2
#define INTERPOSE_REVAL_NEG 3
#define INTERPOSE_PARTIAL 4
extern struct dentry *unionfs_interpose(struct dentry *this_dentry,
struct super_block *sb, int flag);
#ifdef CONFIG_UNION_FS_XATTR
/* Extended attribute functions. */
extern void *unionfs_xattr_alloc(size_t size, size_t limit);
static inline void unionfs_xattr_kfree(const void *p)
{
kfree(p);
}
extern ssize_t unionfs_getxattr(struct dentry *dentry, const char *name,
void *value, size_t size);
extern int unionfs_removexattr(struct dentry *dentry, const char *name);
extern ssize_t unionfs_listxattr(struct dentry *dentry, char *list,
size_t size);
extern int unionfs_setxattr(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags);
#endif /* CONFIG_UNION_FS_XATTR */
/* The root directory is unhashed, but isn't deleted. */
static inline int d_deleted(struct dentry *d)
{
return d_unhashed(d) && (d != d->d_sb->s_root);
}
/* unionfs_permission, check if we should bypass error to facilitate copyup */
#define IS_COPYUP_ERR(err) ((err) == -EROFS)
/* unionfs_open, check if we need to copyup the file */
#define OPEN_WRITE_FLAGS (O_WRONLY | O_RDWR | O_APPEND)
#define IS_WRITE_FLAG(flag) ((flag) & OPEN_WRITE_FLAGS)
static inline int branchperms(const struct super_block *sb, int index)
{
BUG_ON(index < 0);
return UNIONFS_SB(sb)->data[index].branchperms;
}
static inline int set_branchperms(struct super_block *sb, int index, int perms)
{
BUG_ON(index < 0);
UNIONFS_SB(sb)->data[index].branchperms = perms;
return perms;
}
/* check if readonly lower inode, but possibly unlinked (no inode->i_sb) */
static inline int __is_rdonly(const struct inode *inode)
{
/* if unlinked, can't be readonly (?) */
if (!inode->i_sb)
return 0;
return IS_RDONLY(inode);
}
/* Is this file on a read-only branch? */
static inline int is_robranch_super(const struct super_block *sb, int index)
{
int ret;
ret = (!(branchperms(sb, index) & MAY_WRITE)) ? -EROFS : 0;
return ret;
}
/* Is this file on a read-only branch? */
static inline int is_robranch_idx(const struct dentry *dentry, int index)
{
struct super_block *lower_sb;
BUG_ON(index < 0);
if (!(branchperms(dentry->d_sb, index) & MAY_WRITE))
return -EROFS;
lower_sb = unionfs_lower_super_idx(dentry->d_sb, index);
BUG_ON(lower_sb == NULL);
/*
* test sb flags directly, not IS_RDONLY(lower_inode) because the
* lower_dentry could be a negative.
*/
if (lower_sb->s_flags & MS_RDONLY)
return -EROFS;
return 0;
}
static inline int is_robranch(const struct dentry *dentry)
{
int index;
index = UNIONFS_D(dentry)->bstart;
BUG_ON(index < 0);
return is_robranch_idx(dentry, index);
}
/*
* EXTERNALS:
*/
extern int check_branch(const struct path *path);
extern int parse_branch_mode(const char *name, int *perms);
/* locking helpers */
static inline struct dentry *lock_parent(struct dentry *dentry)
{
struct dentry *dir = dget_parent(dentry);
mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
return dir;
}
static inline struct dentry *lock_parent_wh(struct dentry *dentry)
{
struct dentry *dir = dget_parent(dentry);
mutex_lock_nested(&dir->d_inode->i_mutex, UNIONFS_DMUTEX_WHITEOUT);
return dir;
}
static inline void unlock_dir(struct dentry *dir)
{
mutex_unlock(&dir->d_inode->i_mutex);
dput(dir);
}
/* lock base inode mutex before calling lookup_one_len */
static inline struct dentry *lookup_lck_len(const char *name,
struct dentry *base, int len)
{
struct dentry *d;
mutex_lock(&base->d_inode->i_mutex);
d = lookup_one_len(name, base, len); // XXX: pass flags?
mutex_unlock(&base->d_inode->i_mutex);
return d;
}
static inline struct vfsmount *unionfs_mntget(struct dentry *dentry,
int bindex)
{
struct vfsmount *mnt;
BUG_ON(!dentry || bindex < 0);
mnt = mntget(unionfs_lower_mnt_idx(dentry, bindex));
#ifdef CONFIG_UNION_FS_DEBUG
if (!mnt)
pr_debug("unionfs: mntget: mnt=%p bindex=%d\n",
mnt, bindex);
#endif /* CONFIG_UNION_FS_DEBUG */
return mnt;
}
static inline void unionfs_mntput(struct dentry *dentry, int bindex)
{
struct vfsmount *mnt;
if (!dentry && bindex < 0)
return;
BUG_ON(!dentry || bindex < 0);
mnt = unionfs_lower_mnt_idx(dentry, bindex);
#ifdef CONFIG_UNION_FS_DEBUG
/*
* Directories can have NULL lower objects in between start/end, but
* NOT if at the start/end range. We cannot verify that this dentry
* is a type=DIR, because it may already be a negative dentry. But
* if dbstart is greater than dbend, we know that this couldn't have
* been a regular file: it had to have been a directory.
*/
if (!mnt && !(bindex > dbstart(dentry) && bindex < dbend(dentry)))
pr_debug("unionfs: mntput: mnt=%p bindex=%d\n", mnt, bindex);
#endif /* CONFIG_UNION_FS_DEBUG */
mntput(mnt);
}
#ifdef CONFIG_UNION_FS_DEBUG
/* useful for tracking code reachability */
#define UDBG pr_debug("DBG:%s:%s:%d\n", __FILE__, __func__, __LINE__)
#define unionfs_check_inode(i) __unionfs_check_inode((i), \
__FILE__, __func__, __LINE__)
#define unionfs_check_dentry(d) __unionfs_check_dentry((d), \
__FILE__, __func__, __LINE__)
#define unionfs_check_file(f) __unionfs_check_file((f), \
__FILE__, __func__, __LINE__)
#define unionfs_check_nd(n) __unionfs_check_nd((n), \
__FILE__, __func__, __LINE__)
#define show_branch_counts(sb) __show_branch_counts((sb), \
__FILE__, __func__, __LINE__)
#define show_inode_times(i) __show_inode_times((i), \
__FILE__, __func__, __LINE__)
#define show_dinode_times(d) __show_dinode_times((d), \
__FILE__, __func__, __LINE__)
#define show_inode_counts(i) __show_inode_counts((i), \
__FILE__, __func__, __LINE__)
extern void __unionfs_check_inode(const struct inode *inode, const char *fname,
const char *fxn, int line);
extern void __unionfs_check_dentry(const struct dentry *dentry,
const char *fname, const char *fxn,
int line);
extern void __unionfs_check_file(const struct file *file,
const char *fname, const char *fxn, int line);
extern void __show_branch_counts(const struct super_block *sb,
const char *file, const char *fxn, int line);
extern void __show_inode_times(const struct inode *inode,
const char *file, const char *fxn, int line);
extern void __show_dinode_times(const struct dentry *dentry,
const char *file, const char *fxn, int line);
extern void __show_inode_counts(const struct inode *inode,
const char *file, const char *fxn, int line);
#else /* not CONFIG_UNION_FS_DEBUG */
/* we leave useful hooks for these check functions throughout the code */
#define unionfs_check_inode(i) do { } while (0)
#define unionfs_check_dentry(d) do { } while (0)
#define unionfs_check_file(f) do { } while (0)
#define unionfs_check_nd(n) do { } while (0)
#define show_branch_counts(sb) do { } while (0)
#define show_inode_times(i) do { } while (0)
#define show_dinode_times(d) do { } while (0)
#define show_inode_counts(i) do { } while (0)
#define UDBG do { } while (0)
#endif /* not CONFIG_UNION_FS_DEBUG */
#endif /* not _UNION_H_ */
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