Message-Id: <11972545401606-git-send-email-ezk@cs.sunysb.edu>
Date:	Sun,  9 Dec 2007 21:41:44 -0500
From:	Erez Zadok <ezk@...sunysb.edu>
To:	hch@...radead.org, viro@....linux.org.uk, akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	Erez Zadok <ezk@...sunysb.edu>
Subject: [PATCH 11/42] Unionfs: main header file

Signed-off-by: Erez Zadok <ezk@...sunysb.edu>
---
 fs/unionfs/union.h |  591 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 591 insertions(+), 0 deletions(-)
 create mode 100644 fs/unionfs/union.h

diff --git a/fs/unionfs/union.h b/fs/unionfs/union.h
new file mode 100644
index 0000000..20bff7b
--- /dev/null
+++ b/fs/unionfs/union.h
@@ -0,0 +1,591 @@
+/*
+ * Copyright (c) 2003-2007 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) 2003-2007 Stony Brook University
+ * Copyright (c) 2003-2007 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/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/smp_lock.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 <asm/system.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;
+
+/* How long should an entry be allowed to persist */
+#define RDCACHE_JIFFIES	(5*HZ)
+
+/* 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 */
+};
+
+/* unionfs inode data in memory */
+struct unionfs_inode_info {
+	int bstart;
+	int bend;
+	atomic_t generation;
+	int stale;
+	/* 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;
+	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 rw_semaphore rwsem;
+	pid_t write_lock_owner;	/* PID of rw_sem owner (write lock) */
+	int high_branch_id;	/* last unique branch ID given */
+	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_MIN];
+};
+
+/* 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);
+
+/* 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;
+}
+
+static inline void unionfs_read_lock(struct super_block *sb)
+{
+	if (UNIONFS_SB(sb)->write_lock_owner &&
+	    UNIONFS_SB(sb)->write_lock_owner == current->pid)
+		return;
+	down_read(&UNIONFS_SB(sb)->rwsem);
+}
+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)
+{
+	if (d2 < d1) {
+		struct dentry *tmp = d1;
+		d1 = d2;
+		d2 = tmp;
+	}
+	unionfs_lock_dentry(d1);
+	unionfs_lock_dentry(d2);
+}
+
+extern int new_dentry_private_data(struct dentry *dentry);
+extern void free_dentry_private_data(struct dentry *dentry);
+extern void update_bstart(struct dentry *dentry);
+extern int init_lower_nd(struct nameidata *nd, unsigned int flags);
+extern void release_lower_nd(struct nameidata *nd, int err);
+
+/*
+ * 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);
+extern int make_dir_opaque(struct dentry *dir, int bindex);
+
+/* partial lookup */
+extern int unionfs_partial_lookup(struct dentry *dentry);
+
+/*
+ * Pass an unionfs dentry and an index and it will try to create a whiteout
+ * in branch 'index'.
+ *
+ * On error, it will proceed to a branch to the left
+ */
+extern int create_whiteout(struct dentry *dentry, int start);
+/* 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);
+
+extern int remove_whiteouts(struct dentry *dentry,
+			    struct dentry *lower_dentry, int bindex);
+
+extern int do_delete_whiteouts(struct dentry *dentry, int bindex,
+			       struct unionfs_dir_state *namelist);
+
+/* Is this directory empty: 0 if it is empty, -ENOTEMPTY if not. */
+extern int check_empty(struct dentry *dentry,
+		       struct unionfs_dir_state **namelist);
+/* Delete whiteouts from this directory in branch bindex. */
+extern int delete_whiteouts(struct dentry *dentry, int bindex,
+			    struct unionfs_dir_state *namelist);
+
+/* Re-lookup a lower dentry. */
+extern int unionfs_refresh_lower_dentry(struct dentry *dentry, int bindex);
+
+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, 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, struct dentry *dentry,
+			 int datasync);
+extern int unionfs_fasync(int fd, struct file *file, int flag);
+
+/* Inode operations */
+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_chain(struct dentry *dentry,
+					 struct nameidata *nd, bool willwrite);
+extern bool is_newer_lower(const struct dentry *dentry);
+
+/* 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);
+}
+
+struct dentry *unionfs_lookup_backend(struct dentry *dentry,
+				      struct nameidata *nd, int lookupmode);
+
+/* 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;
+}
+
+/* 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);
+}
+
+/* What do we use for whiteouts. */
+#define UNIONFS_WHPFX ".wh."
+#define UNIONFS_WHLEN 4
+/*
+ * If a directory contains this file, then it is opaque.  We start with the
+ * .wh. flag so that it is blocked by lookup.
+ */
+#define UNIONFS_DIR_OPAQUE_NAME "__dir_opaque"
+#define UNIONFS_DIR_OPAQUE UNIONFS_WHPFX UNIONFS_DIR_OPAQUE_NAME
+
+/*
+ * EXTERNALS:
+ */
+extern char *alloc_whname(const char *name, int len);
+extern int check_branch(struct nameidata *nd);
+extern int parse_branch_mode(const char *name, int *perms);
+
+/*
+ * These two functions are here because it is kind of daft to copy and paste
+ * the contents of the two functions to 32+ places in unionfs
+ */
+static inline struct dentry *lock_parent(struct dentry *dentry)
+{
+	struct dentry *dir = dget(dentry->d_parent);
+
+	mutex_lock(&dir->d_inode->i_mutex);
+	return dir;
+}
+
+static inline void unlock_dir(struct dentry *dir)
+{
+	mutex_unlock(&dir->d_inode->i_mutex);
+	dput(dir);
+}
+
+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__, __FUNCTION__, __LINE__)
+
+#define unionfs_check_inode(i)	__unionfs_check_inode((i),	\
+	__FILE__, __FUNCTION__, __LINE__)
+#define unionfs_check_dentry(d)	__unionfs_check_dentry((d),	\
+	__FILE__, __FUNCTION__, __LINE__)
+#define unionfs_check_file(f)	__unionfs_check_file((f),	\
+	__FILE__, __FUNCTION__, __LINE__)
+#define unionfs_check_nd(n)	__unionfs_check_nd((n),		\
+	__FILE__, __FUNCTION__, __LINE__)
+#define show_branch_counts(sb)	__show_branch_counts((sb),	\
+	__FILE__, __FUNCTION__, __LINE__)
+#define show_inode_times(i)	__show_inode_times((i),		\
+	__FILE__, __FUNCTION__, __LINE__)
+#define show_dinode_times(d)	__show_dinode_times((d),	\
+	__FILE__, __FUNCTION__, __LINE__)
+#define show_inode_counts(i)	__show_inode_counts((i),	\
+	__FILE__, __FUNCTION__, __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 __unionfs_check_nd(const struct nameidata *nd,
+			       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)
+
+#endif /* not CONFIG_UNION_FS_DEBUG */
+
+#endif	/* not _UNION_H_ */
-- 
1.5.2.2

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