dir.c

嵌入式系统设计与实验教材二源码linux内核移植与编译

/*
 * Directory operations for Coda filesystem
 * Original version: (C) 1996 P. Braam and M. Callahan
 * Rewritten for Linux 2.1. (C) 1997 Carnegie Mellon University
 * 
 * Carnegie Mellon encourages users to contribute improvements to
 * the Coda project. Contact Peter Braam ([e-mail]).
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/locks.h>
#include <linux/string.h>
#include <linux/smp_lock.h>

#include <asm/uaccess.h>

#include <linux/coda.h>
#include <linux/coda_linux.h>
#include <linux/coda_psdev.h>
#include <linux/coda_fs_i.h>
#include <linux/coda_cache.h>
#include <linux/coda_proc.h>

/* dir inode-ops */
static int coda_create(struct inode *dir, struct dentry *new, int mode);
static int coda_mknod(struct inode *dir, struct dentry *new, int mode, int rdev);
static struct dentry *coda_lookup(struct inode *dir, struct dentry *target);
static int coda_link(struct dentry *old_dentry, struct inode *dir_inode, 
		     struct dentry *entry);
static int coda_unlink(struct inode *dir_inode, struct dentry *entry);
static int coda_symlink(struct inode *dir_inode, struct dentry *entry,
			const char *symname);
static int coda_mkdir(struct inode *dir_inode, struct dentry *entry, int mode);
static int coda_rmdir(struct inode *dir_inode, struct dentry *entry);
static int coda_rename(struct inode *old_inode, struct dentry *old_dentry, 
                       struct inode *new_inode, struct dentry *new_dentry);

/* dir file-ops */
static int coda_readdir(struct file *file, void *dirent, filldir_t filldir);

/* dentry ops */
static int coda_dentry_revalidate(struct dentry *de, int);
static int coda_dentry_delete(struct dentry *);

/* support routines */
static void coda_prepare_fakefile(struct file *coda_file, 
				  struct dentry *open_dentry,
				  struct file *open_file);
static int coda_venus_readdir(struct file *filp, void *dirent, 
			      filldir_t filldir);
int coda_fsync(struct file *, struct dentry *dentry, int datasync);

int coda_hasmknod;

struct dentry_operations coda_dentry_operations =
{
	d_revalidate:	coda_dentry_revalidate,
	d_delete:	coda_dentry_delete,
};

struct inode_operations coda_dir_inode_operations =
{
	create:		coda_create,
	lookup:		coda_lookup,
	link:		coda_link,
	unlink:		coda_unlink,
	symlink:	coda_symlink,
	mkdir:		coda_mkdir,
	rmdir:		coda_rmdir,
	mknod:		coda_mknod,
	rename:		coda_rename,
	permission:	coda_permission,
        revalidate:	coda_revalidate_inode,
	setattr:	coda_notify_change,
};

struct file_operations coda_dir_operations = {
	read:		generic_read_dir,
	readdir:	coda_readdir,
	open:		coda_open,
	flush:  	coda_flush,
	release:	coda_release,
	fsync:		coda_fsync,
};


/* inode operations for directories */
/* access routines: lookup, readlink, permission */
static struct dentry *coda_lookup(struct inode *dir, struct dentry *entry)
{
	struct inode *res_inode = NULL;
	struct ViceFid resfid = {0,0,0};
	int dropme = 0; /* to indicate entry should not be cached */
	int type = 0;
	int error = 0;
	const char *name = entry->d_name.name;
	size_t length = entry->d_name.len;
	
	if ( length > CODA_MAXNAMLEN ) {
	        printk("name too long: lookup, %s (%*s)\n", 
		       coda_i2s(dir), (int)length, name);
		return ERR_PTR(-ENAMETOOLONG);
	}

        CDEBUG(D_INODE, "name %s, len %ld in ino %ld, fid %s\n", 
	       name, (long)length, dir->i_ino, coda_i2s(dir));

        /* control object, create inode on the fly */
        if (coda_isroot(dir) && coda_iscontrol(name, length)) {
	        error = coda_cnode_makectl(&res_inode, dir->i_sb);
		CDEBUG(D_SPECIAL, 
		       "Lookup on CTL object; dir ino %ld, count %d\n", 
		       dir->i_ino, atomic_read(&dir->i_count));
		dropme = 1;
                goto exit;
        }

	error = venus_lookup(dir->i_sb, coda_i2f(dir), 
			     (const char *)name, length, &type, &resfid);

	res_inode = NULL;
	if (!error) {
		if (type & CODA_NOCACHE) {
			type &= (~CODA_NOCACHE);
			CDEBUG(D_INODE, "dropme set for %s\n", 
			       coda_f2s(&resfid));
			dropme = 1;
		}

	    	error = coda_cnode_make(&res_inode, &resfid, dir->i_sb);
		if (error) return ERR_PTR(error);
	} else if (error != -ENOENT) {
	        CDEBUG(D_INODE, "error for %s(%*s)%d\n",
		       coda_i2s(dir), (int)length, name, error);
		return ERR_PTR(error);
	}
	CDEBUG(D_INODE, "lookup: %s is (%s), type %d result %d, dropme %d\n",
	       name, coda_f2s(&resfid), type, error, dropme);

exit:
	entry->d_time = 0;
	entry->d_op = &coda_dentry_operations;
	d_add(entry, res_inode);
	if ( dropme ) {
		d_drop(entry);
		coda_flag_inode(res_inode, C_VATTR);
	}
        return NULL;
}


int coda_permission(struct inode *inode, int mask)
{
        int error;
 
	coda_vfs_stat.permission++;

        if ( mask == 0 )
                return 0;

	if ( coda_access_cache ) {
		coda_permission_stat.count++;

		if ( coda_cache_check(inode, mask) ) {
			coda_permission_stat.hit_count++;
			return 0; 
		}
	}

        CDEBUG(D_INODE, "mask is %o\n", mask);
        error = venus_access(inode->i_sb, coda_i2f(inode), mask);
    
        CDEBUG(D_INODE, "fid: %s, ino: %ld (mask: %o) error: %d\n", 
	       coda_i2s(inode), inode->i_ino, mask, error);

	if (!error)
		coda_cache_enter(inode, mask);

        return error; 
}


static inline void coda_dir_changed(struct inode *dir, int link)
{
#ifdef REQUERY_VENUS_FOR_MTIME
	/* invalidate the directory cnode's attributes so we refetch the
	 * attributes from venus next time the inode is referenced */
	coda_flag_inode(dir, C_VATTR);
#else
	/* optimistically we can also act as if our nose bleeds. The
         * granularity of the mtime is coarse anyways so we might actually be
         * right most of the time. Note: we only do this for directories. */
	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
#endif
	if (link)
		dir->i_nlink += link;
}

/* creation routines: create, mknod, mkdir, link, symlink */
static int coda_create(struct inode *dir, struct dentry *de, int mode)
{
        int error=0;
	const char *name=de->d_name.name;
	int length=de->d_name.len;
	struct inode *inode = NULL;
	struct ViceFid newfid;
	struct coda_vattr attrs;

	coda_vfs_stat.create++;

	CDEBUG(D_INODE, "name: %s, length %d, mode %o\n", name, length, mode);

	if (coda_isroot(dir) && coda_iscontrol(name, length))
		return -EPERM;

	error = venus_create(dir->i_sb, coda_i2f(dir), name, length, 
				0, mode, 0, &newfid, &attrs);

        if ( error ) {
		CDEBUG(D_INODE, "create: %s, result %d\n",
		       coda_f2s(&newfid), error); 
		d_drop(de);
		return error;
	}

	inode = coda_iget(dir->i_sb, &newfid, &attrs);
	if ( IS_ERR(inode) ) {
		d_drop(de);
		return PTR_ERR(inode);
	}

	/* invalidate the directory cnode's attributes */
	coda_dir_changed(dir, 0);
	d_instantiate(de, inode);
        return 0;
}

static int coda_mknod(struct inode *dir, struct dentry *de, int mode, int rdev)
{
        int error=0;
	const char *name=de->d_name.name;
	int length=de->d_name.len;
	struct inode *result = NULL;
	struct ViceFid newfid;
	struct coda_vattr attrs;

	if ( coda_hasmknod == 0 )
		return -EIO;

	coda_vfs_stat.create++;

	CDEBUG(D_INODE, "name: %s, length %d, mode %o, rdev %x\n",
	       name, length, mode, rdev);

	if (coda_isroot(dir) && coda_iscontrol(name, length))
		return -EPERM;

	error = venus_create(dir->i_sb, coda_i2f(dir), name, length, 
				0, mode, rdev, &newfid, &attrs);

        if ( error ) {
		CDEBUG(D_INODE, "mknod: %s, result %d\n",
		       coda_f2s(&newfid), error); 
		d_drop(de);
		return error;
	}

	error = coda_cnode_make(&result, &newfid, dir->i_sb);
	if ( error ) {
		d_drop(de);
		result = NULL;
		return error;
	}

	/* invalidate the directory cnode's attributes */
	coda_dir_changed(dir, 0);
	d_instantiate(de, result);
        return 0;
}			     

static int coda_mkdir(struct inode *dir, struct dentry *de, int mode)
{
	struct inode *inode;
	struct coda_vattr attr;
	const char *name = de->d_name.name;
	int len = de->d_name.len;
	int error;
	struct ViceFid newfid;

	coda_vfs_stat.mkdir++;

	if (coda_isroot(dir) && coda_iscontrol(name, len))
		return -EPERM;

	CDEBUG(D_INODE, "mkdir %s (len %d) in %s, mode %o.\n", 
	       name, len, coda_i2s(dir), mode);

	attr.va_mode = mode;
	error = venus_mkdir(dir->i_sb, coda_i2f(dir), 
			       name, len, &newfid, &attr);
        
        if ( error ) {
	        CDEBUG(D_INODE, "mkdir error: %s result %d\n", 
		       coda_f2s(&newfid), error); 
		d_drop(de);
                return error;
        }
         
	CDEBUG(D_INODE, "mkdir: new dir has fid %s.\n", 
	       coda_f2s(&newfid)); 

	error = coda_cnode_make(&inode, &newfid, dir->i_sb);
	if ( error ) {
		d_drop(de);
		return error;
	}
	
	/* invalidate the directory cnode's attributes */
	coda_dir_changed(dir, 1);
	d_instantiate(de, inode);
        return 0;
}

/* try to make de an entry in dir_inodde linked to source_de */ 
static int coda_link(struct dentry *source_de, struct inode *dir_inode, 
	  struct dentry *de)
{
	struct inode *inode = source_de->d_inode;
        const char * name = de->d_name.name;
	int len = de->d_name.len;
	int error;

	coda_vfs_stat.link++;

	if (coda_isroot(dir_inode) && coda_iscontrol(name, len))
		return -EPERM;

	CDEBUG(D_INODE, "old: fid: %s\n", coda_i2s(inode));
	CDEBUG(D_INODE, "directory: %s\n", coda_i2s(dir_inode));

	error = venus_link(dir_inode->i_sb, coda_i2f(inode),
			   coda_i2f(dir_inode), (const char *)name, len);

	if (error) { 
		d_drop(de);
		goto out;
	}

	coda_dir_changed(dir_inode, 0);
	atomic_inc(&inode->i_count);
	d_instantiate(de, inode);
	inode->i_nlink++;
        
out:
	CDEBUG(D_INODE, "link result %d\n",error);
	return(error);
}


static int coda_symlink(struct inode *dir_inode, struct dentry *de,
			const char *symname)
{
        const char *name = de->d_name.name;
	int len = de->d_name.len;
	int symlen;
        int error=0;
        
	coda_vfs_stat.symlink++;

	if (coda_isroot(dir_inode) && coda_iscontrol(name, len))
		return -EPERM;

	symlen = strlen(symname);
	if ( symlen > CODA_MAXPATHLEN )
                return -ENAMETOOLONG;

        CDEBUG(D_INODE, "symname: %s, length: %d\n", symname, symlen);

	/*
	 * This entry is now negative. Since we do not create
	 * an inode for the entry we have to drop it. 
	 */