dir.c

elinux jffs初始版本 具体了解JFFS的文件系统！

/*
 *  dir.c
 *
 *  Copyright (C) 1995, 1996 by Paal-Kr. Engstad and Volker Lendecke
 *
 */

#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/stat.h>
#include <linux/kernel.h>
#include <linux/malloc.h>
#include <linux/mm.h>
#include <linux/smb_fs.h>
#include <linux/smbno.h>
#include <asm/segment.h>
#include <asm/semaphore.h>
#include <linux/errno.h>

static int
 smb_dir_read(struct inode *inode, struct file *filp, char *buf, int count);

static int
 smb_readdir(struct inode *inode, struct file *filp,
	     void *dirent, filldir_t filldir);

static struct smb_inode_info *
 smb_find_dir_inode(struct inode *parent, const char *name, int len);

static int
 smb_lookup(struct inode *dir, const char *__name,
	    int len, struct inode **result);

static int
 smb_create(struct inode *dir, const char *name, int len, int mode,
	    struct inode **result);

static int
 smb_mkdir(struct inode *dir, const char *name, int len, int mode);

static int
 smb_rmdir(struct inode *dir, const char *name, int len);

static int
 smb_unlink(struct inode *dir, const char *name, int len);

static int
 smb_rename(struct inode *old_dir, const char *old_name, int old_len,
	    struct inode *new_dir, const char *new_name, int new_len,
	    int must_be_dir);

static struct file_operations smb_dir_operations =
{
	NULL,			/* lseek - default */
	smb_dir_read,		/* read - bad */
	NULL,			/* write - bad */
	smb_readdir,		/* readdir */
	NULL,			/* select - default */
	smb_ioctl,		/* ioctl - default */
	NULL,			/* mmap */
	NULL,			/* no special open code */
	NULL,			/* no special release code */
	NULL			/* fsync */
};

struct inode_operations smb_dir_inode_operations =
{
	&smb_dir_operations,	/* default directory file ops */
	smb_create,		/* create */
	smb_lookup,		/* lookup */
	NULL,			/* link */
	smb_unlink,		/* unlink */
	NULL,			/* symlink */
	smb_mkdir,		/* mkdir */
	smb_rmdir,		/* rmdir */
	NULL,			/* mknod */
	smb_rename,		/* rename */
	NULL,			/* readlink */
	NULL,			/* follow_link */
	NULL,			/* readpage */
	NULL,			/* writepage */
	NULL,			/* bmap */
	NULL,			/* truncate */
	NULL,			/* permission */
	NULL			/* smap */
};

static int
strncasecmp(const char *s1, const char *s2, int len)
{
	int result = 0;

	for (; len > 0; len -= 1)
	{
		char c1, c2;

		c1 = (*s1 >= 'a' && *s1 <= 'z') ? *s1 - ('a' - 'A') : *s1;
		c2 = (*s2 >= 'a' && *s2 <= 'z') ? *s2 - ('a' - 'A') : *s2;
		s1 += 1;
		s2 += 1;

		if ((result = c1 - c2) != 0 || c1 == 0)
		{
			return result;
		}
	}
	return result;
}

struct smb_inode_info *
smb_find_inode(struct smb_server *server, ino_t ino)
{
	struct smb_inode_info *root = &(server->root);
	struct smb_inode_info *this = root;

	do
	{
		if (ino == smb_info_ino(this))
		{
			return this;
		}
		this = this->next;
	}
	while (this != root);

	return NULL;
}

static ino_t
smb_fresh_inodes(struct smb_server *server, int no)
{
	static ino_t seed = 1;
	struct smb_inode_info *root = &(server->root);
	struct smb_inode_info *this;

      retry:
	if (seed + no <= no)
	{
		/* avoid inode number of 0 at wrap-around */
		seed += no;
	}
	this = root;
	do
	{
		/* We assume that ino_t is unsigned! */
		if (this->finfo.f_ino - seed < no)
		{
			seed += no;
			goto retry;
		}
		this = this->next;
	}
	while (this != root);

	seed += no;

	return seed - no;
}

static int
smb_dir_read(struct inode *inode, struct file *filp, char *buf, int count)
{
	return -EISDIR;
}


static unsigned long c_ino = 0;
static kdev_t c_dev;
static int c_size;
static int c_seen_eof;
static int c_last_returned_index;
static struct smb_dirent *c_entry = NULL;

static struct smb_dirent *
smb_search_in_cache(struct inode *dir, unsigned long f_pos)
{
	int i;

	if ((dir->i_dev != c_dev) || (dir->i_ino != c_ino))
	{
		return NULL;
	}
	for (i = 0; i < c_size; i++)
	{
		if (f_pos == c_entry[i].f_pos)
		{
			c_last_returned_index = i;
			return &(c_entry[i]);
		}
	}
	return NULL;
}

static int
smb_refill_dir_cache(struct smb_server *server, struct inode *dir,
		     unsigned long f_pos)
{
	int result;
	static struct semaphore sem = MUTEX;
	int i;
	ino_t ino;

	do
	{
		down(&sem);
		result = smb_proc_readdir(server, dir, f_pos,
					  SMB_READDIR_CACHE_SIZE, c_entry);

		if (result <= 0)
		{
			smb_invalid_dir_cache(dir->i_ino);
			up(&sem);
			return result;
		}
		c_seen_eof = (result < SMB_READDIR_CACHE_SIZE);
		c_dev = dir->i_dev;
		c_ino = dir->i_ino;
		c_size = result;
		c_last_returned_index = 0;

		ino = smb_fresh_inodes(server, c_size);
		for (i = 0; i < c_size; i++)
		{
			c_entry[i].f_ino = ino;
			ino += 1;
		}

		up(&sem);

	}
	while ((c_dev != dir->i_dev) || (c_ino != dir->i_ino));

	return result;
}

static int
smb_readdir(struct inode *dir, struct file *filp,
	    void *dirent, filldir_t filldir)
{
	int result, i = 0;
	struct smb_dirent *entry = NULL;
	struct smb_server *server = SMB_SERVER(dir);

	DPRINTK("smb_readdir: filp->f_pos = %d\n", (int) filp->f_pos);
	DDPRINTK("smb_readdir: dir->i_ino = %ld, c_ino = %ld\n",
		 dir->i_ino, c_ino);

	if ((dir == NULL) || !S_ISDIR(dir->i_mode))
	{
		printk("smb_readdir: dir is NULL or not a directory\n");
		return -EBADF;
	}
	if (c_entry == NULL)
	{
		i = sizeof(struct smb_dirent) * SMB_READDIR_CACHE_SIZE;
		c_entry = (struct smb_dirent *) smb_vmalloc(i);
		if (c_entry == NULL)
		{
			printk("smb_readdir: no MEMORY for cache\n");
			return -ENOMEM;
		}
	}
	if (filp->f_pos == 0)
	{
		c_ino = 0;
		c_dev = 0;
		c_seen_eof = 0;

		if (filldir(dirent, ".", 1, filp->f_pos,
			    smb_info_ino(SMB_INOP(dir))) < 0)
		{
			return 0;
		}
		filp->f_pos += 1;
	}
	if (filp->f_pos == 1)
	{
		if (filldir(dirent, "..", 2, filp->f_pos,
			    smb_info_ino(SMB_INOP(dir)->dir)) < 0)
		{
			return 0;
		}
		filp->f_pos += 1;
	}
	entry = smb_search_in_cache(dir, filp->f_pos);

	if (entry == NULL)
	{
		if (c_seen_eof)
		{
			/* End of directory */
			return 0;
		}
		result = smb_refill_dir_cache(server, dir, filp->f_pos);
		if (result <= 0)
		{
			return result;
		}
		entry = c_entry;
	}
	while (entry < &(c_entry[c_size]))
	{
		/* We found it.  For getwd(), we have to return the
		   correct inode in d_ino if the inode is currently in
		   use. Otherwise the inode number does not
		   matter. (You can argue a lot about this..) */

		struct smb_inode_info *ino_info
		= smb_find_dir_inode(dir, entry->name, entry->len);

		ino_t ino = entry->f_ino;

		if (ino_info != NULL)
		{
			ino = smb_info_ino(ino_info);
		}
		DDPRINTK("smb_readdir: entry->name = %s\n", entry->name);
		DDPRINTK("smb_readdir: entry->f_pos = %ld\n", entry->f_pos);

		if (filldir(dirent, entry->name, strlen(entry->name),
			    entry->f_pos, ino) < 0)
		{
			break;
		}
		if ((dir->i_dev != c_dev) || (dir->i_ino != c_ino)
		    || (entry->f_pos != filp->f_pos))
		{
			/* Someone has destroyed the cache while we slept
			   in filldir */
			break;
		}
		filp->f_pos += 1;
		entry += 1;
	}
	return 0;
}

void
smb_init_dir_cache(void)
{
	c_ino = 0;
	c_dev = 0;
	c_entry = NULL;
}

void
smb_invalid_dir_cache(unsigned long ino)
{
	/* TODO: check for dev as well */
	if (ino == c_ino)
	{
		c_ino = 0;
		c_seen_eof = 0;
	}
}

void
smb_free_dir_cache(void)
{
	if (c_entry != NULL)
	{
		smb_vfree(c_entry);
	}
	c_entry = NULL;
}

/* Insert a NEW smb_inode_info into the inode tree of our filesystem,
   under dir. The caller must assure that it's not already there. We
   assume that path is allocated for us. */

static struct inode *
smb_iget(struct inode *dir, struct smb_inode_info *new_inode_info)
{
	struct inode *inode;
	struct smb_inode_info *root;

	if ((dir == NULL) || (new_inode_info == NULL))
	{
		printk("smb_iget: parameter is NULL\n");
		return NULL;
	}
	new_inode_info->state = SMB_INODE_LOOKED_UP;
	new_inode_info->nused = 0;
	new_inode_info->dir = SMB_INOP(dir);

	SMB_INOP(dir)->nused += 1;

	/*
	 * We have to link the new inode_info into the doubly linked
	 * list of inode_infos to make a complete linear search possible.
	 */
	root = &(SMB_SERVER(dir)->root);

	new_inode_info->prev = root;
	new_inode_info->next = root->next;
	root->next->prev = new_inode_info;
	root->next = new_inode_info;

	if (!(inode = iget(dir->i_sb, smb_info_ino(new_inode_info))))
	{
		printk("smb_iget: iget failed!");
		/*
		 * If we blocked in iget(), another task may have referenced
		 * the info structure ... clean up with smb_free_inode_info.
		 */
		smb_free_inode_info(new_inode_info);
		return NULL;
	}

	return inode;
}

void
smb_free_inode_info(struct smb_inode_info *i)
{
	if (i == NULL)
	{
		printk("smb_free_inode: i == NULL\n");
		return;
	}
	i->state = SMB_INODE_CACHED;
	while ((i->nused == 0) && (i->state == SMB_INODE_CACHED))
	{
		struct smb_inode_info *dir = i->dir;

		i->next->prev = i->prev;
		i->prev->next = i->next;

		smb_kfree_s(i, sizeof(struct smb_inode_info));

		if (dir == NULL)