root.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 823 行 · 第 1/2 页

/* -*- c -*- --------------------------------------------------------------- *
 *
 * linux/fs/autofs/root.c
 *
 *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
 *  Copyright 1999-2000 Jeremy Fitzhardinge <[e-mail]>
 *  Copyright 2001-2003 Ian Kent <[e-mail]>
 *
 * This file is part of the Linux kernel and is made available under
 * the terms of the GNU General Public License, version 2, or at your
 * option, any later version, incorporated herein by reference.
 *
 * ------------------------------------------------------------------------- */

#include <linux/errno.h>
#include <linux/stat.h>
#include <linux/param.h>
#include <linux/time.h>
#include <linux/smp_lock.h>
#include "autofs_i.h"

static struct dentry *autofs4_dir_lookup(struct inode *,struct dentry *, struct nameidata *);
static int autofs4_dir_symlink(struct inode *,struct dentry *,const char *);
static int autofs4_dir_unlink(struct inode *,struct dentry *);
static int autofs4_dir_rmdir(struct inode *,struct dentry *);
static int autofs4_dir_mkdir(struct inode *,struct dentry *,int);
static int autofs4_root_ioctl(struct inode *, struct file *,unsigned int,unsigned long);
static int autofs4_dir_open(struct inode *inode, struct file *file);
static int autofs4_dir_close(struct inode *inode, struct file *file);
static int autofs4_dir_readdir(struct file * filp, void * dirent, filldir_t filldir);
static int autofs4_root_readdir(struct file * filp, void * dirent, filldir_t filldir);
static struct dentry *autofs4_root_lookup(struct inode *,struct dentry *, struct nameidata *);
static int autofs4_dcache_readdir(struct file *, void *, filldir_t);

struct file_operations autofs4_root_operations = {
	.open		= dcache_dir_open,
	.release	= dcache_dir_close,
	.read		= generic_read_dir,
	.readdir	= autofs4_root_readdir,
	.ioctl		= autofs4_root_ioctl,
};

struct file_operations autofs4_dir_operations = {
	.open		= autofs4_dir_open,
	.release	= autofs4_dir_close,
	.read		= generic_read_dir,
	.readdir	= autofs4_dir_readdir,
};

struct inode_operations autofs4_root_inode_operations = {
	.lookup		= autofs4_root_lookup,
	.unlink		= autofs4_dir_unlink,
	.symlink	= autofs4_dir_symlink,
	.mkdir		= autofs4_dir_mkdir,
	.rmdir		= autofs4_dir_rmdir,
};

struct inode_operations autofs4_dir_inode_operations = {
	.lookup		= autofs4_dir_lookup,
	.unlink		= autofs4_dir_unlink,
	.symlink	= autofs4_dir_symlink,
	.mkdir		= autofs4_dir_mkdir,
	.rmdir		= autofs4_dir_rmdir,
};

static int autofs4_root_readdir(struct file *file, void *dirent,
				filldir_t filldir)
{
	struct autofs_sb_info *sbi = autofs4_sbi(file->f_dentry->d_sb);
	int oz_mode = autofs4_oz_mode(sbi);

	DPRINTK("called, filp->f_pos = %lld", file->f_pos);

	/*
	 * Don't set reghost flag if:
	 * 1) f_pos is larger than zero -- we've already been here.
	 * 2) we haven't even enabled reghosting in the 1st place.
	 * 3) this is the daemon doing a readdir
	 */
	if (oz_mode && file->f_pos == 0 && sbi->reghost_enabled)
		sbi->needs_reghost = 1;

	DPRINTK("needs_reghost = %d", sbi->needs_reghost);

	return autofs4_dcache_readdir(file, dirent, filldir);
}

/* Update usage from here to top of tree, so that scan of
   top-level directories will give a useful result */
static void autofs4_update_usage(struct dentry *dentry)
{
	struct dentry *top = dentry->d_sb->s_root;

	spin_lock(&dcache_lock);
	for(; dentry != top; dentry = dentry->d_parent) {
		struct autofs_info *ino = autofs4_dentry_ino(dentry);

		if (ino) {
			update_atime(dentry->d_inode);
			ino->last_used = jiffies;
		}
	}
	spin_unlock(&dcache_lock);
}

/*
 * From 2.4 kernel readdir.c
 */
static int autofs4_dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
	int i;
	struct dentry *dentry = filp->f_dentry;

	i = filp->f_pos;
	switch (i) {
		case 0:
			if (filldir(dirent, ".", 1, i, dentry->d_inode->i_ino, DT_DIR) < 0)
				break;
			i++;
			filp->f_pos++;
			/* fallthrough */
		case 1:
			if (filldir(dirent, "..", 2, i, dentry->d_parent->d_inode->i_ino, DT_DIR) < 0)
				break;
			i++;
			filp->f_pos++;
			/* fallthrough */
		default: {
			struct list_head *list;
			int j = i-2;

			spin_lock(&dcache_lock);
			list = dentry->d_subdirs.next;

			for (;;) {
				if (list == &dentry->d_subdirs) {
					spin_unlock(&dcache_lock);
					return 0;
				}
				if (!j)
					break;
				j--;
				list = list->next;
			}

			while(1) {
				struct dentry *de = list_entry(list, struct dentry, d_child);

				if (!d_unhashed(de) && de->d_inode) {
					spin_unlock(&dcache_lock);
					if (filldir(dirent, de->d_name.name, de->d_name.len, filp->f_pos, de->d_inode->i_ino, DT_UNKNOWN) < 0)
						break;
					spin_lock(&dcache_lock);
				}
				filp->f_pos++;
				list = list->next;
				if (list != &dentry->d_subdirs)
					continue;
				spin_unlock(&dcache_lock);
				break;
			}
		}
	}
	return 0;
}

static int autofs4_dir_open(struct inode *inode, struct file *file)
{
	struct dentry *dentry = file->f_dentry;
	struct vfsmount *mnt = file->f_vfsmnt;
	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
	int status;

	DPRINTK("file=%p dentry=%p %.*s",
		file, dentry, dentry->d_name.len, dentry->d_name.name);

	if (autofs4_oz_mode(sbi))
		goto out;

	if (autofs4_ispending(dentry)) {
		DPRINTK("dentry busy");
		return -EBUSY;
	}

	if (!d_mountpoint(dentry) && dentry->d_op && dentry->d_op->d_revalidate) {
		struct nameidata nd;
		int empty;

		/* In case there are stale directory dentrys from a failed mount */
		spin_lock(&dcache_lock);
		empty = list_empty(&dentry->d_subdirs);
		spin_unlock(&dcache_lock);

		if (!empty)
			d_invalidate(dentry);

		nd.flags = LOOKUP_DIRECTORY;
		status = (dentry->d_op->d_revalidate)(dentry, &nd);

		if (!status)
			return -ENOENT;
	}

	if (d_mountpoint(dentry)) {
		struct file *fp = NULL;
		struct vfsmount *fp_mnt = mntget(mnt);
		struct dentry *fp_dentry = dget(dentry);

		while (follow_down(&fp_mnt, &fp_dentry) && d_mountpoint(fp_dentry));

		fp = dentry_open(fp_dentry, fp_mnt, file->f_flags);
		status = PTR_ERR(fp);
		if (IS_ERR(fp)) {
			file->private_data = NULL;
			return status;
		}
		file->private_data = fp;
	}
out:
	return 0;
}

static int autofs4_dir_close(struct inode *inode, struct file *file)
{
	struct dentry *dentry = file->f_dentry;
	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);

	DPRINTK("file=%p dentry=%p %.*s",
		file, dentry, dentry->d_name.len, dentry->d_name.name);

	if (autofs4_oz_mode(sbi))
		goto out;

	if (autofs4_ispending(dentry)) {
		DPRINTK("dentry busy");
		return -EBUSY;
	}

	if (d_mountpoint(dentry)) {
		struct file *fp = file->private_data;

		if (!fp)
			return -ENOENT;

		filp_close(fp, current->files);
		file->private_data = NULL;
	}
out:
	return 0;
}

static int autofs4_dir_readdir(struct file *file, void *dirent, filldir_t filldir)
{
	struct dentry *dentry = file->f_dentry;
	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
	int status;

	DPRINTK("file=%p dentry=%p %.*s",
		file, dentry, dentry->d_name.len, dentry->d_name.name);

	if (autofs4_oz_mode(sbi))
		goto out;

	if (autofs4_ispending(dentry)) {
		DPRINTK("dentry busy");
		return -EBUSY;
	}

	if (d_mountpoint(dentry)) {
		struct file *fp = file->private_data;

		if (!fp)
			return -ENOENT;

		if (!fp->f_op || !fp->f_op->readdir)
			goto out;

		status = vfs_readdir(fp, filldir, dirent);
		file->f_pos = fp->f_pos;
		if (status)
			autofs4_copy_atime(file, fp);
		return status;
	}
out:
	return autofs4_dcache_readdir(file, dirent, filldir);
}

static int try_to_fill_dentry(struct dentry *dentry, 
			      struct super_block *sb,
			      struct autofs_sb_info *sbi, int flags)
{
	struct autofs_info *de_info = autofs4_dentry_ino(dentry);
	int status = 0;

	/* Block on any pending expiry here; invalidate the dentry
           when expiration is done to trigger mount request with a new
           dentry */
	if (de_info && (de_info->flags & AUTOFS_INF_EXPIRING)) {
		DPRINTK("waiting for expire %p name=%.*s",
			 dentry, dentry->d_name.len, dentry->d_name.name);

		status = autofs4_wait(sbi, dentry, NFY_NONE);
		
		DPRINTK("expire done status=%d", status);
		
		return 0;
	}

	DPRINTK("dentry=%p %.*s ino=%p",
		 dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode);

	/* Wait for a pending mount, triggering one if there isn't one already */
	if (dentry->d_inode == NULL) {
		DPRINTK("waiting for mount name=%.*s",
			 dentry->d_name.len, dentry->d_name.name);

		status = autofs4_wait(sbi, dentry, NFY_MOUNT);
		 
		DPRINTK("mount done status=%d", status);

		if (status && dentry->d_inode)
			return 0; /* Try to get the kernel to invalidate this dentry */
		
		/* Turn this into a real negative dentry? */
		if (status == -ENOENT) {
			dentry->d_time = jiffies + AUTOFS_NEGATIVE_TIMEOUT;
			spin_lock(&dentry->d_lock);
			dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
			spin_unlock(&dentry->d_lock);
			return 1;
		} else if (status) {
			/* Return a negative dentry, but leave it "pending" */
			return 1;
		}
	/* Trigger mount for path component or follow link */
	} else if (flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY) ||
			current->link_count) {
		DPRINTK("waiting for mount name=%.*s",
			dentry->d_name.len, dentry->d_name.name);

		spin_lock(&dentry->d_lock);
		dentry->d_flags |= DCACHE_AUTOFS_PENDING;
		spin_unlock(&dentry->d_lock);
		status = autofs4_wait(sbi, dentry, NFY_MOUNT);

		DPRINTK("mount done status=%d", status);

		if (status) {
			spin_lock(&dentry->d_lock);
			dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
			spin_unlock(&dentry->d_lock);
			return 0;
		}
	}

	/* We don't update the usages for the autofs daemon itself, this
	   is necessary for recursive autofs mounts */
	if (!autofs4_oz_mode(sbi))
		autofs4_update_usage(dentry);

	spin_lock(&dentry->d_lock);
	dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
	spin_unlock(&dentry->d_lock);
	return 1;
}

/*
 * Revalidate is called on every cache lookup.  Some of those
 * cache lookups may actually happen while the dentry is not
 * yet completely filled in, and revalidate has to delay such
 * lookups..
 */
static int autofs4_revalidate(struct dentry * dentry, struct nameidata *nd)
{
	struct inode * dir = dentry->d_parent->d_inode;
	struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
	int oz_mode = autofs4_oz_mode(sbi);
	int flags = nd ? nd->flags : 0;
	int status = 1;

	/* Pending dentry */
	if (autofs4_ispending(dentry)) {
		if (!oz_mode)
			status = try_to_fill_dentry(dentry, dir->i_sb, sbi, flags);
		return status;
	}

	/* Negative dentry.. invalidate if "old" */
	if (dentry->d_inode == NULL)
		return (dentry->d_time - jiffies <= AUTOFS_NEGATIVE_TIMEOUT);

	/* Check for a non-mountpoint directory with no contents */
	spin_lock(&dcache_lock);
	if (S_ISDIR(dentry->d_inode->i_mode) &&
	    !d_mountpoint(dentry) && 
	    list_empty(&dentry->d_subdirs)) {
		DPRINTK("dentry=%p %.*s, emptydir",
			 dentry, dentry->d_name.len, dentry->d_name.name);
		spin_unlock(&dcache_lock);
		if (!oz_mode)
			status = try_to_fill_dentry(dentry, dir->i_sb, sbi, flags);
		return status;
	}
	spin_unlock(&dcache_lock);

	/* Update the usage list */
	if (!oz_mode)
		autofs4_update_usage(dentry);

	return 1;
}