dir.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 667 行 · 第 1/2 页

	int ret;

	_enter("{%lu},%u,,", dir->i_ino, *fpos);

	if (AFS_FS_I(dir)->flags & AFS_VNODE_DELETED) {
		_leave(" = -ESTALE");
		return -ESTALE;
	}

	/* round the file position up to the next entry boundary */
	*fpos += sizeof(union afs_dirent) - 1;
	*fpos &= ~(sizeof(union afs_dirent) - 1);

	/* walk through the blocks in sequence */
	ret = 0;
	while (*fpos < dir->i_size) {
		blkoff = *fpos & ~(sizeof(union afs_dir_block) - 1);

		/* fetch the appropriate page from the directory */
		page = afs_dir_get_page(dir, blkoff / PAGE_SIZE);
		if (IS_ERR(page)) {
			ret = PTR_ERR(page);
			break;
		}

		limit = blkoff & ~(PAGE_SIZE - 1);

		dbuf = page_address(page);

		/* deal with the individual blocks stashed on this page */
		do {
			dblock = &dbuf->blocks[(blkoff % PAGE_SIZE) /
					       sizeof(union afs_dir_block)];
			ret = afs_dir_iterate_block(fpos, dblock, blkoff,
						    cookie, filldir);
			if (ret != 1) {
				afs_dir_put_page(page);
				goto out;
			}

			blkoff += sizeof(union afs_dir_block);

		} while (*fpos < dir->i_size && blkoff < limit);

		afs_dir_put_page(page);
		ret = 0;
	}

 out:
	_leave(" = %d", ret);
	return ret;
} /* end afs_dir_iterate() */

/*****************************************************************************/
/*
 * read an AFS directory
 */
static int afs_dir_readdir(struct file *file, void *cookie, filldir_t filldir)
{
	unsigned fpos;
	int ret;

	_enter("{%Ld,{%lu}}", file->f_pos, file->f_dentry->d_inode->i_ino);

	fpos = file->f_pos;
	ret = afs_dir_iterate(file->f_dentry->d_inode, &fpos, cookie, filldir);
	file->f_pos = fpos;

	_leave(" = %d", ret);
	return ret;
} /* end afs_dir_readdir() */

/*****************************************************************************/
/*
 * search the directory for a name
 * - if afs_dir_iterate_block() spots this function, it'll pass the FID
 *   uniquifier through dtype
 */
static int afs_dir_lookup_filldir(void *_cookie, const char *name, int nlen,
				  loff_t fpos, ino_t ino, unsigned dtype)
{
	struct afs_dir_lookup_cookie *cookie = _cookie;

	_enter("{%s,%Zu},%s,%u,,%lu,%u",
	       cookie->name, cookie->nlen, name, nlen, ino, dtype);

	if (cookie->nlen != nlen || memcmp(cookie->name, name, nlen) != 0) {
		_leave(" = 0 [no]");
		return 0;
	}

	cookie->fid.vnode = ino;
	cookie->fid.unique = dtype;
	cookie->found = 1;

	_leave(" = -1 [found]");
	return -1;
} /* end afs_dir_lookup_filldir() */

/*****************************************************************************/
/*
 * look up an entry in a directory
 */
static struct dentry *afs_dir_lookup(struct inode *dir, struct dentry *dentry,
				     struct nameidata *nd)
{
	struct afs_dir_lookup_cookie cookie;
	struct afs_super_info *as;
	struct afs_vnode *vnode;
	struct inode *inode;
	unsigned fpos;
	int ret;

	_enter("{%lu},%p{%s}", dir->i_ino, dentry, dentry->d_name.name);

	/* insanity checks first */
	BUG_ON(sizeof(union afs_dir_block) != 2048);
	BUG_ON(sizeof(union afs_dirent) != 32);

	if (dentry->d_name.len > 255) {
		_leave(" = -ENAMETOOLONG");
		return ERR_PTR(-ENAMETOOLONG);
	}

	vnode = AFS_FS_I(dir);
	if (vnode->flags & AFS_VNODE_DELETED) {
		_leave(" = -ESTALE");
		return ERR_PTR(-ESTALE);
	}

	as = dir->i_sb->s_fs_info;

	/* search the directory */
	cookie.name	= dentry->d_name.name;
	cookie.nlen	= dentry->d_name.len;
	cookie.fid.vid	= as->volume->vid;
	cookie.found	= 0;

	fpos = 0;
	ret = afs_dir_iterate(dir, &fpos, &cookie, afs_dir_lookup_filldir);
	if (ret < 0) {
		_leave(" = %d", ret);
		return ERR_PTR(ret);
	}

	ret = -ENOENT;
	if (!cookie.found) {
		_leave(" = %d", ret);
		return ERR_PTR(ret);
	}

	/* instantiate the dentry */
	ret = afs_iget(dir->i_sb, &cookie.fid, &inode);
	if (ret < 0) {
		_leave(" = %d", ret);
		return ERR_PTR(ret);
	}

	dentry->d_op = &afs_fs_dentry_operations;
	dentry->d_fsdata = (void *) (unsigned long) vnode->status.version;

	d_add(dentry, inode);
	_leave(" = 0 { vn=%u u=%u } -> { ino=%lu v=%lu }",
	       cookie.fid.vnode,
	       cookie.fid.unique,
	       dentry->d_inode->i_ino,
	       dentry->d_inode->i_version);

	return NULL;
} /* end afs_dir_lookup() */

/*****************************************************************************/
/*
 * check that a dentry lookup hit has found a valid entry
 * - NOTE! the hit can be a negative hit too, so we can't assume we have an
 *   inode
 * (derived from nfs_lookup_revalidate)
 */
static int afs_d_revalidate(struct dentry *dentry, struct nameidata *nd)
{
	struct afs_dir_lookup_cookie cookie;
	struct dentry *parent;
	struct inode *inode, *dir;
	unsigned fpos;
	int ret;

	_enter("{sb=%p n=%s},", dentry->d_sb, dentry->d_name.name);

	/* lock down the parent dentry so we can peer at it */
	parent = dget_parent(dentry->d_parent);

	dir = parent->d_inode;
	inode = dentry->d_inode;

	/* handle a negative dentry */
	if (!inode)
		goto out_bad;

	/* handle a bad inode */
	if (is_bad_inode(inode)) {
		printk("kAFS: afs_d_revalidate: %s/%s has bad inode\n",
		       dentry->d_parent->d_name.name, dentry->d_name.name);
		goto out_bad;
	}

	/* force a full look up if the parent directory changed since last the
	 * server was consulted
	 * - otherwise this inode must still exist, even if the inode details
	 *   themselves have changed
	 */
	if (AFS_FS_I(dir)->flags & AFS_VNODE_CHANGED)
		afs_vnode_fetch_status(AFS_FS_I(dir));

	if (AFS_FS_I(dir)->flags & AFS_VNODE_DELETED) {
		_debug("%s: parent dir deleted", dentry->d_name.name);
		goto out_bad;
	}

	if (AFS_FS_I(inode)->flags & AFS_VNODE_DELETED) {
		_debug("%s: file already deleted", dentry->d_name.name);
		goto out_bad;
	}

	if ((unsigned long) dentry->d_fsdata !=
	    (unsigned long) AFS_FS_I(dir)->status.version) {
		_debug("%s: parent changed %lu -> %u",
		       dentry->d_name.name,
		       (unsigned long) dentry->d_fsdata,
		       (unsigned) AFS_FS_I(dir)->status.version);

		/* search the directory for this vnode */
		cookie.name	= dentry->d_name.name;
		cookie.nlen	= dentry->d_name.len;
		cookie.fid.vid	= AFS_FS_I(inode)->volume->vid;
		cookie.found	= 0;

		fpos = 0;
		ret = afs_dir_iterate(dir, &fpos, &cookie,
				      afs_dir_lookup_filldir);
		if (ret < 0) {
			_debug("failed to iterate dir %s: %d",
			       parent->d_name.name, ret);
			goto out_bad;
		}

		if (!cookie.found) {
			_debug("%s: dirent not found", dentry->d_name.name);
			goto not_found;
		}

		/* if the vnode ID has changed, then the dirent points to a
		 * different file */
		if (cookie.fid.vnode != AFS_FS_I(inode)->fid.vnode) {
			_debug("%s: dirent changed", dentry->d_name.name);
			goto not_found;
		}

		/* if the vnode ID uniqifier has changed, then the file has
		 * been deleted */
		if (cookie.fid.unique != AFS_FS_I(inode)->fid.unique) {
			_debug("%s: file deleted (uq %u -> %u I:%lu)",
			       dentry->d_name.name,
			       cookie.fid.unique,
			       AFS_FS_I(inode)->fid.unique,
			       inode->i_version);
			spin_lock(&AFS_FS_I(inode)->lock);
			AFS_FS_I(inode)->flags |= AFS_VNODE_DELETED;
			spin_unlock(&AFS_FS_I(inode)->lock);
			invalidate_remote_inode(inode);
			goto out_bad;
		}

		dentry->d_fsdata =
			(void *) (unsigned long) AFS_FS_I(dir)->status.version;
	}

 out_valid:
	dput(parent);
	_leave(" = 1 [valid]");
	return 1;

	/* the dirent, if it exists, now points to a different vnode */
 not_found:
	spin_lock(&dentry->d_lock);
	dentry->d_flags |= DCACHE_NFSFS_RENAMED;
	spin_unlock(&dentry->d_lock);

 out_bad:
	if (inode) {
		/* don't unhash if we have submounts */
		if (have_submounts(dentry))
			goto out_valid;
	}

	shrink_dcache_parent(dentry);

	_debug("dropping dentry %s/%s",
	       dentry->d_parent->d_name.name, dentry->d_name.name);
	d_drop(dentry);

	dput(parent);

	_leave(" = 0 [bad]");
	return 0;
} /* end afs_d_revalidate() */

/*****************************************************************************/
/*
 * allow the VFS to enquire as to whether a dentry should be unhashed (mustn't
 * sleep)
 * - called from dput() when d_count is going to 0.
 * - return 1 to request dentry be unhashed, 0 otherwise
 */
static int afs_d_delete(struct dentry *dentry)
{
	_enter("%s", dentry->d_name.name);

	if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
		goto zap;

	if (dentry->d_inode) {
		if (AFS_FS_I(dentry->d_inode)->flags & AFS_VNODE_DELETED)
			goto zap;
	}

	_leave(" = 0 [keep]");
	return 0;

 zap:
	_leave(" = 1 [zap]");
	return 1;
} /* end afs_d_delete() */