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Commit a02de960 authored by David Howells's avatar David Howells
Browse files

VFS: Make more complete truncate operation available to CacheFiles 



Make a more complete truncate operation available to CacheFiles (including
security checks and suchlike) so that it can use this to clear invalidated
cache files.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Acked-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent ef778e7a

fs/open.c

+27 −23
Original line number Original line Diff line number Diff line
@@ -61,33 +61,22 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs, 
	return ret;

	return ret;

}

}





static long do_sys_truncate(const char __user *pathname, loff_t length)

long vfs_truncate(struct path *path, loff_t length)

{

{

	struct path path;

	struct inode *inode;

	struct inode *inode;

	int error;

	long error;



	error = -EINVAL;

	if (length < 0)	/* sorry, but loff_t says... */

		goto out;





	error = user_path(pathname, &path);

	inode = path->dentry->d_inode;

	if (error)

		goto out;

	inode = path.dentry->d_inode;





	/* For directories it's -EISDIR, for other non-regulars - -EINVAL */

	/* For directories it's -EISDIR, for other non-regulars - -EINVAL */

	error = -EISDIR;

	if (S_ISDIR(inode->i_mode))

	if (S_ISDIR(inode->i_mode))

		goto dput_and_out;

		return -EISDIR;



	error = -EINVAL;

	if (!S_ISREG(inode->i_mode))

	if (!S_ISREG(inode->i_mode))

		goto dput_and_out;

		return -EINVAL;





	error = mnt_want_write(path.mnt);

	error = mnt_want_write(path->mnt);

	if (error)

	if (error)

		goto dput_and_out;

		goto out;





	error = inode_permission(inode, MAY_WRITE);

	error = inode_permission(inode, MAY_WRITE);

	if (error)

	if (error)
@@ -111,19 +100,34 @@ static long do_sys_truncate(const char __user *pathname, loff_t length) 




	error = locks_verify_truncate(inode, NULL, length);

	error = locks_verify_truncate(inode, NULL, length);

	if (!error)

	if (!error)

		error = security_path_truncate(&path);

		error = security_path_truncate(path);

	if (!error)

	if (!error)

		error = do_truncate(path.dentry, length, 0, NULL);

		error = do_truncate(path->dentry, length, 0, NULL);





put_write_and_out:

put_write_and_out:

	put_write_access(inode);

	put_write_access(inode);

mnt_drop_write_and_out:

mnt_drop_write_and_out:

	mnt_drop_write(path.mnt);

	mnt_drop_write(path->mnt);

dput_and_out:

	path_put(&path);

out:

out:

	return error;

	return error;

}

}

EXPORT_SYMBOL_GPL(vfs_truncate);



static long do_sys_truncate(const char __user *pathname, loff_t length)

{

	struct path path;

	int error;



	if (length < 0)	/* sorry, but loff_t says... */

		return -EINVAL;



	error = user_path(pathname, &path);

	if (!error) {

		error = vfs_truncate(&path, length);

		path_put(&path);

	}

	return error;

}





SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)

SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)

{

{

include/linux/fs.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -1999,6 +1999,7 @@ struct filename { 
	bool			separate; /* should "name" be freed? */

	bool			separate; /* should "name" be freed? */

};

};





extern long vfs_truncate(struct path *, loff_t);

extern int do_truncate(struct dentry *, loff_t start, unsigned int time_attrs,

extern int do_truncate(struct dentry *, loff_t start, unsigned int time_attrs,

		       struct file *filp);

		       struct file *filp);

extern int do_fallocate(struct file *file, int mode, loff_t offset,

extern int do_fallocate(struct file *file, int mode, loff_t offset,