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Revision af5a30d8cfcfc561336f982b06345d6b815e0bb3 authored by Nick Piggin on 03 June 2010, 12:01:46 UTC, committed by Al Viro on 04 June 2010, 21:16:30 UTC 
fix truncate inode time modification breakage
 
mtime and ctime should be changed only if the file size has actually
changed. Patches changing ext2 and tmpfs from vmtruncate to new truncate
sequence has caused regressions where they always update timestamps.

There is some strange cases in POSIX where truncate(2) must not update
times unless the size has acutally changed, see 6e656be89.

This area is all still rather buggy in different ways in a lot of
filesystems and needs a cleanup and audit (ideally the vfs will provide
a simple attribute or call to direct all filesystems exactly which
attributes to change). But coming up with the best solution will take a
while and is not appropriate for rc anyway.

So fix recent regression for now.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
1 parent 8718d36
Raw File
nfsctl.c 
/*
 *	fs/nfsctl.c
 *
 *	This should eventually move to userland.
 *
 */
#include <linux/types.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/nfsd/syscall.h>
#include <linux/cred.h>
#include <linux/sched.h>
#include <linux/linkage.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/syscalls.h>
#include <asm/uaccess.h>

/*
 * open a file on nfsd fs
 */

static struct file *do_open(char *name, int flags)
{
	struct nameidata nd;
	struct vfsmount *mnt;
	int error;

	mnt = do_kern_mount("nfsd", 0, "nfsd", NULL);
	if (IS_ERR(mnt))
		return (struct file *)mnt;

	error = vfs_path_lookup(mnt->mnt_root, mnt, name, 0, &nd);
	mntput(mnt);	/* drop do_kern_mount reference */
	if (error)
		return ERR_PTR(error);

	if (flags == O_RDWR)
		error = may_open(&nd.path, MAY_READ|MAY_WRITE, flags);
	else
		error = may_open(&nd.path, MAY_WRITE, flags);

	if (!error)
		return dentry_open(nd.path.dentry, nd.path.mnt, flags,
				   current_cred());

	path_put(&nd.path);
	return ERR_PTR(error);
}

static struct {
	char *name; int wsize; int rsize;
} map[] = {
	[NFSCTL_SVC] = {
		.name	= ".svc",
		.wsize	= sizeof(struct nfsctl_svc)
	},
	[NFSCTL_ADDCLIENT] = {
		.name	= ".add",
		.wsize	= sizeof(struct nfsctl_client)
	},
	[NFSCTL_DELCLIENT] = {
		.name	= ".del",
		.wsize	= sizeof(struct nfsctl_client)
	},
	[NFSCTL_EXPORT] = {
		.name	= ".export",
		.wsize	= sizeof(struct nfsctl_export)
	},
	[NFSCTL_UNEXPORT] = {
		.name	= ".unexport",
		.wsize	= sizeof(struct nfsctl_export)
	},
	[NFSCTL_GETFD] = {
		.name	= ".getfd",
		.wsize	= sizeof(struct nfsctl_fdparm),
		.rsize	= NFS_FHSIZE
	},
	[NFSCTL_GETFS] = {
		.name	= ".getfs",
		.wsize	= sizeof(struct nfsctl_fsparm),
		.rsize	= sizeof(struct knfsd_fh)
	},
};

SYSCALL_DEFINE3(nfsservctl, int, cmd, struct nfsctl_arg __user *, arg,
		void __user *, res)
{
	struct file *file;
	void __user *p = &arg->u;
	int version;
	int err;

	if (copy_from_user(&version, &arg->ca_version, sizeof(int)))
		return -EFAULT;

	if (version != NFSCTL_VERSION)
		return -EINVAL;

	if (cmd < 0 || cmd >= ARRAY_SIZE(map) || !map[cmd].name)
		return -EINVAL;

	file = do_open(map[cmd].name, map[cmd].rsize ? O_RDWR : O_WRONLY);	
	if (IS_ERR(file))
		return PTR_ERR(file);
	err = file->f_op->write(file, p, map[cmd].wsize, &file->f_pos);
	if (err >= 0 && map[cmd].rsize)
		err = file->f_op->read(file, res, map[cmd].rsize, &file->f_pos);
	if (err >= 0)
		err = 0;
	fput(file);
	return err;
}
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