file.c

linux 内核源代码

}

static int nfs_write_end(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned copied,
			struct page *page, void *fsdata)
{
	unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
	int status;

	lock_kernel();
	status = nfs_updatepage(file, page, offset, copied);
	unlock_kernel();

	unlock_page(page);
	page_cache_release(page);

	return status < 0 ? status : copied;
}

static void nfs_invalidate_page(struct page *page, unsigned long offset)
{
	if (offset != 0)
		return;
	/* Cancel any unstarted writes on this page */
	nfs_wb_page_cancel(page->mapping->host, page);
}

static int nfs_release_page(struct page *page, gfp_t gfp)
{
	/* If PagePrivate() is set, then the page is not freeable */
	return 0;
}

static int nfs_launder_page(struct page *page)
{
	return nfs_wb_page(page->mapping->host, page);
}

const struct address_space_operations nfs_file_aops = {
	.readpage = nfs_readpage,
	.readpages = nfs_readpages,
	.set_page_dirty = __set_page_dirty_nobuffers,
	.writepage = nfs_writepage,
	.writepages = nfs_writepages,
	.write_begin = nfs_write_begin,
	.write_end = nfs_write_end,
	.invalidatepage = nfs_invalidate_page,
	.releasepage = nfs_release_page,
#ifdef CONFIG_NFS_DIRECTIO
	.direct_IO = nfs_direct_IO,
#endif
	.launder_page = nfs_launder_page,
};

static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct page *page)
{
	struct file *filp = vma->vm_file;
	unsigned pagelen;
	int ret = -EINVAL;
	void *fsdata;
	struct address_space *mapping;
	loff_t offset;

	lock_page(page);
	mapping = page->mapping;
	if (mapping != vma->vm_file->f_path.dentry->d_inode->i_mapping) {
		unlock_page(page);
		return -EINVAL;
	}
	pagelen = nfs_page_length(page);
	offset = (loff_t)page->index << PAGE_CACHE_SHIFT;
	unlock_page(page);

	/*
	 * we can use mapping after releasing the page lock, because:
	 * we hold mmap_sem on the fault path, which should pin the vma
	 * which should pin the file, which pins the dentry which should
	 * hold a reference on inode.
	 */

	if (pagelen) {
		struct page *page2 = NULL;
		ret = nfs_write_begin(filp, mapping, offset, pagelen,
			       	0, &page2, &fsdata);
		if (!ret)
			ret = nfs_write_end(filp, mapping, offset, pagelen,
				       	pagelen, page2, fsdata);
	}
	return ret;
}

static struct vm_operations_struct nfs_file_vm_ops = {
	.fault = filemap_fault,
	.page_mkwrite = nfs_vm_page_mkwrite,
};

static int nfs_need_sync_write(struct file *filp, struct inode *inode)
{
	struct nfs_open_context *ctx;

	if (IS_SYNC(inode) || (filp->f_flags & O_SYNC))
		return 1;
	ctx = nfs_file_open_context(filp);
	if (test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags))
		return 1;
	return 0;
}

static ssize_t nfs_file_write(struct kiocb *iocb, const struct iovec *iov,
				unsigned long nr_segs, loff_t pos)
{
	struct dentry * dentry = iocb->ki_filp->f_path.dentry;
	struct inode * inode = dentry->d_inode;
	ssize_t result;
	size_t count = iov_length(iov, nr_segs);

#ifdef CONFIG_NFS_DIRECTIO
	if (iocb->ki_filp->f_flags & O_DIRECT)
		return nfs_file_direct_write(iocb, iov, nr_segs, pos);
#endif

	dfprintk(VFS, "nfs: write(%s/%s(%ld), %lu@%Ld)\n",
		dentry->d_parent->d_name.name, dentry->d_name.name,
		inode->i_ino, (unsigned long) count, (long long) pos);

	result = -EBUSY;
	if (IS_SWAPFILE(inode))
		goto out_swapfile;
	/*
	 * O_APPEND implies that we must revalidate the file length.
	 */
	if (iocb->ki_filp->f_flags & O_APPEND) {
		result = nfs_revalidate_file_size(inode, iocb->ki_filp);
		if (result)
			goto out;
	}

	result = count;
	if (!count)
		goto out;

	nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, count);
	result = generic_file_aio_write(iocb, iov, nr_segs, pos);
	/* Return error values for O_SYNC and IS_SYNC() */
	if (result >= 0 && nfs_need_sync_write(iocb->ki_filp, inode)) {
		int err = nfs_do_fsync(nfs_file_open_context(iocb->ki_filp), inode);
		if (err < 0)
			result = err;
	}
out:
	return result;

out_swapfile:
	printk(KERN_INFO "NFS: attempt to write to active swap file!\n");
	goto out;
}

static int do_getlk(struct file *filp, int cmd, struct file_lock *fl)
{
	struct inode *inode = filp->f_mapping->host;
	int status = 0;

	lock_kernel();
	/* Try local locking first */
	posix_test_lock(filp, fl);
	if (fl->fl_type != F_UNLCK) {
		/* found a conflict */
		goto out;
	}

	if (nfs_have_delegation(inode, FMODE_READ))
		goto out_noconflict;

	if (NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM)
		goto out_noconflict;

	status = NFS_PROTO(inode)->lock(filp, cmd, fl);
out:
	unlock_kernel();
	return status;
out_noconflict:
	fl->fl_type = F_UNLCK;
	goto out;
}

static int do_vfs_lock(struct file *file, struct file_lock *fl)
{
	int res = 0;
	switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
		case FL_POSIX:
			res = posix_lock_file_wait(file, fl);
			break;
		case FL_FLOCK:
			res = flock_lock_file_wait(file, fl);
			break;
		default:
			BUG();
	}
	if (res < 0)
		dprintk(KERN_WARNING "%s: VFS is out of sync with lock manager"
			" - error %d!\n",
				__FUNCTION__, res);
	return res;
}

static int do_unlk(struct file *filp, int cmd, struct file_lock *fl)
{
	struct inode *inode = filp->f_mapping->host;
	int status;

	/*
	 * Flush all pending writes before doing anything
	 * with locks..
	 */
	nfs_sync_mapping(filp->f_mapping);

	/* NOTE: special case
	 * 	If we're signalled while cleaning up locks on process exit, we
	 * 	still need to complete the unlock.
	 */
	lock_kernel();
	/* Use local locking if mounted with "-onolock" */
	if (!(NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM))
		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
	else
		status = do_vfs_lock(filp, fl);
	unlock_kernel();
	return status;
}

static int do_setlk(struct file *filp, int cmd, struct file_lock *fl)
{
	struct inode *inode = filp->f_mapping->host;
	int status;

	/*
	 * Flush all pending writes before doing anything
	 * with locks..
	 */
	status = nfs_sync_mapping(filp->f_mapping);
	if (status != 0)
		goto out;

	lock_kernel();
	/* Use local locking if mounted with "-onolock" */
	if (!(NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM)) {
		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
		/* If we were signalled we still need to ensure that
		 * we clean up any state on the server. We therefore
		 * record the lock call as having succeeded in order to
		 * ensure that locks_remove_posix() cleans it out when
		 * the process exits.
		 */
		if (status == -EINTR || status == -ERESTARTSYS)
			do_vfs_lock(filp, fl);
	} else
		status = do_vfs_lock(filp, fl);
	unlock_kernel();
	if (status < 0)
		goto out;
	/*
	 * Make sure we clear the cache whenever we try to get the lock.
	 * This makes locking act as a cache coherency point.
	 */
	nfs_sync_mapping(filp->f_mapping);
	nfs_zap_caches(inode);
out:
	return status;
}

/*
 * Lock a (portion of) a file
 */
static int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
{
	struct inode * inode = filp->f_mapping->host;

	dprintk("NFS: nfs_lock(f=%s/%ld, t=%x, fl=%x, r=%Ld:%Ld)\n",
			inode->i_sb->s_id, inode->i_ino,
			fl->fl_type, fl->fl_flags,
			(long long)fl->fl_start, (long long)fl->fl_end);
	nfs_inc_stats(inode, NFSIOS_VFSLOCK);

	/* No mandatory locks over NFS */
	if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
		return -ENOLCK;

	if (IS_GETLK(cmd))
		return do_getlk(filp, cmd, fl);
	if (fl->fl_type == F_UNLCK)
		return do_unlk(filp, cmd, fl);
	return do_setlk(filp, cmd, fl);
}

/*
 * Lock a (portion of) a file
 */
static int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
{
	dprintk("NFS: nfs_flock(f=%s/%ld, t=%x, fl=%x)\n",
			filp->f_path.dentry->d_inode->i_sb->s_id,
			filp->f_path.dentry->d_inode->i_ino,
			fl->fl_type, fl->fl_flags);

	/*
	 * No BSD flocks over NFS allowed.
	 * Note: we could try to fake a POSIX lock request here by
	 * using ((u32) filp | 0x80000000) or some such as the pid.
	 * Not sure whether that would be unique, though, or whether
	 * that would break in other places.
	 */
	if (!(fl->fl_flags & FL_FLOCK))
		return -ENOLCK;

	/* We're simulating flock() locks using posix locks on the server */
	fl->fl_owner = (fl_owner_t)filp;
	fl->fl_start = 0;
	fl->fl_end = OFFSET_MAX;

	if (fl->fl_type == F_UNLCK)
		return do_unlk(filp, cmd, fl);
	return do_setlk(filp, cmd, fl);
}

static int nfs_setlease(struct file *file, long arg, struct file_lock **fl)
{
	/*
	 * There is no protocol support for leases, so we have no way
	 * to implement them correctly in the face of opens by other
	 * clients.
	 */
	return -EINVAL;
}