[1/3] #6823 page reading with mandatory locking style

Signed-off-by: Pavel Shilovsky <piastryyy@gmail.com>

On Wed, 24 Mar 2010 11:55:31 +0300
piastry@etersoft.ru wrote:

> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> index 5183bc2..2b894bd 100644
> --- a/fs/cifs/cifsfs.c
> +++ b/fs/cifs/cifsfs.c
> @@ -616,6 +616,51 @@ cifs_get_sb(struct file_system_type *fs_type,
>  	return 0;
>  }
>  
> +static ssize_t cifs_sync_read(struct file *filp, char __user *buf,
> +				size_t len, loff_t *ppos)
> +{
> +	int retval, read, posix_locking = 0;
> +	struct file_lock pfLock;
> +	struct cifsInodeInfo *cifsInode;
> +	struct cifs_sb_info *cifs_sb;
> +	struct cifsTconInfo *tcon;
> +
> +	cifs_sb = CIFS_SB(filp->f_path.dentry->d_sb);
> +	tcon = cifs_sb->tcon;
> +	if ((tcon->ses->capabilities & CAP_UNIX) &&
> +	    (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
> +	    ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
> +		posix_locking = 1;
> +
> +	retval = cifs_revalidate(filp->f_path.dentry);
> +	if (retval < 0)
> +		return (ssize_t)retval;
> +
> +	memset(&pfLock, 0, sizeof(pfLock));
> +	pfLock.fl_type = F_RDLCK;
> +	pfLock.fl_start = *ppos;
> +	pfLock.fl_end = *ppos+len;
> +	cifsInode = CIFS_I(filp->f_path.dentry->d_inode);
> +	if (cifsInode == NULL)
> +		return -ENOENT;
> +
> +	if (!CIFS_I(filp->f_path.dentry->d_inode)->clientCanCacheRead &&
> +							!posix_locking) {
> +		retval = cifs_lock(filp, F_GETLK, &pfLock);
> +		if (retval < 0)
> +			return (ssize_t)retval;
> +		if (pfLock.fl_type == F_UNLCK)
> +			read = do_sync_read(filp, buf, len, ppos);
> +		else
> +			return -EACCES;
> +	} else
> +		read = do_sync_read(filp, buf, len, ppos);
> +
> +	if (read == -EACCES && !posix_locking)
> +		read = cifs_user_read(filp, buf, len, ppos);
> +	return read;
> +}
> +
>  static ssize_t cifs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
>  				   unsigned long nr_segs, loff_t pos)
>  {
> @@ -737,7 +782,7 @@ const struct inode_operations cifs_symlink_inode_ops = {
>  };
>  
>  const struct file_operations cifs_file_ops = {
> -	.read = do_sync_read,
> +	.read = cifs_sync_read,
>  	.write = do_sync_write,
>  	.aio_read = generic_file_aio_read,
>  	.aio_write = cifs_file_aio_write,
> 
>  Signed-off-by: Pavel Shilovsky <piastryyy@gmail.com>

I have no clue what this patch is intended to do. Can you possibly
explain it, preferably in a resent patch with proper patch descripion
and signed-off-by line at the beginning?