CIFS: Add rwpidforward mount option

Add rwpidforward mount option that switches on a mode when we forward
pid of a process who opened a file to any read and write operation.

This can prevent applications like WINE from failing on read or write
operation on a previously locked file region from the same netfd from
another process if we use mandatory brlock style.

It is actual for WINE because during a run of WINE program two processes
work on the same netfd - share the same file struct between several VFS
fds:
1) WINE-server does open and lock;
2) WINE-application does read and write.

Signed-off-by: Pavel Shilovsky <[e-mail]>
Signed-off-by: Steve French <[e-mail]>

fs/cifs/README

···
 		otherwise - read from the server. All written data are stored
 		in the cache, but if the client doesn't have Exclusive Oplock,
 		it writes the data to the server.
+  rwpidforward  Forward pid of a process who opened a file to any read or write
+		operation on that file. This prevent applications like WINE
+		from failing on read and write if we use mandatory brlock style.
   acl   	Allow setfacl and getfacl to manage posix ACLs if server
 		supports them.  (default)
   noacl 	Do not allow setfacl and getfacl calls on this mount

fs/cifs/cifs_fs_sb.h

···
 #define CIFS_MOUNT_MF_SYMLINKS	0x10000 /* Minshall+French Symlinks enabled */
 #define CIFS_MOUNT_MULTIUSER	0x20000 /* multiuser mount */
 #define CIFS_MOUNT_STRICT_IO	0x40000 /* strict cache mode */
+#define CIFS_MOUNT_RWPIDFORWARD	0x80000 /* use pid forwarding for rw */
 
 struct cifs_sb_info {
 	struct rb_root tlink_tree;

fs/cifs/cifsfs.c

···
 		seq_printf(s, ",nocase");
 	if (tcon->retry)
 		seq_printf(s, ",hard");
+	if (tcon->unix_ext)
+		seq_printf(s, ",unix");
+	else
+		seq_printf(s, ",nounix");
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS)
 		seq_printf(s, ",posixpaths");
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SET_UID)
 		seq_printf(s, ",setuids");
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM)
 		seq_printf(s, ",serverino");
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
+		seq_printf(s, ",rwpidforward");
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL)
+		seq_printf(s, ",forcemand");
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_DIRECT_IO)
 		seq_printf(s, ",directio");
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_XATTR)

fs/cifs/cifsglob.h

···
 	bool fsc:1;	/* enable fscache */
 	bool mfsymlinks:1; /* use Minshall+French Symlinks */
 	bool multiuser:1;
+	bool rwpidforward:1; /* pid forward for read/write operations */
 	unsigned int rsize;
 	unsigned int wsize;
 	bool sockopt_tcp_nodelay:1;

fs/cifs/cifsproto.h

···
 extern int CIFSSMBFlush(const int xid, struct cifsTconInfo *tcon,
 			const int smb_file_id);
 
-extern int CIFSSMBRead(const int xid, struct cifsTconInfo *tcon,
-			const int netfid, unsigned int count,
-			const __u64 lseek, unsigned int *nbytes, char **buf,
+extern int CIFSSMBRead(const int xid, struct cifs_io_parms *io_parms,
+			unsigned int *nbytes, char **buf,
 			int *return_buf_type);
 extern int CIFSSMBWrite(const int xid, struct cifs_io_parms *io_parms,
 			unsigned int *nbytes, const char *buf,

fs/cifs/cifssmb.c

···
 }
 
 int
-CIFSSMBRead(const int xid, struct cifsTconInfo *tcon, const int netfid,
-	    const unsigned int count, const __u64 lseek, unsigned int *nbytes,
+CIFSSMBRead(const int xid, struct cifs_io_parms *io_parms, unsigned int *nbytes,
 	    char **buf, int *pbuf_type)
 {
 	int rc = -EACCES;
···
 	int wct;
 	int resp_buf_type = 0;
 	struct kvec iov[1];
+	__u32 pid = io_parms->pid;
+	__u16 netfid = io_parms->netfid;
+	__u64 offset = io_parms->offset;
+	struct cifsTconInfo *tcon = io_parms->tcon;
+	unsigned int count = io_parms->length;
 
 	cFYI(1, "Reading %d bytes on fid %d", count, netfid);
 	if (tcon->ses->capabilities & CAP_LARGE_FILES)
 		wct = 12;
 	else {
 		wct = 10; /* old style read */
-		if ((lseek >> 32) > 0)  {
+		if ((offset >> 32) > 0)  {
 			/* can not handle this big offset for old */
 			return -EIO;
 		}
···
 	if (rc)
 		return rc;
 
+	pSMB->hdr.Pid = cpu_to_le16((__u16)pid);
+	pSMB->hdr.PidHigh = cpu_to_le16((__u16)(pid >> 16));
+
 	/* tcon and ses pointer are checked in smb_init */
 	if (tcon->ses->server == NULL)
 		return -ECONNABORTED;
 
 	pSMB->AndXCommand = 0xFF;       /* none */
 	pSMB->Fid = netfid;
-	pSMB->OffsetLow = cpu_to_le32(lseek & 0xFFFFFFFF);
+	pSMB->OffsetLow = cpu_to_le32(offset & 0xFFFFFFFF);
 	if (wct == 12)
-		pSMB->OffsetHigh = cpu_to_le32(lseek >> 32);
+		pSMB->OffsetHigh = cpu_to_le32(offset >> 32);
 
 	pSMB->Remaining = 0;
 	pSMB->MaxCount = cpu_to_le16(count & 0xFFFF);

fs/cifs/connect.c

···
 			vol->server_ino = 1;
 		} else if (strnicmp(data, "noserverino", 9) == 0) {
 			vol->server_ino = 0;
+		} else if (strnicmp(data, "rwpidforward", 4) == 0) {
+			vol->rwpidforward = 1;
 		} else if (strnicmp(data, "cifsacl", 7) == 0) {
 			vol->cifs_acl = 1;
 		} else if (strnicmp(data, "nocifsacl", 9) == 0) {
···
 		cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_NOSSYNC;
 	if (pvolume_info->mand_lock)
 		cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_NOPOSIXBRL;
+	if (pvolume_info->rwpidforward)
+		cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_RWPIDFORWARD;
 	if (pvolume_info->cifs_acl)
 		cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_CIFS_ACL;
 	if (pvolume_info->override_uid)

fs/cifs/file.c

···
 			else
 				posix_lock_type = CIFS_WRLCK;
 			rc = CIFSSMBPosixLock(xid, tcon, netfid, 1 /* get */,
-					length,	pfLock,
-					posix_lock_type, wait_flag);
+					length, pfLock, posix_lock_type,
+					wait_flag);
 			FreeXid(xid);
 			return rc;
 		}
···
 			posix_lock_type = CIFS_UNLCK;
 
 		rc = CIFSSMBPosixLock(xid, tcon, netfid, 0 /* set */,
-				      length, pfLock,
-				      posix_lock_type, wait_flag);
+				      length, pfLock, posix_lock_type,
+				      wait_flag);
 	} else {
 		struct cifsFileInfo *fid = file->private_data;
 
···
 {
 	int rc;
 	struct inode *inode = mapping->host;
+	struct cifsFileInfo *cfile = file->private_data;
+	struct cifs_sb_info *cifs_sb = CIFS_SB(cfile->dentry->d_sb);
+	__u32 pid;
+
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
+		pid = cfile->pid;
+	else
+		pid = current->tgid;
 
 	cFYI(1, "write_end for page %p from pos %lld with %d bytes",
 		 page, pos, copied);
···
 		/* BB check if anything else missing out of ppw
 		   such as updating last write time */
 		page_data = kmap(page);
-		rc = cifs_write(file->private_data, current->tgid,
-				page_data + offset, copied, &pos);
+		rc = cifs_write(cfile, pid, page_data + offset, copied, &pos);
 		/* if (rc < 0) should we set writebehind rc? */
 		kunmap(page);
 
···
 	struct cifs_sb_info *cifs_sb;
 	struct cifs_io_parms io_parms;
 	int xid, rc;
+	__u32 pid;
 
 	len = iov_length(iov, nr_segs);
 	if (!len)
···
 
 	xid = GetXid();
 	open_file = file->private_data;
+
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
+		pid = open_file->pid;
+	else
+		pid = current->tgid;
+
 	pTcon = tlink_tcon(open_file->tlink);
 	inode = file->f_path.dentry->d_inode;
 
···
 					break;
 			}
 			io_parms.netfid = open_file->netfid;
-			io_parms.pid = current->tgid;
+			io_parms.pid = pid;
 			io_parms.tcon = pTcon;
 			io_parms.offset = *poffset;
 			io_parms.length = cur_len;
···
 	struct cifsTconInfo *pTcon;
 	struct cifsFileInfo *open_file;
 	struct smb_com_read_rsp *pSMBr;
+	struct cifs_io_parms io_parms;
 	char *read_data;
+	__u32 pid;
 
 	if (!nr_segs)
 		return 0;
···
 
 	open_file = file->private_data;
 	pTcon = tlink_tcon(open_file->tlink);
+
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
+		pid = open_file->pid;
+	else
+		pid = current->tgid;
 
 	if ((file->f_flags & O_ACCMODE) == O_WRONLY)
 		cFYI(1, "attempting read on write only file instance");
···
 				if (rc != 0)
 					break;
 			}
-			rc = CIFSSMBRead(xid, pTcon, open_file->netfid,
-					 cur_len, *poffset, &bytes_read,
+			io_parms.netfid = open_file->netfid;
+			io_parms.pid = pid;
+			io_parms.tcon = pTcon;
+			io_parms.offset = *poffset;
+			io_parms.length = len;
+			rc = CIFSSMBRead(xid, &io_parms, &bytes_read,
 					 &read_data, &buf_type);
 			pSMBr = (struct smb_com_read_rsp *)read_data;
 			if (read_data) {
···
 	int xid;
 	char *current_offset;
 	struct cifsFileInfo *open_file;
+	struct cifs_io_parms io_parms;
 	int buf_type = CIFS_NO_BUFFER;
+	__u32 pid;
 
 	xid = GetXid();
 	cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
···
 	}
 	open_file = file->private_data;
 	pTcon = tlink_tcon(open_file->tlink);
+
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
+		pid = open_file->pid;
+	else
+		pid = current->tgid;
 
 	if ((file->f_flags & O_ACCMODE) == O_WRONLY)
 		cFYI(1, "attempting read on write only file instance");
···
 				if (rc != 0)
 					break;
 			}
-			rc = CIFSSMBRead(xid, pTcon,
-					 open_file->netfid,
-					 current_read_size, *poffset,
-					 &bytes_read, &current_offset,
-					 &buf_type);
+			io_parms.netfid = open_file->netfid;
+			io_parms.pid = pid;
+			io_parms.tcon = pTcon;
+			io_parms.offset = *poffset;
+			io_parms.length = current_read_size;
+			rc = CIFSSMBRead(xid, &io_parms, &bytes_read,
+					 &current_offset, &buf_type);
 		}
 		if (rc || (bytes_read == 0)) {
 			if (total_read) {
···
 	char *smb_read_data = NULL;
 	struct smb_com_read_rsp *pSMBr;
 	struct cifsFileInfo *open_file;
+	struct cifs_io_parms io_parms;
 	int buf_type = CIFS_NO_BUFFER;
+	__u32 pid;
 
 	xid = GetXid();
 	if (file->private_data == NULL) {
···
 		goto read_complete;
 
 	cFYI(DBG2, "rpages: num pages %d", num_pages);
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
+		pid = open_file->pid;
+	else
+		pid = current->tgid;
+
 	for (i = 0; i < num_pages; ) {
 		unsigned contig_pages;
 		struct page *tmp_page;
···
 				if (rc != 0)
 					break;
 			}
-
-			rc = CIFSSMBRead(xid, pTcon,
-					 open_file->netfid,
-					 read_size, offset,
-					 &bytes_read, &smb_read_data,
-					 &buf_type);
+			io_parms.netfid = open_file->netfid;
+			io_parms.pid = pid;
+			io_parms.tcon = pTcon;
+			io_parms.offset = offset;
+			io_parms.length = read_size;
+			rc = CIFSSMBRead(xid, &io_parms, &bytes_read,
+					 &smb_read_data, &buf_type);
 			/* BB more RC checks ? */
 			if (rc == -EAGAIN) {
 				if (smb_read_data) {

fs/cifs/inode.c

···
 	__u16 netfid;
 	struct tcon_link *tlink;
 	struct cifsTconInfo *tcon;
+	struct cifs_io_parms io_parms;
 	char buf[24];
 	unsigned int bytes_read;
 	char *pbuf;
···
 	if (rc == 0) {
 		int buf_type = CIFS_NO_BUFFER;
 			/* Read header */
-		rc = CIFSSMBRead(xid, tcon, netfid,
-				 24 /* length */, 0 /* offset */,
-				 &bytes_read, &pbuf, &buf_type);
+		io_parms.netfid = netfid;
+		io_parms.pid = current->tgid;
+		io_parms.tcon = tcon;
+		io_parms.offset = 0;
+		io_parms.length = 24;
+		rc = CIFSSMBRead(xid, &io_parms, &bytes_read, &pbuf,
+				 &buf_type);
 		if ((rc == 0) && (bytes_read >= 8)) {
 			if (memcmp("IntxBLK", pbuf, 8) == 0) {
 				cFYI(1, "Block device");

fs/cifs/link.c

···
 	unsigned int bytes_read = 0;
 	int buf_type = CIFS_NO_BUFFER;
 	unsigned int link_len = 0;
+	struct cifs_io_parms io_parms;
 	FILE_ALL_INFO file_info;
 
 	rc = CIFSSMBOpen(xid, tcon, searchName, FILE_OPEN, GENERIC_READ,
···
 	if (!buf)
 		return -ENOMEM;
 	pbuf = buf;
+	io_parms.netfid = netfid;
+	io_parms.pid = current->tgid;
+	io_parms.tcon = tcon;
+	io_parms.offset = 0;
+	io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 
-	rc = CIFSSMBRead(xid, tcon, netfid,
-			 CIFS_MF_SYMLINK_FILE_SIZE /* length */,
-			 0 /* offset */,
-			 &bytes_read, &pbuf, &buf_type);
+	rc = CIFSSMBRead(xid, &io_parms, &bytes_read, &pbuf, &buf_type);
 	CIFSSMBClose(xid, tcon, netfid);
 	if (rc != 0) {
 		kfree(buf);
···
 	__u16 netfid = 0;
 	struct tcon_link *tlink;
 	struct cifsTconInfo *pTcon;
+	struct cifs_io_parms io_parms;
 	u8 *buf;
 	char *pbuf;
 	unsigned int bytes_read = 0;
···
 		goto out;
 	}
 	pbuf = buf;
+	io_parms.netfid = netfid;
+	io_parms.pid = current->tgid;
+	io_parms.tcon = pTcon;
+	io_parms.offset = 0;
+	io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 
-	rc = CIFSSMBRead(xid, pTcon, netfid,
-			 CIFS_MF_SYMLINK_FILE_SIZE /* length */,
-			 0 /* offset */,
-			 &bytes_read, &pbuf, &buf_type);
+	rc = CIFSSMBRead(xid, &io_parms, &bytes_read, &pbuf, &buf_type);
 	CIFSSMBClose(xid, pTcon, netfid);
 	if (rc != 0) {
 		kfree(buf);