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 <piastry@etersoft.ru>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 12 insertions, 5 deletions

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index f39fa08..19fd815 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -1382,8 +1382,7 @@ openRetry:
 }
 
 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;
@@ -1393,13 +1392,18 @@ CIFSSMBRead(const int xid, struct cifsTconInfo *tcon, const int netfid,
 	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;
 		}
@@ -1410,15 +1414,18 @@ CIFSSMBRead(const int xid, struct cifsTconInfo *tcon, const int netfid,
 	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);