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 f39fa08b9b0e..19fd8158bb47 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);