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>

10 files changed, 115 insertions, 39 deletions

diff --git a/fs/cifs/README b/fs/cifs/README
index 4a3ca0e5ca24..c5c2c5e5f0f2 100644
--- a/fs/cifs/README
+++ b/fs/cifs/README
@@ -457,6 +457,9 @@ A partial list of the supported mount options follows:
                 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
diff --git a/fs/cifs/cifs_fs_sb.h b/fs/cifs/cifs_fs_sb.h
index c96b44b4e262..ffb1459dc6ec 100644
--- a/fs/cifs/cifs_fs_sb.h
+++ b/fs/cifs/cifs_fs_sb.h
@@ -41,6 +41,7 @@
 #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;
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 360fe2ec2a19..26981bf2cf3f 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -415,12 +415,20 @@ cifs_show_options(struct seq_file *s, struct vfsmount *m)
                 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)
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index ca0c3789206e..310cddabd3fd 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -200,6 +200,7 @@ struct smb_vol {
         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;
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index e41f6071cdd2..17063455918f 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -345,9 +345,8 @@ extern int CIFSSMBClose(const int xid, struct cifsTconInfo *tcon,
 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,
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);
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 261ca81d5e49..21bc83586beb 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1359,6 +1359,8 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
                         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) {
@@ -2708,6 +2710,8 @@ void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
                 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)
diff --git a/fs/cifs/fi