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, 62 insertions, 20 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index dfc0d35b1470..7db74d17a429 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -725,8 +725,8 @@ int cifs_lock(struct file *file, int cmd, struct file_lock *pfLock)
                         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;
                 }
@@ -797,8 +797,8 @@ int cifs_lock(struct file *file, int cmd, struct file_lock *pfLock)
                         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;
 
@@ -1346,6 +1346,14 @@ static int cifs_write_end(struct file *file, struct address_space *mapping,
 {
         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);
@@ -1369,8 +1377,7 @@ static int cifs_write_end(struct file *file, struct address_space *mapping,
                 /* 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);
 
@@ -1523,6 +1530,7 @@ cifs_iovec_write(struct file *file, const struct iovec *iov,
         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)
@@ -1554,6 +1562,12 @@ cifs_iovec_write(struct file *file, const struct iovec *iov,
 
         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;
 
@@ -1581,7 +1595,7 @@ cifs_iovec_write(struct file *file, const struct iovec *iov,
                                         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;
@@ -1682,7 +1696,9 @@ cifs_iovec_read(struct file *file, const struct iovec *iov,
         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;
@@ -1697,6 +1713,11 @@ cifs_iovec_read(struct file *file, const struct iovec *iov,
         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");
 
@@ -1712,8 +1733,12 @@ cifs_iovec_read(struct file *file, const struct iovec *iov,
                                 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) {
@@ -1794,7 +1819,9 @@ static ssize_t cifs_read(struct file *file, char *read_data, size_t read_size,
         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);
@@ -1807,6 +1834,11 @@ static ssize_t cifs_read(struct file *file, char *read_data, size_t read_size,
         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");
 
@@ -1829,11 +1861,13 @@ static ssize_t cifs_read(struct file *file, char *read_data, size_t read_size,
                                 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) {
@@ -1970,7 +2004,9 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
         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) {
@@ -1992,6 +2028,11 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
                 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;
@@ -2033,12 +2074,13 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
                                 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) {