CIFS: Calculate the correct request length based on page offset and tail size

It's possible that the page offset is non-zero in the pages in a request,
change the function to calculate the correct data buffer length.

Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index e7254e3..d6cff1e 100644 (file)
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -212,10 +212,24 @@ rqst_len(struct smb_rqst *rqst)
        for (i = 0; i < rqst->rq_nvec; i++)
                buflen += iov[i].iov_len;
 
-       /* add in the page array if there is one */
+       /*
+        * Add in the page array if there is one. The caller needs to make
+        * sure rq_offset and rq_tailsz are set correctly. If a buffer of
+        * multiple pages ends at page boundary, rq_tailsz needs to be set to
+        * PAGE_SIZE.
+        */
        if (rqst->rq_npages) {
-               buflen += rqst->rq_pagesz * (rqst->rq_npages - 1);
-               buflen += rqst->rq_tailsz;
+               if (rqst->rq_npages == 1)
+                       buflen += rqst->rq_tailsz;
+               else {
+                       /*
+                        * If there is more than one page, calculate the
+                        * buffer length based on rq_offset and rq_tailsz
+                        */
+                       buflen += rqst->rq_pagesz * (rqst->rq_npages - 1) -
+                                       rqst->rq_offset;
+                       buflen += rqst->rq_tailsz;
+               }
        }
 
        return buflen;