cifs: don't bother with kmap on read_pages side

just do ITER_BVEC recvmsg

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 55 insertions, 70 deletions

diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 7d5f53a01922..0f9a6bc4ba43 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -179,10 +179,9 @@ extern int set_cifs_acl(struct cifs_ntsd *, __u32, struct inode *,
 
 extern void dequeue_mid(struct mid_q_entry *mid, bool malformed);
 extern int cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
-                     unsigned int to_read);
-extern int cifs_readv_from_socket(struct TCP_Server_Info *server,
-                struct kvec *iov_orig, unsigned int nr_segs,
-                unsigned int to_read);
+                                 unsigned int to_read);
+extern int cifs_read_page_from_socket(struct TCP_Server_Info *server,
+                                      struct page *page, unsigned int to_read);
 extern void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
                                struct cifs_sb_info *cifs_sb);
 extern int cifs_match_super(struct super_block *, void *);
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index eb426658566d..e33c5e0ecfd0 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -501,39 +501,34 @@ server_unresponsive(struct TCP_Server_Info *server)
         return false;
 }
 
-int
-cifs_readv_from_socket(struct TCP_Server_Info *server, struct kvec *iov_orig,
-                       unsigned int nr_segs, unsigned int to_read)
+static int
+cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg)
 {
         int length = 0;
         int total_read;
-        struct msghdr smb_msg;
 
-        smb_msg.msg_control = NULL;
-        smb_msg.msg_controllen = 0;
-        iov_iter_kvec(&smb_msg.msg_iter, READ | ITER_KVEC,
-                      iov_orig, nr_segs, to_read);
+        smb_msg->msg_control = NULL;
+        smb_msg->msg_controllen = 0;
 
-        for (total_read = 0; msg_data_left(&smb_msg); total_read += length) {
+        for (total_read = 0; msg_data_left(smb_msg); total_read += length) {
                 try_to_freeze();
 
-                if (server_unresponsive(server)) {
-                        total_read = -ECONNABORTED;
-                        break;
-                }
+                if (server_unresponsive(server))
+                        return -ECONNABORTED;
 
-                length = sock_recvmsg(server->ssocket, &smb_msg, 0);
+                length = sock_recvmsg(server->ssocket, smb_msg, 0);
 
-                if (server->tcpStatus == CifsExiting) {
-                        total_read = -ESHUTDOWN;
-                        break;
-                } else if (server->tcpStatus == CifsNeedReconnect) {
+                if (server->tcpStatus == CifsExiting)
+                        return -ESHUTDOWN;
+
+                if (server->tcpStatus == CifsNeedReconnect) {
                         cifs_reconnect(server);
-                        total_read = -ECONNABORTED;
-                        break;
-                } else if (length == -ERESTARTSYS ||
-                           length == -EAGAIN ||
-                           length == -EINTR) {
+                        return -ECONNABORTED;
+                }
+
+                if (length == -ERESTARTSYS ||
+                    length == -EAGAIN ||
+                    length == -EINTR) {
                         /*
                          * Minimum sleep to prevent looping, allowing socket
                          * to clear and app threads to set tcpStatus
@@ -542,11 +537,12 @@ cifs_readv_from_socket(struct TCP_Server_Info *server, struct kvec *iov_orig,
                         usleep_range(1000, 2000);
                         length = 0;
                         continue;
-                } else if (length <= 0) {
+                }
+
+                if (length <= 0) {
                         cifs_dbg(FYI, "Received no data or error: %d\n", length);
                         cifs_reconnect(server);
-                        total_read = -ECONNABORTED;
-                        break;
+                        return -ECONNABORTED;
                 }
         }
         return total_read;
@@ -556,12 +552,21 @@ int
 cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
                       unsigned int to_read)
 {
-        struct kvec iov;
+        struct msghdr smb_msg;
+        struct kvec iov = {.iov_base = buf, .iov_len = to_read};
+        iov_iter_kvec(&smb_msg.msg_iter, READ | ITER_KVEC, &iov, 1, to_read);
 
-        iov.iov_base = buf;
-        iov.iov_len = to_read;
+        return cifs_readv_from_socket(server, &smb_msg);
+}
 
-        return cifs_readv_from_socket(server, &iov, 1, to_read);
+int
+cifs_read_page_from_socket(struct TCP_Server_Info *server, struct page *page,
+                      unsigned int to_read)
+{
+        struct msghdr smb_msg;
+        struct bio_vec bv = {.bv_page = page, .bv_len = to_read};
+        iov_iter_bvec(&smb_msg.msg_iter, READ | ITER_BVEC, &bv, 1, to_read);
+        return cifs_readv_from_socket(server, &smb_msg);
 }
 
 static bool
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index ff882aeaccc6..0f718679186e 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2855,39 +2855,31 @@ cifs_uncached_read_into_pages(struct TCP_Server_Info *server,
         int result = 0;
         unsigned int i;
         unsigned int nr_pages = rdata->nr_pages;
-        struct kvec iov;
 
         rdata->got_bytes = 0;
         rdata->tailsz = PAGE_SIZE;
         for (i = 0; i < nr_pages; i++) {
                 struct page *page = rdata->pages[i];
+                size_t n;
 
-                if (len >= PAGE_SIZE) {
-                        /* enough data to fill the page */
-                        iov.iov_base = kmap(page);
-                        iov.iov_len = PAGE_SIZE;
-                        cifs_dbg(FYI, "%u: iov_base=%p iov_len=%zu\n",
-                                 i, iov.iov_base, iov.iov_len);
-                        len -= PAGE_SIZE;
-                } else if (len > 0) {
-                        /* enough for partial page, fill and zero the rest */
-                        iov.iov_base = kmap(page);
-                        iov.iov_len = len;
-                        cifs_dbg(FYI, "%u: iov_base=%p iov_len=%zu\n",
-                                 i, iov.iov_base, iov.iov_len);
-                        memset(iov.iov_base + len, '\0', PAGE_SIZE - len);
-                        rdata->tailsz = len;
-                        len = 0;
-                } else {
+                if (len <= 0) {
                         /* no need to hold page hostage */
                         rdata->pages[i] = NULL;
                         rdata->nr_pages--;
                         put_page(page);
                         continue;
                 }
-
-                result = cifs_readv_from_socket(server, &iov, 1, iov.iov_len);
-                kunmap(page);
+                n = len;
+                if (len >= PAGE_SIZE) {
+                        /* enough data to fill the page */
+                        n = PAGE_SIZE;
+                        len -= n;
+                } else {
+                        zero_user(page, len, PAGE_SIZE - len);
+                        rdata->tailsz = len;
+                        len = 0;
+                }
+                result = cifs_read_page_from_socket(server, page, n);
                 if (result < 0)
                         break;
 
@@ -3303,7 +3295,6 @@ cifs_readpages_read_into_pages(struct TCP_Server_Info *server,
         u64 eof;
         pgoff_t eof_index;
         unsigned int nr_pages = rdata->nr_pages;
-        struct kvec iov;
 
         /* determine the eof that the server (probably) has */
         eof = CIFS_I(rdata->mapping->host)->server_eof;
@@ -3314,23 +3305,14 @@ cifs_readpages_read_into_pages(struct TCP_Server_Info *server,
         rdata->tailsz = PAGE_CACHE_SIZE;
         for (i = 0; i < nr_pages; i++) {
                 struct page *page = rdata->pages[i];
+                size_t n = PAGE_CACHE_SIZE;
 
                 if (len >= PAGE_CACHE_SIZE) {
-                        /* enough data to fill the page */
-                        iov.iov_base = kmap(page);
-                        iov.iov_len = PAGE_CACHE_SIZE;
-                        cifs_dbg(FYI, "%u: idx=%lu iov_base=%p iov_len=%zu\n",
-                                 i, page->index, iov.iov_base, iov.iov_len);
                         len -= PAGE_CACHE_SIZE;
                 } else if (len > 0) {
                         /* enough for partial page, fill and zero the rest */
-                        iov.iov_base = kmap(page);
-                        iov.iov_len = len;
-                        cifs_dbg(FYI, "%u: idx=%lu iov_base=%p iov_len=%zu\n",
-                                 i, page->index, iov.iov_base, iov.iov_len);
-                        memset(iov.iov_base + len,
-                                '\0', PAGE_CACHE_SIZE - len);
-                        rdata->tailsz = len;
+                        zero_user(page, len, PAGE_CACHE_SIZE - len);
+                        n = rdata->tailsz = len;
                         len = 0;
                 } else if (page->index > eof_index) {
                         /*
@@ -3360,8 +3342,7 @@ cifs_readpages_read_into_pages(struct TCP_Server_Info *server,
                         continue;
                 }
 
-                result = cifs_readv_from_socket(server, &iov, 1, iov.iov_len);
-                kunmap(page);
+                result = cifs_read_page_from_socket(server, page, n);
                 if (result < 0)
                         break;