1 files changed, 38 insertions, 21 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 78db68a5cf44..94b7788c3189 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1653,24 +1653,26 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
                          * If yes, we have encountered a double deliminator
                          * reset the NULL character to the deliminator
                          */
-                        if (tmp_end < end && tmp_end[1] == delim)
+                        if (tmp_end < end && tmp_end[1] == delim) {
                                 tmp_end[0] = delim;
 
-                        /* Keep iterating until we get to a single deliminator
-                         * OR the end
-                         */
-                        while ((tmp_end = strchr(tmp_end, delim)) != NULL &&
-                               (tmp_end[1] == delim)) {
-                                tmp_end = (char *) &tmp_end[2];
-                        }
+                                /* Keep iterating until we get to a single
+                                 * deliminator OR the end
+                                 */
+                                while ((tmp_end = strchr(tmp_end, delim))
+                                        != NULL && (tmp_end[1] == delim)) {
+                                                tmp_end = (char *) &tmp_end[2];
+                                }
 
-                        /* Reset var options to point to next element */
-                        if (tmp_end) {
-                                tmp_end[0] = '\0';
-                                options = (char *) &tmp_end[1];
-                        } else
-                                /* Reached the end of the mount option string */
-                                options = end;
+                                /* Reset var options to point to next element */
+                                if (tmp_end) {
+                                        tmp_end[0] = '\0';
+                                        options = (char *) &tmp_end[1];
+                                } else
+                                        /* Reached the end of the mount option
+                                         * string */
+                                        options = end;
+                        }
 
                         /* Now build new password string */
                         temp_len = strlen(value);
@@ -3443,6 +3445,18 @@ void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
 #define CIFS_DEFAULT_NON_POSIX_RSIZE (60 * 1024)
 #define CIFS_DEFAULT_NON_POSIX_WSIZE (65536)
 
+/*
+ * On hosts with high memory, we can't currently support wsize/rsize that are
+ * larger than we can kmap at once. Cap the rsize/wsize at
+ * LAST_PKMAP * PAGE_SIZE. We'll never be able to fill a read or write request
+ * larger than that anyway.
+ */
+#ifdef CONFIG_HIGHMEM
+#define CIFS_KMAP_SIZE_LIMIT    (LAST_PKMAP * PAGE_CACHE_SIZE)
+#else /* CONFIG_HIGHMEM */
+#define CIFS_KMAP_SIZE_LIMIT    (1<<24)
+#endif /* CONFIG_HIGHMEM */
+
 static unsigned int
 cifs_negotiate_wsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info)
 {
@@ -3473,6 +3487,9 @@ cifs_negotiate_wsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info)
                 wsize = min_t(unsigned int, wsize,
                                 server->maxBuf - sizeof(WRITE_REQ) + 4);
 
+        /* limit to the amount that we can kmap at once */
+        wsize = min_t(unsigned int, wsize, CIFS_KMAP_SIZE_LIMIT);
+
         /* hard limit of CIFS_MAX_WSIZE */
         wsize = min_t(unsigned int, wsize, CIFS_MAX_WSIZE);
 
@@ -3493,18 +3510,15 @@ cifs_negotiate_rsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info)
          * MS-CIFS indicates that servers are only limited by the client's
          * bufsize for reads, testing against win98se shows that it throws
          * INVALID_PARAMETER errors if you try to request too large a read.
+         * OS/2 just sends back short reads.
          *
-         * If the server advertises a MaxBufferSize of less than one page,
-         * assume that it also can't satisfy reads larger than that either.
-         *
-         * FIXME: Is there a better heuristic for this?
+         * If the server doesn't advertise CAP_LARGE_READ_X, then assume that
+         * it can't handle a read request larger than its MaxBufferSize either.
          */
         if (tcon->unix_ext && (unix_cap & CIFS_UNIX_LARGE_READ_CAP))
                 defsize = CIFS_DEFAULT_IOSIZE;
         else if (server->capabilities & CAP_LARGE_READ_X)
                 defsize = CIFS_DEFAULT_NON_POSIX_RSIZE;
-        else if (server->maxBuf >= PAGE_CACHE_SIZE)
-                defsize = CIFSMaxBufSize;
         else
                 defsize = server->maxBuf - sizeof(READ_RSP);
 
@@ -3517,6 +3531,9 @@ cifs_negotiate_rsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info)
         if (!(server->capabilities & CAP_LARGE_READ_X))
                 rsize = min_t(unsigned int, CIFSMaxBufSize, rsize);
 
+        /* limit to the amount that we can kmap at once */
+        rsize = min_t(unsigned int, rsize, CIFS_KMAP_SIZE_LIMIT);
+
         /* hard limit of CIFS_MAX_RSIZE */
         rsize = min_t(unsigned int, rsize, CIFS_MAX_RSIZE);