2 files changed, 84 insertions, 50 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 3d518b9e8c18..06dfaacfea5d 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2310,16 +2310,16 @@ compare_mount_options(struct super_block *sb, struct cifs_mnt_data *mnt_data)
             (new->mnt_cifs_flags & CIFS_MOUNT_MASK))
                 return 0;
 
-        if (old->rsize != new->rsize)
-                return 0;
-
         /*
-         * We want to share sb only if we don't specify wsize or specified wsize
-         * is greater or equal than existing one.
+         * We want to share sb only if we don't specify an r/wsize or
+         * specified r/wsize is greater than or equal to existing one.
          */
         if (new->wsize && new->wsize < old->wsize)
                 return 0;
 
+        if (new->rsize && new->rsize < old->rsize)
+                return 0;
+
         if (old->mnt_uid != new->mnt_uid || old->mnt_gid != new->mnt_gid)
                 return 0;
 
@@ -2757,14 +2757,6 @@ void reset_cifs_unix_caps(int xid, struct cifs_tcon *tcon,
                                         CIFS_MOUNT_POSIX_PATHS;
                 }
 
-                if (cifs_sb && (cifs_sb->rsize > 127 * 1024)) {
-                        if ((cap & CIFS_UNIX_LARGE_READ_CAP) == 0) {
-                                cifs_sb->rsize = 127 * 1024;
-                                cFYI(DBG2, "larger reads not supported by srv");
-                        }
-                }
-
-
                 cFYI(1, "Negotiate caps 0x%x", (int)cap);
 #ifdef CONFIG_CIFS_DEBUG2
                 if (cap & CIFS_UNIX_FCNTL_CAP)
@@ -2809,27 +2801,11 @@ void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
         spin_lock_init(&cifs_sb->tlink_tree_lock);
         cifs_sb->tlink_tree = RB_ROOT;
 
-        if (pvolume_info->rsize > CIFSMaxBufSize) {
-                cERROR(1, "rsize %d too large, using MaxBufSize",
-                        pvolume_info->rsize);
-                cifs_sb->rsize = CIFSMaxBufSize;
-        } else if ((pvolume_info->rsize) &&
-                        (pvolume_info->rsize <= CIFSMaxBufSize))
-                cifs_sb->rsize = pvolume_info->rsize;
-        else /* default */
-                cifs_sb->rsize = CIFSMaxBufSize;
-
-        if (cifs_sb->rsize < 2048) {
-                cifs_sb->rsize = 2048;
-                /* Windows ME may prefer this */
-                cFYI(1, "readsize set to minimum: 2048");
-        }
-
         /*
-         * Temporarily set wsize for matching superblock. If we end up using
-         * new sb then cifs_negotiate_wsize will later negotiate it downward
-         * if needed.
+         * Temporarily set r/wsize for matching superblock. If we end up using
+         * new sb then client will later negotiate it downward if needed.
          */
+        cifs_sb->rsize = pvolume_info->rsize;
         cifs_sb->wsize = pvolume_info->wsize;
 
         cifs_sb->mnt_uid = pvolume_info->linux_uid;
@@ -2904,29 +2880,41 @@ void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
 }
 
 /*
- * When the server supports very large writes via POSIX extensions, we can
- * allow up to 2^24-1, minus the size of a WRITE_AND_X header, not including
- * the RFC1001 length.
+ * When the server supports very large reads and writes via POSIX extensions,
+ * we can allow up to 2^24-1, minus the size of a READ/WRITE_AND_X header, not
+ * including the RFC1001 length.
  *
  * Note that this might make for "interesting" allocation problems during
  * writeback however as we have to allocate an array of pointers for the
  * pages. A 16M write means ~32kb page array with PAGE_CACHE_SIZE == 4096.
+ *
+ * For reads, there is a similar problem as we need to allocate an array
+ * of kvecs to handle the receive, though that should only need to be done
+ * once.
  */
 #define CIFS_MAX_WSIZE ((1<<24) - 1 - sizeof(WRITE_REQ) + 4)
+#define CIFS_MAX_RSIZE ((1<<24) - sizeof(READ_RSP) + 4)
 
 /*
- * When the server doesn't allow large posix writes, only allow a wsize of
- * 2^17-1 minus the size of the WRITE_AND_X header. That allows for a write up
- * to the maximum size described by RFC1002.
+ * When the server doesn't allow large posix writes, only allow a rsize/wsize
+ * of 2^17-1 minus the size of the call header. That allows for a read or
+ * write up to the maximum size described by RFC1002.
  */
 #define CIFS_MAX_RFC1002_WSIZE ((1<<17) - 1 - sizeof(WRITE_REQ) + 4)
+#define CIFS_MAX_RFC1002_RSIZE ((1<<17) - 1 - sizeof(READ_RSP) + 4)
 
 /*
  * The default wsize is 1M. find_get_pages seems to return a maximum of 256
  * pages in a single call. With PAGE_CACHE_SIZE == 4k, this means we can fill
  * a single wsize request with a single call.
  */
-#define CIFS_DEFAULT_WSIZE (1024 * 1024)
+#define CIFS_DEFAULT_IOSIZE (1024 * 1024)
+
+/*
+ * Windows only supports a max of 60k reads. Default to that when posix
+ * extensions aren't in force.
+ */
+#define CIFS_DEFAULT_NON_POSIX_RSIZE (60 * 1024)
 
 static unsigned int
 cifs_negotiate_wsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info)
@@ -2934,7 +2922,7 @@ cifs_negotiate_wsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info)
         __u64 unix_cap = le64_to_cpu(tcon->fsUnixInfo.Capability);
         struct TCP_Server_Info *server = tcon->ses->server;
         unsigned int wsize = pvolume_info->wsize ? pvolume_info->wsize :
-                                CIFS_DEFAULT_WSIZE;
+                                CIFS_DEFAULT_IOSIZE;
 
         /* can server support 24-bit write sizes? (via UNIX extensions) */
         if (!tcon->unix_ext || !(unix_cap & CIFS_UNIX_LARGE_WRITE_CAP))
@@ -2957,6 +2945,50 @@ cifs_negotiate_wsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info)
         return wsize;
 }
 
+static unsigned int
+cifs_negotiate_rsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info)
+{
+        __u64 unix_cap = le64_to_cpu(tcon->fsUnixInfo.Capability);
+        struct TCP_Server_Info *server = tcon->ses->server;
+        unsigned int rsize, defsize;
+
+        /*
+         * Set default value...
+         *
+         * HACK alert! Ancient servers have very small buffers. Even though
+         * 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.
+         *
+         * 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 (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);
+
+        rsize = pvolume_info->rsize ? pvolume_info->rsize : defsize;
+
+        /*
+         * no CAP_LARGE_READ_X? Then MS-CIFS states that we must limit this to
+         * the client's MaxBufferSize.
+         */
+        if (!(server->capabilities & CAP_LARGE_READ_X))
+                rsize = min_t(unsigned int, CIFSMaxBufSize, rsize);
+
+        /* hard limit of CIFS_MAX_RSIZE */
+        rsize = min_t(unsigned int, rsize, CIFS_MAX_RSIZE);
+
+        return rsize;
+}
+
 static int
 is_path_accessible(int xid, struct cifs_tcon *tcon,
                    struct cifs_sb_info *cifs_sb, const char *full_path)
@@ -3234,14 +3266,8 @@ try_mount_again:
                 CIFSSMBQFSAttributeInfo(xid, tcon);
         }
 
-        if ((tcon->unix_ext == 0) && (cifs_sb->rsize > (1024 * 127))) {
-                cifs_sb->rsize = 1024 * 127;
-                cFYI(DBG2, "no very large read support, rsize now 127K");
-        }
-        if (!(tcon->ses->capabilities & CAP_LARGE_READ_X))
-                cifs_sb->rsize = min(cifs_sb->rsize, CIFSMaxBufSize);
-
         cifs_sb->wsize = cifs_negotiate_wsize(tcon, volume_info);
+        cifs_sb->rsize = cifs_negotiate_rsize(tcon, volume_info);
 
 remote_path_check:
 #ifdef CONFIG_CIFS_DFS_UPCALL
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 8f6917816fec..a3b545ff5250 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1758,6 +1758,7 @@ cifs_iovec_read(struct file *file, const struct iovec *iov,
         struct smb_com_read_rsp *pSMBr;
         struct cifs_io_parms io_parms;
         char *read_data;
+        unsigned int rsize;
         __u32 pid;
 
         if (!nr_segs)
@@ -1770,6 +1771,9 @@ cifs_iovec_read(struct file *file, const struct iovec *iov,
         xid = GetXid();
         cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
 
+        /* FIXME: set up handlers for larger reads and/or convert to async */
+        rsize = min_t(unsigned int, cifs_sb->rsize, CIFSMaxBufSize);
+
         open_file = file->private_data;
         pTcon = tlink_tcon(open_file->tlink);
 
@@ -1782,7 +1786,7 @@ cifs_iovec_read(struct file *file, const struct iovec *iov,
                 cFYI(1, "attempting read on write only file instance");
 
         for (total_read = 0; total_read < len; total_read += bytes_read) {
-                cur_len = min_t(const size_t, len - total_read, cifs_sb->rsize);
+                cur_len = min_t(const size_t, len - total_read, rsize);
                 rc = -EAGAIN;
                 read_data = NULL;
 
@@ -1874,6 +1878,7 @@ static ssize_t cifs_read(struct file *file, char *read_data, size_t read_size,
         unsigned int bytes_read = 0;
         unsigned int total_read;
         unsigned int current_read_size;
+        unsigned int rsize;
         struct cifs_sb_info *cifs_sb;
         struct cifs_tcon *pTcon;
         int xid;
@@ -1886,6 +1891,9 @@ static ssize_t cifs_read(struct file *file, char *read_data, size_t read_size,
         xid = GetXid();
         cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
 
+        /* FIXME: set up handlers for larger reads and/or convert to async */
+        rsize = min_t(unsigned int, cifs_sb->rsize, CIFSMaxBufSize);
+
         if (file->private_data == NULL) {
                 rc = -EBADF;
                 FreeXid(xid);
@@ -1905,8 +1913,8 @@ static ssize_t cifs_read(struct file *file, char *read_data, size_t read_size,
         for (total_read = 0, current_offset = read_data;
              read_size > total_read;
              total_read += bytes_read, current_offset += bytes_read) {
-                current_read_size = min_t(uint, read_size - total_read,
-                                          cifs_sb->rsize);
+                current_read_size = min_t(uint, read_size - total_read, rsize);
+
                 /* For windows me and 9x we do not want to request more
                 than it negotiated since it will refuse the read then */
                 if ((pTcon->ses) &&