CIFS: Fix rsize usage for sync read

If a server changes maximum buffer size for read requests (rsize)
on reconnect we can fail on repeating with a big size buffer on
-EAGAIN error in cifs_read. Fix this by checking rsize all the
time before repeating requests.

Reviewed-by: Shirish Pargaonkar <spargaonkar@suse.com>
Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 14 insertions, 12 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index bbc38594b39a..00b2a254ff1c 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3148,18 +3148,19 @@ cifs_read(struct file *file, char *read_data, size_t read_size, loff_t *offset)
 
         for (total_read = 0, cur_offset = read_data; read_size > total_read;
              total_read += bytes_read, cur_offset += bytes_read) {
-                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 ((tcon->ses) && !(tcon->ses->capabilities &
+                do {
+                        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 ((tcon->ses) && !(tcon->ses->capabilities &
                                 tcon->ses->server->vals->cap_large_files)) {
-                        current_read_size = min_t(uint, current_read_size,
-                                        CIFSMaxBufSize);
-                }
-                rc = -EAGAIN;
-                while (rc == -EAGAIN) {
+                                current_read_size = min_t(uint,
+                                        current_read_size, CIFSMaxBufSize);
+                        }
                         if (open_file->invalidHandle) {
                                 rc = cifs_reopen_file(open_file, true);
                                 if (rc != 0)
@@ -3172,7 +3173,8 @@ cifs_read(struct file *file, char *read_data, size_t read_size, loff_t *offset)
                         rc = server->ops->sync_read(xid, open_file, &io_parms,
                                                     &bytes_read, &cur_offset,
                                                     &buf_type);
-                }
+                } while (rc == -EAGAIN);
+
                 if (rc || (bytes_read == 0)) {
                         if (total_read) {
                                 break;