[CIFS] Do not overwrite aops

cifs should not be overwriting an element of the aops structure, since the
structure is shared by all cifs inodes.  Instead define a separate aops
structure to suit each purpose.

I also took the liberty of replacing a hard-coded 4096 with PAGE_CACHE_SIZE

Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: Steven French <sfrench@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>

4 files changed, 35 insertions, 12 deletions

diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h
index 2fc6d6527f1..3011df988bd 100644
--- a/fs/cifs/cifsfs.h
+++ b/fs/cifs/cifsfs.h
@@ -33,6 +33,7 @@
 #endif
 
 extern struct address_space_operations cifs_addr_ops;
+extern struct address_space_operations cifs_addr_ops_smallbuf;
 
 /* Functions related to super block operations */
 extern struct super_operations cifs_super_ops;
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 379369ecda9..d62e29fe91f 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1959,3 +1959,19 @@ struct address_space_operations cifs_addr_ops = {
         /* .sync_page = cifs_sync_page, */
         /* .direct_IO = */
 };
+
+/*
+ * cifs_readpages requires the server to support a buffer large enough to
+ * contain the header plus one complete page of data.  Otherwise, we need
+ * to leave cifs_readpages out of the address space operations.
+ */
+struct address_space_operations cifs_addr_ops_smallbuf = {
+        .readpage = cifs_readpage,
+        .writepage = cifs_writepage,
+        .writepages = cifs_writepages,
+        .prepare_write = cifs_prepare_write,
+        .commit_write = cifs_commit_write,
+        .set_page_dirty = __set_page_dirty_nobuffers,
+        /* .sync_page = cifs_sync_page, */
+        /* .direct_IO = */
+};
diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index a609d266803..b88147c1dc2 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -180,11 +180,12 @@ int cifs_get_inode_info_unix(struct inode **pinode,
                         else /* not direct, send byte range locks */ 
                                 inode->i_fop = &cifs_file_ops;
 
-                        inode->i_data.a_ops = &cifs_addr_ops;
                         /* check if server can support readpages */
                         if(pTcon->ses->server->maxBuf < 
-                            4096 + MAX_CIFS_HDR_SIZE)
-                                inode->i_data.a_ops->readpages = NULL;
+                            PAGE_CACHE_SIZE + MAX_CIFS_HDR_SIZE)
+                                inode->i_data.a_ops = &cifs_addr_ops_smallbuf;
+                        else
+                                inode->i_data.a_ops = &cifs_addr_ops;
                 } else if (S_ISDIR(inode->i_mode)) {
                         cFYI(1, ("Directory inode"));
                         inode->i_op = &cifs_dir_inode_ops;
@@ -519,10 +520,11 @@ int cifs_get_inode_info(struct inode **pinode,
                         else /* not direct, send byte range locks */
                                 inode->i_fop = &cifs_file_ops;
 
-                        inode->i_data.a_ops = &cifs_addr_ops;
                         if(pTcon->ses->server->maxBuf < 
-                             4096 + MAX_CIFS_HDR_SIZE)
-                                inode->i_data.a_ops->readpages = NULL;
+                             PAGE_CACHE_SIZE + MAX_CIFS_HDR_SIZE)
+                                inode->i_data.a_ops = &cifs_addr_ops_smallbuf;
+                        else
+                                inode->i_data.a_ops = &cifs_addr_ops;
                 } else if (S_ISDIR(inode->i_mode)) {
                         cFYI(1, ("Directory inode"));
                         inode->i_op = &cifs_dir_inode_ops;
diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index 53903a27f78..e3e762d774d 100644
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -21,6 +21,7 @@
  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  */
 #include <linux/fs.h>
+#include <linux/pagemap.h>
 #include <linux/stat.h>
 #include <linux/smp_lock.h>
 #include "cifspdu.h"
@@ -216,11 +217,13 @@ static void fill_in_inode(struct inode *tmp_inode,
                 else
                         tmp_inode->i_fop = &cifs_file_ops;
 
-                tmp_inode->i_data.a_ops = &cifs_addr_ops;
                 if((cifs_sb->tcon) && (cifs_sb->tcon->ses) &&
                    (cifs_sb->tcon->ses->server->maxBuf <
-                        4096 + MAX_CIFS_HDR_SIZE))
-                        tmp_inode->i_data.a_ops->readpages = NULL;
+                        PAGE_CACHE_SIZE + MAX_CIFS_HDR_SIZE))
+                        tmp_inode->i_data.a_ops = &cifs_addr_ops_smallbuf;
+                else
+                        tmp_inode->i_data.a_ops = &cifs_addr_ops;
+
                 if(isNewInode)
                         return; /* No sense invalidating pages for new inode
                                    since have not started caching readahead file
@@ -339,11 +342,12 @@ static void unix_fill_in_inode(struct inode *tmp_inode,
                 else
                         tmp_inode->i_fop = &cifs_file_ops;
 
-                tmp_inode->i_data.a_ops = &cifs_addr_ops;
                 if((cifs_sb->tcon) && (cifs_sb->tcon->ses) &&
                    (cifs_sb->tcon->ses->server->maxBuf < 
-                        4096 + MAX_CIFS_HDR_SIZE))
-                        tmp_inode->i_data.a_ops->readpages = NULL;
+                        PAGE_CACHE_SIZE + MAX_CIFS_HDR_SIZE))
+                        tmp_inode->i_data.a_ops = &cifs_addr_ops_smallbuf;
+                else
+                        tmp_inode->i_data.a_ops = &cifs_addr_ops;
 
                 if(isNewInode)
                         return; /* No sense invalidating pages for new inode since we