[PATCH] cifs: Fix caching problem

pointed out by Dave Stahl and Vince Negri in which cifs can update the
last modify time on a server modified file without invalidating the
local cached data due to an intervening readdir. 

Signed-off-by: Steve French (sfrench@us.ibm.com)
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 57 insertions, 13 deletions

diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index 7ca876b6f2ab..39170cffcad8 100644
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -3,7 +3,7 @@
  *
  *   Directory search handling
  * 
- *   Copyright (C) International Business Machines  Corp., 2004
+ *   Copyright (C) International Business Machines  Corp., 2004, 2005
  *   Author(s): Steve French (sfrench@us.ibm.com)
  *
  *   This library is free software; you can redistribute it and/or modify
@@ -65,14 +65,14 @@ static int construct_dentry(struct qstr *qstring, struct file *file,
         struct cifsTconInfo *pTcon;
         int rc = 0;
 
-        cFYI(1, ("For %s ", qstring->name));
+        cFYI(1, ("For %s", qstring->name));
         cifs_sb = CIFS_SB(file->f_dentry->d_sb);
         pTcon = cifs_sb->tcon;
 
         qstring->hash = full_name_hash(qstring->name, qstring->len);
         tmp_dentry = d_lookup(file->f_dentry, qstring);
         if (tmp_dentry) {
-                cFYI(0, (" existing dentry with inode 0x%p", tmp_dentry->d_inode));
+                cFYI(0, ("existing dentry with inode 0x%p", tmp_dentry->d_inode));
                 *ptmp_inode = tmp_dentry->d_inode;
 /* BB overwrite old name? i.e. tmp_dentry->d_name and tmp_dentry->d_name.len??*/
                 if(*ptmp_inode == NULL) {
@@ -105,8 +105,11 @@ static int construct_dentry(struct qstr *qstring, struct file *file,
 }
 
 static void fill_in_inode(struct inode *tmp_inode,
-        FILE_DIRECTORY_INFO *pfindData, int *pobject_type)
+        FILE_DIRECTORY_INFO *pfindData, int *pobject_type, int isNewInode)
 {
+        loff_t local_size;
+        struct timespec local_mtime;
+
         struct cifsInodeInfo *cifsInfo = CIFS_I(tmp_inode);
         struct cifs_sb_info *cifs_sb = CIFS_SB(tmp_inode->i_sb);
         __u32 attr = le32_to_cpu(pfindData->ExtFileAttributes);
@@ -116,6 +119,10 @@ static void fill_in_inode(struct inode *tmp_inode,
         cifsInfo->cifsAttrs = attr;
         cifsInfo->time = jiffies;
 
+        /* save mtime and size */
+        local_mtime = tmp_inode->i_mtime;
+        local_size  = tmp_inode->i_size;
+
         /* Linux can not store file creation time unfortunately so ignore it */
         tmp_inode->i_atime =
             cifs_NTtimeToUnix(le64_to_cpu(pfindData->LastAccessTime));
@@ -134,7 +141,6 @@ static void fill_in_inode(struct inode *tmp_inode,
                 tmp_inode->i_mode = cifs_sb->mnt_file_mode;
         }
 
-        cFYI(0,("CIFS FFIRST: Attributes came in as 0x%x",attr));
         if (attr & ATTR_DIRECTORY) {
                 *pobject_type = DT_DIR;
                 /* override default perms since we do not lock dirs */
@@ -175,30 +181,46 @@ static void fill_in_inode(struct inode *tmp_inode,
               (unsigned long)tmp_inode->i_size, tmp_inode->i_blocks,
               tmp_inode->i_blksize));
         if (S_ISREG(tmp_inode->i_mode)) {
-                cFYI(1, (" File inode "));
+                cFYI(1, ("File inode"));
                 tmp_inode->i_op = &cifs_file_inode_ops;
                 if(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_DIRECT_IO)
                         tmp_inode->i_fop = &cifs_file_direct_ops;
                 else
                         tmp_inode->i_fop = &cifs_file_ops;
                 tmp_inode->i_data.a_ops = &cifs_addr_ops;
+
+                if(isNewInode)
+                        return; /* No sense invalidating pages for new inode since we
+                                           have not started caching readahead file data yet */
+
+                if (timespec_equal(&tmp_inode->i_mtime, &local_mtime) &&
+                        (local_size == tmp_inode->i_size)) {
+                        cFYI(1, ("inode exists but unchanged"));
+                } else {
+                        /* file may have changed on server */
+                        cFYI(1, ("invalidate inode, readdir detected change"));
+                        invalidate_remote_inode(tmp_inode);
+                }
         } else if (S_ISDIR(tmp_inode->i_mode)) {
-                cFYI(1, (" Directory inode"));
+                cFYI(1, ("Directory inode"));
                 tmp_inode->i_op = &cifs_dir_inode_ops;
                 tmp_inode->i_fop = &cifs_dir_ops;
         } else if (S_ISLNK(tmp_inode->i_mode)) {
-                cFYI(1, (" Symbolic Link inode "));
+                cFYI(1, ("Symbolic Link inode"));
                 tmp_inode->i_op = &cifs_symlink_inode_ops;
         } else {
-                cFYI(1, (" Init special inode "));
+                cFYI(1, ("Init special inode"));
                 init_special_inode(tmp_inode, tmp_inode->i_mode,
                                    tmp_inode->i_rdev);
         }
 }
 
 static void unix_fill_in_inode(struct inode *tmp_inode,
-        FILE_UNIX_INFO *pfindData, int *pobject_type)
+        FILE_UNIX_INFO *pfindData, int *pobject_type, int isNewInode)
 {
+        loff_t local_size;
+        struct timespec local_mtime;
+
         struct cifsInodeInfo *cifsInfo = CIFS_I(tmp_inode);
         struct cifs_sb_info *cifs_sb = CIFS_SB(tmp_inode->i_sb);
 
@@ -208,6 +230,10 @@ static void unix_fill_in_inode(struct inode *tmp_inode,
         cifsInfo->time = jiffies;
         atomic_inc(&cifsInfo->inUse);
 
+        /* save mtime and size */
+        local_mtime = tmp_inode->i_mtime;
+        local_size  = tmp_inode->i_size;
+
         tmp_inode->i_atime =
             cifs_NTtimeToUnix(le64_to_cpu(pfindData->LastAccessTime));
         tmp_inode->i_mtime =
@@ -265,6 +291,19 @@ 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(isNewInode)
+                        return; /* No sense invalidating pages for new inode since we
+                                           have not started caching readahead file data yet */
+
+                if (timespec_equal(&tmp_inode->i_mtime, &local_mtime) &&
+                        (local_size == tmp_inode->i_size)) {
+                        cFYI(1, ("inode exists but unchanged"));
+                } else {
+                        /* file may have changed on server */
+                        cFYI(1, ("invalidate inode, readdir detected change"));
+                        invalidate_remote_inode(tmp_inode);
+                }
         } else if (S_ISDIR(tmp_inode->i_mode)) {
                 cFYI(1, ("Directory inode"));
                 tmp_inode->i_op = &cifs_dir_inode_ops;
@@ -321,7 +360,7 @@ static int initiate_cifs_search(const int xid, struct file *file)
                 return -ENOMEM;
         }
 
-        cFYI(1, ("Full path: %s start at: %lld ", full_path, file->f_pos));
+        cFYI(1, ("Full path: %s start at: %lld", full_path, file->f_pos));
 
 ffirst_retry:
         /* test for Unix extensions */
@@ -666,10 +705,15 @@ static int cifs_filldir(char *pfindEntry, struct file *file,
                 insert_inode_hash(tmp_inode);
         }
 
+        /* we pass in rc below, indicating whether it is a new inode,
+           so we can figure out whether to invalidate the inode cached
+           data if the file has changed */
         if(pCifsF->srch_inf.info_level == SMB_FIND_FILE_UNIX) {
-                unix_fill_in_inode(tmp_inode,(FILE_UNIX_INFO *)pfindEntry,&obj_type);
+                unix_fill_in_inode(tmp_inode,
+                                   (FILE_UNIX_INFO *)pfindEntry,&obj_type, rc);
         } else {
-                fill_in_inode(tmp_inode,(FILE_DIRECTORY_INFO *)pfindEntry,&obj_type);
+                fill_in_inode(tmp_inode,
+                              (FILE_DIRECTORY_INFO *)pfindEntry,&obj_type, rc);
         }
         
         rc = filldir(direntry,qstring.name,qstring.len,file->f_pos,tmp_inode->i_ino,obj_type);