cifs: use CreationTime like an i_generation field

Reduce false inode collisions by using the CreationTime like an
i_generation field. This way, even if the server ends up reusing
a uniqueid after a delete/create cycle, we can avoid matching
the inode incorrectly.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

4 files changed, 11 insertions, 0 deletions

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 5abfedaa5e78..5e7075d5f139 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -329,6 +329,8 @@ cifs_alloc_inode(struct super_block *sb)
         cifs_inode->invalid_mapping = false;
         cifs_inode->vfs_inode.i_blkbits = 14;  /* 2**14 = CIFS_MAX_MSGSIZE */
         cifs_inode->server_eof = 0;
+        cifs_inode->uniqueid = 0;
+        cifs_inode->createtime = 0;
 
         /* Can not set i_flags here - they get immediately overwritten
            to zero by the VFS */
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index e6590e69fb0e..606ca8bb7102 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -453,6 +453,7 @@ struct cifsInodeInfo {
         bool invalid_mapping:1;         /* pagecache is invalid */
         u64  server_eof;                /* current file size on server */
         u64  uniqueid;                  /* server inode number */
+        u64  createtime;                /* creation time on server */
 #ifdef CONFIG_CIFS_FSCACHE
         struct fscache_cookie *fscache;
 #endif
@@ -573,6 +574,7 @@ struct cifs_fattr {
         u64             cf_uniqueid;
         u64             cf_eof;
         u64             cf_bytes;
+        u64             cf_createtime;
         uid_t           cf_uid;
         gid_t           cf_gid;
         umode_t         cf_mode;
diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index a853a89857a5..0c7e36910e31 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -518,6 +518,7 @@ cifs_all_info_to_fattr(struct cifs_fattr *fattr, FILE_ALL_INFO *info,
 
         fattr->cf_eof = le64_to_cpu(info->EndOfFile);
         fattr->cf_bytes = le64_to_cpu(info->AllocationSize);
+        fattr->cf_createtime = le64_to_cpu(info->CreationTime);
 
         if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
                 fattr->cf_mode = S_IFDIR | cifs_sb->mnt_dir_mode;
@@ -779,6 +780,10 @@ cifs_find_inode(struct inode *inode, void *opaque)
         if (CIFS_I(inode)->uniqueid != fattr->cf_uniqueid)
                 return 0;
 
+        /* use createtime like an i_generation field */
+        if (CIFS_I(inode)->createtime != fattr->cf_createtime)
+                return 0;
+
         /* don't match inode of different type */
         if ((inode->i_mode & S_IFMT) != (fattr->cf_mode & S_IFMT))
                 return 0;
@@ -796,6 +801,7 @@ cifs_init_inode(struct inode *inode, void *opaque)
         struct cifs_fattr *fattr = (struct cifs_fattr *) opaque;
 
         CIFS_I(inode)->uniqueid = fattr->cf_uniqueid;
+        CIFS_I(inode)->createtime = fattr->cf_createtime;
         return 0;
 }
 
diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index ec5b68e3b928..76b1b37c9e6b 100644
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -160,6 +160,7 @@ cifs_dir_info_to_fattr(struct cifs_fattr *fattr, FILE_DIRECTORY_INFO *info,
         fattr->cf_cifsattrs = le32_to_cpu(info->ExtFileAttributes);
         fattr->cf_eof = le64_to_cpu(info->EndOfFile);
         fattr->cf_bytes = le64_to_cpu(info->AllocationSize);
+        fattr->cf_createtime = le64_to_cpu(info->CreationTime);
         fattr->cf_atime = cifs_NTtimeToUnix(info->LastAccessTime);
         fattr->cf_ctime = cifs_NTtimeToUnix(info->ChangeTime);
         fattr->cf_mtime = cifs_NTtimeToUnix(info->LastWriteTime);