[PATCH 2/3] cifs: use CreationTime like an i_generation field

[Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

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-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 fs/cifs/cifsfs.c   |    2 ++
 fs/cifs/cifsglob.h |    2 ++
 fs/cifs/inode.c    |    6 ++++++
 fs/cifs/readdir.c  |    1 +
 4 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 484e52b..e409216 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -314,6 +314,8 @@ 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 e15d7a5..a0fd2c2 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -382,6 +382,7 @@ 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 */
 	struct inode vfs_inode;
 };
 
@@ -499,6 +500,7 @@ 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 f64b95f..35e2466 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -487,6 +487,7 @@ 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;
@@ -727,6 +728,10 @@ 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;
@@ -750,6 +755,7 @@ 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 daf1753..8bd18be 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);
-- 
1.6.6.1