[PATCH v2] fuse: fix stat call on 32 bit platforms

[Pavel Shilovsky <piastry@etersoft.ru>]

Now we store attr->ino at inode->i_ino, return attr->ino at the
first time and then return inode->i_ino if the attribute timeout
isn't expired. That's wrong on 32 bit platforms because attr->ino
is 64 bit and inode->i_ino is 32 bit in this case.

Fix this by squashing attr->ino into inode->i_ino and returning
the last one all the time we call getattr.

Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
---
 fs/fuse/dir.c   |    2 +-
 fs/fuse/inode.c |   14 +++++++++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index df5ac04..30c3976 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -776,7 +776,7 @@ static void fuse_fillattr(struct inode *inode, struct fuse_attr *attr,
 			  struct kstat *stat)
 {
 	stat->dev = inode->i_sb->s_dev;
-	stat->ino = attr->ino;
+	stat->ino = inode->i_ino;
 	stat->mode = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
 	stat->nlink = attr->nlink;
 	stat->uid = attr->uid;
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 26783eb..6c2a272 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -139,6 +139,18 @@ static int fuse_remount_fs(struct super_block *sb, int *flags, char *data)
 	return 0;
 }
 
+/*
+ * ino_t is 32-bits on 32-bit arch. We have to squash the 64-bit value down
+ * so that it will fit.
+ */
+static ino_t fuse_uniqueid_to_ino(u64 uniqueid)
+{
+	ino_t ino = (ino_t) uniqueid;
+	if (sizeof(ino_t) < sizeof(u64))
+		ino ^= uniqueid >> (sizeof(u64) - sizeof(ino_t)) * 8;
+	return ino;
+}
+
 void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
 				   u64 attr_valid)
 {
@@ -148,7 +160,7 @@ void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
 	fi->attr_version = ++fc->attr_version;
 	fi->i_time = attr_valid;
 
-	inode->i_ino     = attr->ino;
+	inode->i_ino     = fuse_uniqueid_to_ino(attr->ino);
 	inode->i_mode    = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
 	set_nlink(inode, attr->nlink);
 	inode->i_uid     = attr->uid;
-- 
1.7.1