[PATCH 3.12 094/118] exportfs: fix 32-bit nfsd handling of 64-bit inode numbers

Greg Kroah-Hartman
2013-12-18T21:14:08Z

From: "J. Bruce Fields" <bfields@redhat.com>

commit 950ee9566a5b6cc45d15f5fe044bab4f1e8b62cb upstream.

Symptoms were spurious -ENOENTs on stat of an NFS filesystem from a
32-bit NFS server exporting a very large XFS filesystem, when the
server's cache is cold (so the inodes in question are not in cache).

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reported-by: Trevor Cordes <trevor@tecnopolis.ca>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/exportfs/expfs.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)

--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -215,7 +215,7 @@ struct getdents_callback {
struct dir_context ctx;
char *name; /* name that was found. It already points to a
buffer NAME_MAX+1 is size */
- unsigned long ino; /* the inum we are looking for */
+ u64 ino; /* the inum we are looking for */
int found; /* inode matched? */
int sequence; /* sequence counter */
};
@@ -255,10 +255,14 @@ static int get_name(const struct path *p
struct inode *dir = path->dentry->d_inode;
int error;
struct file *file;
+ struct kstat stat;
+ struct path child_path = {
+ .mnt = path->mnt,
+ .dentry = child,
+ };
struct getdents_callback buffer = {
.ctx.actor = filldir_one,
.name = name,
- .ino = child->d_inode->i_ino
};

error = -ENOTDIR;
@@ -268,6 +272,16 @@ static int get_name(const struct path *p
if (!dir->i_fop)
goto out;
/*
+ * inode->i_ino is unsigned long, kstat->ino is u64, so the
+ * former would be insufficient on 32-bit hosts when the
+ * filesystem supports 64-bit inode numbers. So we need to
+ * actually call ->getattr, not just read i_ino:
+ */
+ error = vfs_getattr_nosec(&child_path, &stat);
+ if (error)
+ return error;
+ buffer.ino = stat.ino;
+ /*
* Open the directory ...
*/
file = dentry_open(path, O_RDONLY, cred);