exportfs: fix 32-bit nfsd handling of 64-bit inode numbers

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>

diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index a235f0016889b557e06d6273f0f3dca7d873a608..c43fe9b39ff2dc366e8e26f9d2806b93bb28a2e7 100644 (file)
--- 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 *path, char *name, struct dentry *child)
        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;
@@ -267,6 +271,16 @@ static int get_name(const struct path *path, char *name, struct dentry *child)
        error = -EINVAL;
        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 ...
         */