NFSD: Ensure nf_inode is never dereferenced

The documenting comment for struct nf_file states:

/*
 * A representation of a file that has been opened by knfsd. These are hashed
 * in the hashtable by inode pointer value. Note that this object doesn't
 * hold a reference to the inode by itself, so the nf_inode pointer should
 * never be dereferenced, only used for comparison.
 */

Replace the two existing dereferences to make the comment always
true.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 58721fc..57d06a2 100644 (file)
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -228,12 +228,11 @@ nfsd_file_mark_put(struct nfsd_file_mark *nfm)
 }
 
 static struct nfsd_file_mark *
-nfsd_file_mark_find_or_create(struct nfsd_file *nf)
+nfsd_file_mark_find_or_create(struct nfsd_file *nf, struct inode *inode)
 {
        int                     err;
        struct fsnotify_mark    *mark;
        struct nfsd_file_mark   *nfm = NULL, *new;
-       struct inode *inode = nf->nf_inode;
 
        do {
                fsnotify_group_lock(nfsd_file_fsnotify_group);
@@ -1144,7 +1143,7 @@ out_status:
 
 open_file:
        trace_nfsd_file_alloc(nf);
-       nf->nf_mark = nfsd_file_mark_find_or_create(nf);
+       nf->nf_mark = nfsd_file_mark_find_or_create(nf, key.inode);
        if (nf->nf_mark) {
                if (open) {
                        status = nfsd_open_verified(rqstp, fhp, may_flags,

diff --git a/fs/nfsd/filecache.h b/fs/nfsd/filecache.h
index 28145f1..8e8c0c4 100644 (file)
--- a/fs/nfsd/filecache.h
+++ b/fs/nfsd/filecache.h
@@ -39,7 +39,7 @@ struct nfsd_file {
 #define NFSD_FILE_PENDING      (1)
 #define NFSD_FILE_REFERENCED   (2)
        unsigned long           nf_flags;
-       struct inode            *nf_inode;
+       struct inode            *nf_inode;      /* don't deref */
        refcount_t              nf_ref;
        unsigned char           nf_may;
        struct nfsd_file_mark   *nf_mark;

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 9d1a3e1..994bd11 100644 (file)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2564,7 +2564,7 @@ static void nfs4_show_fname(struct seq_file *s, struct nfsd_file *f)
 
 static void nfs4_show_superblock(struct seq_file *s, struct nfsd_file *f)
 {
-       struct inode *inode = f->nf_inode;
+       struct inode *inode = file_inode(f->nf_file);
 
        seq_printf(s, "superblock: \"%02x:%02x:%ld\"",
                                        MAJOR(inode->i_sb->s_dev),