knfsd: nfsd4: don't delegate files that have had conflicts

One more incremental delegation policy improvement: don't give out a
delegation on a file if conflicting access has previously required that a
delegation be revoked on that file.  (In practice we'll forget about the
conflict when the struct nfs4_file is removed on close, so this is of limited
use for now, though it should at least solve a temporary problem with
self-conflicts on write opens from the same client.)

Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 5 insertions, 0 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 46249886ea86..e4a4c87ec8c6 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -195,6 +195,8 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_stateid *stp, struct svc_f
         struct nfs4_callback *cb = &stp->st_stateowner->so_client->cl_callback;
 
         dprintk("NFSD alloc_init_deleg\n");
+        if (fp->fi_had_conflict)
+                return NULL;
         if (num_delegations > max_delegations)
                 return NULL;
         dp = kmem_cache_alloc(deleg_slab, GFP_KERNEL);
@@ -1002,6 +1004,7 @@ alloc_init_file(struct inode *ino)
                 list_add(&fp->fi_hash, &file_hashtbl[hashval]);
                 fp->fi_inode = igrab(ino);
                 fp->fi_id = current_fileid++;
+                fp->fi_had_conflict = false;
                 return fp;
         }
         return NULL;
@@ -1328,6 +1331,7 @@ do_recall(void *__dp)
 {
         struct nfs4_delegation *dp = __dp;
 
+        dp->dl_file->fi_had_conflict = true;
         nfsd4_cb_recall(dp);
         return 0;
 }
diff --git a/include/linux/nfsd/state.h b/include/linux/nfsd/state.h
index 732de9cad4a8..db348f749376 100644
--- a/include/linux/nfsd/state.h
+++ b/include/linux/nfsd/state.h
@@ -224,6 +224,7 @@ struct nfs4_file {
         struct inode            *fi_inode;
         u32                     fi_id;      /* used with stateowner->so_id 
                                              * for stateid_hashtbl hash */
+        bool                    fi_had_conflict;
 };
 
 /*