NFSv4: Ensure that we track the NFSv4 lock state in read/write requests.

This patch fixes bugzilla entry 14501:
  https://bugzilla.kernel.org/show_bug.cgi?id=14501

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 66 insertions, 4 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 099b3518feea..ec7a8f96a2c2 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -530,6 +530,68 @@ out:
         return err;
 }
 
+static void nfs_init_lock_context(struct nfs_lock_context *l_ctx)
+{
+        atomic_set(&l_ctx->count, 1);
+        l_ctx->lockowner = current->files;
+        l_ctx->pid = current->tgid;
+        INIT_LIST_HEAD(&l_ctx->list);
+}
+
+static struct nfs_lock_context *__nfs_find_lock_context(struct nfs_open_context *ctx)
+{
+        struct nfs_lock_context *pos;
+
+        list_for_each_entry(pos, &ctx->lock_context.list, list) {
+                if (pos->lockowner != current->files)
+                        continue;
+                if (pos->pid != current->tgid)
+                        continue;
+                atomic_inc(&pos->count);
+                return pos;
+        }
+        return NULL;
+}
+
+struct nfs_lock_context *nfs_get_lock_context(struct nfs_open_context *ctx)
+{
+        struct nfs_lock_context *res, *new = NULL;
+        struct inode *inode = ctx->path.dentry->d_inode;
+
+        spin_lock(&inode->i_lock);
+        res = __nfs_find_lock_context(ctx);
+        if (res == NULL) {
+                spin_unlock(&inode->i_lock);
+                new = kmalloc(sizeof(*new), GFP_KERNEL);
+                if (new == NULL)
+                        return NULL;
+                nfs_init_lock_context(new);
+                spin_lock(&inode->i_lock);
+                res = __nfs_find_lock_context(ctx);
+                if (res == NULL) {
+                        list_add_tail(&new->list, &ctx->lock_context.list);
+                        new->open_context = ctx;
+                        res = new;
+                        new = NULL;
+                }
+        }
+        spin_unlock(&inode->i_lock);
+        kfree(new);
+        return res;
+}
+
+void nfs_put_lock_context(struct nfs_lock_context *l_ctx)
+{
+        struct nfs_open_context *ctx = l_ctx->open_context;
+        struct inode *inode = ctx->path.dentry->d_inode;
+
+        if (!atomic_dec_and_lock(&l_ctx->count, &inode->i_lock))
+                return;
+        list_del(&l_ctx->list);
+        spin_unlock(&inode->i_lock);
+        kfree(l_ctx);
+}
+
 /**
  * nfs_close_context - Common close_context() routine NFSv2/v3
  * @ctx: pointer to context
@@ -566,11 +628,11 @@ static struct nfs_open_context *alloc_nfs_open_context(struct path *path, struct
                 path_get(&ctx->path);
                 ctx->cred = get_rpccred(cred);
                 ctx->state = NULL;
-                ctx->lockowner = current->files;
                 ctx->flags = 0;
                 ctx->error = 0;
                 ctx->dir_cookie = 0;
-                atomic_set(&ctx->count, 1);
+                nfs_init_lock_context(&ctx->lock_context);
+                ctx->lock_context.open_context = ctx;
         }
         return ctx;
 }
@@ -578,7 +640,7 @@ static struct nfs_open_context *alloc_nfs_open_context(struct path *path, struct
 struct nfs_open_context *get_nfs_open_context(struct nfs_open_context *ctx)
 {
         if (ctx != NULL)
-                atomic_inc(&ctx->count);
+                atomic_inc(&ctx->lock_context.count);
         return ctx;
 }
 
@@ -586,7 +648,7 @@ static void __put_nfs_open_context(struct nfs_open_context *ctx, int is_sync)
 {
         struct inode *inode = ctx->path.dentry->d_inode;
 
-        if (!atomic_dec_and_lock(&ctx->count, &inode->i_lock))
+        if (!atomic_dec_and_lock(&ctx->lock_context.count, &inode->i_lock))
                 return;
         list_del(&ctx->list);
         spin_unlock(&inode->i_lock);