NFS: O_DIRECT async IO may lose context

The struct nfs_direct_req currently keeps a pointer to the file descriptor
without referencing it. This may cause problems if the parent process is
killed.

The nfs_open_context should normally have all the information that we're
currently using the filp for, and unlike fput(), is safe to release from
an rpciod process context.

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

1 files changed, 12 insertions, 18 deletions

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index f0f2053c7a61..e6585b9ff45a 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -71,7 +71,7 @@ struct nfs_direct_req {
         /* I/O parameters */
         struct list_head        list,           /* nfs_read/write_data structs */
                                 rewrite_list;   /* saved nfs_write_data structs */
-        struct file *           filp;           /* file descriptor */
+        struct nfs_open_context *ctx;           /* file open context info */
         struct kiocb *          iocb;           /* controlling i/o request */
         wait_queue_head_t       wait;           /* wait for i/o completion */
         struct inode *          inode;          /* target file of i/o */
@@ -176,6 +176,7 @@ static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
         INIT_LIST_HEAD(&dreq->list);
         INIT_LIST_HEAD(&dreq->rewrite_list);
         dreq->iocb = NULL;
+        dreq->ctx = NULL;
         spin_lock_init(&dreq->lock);
         dreq->outstanding = 0;
         dreq->count = 0;
@@ -188,6 +189,9 @@ static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
 static void nfs_direct_req_release(struct kref *kref)
 {
         struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
+
+        if (dreq->ctx != NULL)
+                put_nfs_open_context(dreq->ctx);
         kmem_cache_free(nfs_direct_cachep, dreq);
 }
 
@@ -235,7 +239,6 @@ static void nfs_direct_complete(struct nfs_direct_req *dreq)
         } else
                 wake_up(&dreq->wait);
 
-        iput(dreq->inode);
         kref_put(&dreq->kref, nfs_direct_req_release);
 }
 
@@ -317,10 +320,8 @@ static const struct rpc_call_ops nfs_read_direct_ops = {
  */
 static void nfs_direct_read_schedule(struct nfs_direct_req *dreq)
 {
-        struct file *file = dreq->filp;
-        struct inode *inode = file->f_mapping->host;
-        struct nfs_open_context *ctx = (struct nfs_open_context *)
-                                                        file->private_data;
+        struct nfs_open_context *ctx = dreq->ctx;
+        struct inode *inode = ctx->dentry->d_inode;
         struct list_head *list = &dreq->list;
         struct page **pages = dreq->pages;
         size_t count = dreq->user_count;
@@ -396,9 +397,8 @@ static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size
         dreq->pos = pos;
         dreq->pages = pages;
         dreq->npages = nr_pages;
-        igrab(inode);
         dreq->inode = inode;
-        dreq->filp = iocb->ki_filp;
+        dreq->ctx = get_nfs_open_context((struct nfs_open_context *)iocb->ki_filp->private_data);
         if (!is_sync_kiocb(iocb))
                 dreq->iocb = iocb;
 
@@ -462,14 +462,11 @@ static const struct rpc_call_ops nfs_commit_direct_ops = {
 
 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
 {
-        struct file *file = dreq->filp;
-        struct nfs_open_context *ctx = (struct nfs_open_context *)
-                                                        file->private_data;
         struct nfs_write_data *data = dreq->commit_data;
         struct rpc_task *task = &data->task;
 
         data->inode = dreq->inode;
-        data->cred = ctx->cred;
+        data->cred = dreq->ctx->cred;
 
         data->args.fh = NFS_FH(data->inode);
         data->args.offset = dreq->pos;
@@ -641,10 +638,8 @@ static const struct rpc_call_ops nfs_write_direct_ops = {
  */
 static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, int sync)
 {
-        struct file *file = dreq->filp;
-        struct inode *inode = file->f_mapping->host;
-        struct nfs_open_context *ctx = (struct nfs_open_context *)
-                                                        file->private_data;
+        struct nfs_open_context *ctx = dreq->ctx;
+        struct inode *inode = ctx->dentry->d_inode;
         struct list_head *list = &dreq->list;
         struct page **pages = dreq->pages;
         size_t count = dreq->user_count;
@@ -725,9 +720,8 @@ static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, siz
         dreq->pos = pos;
         dreq->pages = pages;
         dreq->npages = nr_pages;
-        igrab(inode);
         dreq->inode = inode;
-        dreq->filp = iocb->ki_filp;
+        dreq->ctx = get_nfs_open_context((struct nfs_open_context *)iocb->ki_filp->private_data);
         if (!is_sync_kiocb(iocb))
                 dreq->iocb = iocb;