NFS: Fix an O_DIRECT Oops...

We can't call nfs_readdata_release()/nfs_writedata_release() without
first initialising and referencing args.context. Doing so inside
nfs_direct_read_schedule_segment()/nfs_direct_write_schedule_segment()
causes an Oops.

We should rather be calling nfs_readdata_free()/nfs_writedata_free() in
those cases.

Looking at the O_DIRECT code, the "struct nfs_direct_req" is already
referencing the nfs_open_context for us. Since the readdata and writedata
structures carry a reference to that, we can simplify things by getting rid
of the extra nfs_open_context references, so that we can replace all
instances of nfs_readdata_release()/nfs_writedata_release().

Reported-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 16 insertions, 21 deletions

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 489fc01a3204..e4e089a8f294 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -255,7 +255,7 @@ static void nfs_direct_read_release(void *calldata)
 
         if (put_dreq(dreq))
                 nfs_direct_complete(dreq);
-        nfs_readdata_release(calldata);
+        nfs_readdata_free(data);
 }
 
 static const struct rpc_call_ops nfs_read_direct_ops = {
@@ -314,14 +314,14 @@ static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
                                         data->npages, 1, 0, data->pagevec, NULL);
                 up_read(&current->mm->mmap_sem);
                 if (result < 0) {
-                        nfs_readdata_release(data);
+                        nfs_readdata_free(data);
                         break;
                 }
                 if ((unsigned)result < data->npages) {
                         bytes = result * PAGE_SIZE;
                         if (bytes <= pgbase) {
                                 nfs_direct_release_pages(data->pagevec, result);
-                                nfs_readdata_release(data);
+                                nfs_readdata_free(data);
                                 break;
                         }
                         bytes -= pgbase;
@@ -334,7 +334,7 @@ static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
                 data->inode = inode;
                 data->cred = msg.rpc_cred;
                 data->args.fh = NFS_FH(inode);
-                data->args.context = get_nfs_open_context(ctx);
+                data->args.context = ctx;
                 data->args.offset = pos;
                 data->args.pgbase = pgbase;
                 data->args.pages = data->pagevec;
@@ -441,7 +441,7 @@ static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
                 struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
                 list_del(&data->pages);
                 nfs_direct_release_pages(data->pagevec, data->npages);
-                nfs_writedata_release(data);
+                nfs_writedata_free(data);
         }
 }
 
@@ -534,7 +534,7 @@ static void nfs_direct_commit_release(void *calldata)
 
         dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
         nfs_direct_write_complete(dreq, data->inode);
-        nfs_commitdata_release(calldata);
+        nfs_commit_free(data);
 }
 
 static const struct rpc_call_ops nfs_commit_direct_ops = {
@@ -570,7 +570,7 @@ static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
         data->args.fh = NFS_FH(data->inode);
         data->args.offset = 0;
         data->args.count = 0;
-        data->args.context = get_nfs_open_context(dreq->ctx);
+        data->args.context = dreq->ctx;
         data->res.count = 0;
         data->res.fattr = &data->fattr;
         data->res.verf = &data->verf;
@@ -734,14 +734,14 @@ static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
                                         data->npages, 0, 0, data->pagevec, NULL);
                 up_read(&current->mm->mmap_sem);
                 if (result < 0) {
-                        nfs_writedata_release(data);
+                        nfs_writedata_free(data);
                         break;
                 }
                 if ((unsigned)result < data->npages) {
                         bytes = result * PAGE_SIZE;
                         if (bytes <= pgbase) {
                                 nfs_direct_release_pages(data->pagevec, result);
-                                nfs_writedata_release(data);
+                                nfs_writedata_free(data);
                                 break;
                         }
                         bytes -= pgbase;
@@ -756,7 +756,7 @@ static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
                 data->inode = inode;
                 data->cred = msg.rpc_cred;
                 data->args.fh = NFS_FH(inode);
-                data->args.context = get_nfs_open_context(ctx);
+                data->args.context = ctx;
                 data->args.offset = pos;
                 data->args.pgbase = pgbase;
                 data->args.pages = data->pagevec;
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 73ea5e8d66ce..12c9e66d3f1d 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -60,17 +60,15 @@ struct nfs_read_data *nfs_readdata_alloc(unsigned int pagecount)
         return p;
 }
 
-static void nfs_readdata_free(struct nfs_read_data *p)
+void nfs_readdata_free(struct nfs_read_data *p)
 {
         if (p && (p->pagevec != &p->page_array[0]))
                 kfree(p->pagevec);
         mempool_free(p, nfs_rdata_mempool);
 }
 
-void nfs_readdata_release(void *data)
+static void nfs_readdata_release(struct nfs_read_data *rdata)
 {
-        struct nfs_read_data *rdata = data;
-
         put_nfs_open_context(rdata->args.context);
         nfs_readdata_free(rdata);
 }
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 0a0a2ff767c3..a34fae21fe10 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -87,17 +87,15 @@ struct nfs_write_data *nfs_writedata_alloc(unsigned int pagecount)
         return p;
 }
 
-static void nfs_writedata_free(struct nfs_write_data *p)
+void nfs_writedata_free(struct nfs_write_data *p)
 {
         if (p && (p->pagevec != &p->page_array[0]))
                 kfree(p->pagevec);
         mempool_free(p, nfs_wdata_mempool);
 }
 
-void nfs_writedata_release(void *data)
+static void nfs_writedata_release(struct nfs_write_data *wdata)
 {
-        struct nfs_write_data *wdata = data;
-
         put_nfs_open_context(wdata->args.context);
         nfs_writedata_free(wdata);
 }
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index fdffb413b192..f6b90240dd41 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -473,7 +473,6 @@ extern int  nfs_writepages(struct address_space *, struct writeback_control *);
 extern int  nfs_flush_incompatible(struct file *file, struct page *page);
 extern int  nfs_updatepage(struct file *, struct page *, unsigned int, unsigned int);
 extern int nfs_writeback_done(struct rpc_task *, struct nfs_write_data *);
-extern void nfs_writedata_release(void *);
 
 /*
  * Try to write back everything synchronously (but check the
@@ -488,7 +487,6 @@ extern int nfs_wb_page_cancel(struct inode *inode, struct page* page);
 extern int  nfs_commit_inode(struct inode *, int);
 extern struct nfs_write_data *nfs_commitdata_alloc(void);
 extern void nfs_commit_free(struct nfs_write_data *wdata);
-extern void nfs_commitdata_release(void *wdata);
 #else
 static inline int
 nfs_commit_inode(struct inode *inode, int how)
@@ -507,6 +505,7 @@ nfs_have_writebacks(struct inode *inode)
  * Allocate nfs_write_data structures
  */
 extern struct nfs_write_data *nfs_writedata_alloc(unsigned int npages);
+extern void nfs_writedata_free(struct nfs_write_data *);
 
 /*
  * linux/fs/nfs/read.c
@@ -515,7 +514,6 @@ extern int  nfs_readpage(struct file *, struct page *);
 extern int  nfs_readpages(struct file *, struct address_space *,
                 struct list_head *, unsigned);
 extern int  nfs_readpage_result(struct rpc_task *, struct nfs_read_data *);
-extern void nfs_readdata_release(void *data);
 extern int  nfs_readpage_async(struct nfs_open_context *, struct inode *,
                                struct page *);
 
@@ -523,6 +521,7 @@ extern int  nfs_readpage_async(struct nfs_open_context *, struct inode *,
  * Allocate nfs_read_data structures
  */
 extern struct nfs_read_data *nfs_readdata_alloc(unsigned int npages);
+extern void nfs_readdata_free(struct nfs_read_data *);
 
 /*
  * linux/fs/nfs3proc.c