nfs: Use UNSTABLE + COMMIT for NFS O_DIRECT writes

Currently NFS O_DIRECT writes use FILE_SYNC so that a COMMIT is not
necessary.  This simplifies the internal logic, but this could be a
difficult workload for some servers.

Instead, let's send UNSTABLE writes, and after they all complete, send a
COMMIT for the dirty range.  After the COMMIT returns successfully, then do
the wake_up or fire off aio_complete().

Test plan:
Async direct I/O tests against Solaris (or any server that requires
committed unstable writes).  Reboot server during test.

Based on an earlier patch by Chuck Lever <cel@netapp.com>

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

2 files changed, 200 insertions, 25 deletions

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 737990dd4dfe..f0f2053c7a61 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -69,11 +69,15 @@ struct nfs_direct_req {
         struct kref             kref;           /* release manager */
 
         /* I/O parameters */
-        struct list_head        list;           /* nfs_read/write_data structs */
+        struct list_head        list,           /* nfs_read/write_data structs */
+                                rewrite_list;   /* saved nfs_write_data structs */
         struct file *           filp;           /* file descriptor */
         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 */
+        unsigned long           user_addr;      /* location of user's buffer */
+        size_t                  user_count;     /* total bytes to move */
+        loff_t                  pos;            /* starting offset in file */
         struct page **          pages;          /* pages in our buffer */
         unsigned int            npages;         /* count of pages */
 
@@ -82,8 +86,18 @@ struct nfs_direct_req {
         int                     outstanding;    /* i/os we're waiting for */
         ssize_t                 count,          /* bytes actually processed */
                                 error;          /* any reported error */
+
+        /* commit state */
+        struct nfs_write_data * commit_data;    /* special write_data for commits */
+        int                     flags;
+#define NFS_ODIRECT_DO_COMMIT           (1)     /* an unstable reply was received */
+#define NFS_ODIRECT_RESCHED_WRITES      (2)     /* write verification failed */
+        struct nfs_writeverf    verf;           /* unstable write verifier */
 };
 
+static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, int sync);
+static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
+
 /**
  * nfs_direct_IO - NFS address space operation for direct I/O
  * @rw: direction (read or write)
@@ -160,11 +174,13 @@ static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
         kref_init(&dreq->kref);
         init_waitqueue_head(&dreq->wait);
         INIT_LIST_HEAD(&dreq->list);
+        INIT_LIST_HEAD(&dreq->rewrite_list);
         dreq->iocb = NULL;
         spin_lock_init(&dreq->lock);
         dreq->outstanding = 0;
         dreq->count = 0;
         dreq->error = 0;
+        dreq->flags = 0;
 
         return dreq;
 }
@@ -299,7 +315,7 @@ static const struct rpc_call_ops nfs_read_direct_ops = {
  * For each nfs_read_data struct that was allocated on the list, dispatch
  * an NFS READ operation
  */
-static void nfs_direct_read_schedule(struct nfs_direct_req *dreq, unsigned long user_addr, size_t count, loff_t pos)
+static void nfs_direct_read_schedule(struct nfs_direct_req *dreq)
 {
         struct file *file = dreq->filp;
         struct inode *inode = file->f_mapping->host;
@@ -307,11 +323,13 @@ static void nfs_direct_read_schedule(struct nfs_direct_req *dreq, unsigned long
                                                         file->private_data;
         struct list_head *list = &dreq->list;
         struct page **pages = dreq->pages;
+        size_t count = dreq->user_count;
+        loff_t pos = dreq->pos;
         size_t rsize = NFS_SERVER(inode)->rsize;
         unsigned int curpage, pgbase;
 
         curpage = 0;
-        pgbase = user_addr & ~PAGE_MASK;
+        pgbase = dreq->user_addr & ~PAGE_MASK;
         do {
                 struct nfs_read_data *data;
                 size_t bytes;
@@ -373,6 +391,9 @@ static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size
         if (!dreq)
                 return -ENOMEM;
 
+        dreq->user_addr = user_addr;
+        dreq->user_count = count;
+        dreq->pos = pos;
         dreq->pages = pages;
         dreq->npages = nr_pages;
         igrab(inode);
@@ -383,13 +404,137 @@ static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size
 
         nfs_add_stats(inode, NFSIOS_DIRECTREADBYTES, count);
         rpc_clnt_sigmask(clnt, &oldset);
-        nfs_direct_read_schedule(dreq, user_addr, count, pos);
+        nfs_direct_read_schedule(dreq);
         result = nfs_direct_wait(dreq);
         rpc_clnt_sigunmask(clnt, &oldset);
 
         return result;
 }
 
+static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
+{
+        list_splice_init(&dreq->rewrite_list, &dreq->list);
+        while (!list_empty(&dreq->list)) {
+                struct nfs_write_data *data = list_entry(dreq->list.next, struct nfs_write_data, pages);
+                list_del(&data->pages);
+                nfs_writedata_release(data);
+        }
+}
+
+#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
+static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
+{
+        struct list_head *pos;
+
+        list_splice_init(&dreq->rewrite_list, &dreq->list);
+        list_for_each(pos, &dreq->list)
+                dreq->outstanding++;
+        dreq->count = 0;
+
+        nfs_direct_write_schedule(dreq, FLUSH_STABLE);
+}
+
+static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
+{
+        struct nfs_write_data *data = calldata;
+        struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
+
+        /* Call the NFS version-specific code */
+        if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
+                return;
+        if (unlikely(task->tk_status < 0)) {
+                dreq->error = task->tk_status;
+                dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+        }
+        if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
+                dprintk("NFS: %5u commit verify failed\n", task->tk_pid);
+                dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+        }
+
+        dprintk("NFS: %5u commit returned %d\n", task->tk_pid, task->tk_status);
+        nfs_direct_write_complete(dreq, data->inode);
+}
+
+static const struct rpc_call_ops nfs_commit_direct_ops = {
+        .rpc_call_done = nfs_direct_commit_result,
+        .rpc_release = nfs_commit_release,
+};
+
+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->args.fh = NFS_FH(data->inode);
+        data->args.offset = dreq->pos;
+        data->args.count = dreq->user_count;
+        data->res.count = 0;
+        data->res.fattr = &data->fattr;
+        data->res.verf = &data->verf;
+
+        rpc_init_task(&data->task, NFS_CLIENT(dreq->inode), RPC_TASK_ASYNC,
+                                &nfs_commit_direct_ops, data);
+        NFS_PROTO(data->inode)->commit_setup(data, 0);
+
+        data->task.tk_priority = RPC_PRIORITY_NORMAL;
+        data->task.tk_cookie = (unsigned long)data->inode;
+        /* Note: task.tk_ops->rpc_release will free dreq->commit_data */
+        dreq->commit_data = NULL;
+
+        dprintk("NFS: %5u initiated commit call\n", task->tk_pid);
+
+        lock_kernel();
+        rpc_execute(&data->task);
+        unlock_kernel();
+}
+
+static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
+{
+        int flags = dreq->flags;
+
+        dreq->flags = 0;
+        switch (flags) {
+                case NFS_ODIRECT_DO_COMMIT:
+                        nfs_direct_commit_schedule(dreq);
+                        break;
+                case NFS_ODIRECT_RESCHED_WRITES:
+                        nfs_direct_write_reschedule(dreq);
+                        break;
+                default:
+                        nfs_end_data_update(inode);
+                        if (dreq->commit_data != NULL)
+                                nfs_commit_free(dreq->commit_data);
+                        nfs_direct_free_writedata(dreq);
+                        nfs_direct_complete(dreq);
+        }
+}
+
+static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
+{
+        dreq->commit_data = nfs_commit_alloc(0);
+        if (dreq->commit_data != NULL)
+                dreq->commit_data->req = (struct nfs_page *) dreq;
+}
+#else
+static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
+{
+        dreq->commit_data = NULL;
+}
+
+static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
+{
+        nfs_end_data_update(inode);
+        nfs_direct_free_writedata(dreq);
+        nfs_direct_complete(dreq);
+}
+#endif
+
 static struct nfs_direct_req *nfs_direct_write_alloc(size_t nbytes, size_t wsize)
 {
         struct list_head *list;
@@ -424,14 +569,13 @@ static struct nfs_direct_req *nfs_direct_write_alloc(size_t nbytes, size_t wsize
                         break;
                 nbytes -= wsize;
         }
+
+        nfs_alloc_commit_data(dreq);
+
         kref_get(&dreq->kref);
         return dreq;
 }
 
-/*
- * NB: Return the value of the first error return code.  Subsequent
- *     errors after the first one are ignored.
- */
 static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
 {
         struct nfs_write_data *data = calldata;
@@ -440,41 +584,62 @@ static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
 
         if (nfs_writeback_done(task, data) != 0)
                 return;
-        /* If the server fell back to an UNSTABLE write, it's an error. */
-        if (unlikely(data->res.verf->committed != NFS_FILE_SYNC))
-                status = -EIO;
 
         spin_lock(&dreq->lock);
 
         if (likely(status >= 0))
                 dreq->count += data->res.count;
         else
-                dreq->error = status;
+                dreq->error = task->tk_status;
 
+        if (data->res.verf->committed != NFS_FILE_SYNC) {
+                switch (dreq->flags) {
+                        case 0:
+                                memcpy(&dreq->verf, &data->verf, sizeof(dreq->verf));
+                                dreq->flags = NFS_ODIRECT_DO_COMMIT;
+                                break;
+                        case NFS_ODIRECT_DO_COMMIT:
+                                if (memcmp(&dreq->verf, &data->verf, sizeof(dreq->verf))) {
+                                        dprintk("NFS: %5u write verify failed\n", task->tk_pid);
+                                        dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+                                }
+                }
+        }
+        /* In case we have to resend */
+        data->args.stable = NFS_FILE_SYNC;
+
+        spin_unlock(&dreq->lock);
+}
+
+/*
+ * NB: Return the value of the first error return code.  Subsequent
+ *     errors after the first one are ignored.
+ */
+static void nfs_direct_write_release(void *calldata)
+{
+        struct nfs_write_data *data = calldata;
+        struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
+
+        spin_lock(&dreq->lock);
         if (--dreq->outstanding) {
                 spin_unlock(&dreq->lock);
                 return;
         }
-
         spin_unlock(&dreq->lock);
 
-        nfs_end_data_update(data->inode);
-        nfs_direct_complete(dreq);
+        nfs_direct_write_complete(dreq, data->inode);
 }
 
 static const struct rpc_call_ops nfs_write_direct_ops = {
         .rpc_call_done = nfs_direct_write_result,
-        .rpc_release = nfs_writedata_release,
+        .rpc_release = nfs_direct_write_release,
 };
 
 /*
  * For each nfs_write_data struct that was allocated on the list, dispatch
  * an NFS WRITE operation
- *
- * XXX: For now, support only FILE_SYNC writes.  Later we may add
- *      support for UNSTABLE + COMMIT.
  */
-static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned long user_addr, size_t count, loff_t pos)
+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;
@@ -482,11 +647,13 @@ static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned long
                                                         file->private_data;
         struct list_head *list = &dreq->list;
         struct page **pages = dreq->pages;
+        size_t count = dreq->user_count;
+        loff_t pos = dreq->pos;
         size_t wsize = NFS_SERVER(inode)->wsize;
         unsigned int curpage, pgbase;
 
         curpage = 0;
-        pgbase = user_addr & ~PAGE_MASK;
+        pgbase = dreq->user_addr & ~PAGE_MASK;
         do {
                 struct nfs_write_data *data;
                 size_t bytes;
@@ -496,7 +663,7 @@ static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned long
                         bytes = count;
 
                 data = list_entry(list->next, struct nfs_write_data, pages);
-                list_del_init(&data->pages);
+                list_move_tail(&data->pages, &dreq->rewrite_list);
 
                 data->inode = inode;
                 data->cred = ctx->cred;
@@ -512,7 +679,7 @@ static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned long
 
                 rpc_init_task(&data->task, NFS_CLIENT(inode), RPC_TASK_ASYNC,
                                 &nfs_write_direct_ops, data);
-                NFS_PROTO(inode)->write_setup(data, FLUSH_STABLE);
+                NFS_PROTO(inode)->write_setup(data, sync);
 
                 data->task.tk_priority = RPC_PRIORITY_NORMAL;
                 data->task.tk_cookie = (unsigned long) inode;
@@ -544,11 +711,18 @@ static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, siz
         struct inode *inode = iocb->ki_filp->f_mapping->host;
         struct rpc_clnt *clnt = NFS_CLIENT(inode);
         struct nfs_direct_req *dreq;
+        size_t wsize = NFS_SERVER(inode)->wsize;
+        int sync = 0;
 
-        dreq = nfs_direct_write_alloc(count, NFS_SERVER(inode)->wsize);
+        dreq = nfs_direct_write_alloc(count, wsize);
         if (!dreq)
                 return -ENOMEM;
+        if (dreq->commit_data == NULL || count < wsize)
+                sync = FLUSH_STABLE;
 
+        dreq->user_addr = user_addr;
+        dreq->user_count = count;
+        dreq->pos = pos;
         dreq->pages = pages;
         dreq->npages = nr_pages;
         igrab(inode);
@@ -562,7 +736,7 @@ static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, siz
         nfs_begin_data_update(inode);
 
         rpc_clnt_sigmask(clnt, &oldset);
-        nfs_direct_write_schedule(dreq, user_addr, count, pos);
+        nfs_direct_write_schedule(dreq, sync);
         result = nfs_direct_wait(dreq);
         rpc_clnt_sigunmask(clnt, &oldset);
 
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 423f202b881c..9f84c8a5ea43 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -422,6 +422,7 @@ void nfs_commit_free(struct nfs_write_data *p);
 extern int  nfs_sync_inode(struct inode *, unsigned long, unsigned int, int);
 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 extern int  nfs_commit_inode(struct inode *, int);
+extern void nfs_commit_release(void *wdata);
 #else
 static inline int
 nfs_commit_inode(struct inode *inode, int how)