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>
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 737990d..f0f2053 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -69,11 +69,15 @@
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 @@
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 @@
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 @@
* 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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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);