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nfs: Use UNSTABLE + COMMIT for NFS O_DIRECT writes
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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>
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Trond Myklebust authored and Trond Myklebust committed Mar 20, 2006
1 parent e17b1fc commit fad6149
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224 changes: 199 additions & 25 deletions fs/nfs/direct.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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 */

Expand All @@ -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)
Expand Down Expand Up @@ -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;
}
Expand Down Expand Up @@ -299,19 +315,21 @@ 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;
struct nfs_open_context *ctx = (struct nfs_open_context *)
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;
Expand Down Expand Up @@ -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);
Expand All @@ -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;
Expand Down Expand Up @@ -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;
Expand All @@ -440,53 +584,76 @@ 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;
struct nfs_open_context *ctx = (struct nfs_open_context *)
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;
Expand All @@ -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;
Expand All @@ -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;
Expand Down Expand Up @@ -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);
Expand All @@ -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);

Expand Down
1 change: 1 addition & 0 deletions include/linux/nfs_fs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand Down

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