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NFS: "open code" the NFS direct write rescheduler 

An NFSv3/v4 client must reschedule on-the-wire writes if the writes are
UNSTABLE, and the server reboots before the client can complete a
subsequent COMMIT request.

To support direct asynchronous scatter-gather writes, the write
rescheduler in fs/nfs/direct.c must not depend on the I/O parameters
in the controlling nfs_direct_req structure.  iovecs can be somewhat
arbitrarily complex, so there could be an unbounded amount of information
to save for a rarely encountered requirement.

Refactor the direct write rescheduler so it uses information from each
nfs_write_data structure to reschedule writes, instead of caching that
information in the controlling nfs_direct_req structure.

Signed-off-by: Chuck Lever <cel@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Chuck Lever 2006-06-20 12:55:45 -04:00 committed by Trond Myklebust
parent b1c5921c5b
commit fedb595c66
1 changed files with 43 additions and 8 deletions
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51
fs/nfs/direct.c
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@ -94,8 +94,8 @@ struct nfs_direct_req {
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);
static const struct rpc_call_ops nfs_write_direct_ops;
static inline void get_dreq(struct nfs_direct_req *dreq)
{
@ -435,14 +435,51 @@ static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
{
struct list_head *pos;
struct inode *inode = dreq->inode;
struct list_head *p;
struct nfs_write_data *data;
list_splice_init(&dreq->rewrite_list, &dreq->list);
list_for_each(pos, &dreq->list)
get_dreq(dreq);
dreq->count = 0;
get_dreq(dreq);
nfs_direct_write_schedule(dreq, FLUSH_STABLE);
list_for_each(p, &dreq->rewrite_list) {
data = list_entry(p, struct nfs_write_data, pages);
get_dreq(dreq);
/*
* Reset data->res.
*/
nfs_fattr_init(&data->fattr);
data->res.count = data->args.count;
memset(&data->verf, 0, sizeof(data->verf));
/*
* Reuse data->task; data->args should not have changed
* since the original request was sent.
*/
rpc_init_task(&data->task, NFS_CLIENT(inode), RPC_TASK_ASYNC,
&nfs_write_direct_ops, data);
NFS_PROTO(inode)->write_setup(data, FLUSH_STABLE);
data->task.tk_priority = RPC_PRIORITY_NORMAL;
data->task.tk_cookie = (unsigned long) inode;
/*
* We're called via an RPC callback, so BKL is already held.
*/
rpc_execute(&data->task);
dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
data->task.tk_pid,
inode->i_sb->s_id,
(long long)NFS_FILEID(inode),
data->args.count,
(unsigned long long)data->args.offset);
}
if (put_dreq(dreq))
nfs_direct_write_complete(dreq, inode);
}
static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
@ -612,8 +649,6 @@ static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
}
}
}
/* In case we have to resend */
data->args.stable = NFS_FILE_SYNC;
spin_unlock(&dreq->lock);
}