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NFS: Add an iocounter wait function for async RPC tasks

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By sleeping on a new NFS Unlock-On-Close waitqueue, rpc tasks may wait for
a lock context's iocounter to reach zero.  The rpc waitqueue is only woken
when the open_context has the NFS_CONTEXT_UNLOCK flag set in order to
mitigate spurious wake-ups for any iocounter reaching zero.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Benjamin Coddington 2017-04-11 12:50:10 -04:00 committed by Trond Myklebust
parent 50f2112cf7
commit 7d6ddf88c4
5 changed files with 37 additions and 1 deletions
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1
fs/nfs/client.c
View File

@ -218,6 +218,7 @@ static void nfs_cb_idr_remove_locked(struct nfs_client *clp)
static void pnfs_init_server(struct nfs_server *server)
{
rpc_init_wait_queue(&server->roc_rpcwaitq, "pNFS ROC");
rpc_init_wait_queue(&server->uoc_rpcwaitq, "NFS UOC");
}
#else

34
fs/nfs/pagelist.c
View File

@ -102,6 +102,35 @@ nfs_iocounter_wait(struct nfs_lock_context *l_ctx)
TASK_KILLABLE);
}
/**
* nfs_async_iocounter_wait - wait on a rpc_waitqueue for I/O
* to complete
* @task: the rpc_task that should wait
* @l_ctx: nfs_lock_context with io_counter to check
*
* Returns true if there is outstanding I/O to wait on and the
* task has been put to sleep.
*/
bool
nfs_async_iocounter_wait(struct rpc_task *task, struct nfs_lock_context *l_ctx)
{
struct inode *inode = d_inode(l_ctx->open_context->dentry);
bool ret = false;
if (atomic_read(&l_ctx->io_count) > 0) {
rpc_sleep_on(&NFS_SERVER(inode)->uoc_rpcwaitq, task, NULL);
ret = true;
}
if (atomic_read(&l_ctx->io_count) == 0) {
rpc_wake_up_queued_task(&NFS_SERVER(inode)->uoc_rpcwaitq, task);
ret = false;
}
return ret;
}
EXPORT_SYMBOL_GPL(nfs_async_iocounter_wait);
/*
* nfs_page_group_lock - lock the head of the page group
* @req - request in group that is to be locked
@ -385,8 +414,11 @@ static void nfs_clear_request(struct nfs_page *req)
req->wb_page = NULL;
}
if (l_ctx != NULL) {
if (atomic_dec_and_test(&l_ctx->io_count))
if (atomic_dec_and_test(&l_ctx->io_count)) {
wake_up_atomic_t(&l_ctx->io_count);
if (test_bit(NFS_CONTEXT_UNLOCK, &ctx->flags))
rpc_wake_up(&NFS_SERVER(d_inode(ctx->dentry))->uoc_rpcwaitq);
}
nfs_put_lock_context(l_ctx);
req->wb_lock_context = NULL;
}

1
include/linux/nfs_fs.h
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@ -76,6 +76,7 @@ struct nfs_open_context {
#define NFS_CONTEXT_ERROR_WRITE (0)
#define NFS_CONTEXT_RESEND_WRITES (1)
#define NFS_CONTEXT_BAD (2)
#define NFS_CONTEXT_UNLOCK (3)
int error;
struct list_head list;

1
include/linux/nfs_fs_sb.h
View File

@ -222,6 +222,7 @@ struct nfs_server {
u32 mountd_version;
unsigned short mountd_port;
unsigned short mountd_protocol;
struct rpc_wait_queue uoc_rpcwaitq;
};
/* Server capabilities */

1
include/linux/nfs_page.h
View File

@ -141,6 +141,7 @@ extern int nfs_page_group_lock(struct nfs_page *, bool);
extern void nfs_page_group_lock_wait(struct nfs_page *);
extern void nfs_page_group_unlock(struct nfs_page *);
extern bool nfs_page_group_sync_on_bit(struct nfs_page *, unsigned int);
extern bool nfs_async_iocounter_wait(struct rpc_task *, struct nfs_lock_context *);
/*
* Lock the page of an asynchronous request