![Chuck Lever](/assets/img/avatar_default.png)
The tk_pid field is an unsigned short. The proper print format specifier for that type is %5u, not %4d. Also clean up some miscellaneous print formatting nits. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
863 lines
23 KiB
C
863 lines
23 KiB
C
/*
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* linux/fs/nfs/direct.c
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*
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* Copyright (C) 2003 by Chuck Lever <cel@netapp.com>
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*
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* High-performance uncached I/O for the Linux NFS client
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*
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* There are important applications whose performance or correctness
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* depends on uncached access to file data. Database clusters
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* (multiple copies of the same instance running on separate hosts)
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* implement their own cache coherency protocol that subsumes file
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* system cache protocols. Applications that process datasets
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* considerably larger than the client's memory do not always benefit
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* from a local cache. A streaming video server, for instance, has no
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* need to cache the contents of a file.
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*
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* When an application requests uncached I/O, all read and write requests
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* are made directly to the server; data stored or fetched via these
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* requests is not cached in the Linux page cache. The client does not
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* correct unaligned requests from applications. All requested bytes are
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* held on permanent storage before a direct write system call returns to
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* an application.
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*
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* Solaris implements an uncached I/O facility called directio() that
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* is used for backups and sequential I/O to very large files. Solaris
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* also supports uncaching whole NFS partitions with "-o forcedirectio,"
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* an undocumented mount option.
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*
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* Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with
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* help from Andrew Morton.
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*
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* 18 Dec 2001 Initial implementation for 2.4 --cel
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* 08 Jul 2002 Version for 2.4.19, with bug fixes --trondmy
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* 08 Jun 2003 Port to 2.5 APIs --cel
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* 31 Mar 2004 Handle direct I/O without VFS support --cel
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* 15 Sep 2004 Parallel async reads --cel
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* 04 May 2005 support O_DIRECT with aio --cel
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*
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*/
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/smp_lock.h>
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#include <linux/file.h>
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#include <linux/pagemap.h>
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#include <linux/kref.h>
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#include <linux/nfs_fs.h>
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#include <linux/nfs_page.h>
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#include <linux/sunrpc/clnt.h>
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#include <asm/system.h>
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#include <asm/uaccess.h>
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#include <asm/atomic.h>
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#include "iostat.h"
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#define NFSDBG_FACILITY NFSDBG_VFS
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static struct kmem_cache *nfs_direct_cachep;
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/*
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* This represents a set of asynchronous requests that we're waiting on
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*/
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struct nfs_direct_req {
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struct kref kref; /* release manager */
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/* I/O parameters */
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struct nfs_open_context *ctx; /* file open context info */
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struct kiocb * iocb; /* controlling i/o request */
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struct inode * inode; /* target file of i/o */
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/* completion state */
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atomic_t io_count; /* i/os we're waiting for */
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spinlock_t lock; /* protect completion state */
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ssize_t count, /* bytes actually processed */
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error; /* any reported error */
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struct completion completion; /* wait for i/o completion */
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/* commit state */
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struct list_head rewrite_list; /* saved nfs_write_data structs */
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struct nfs_write_data * commit_data; /* special write_data for commits */
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int flags;
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#define NFS_ODIRECT_DO_COMMIT (1) /* an unstable reply was received */
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#define NFS_ODIRECT_RESCHED_WRITES (2) /* write verification failed */
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struct nfs_writeverf verf; /* unstable write verifier */
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};
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static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
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static const struct rpc_call_ops nfs_write_direct_ops;
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static inline void get_dreq(struct nfs_direct_req *dreq)
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{
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atomic_inc(&dreq->io_count);
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}
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static inline int put_dreq(struct nfs_direct_req *dreq)
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{
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return atomic_dec_and_test(&dreq->io_count);
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}
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/**
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* nfs_direct_IO - NFS address space operation for direct I/O
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* @rw: direction (read or write)
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* @iocb: target I/O control block
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* @iov: array of vectors that define I/O buffer
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* @pos: offset in file to begin the operation
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* @nr_segs: size of iovec array
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*
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* The presence of this routine in the address space ops vector means
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* the NFS client supports direct I/O. However, we shunt off direct
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* read and write requests before the VFS gets them, so this method
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* should never be called.
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*/
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ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
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{
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dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
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iocb->ki_filp->f_path.dentry->d_name.name,
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(long long) pos, nr_segs);
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return -EINVAL;
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}
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static void nfs_direct_dirty_pages(struct page **pages, int npages)
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{
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int i;
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for (i = 0; i < npages; i++) {
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struct page *page = pages[i];
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if (!PageCompound(page))
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set_page_dirty_lock(page);
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}
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}
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static void nfs_direct_release_pages(struct page **pages, int npages)
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{
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int i;
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for (i = 0; i < npages; i++)
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page_cache_release(pages[i]);
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}
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static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
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{
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struct nfs_direct_req *dreq;
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dreq = kmem_cache_alloc(nfs_direct_cachep, GFP_KERNEL);
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if (!dreq)
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return NULL;
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kref_init(&dreq->kref);
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kref_get(&dreq->kref);
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init_completion(&dreq->completion);
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INIT_LIST_HEAD(&dreq->rewrite_list);
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dreq->iocb = NULL;
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dreq->ctx = NULL;
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spin_lock_init(&dreq->lock);
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atomic_set(&dreq->io_count, 0);
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dreq->count = 0;
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dreq->error = 0;
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dreq->flags = 0;
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return dreq;
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}
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static void nfs_direct_req_release(struct kref *kref)
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{
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struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
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if (dreq->ctx != NULL)
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put_nfs_open_context(dreq->ctx);
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kmem_cache_free(nfs_direct_cachep, dreq);
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}
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/*
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* Collects and returns the final error value/byte-count.
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*/
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static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
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{
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ssize_t result = -EIOCBQUEUED;
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/* Async requests don't wait here */
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if (dreq->iocb)
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goto out;
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result = wait_for_completion_interruptible(&dreq->completion);
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if (!result)
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result = dreq->error;
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if (!result)
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result = dreq->count;
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out:
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kref_put(&dreq->kref, nfs_direct_req_release);
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return (ssize_t) result;
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}
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/*
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* Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
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* the iocb is still valid here if this is a synchronous request.
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*/
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static void nfs_direct_complete(struct nfs_direct_req *dreq)
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{
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if (dreq->iocb) {
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long res = (long) dreq->error;
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if (!res)
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res = (long) dreq->count;
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aio_complete(dreq->iocb, res, 0);
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}
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complete_all(&dreq->completion);
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kref_put(&dreq->kref, nfs_direct_req_release);
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}
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/*
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* We must hold a reference to all the pages in this direct read request
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* until the RPCs complete. This could be long *after* we are woken up in
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* nfs_direct_wait (for instance, if someone hits ^C on a slow server).
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*/
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static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
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{
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struct nfs_read_data *data = calldata;
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struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
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if (nfs_readpage_result(task, data) != 0)
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return;
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nfs_direct_dirty_pages(data->pagevec, data->npages);
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nfs_direct_release_pages(data->pagevec, data->npages);
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spin_lock(&dreq->lock);
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if (likely(task->tk_status >= 0))
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dreq->count += data->res.count;
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else
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dreq->error = task->tk_status;
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spin_unlock(&dreq->lock);
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if (put_dreq(dreq))
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nfs_direct_complete(dreq);
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}
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static const struct rpc_call_ops nfs_read_direct_ops = {
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.rpc_call_done = nfs_direct_read_result,
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.rpc_release = nfs_readdata_release,
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};
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/*
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* For each rsize'd chunk of the user's buffer, dispatch an NFS READ
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* operation. If nfs_readdata_alloc() or get_user_pages() fails,
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* bail and stop sending more reads. Read length accounting is
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* handled automatically by nfs_direct_read_result(). Otherwise, if
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* no requests have been sent, just return an error.
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*/
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static ssize_t nfs_direct_read_schedule(struct nfs_direct_req *dreq, unsigned long user_addr, size_t count, loff_t pos)
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{
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struct nfs_open_context *ctx = dreq->ctx;
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struct inode *inode = ctx->dentry->d_inode;
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size_t rsize = NFS_SERVER(inode)->rsize;
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unsigned int pgbase;
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int result;
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ssize_t started = 0;
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get_dreq(dreq);
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do {
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struct nfs_read_data *data;
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size_t bytes;
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pgbase = user_addr & ~PAGE_MASK;
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bytes = min(rsize,count);
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result = -ENOMEM;
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data = nfs_readdata_alloc(pgbase + bytes);
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if (unlikely(!data))
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break;
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down_read(¤t->mm->mmap_sem);
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result = get_user_pages(current, current->mm, user_addr,
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data->npages, 1, 0, data->pagevec, NULL);
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up_read(¤t->mm->mmap_sem);
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if (unlikely(result < data->npages)) {
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if (result > 0)
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nfs_direct_release_pages(data->pagevec, result);
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nfs_readdata_release(data);
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break;
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}
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get_dreq(dreq);
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data->req = (struct nfs_page *) dreq;
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data->inode = inode;
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data->cred = ctx->cred;
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data->args.fh = NFS_FH(inode);
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data->args.context = ctx;
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data->args.offset = pos;
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data->args.pgbase = pgbase;
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data->args.pages = data->pagevec;
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data->args.count = bytes;
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data->res.fattr = &data->fattr;
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data->res.eof = 0;
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data->res.count = bytes;
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rpc_init_task(&data->task, NFS_CLIENT(inode), RPC_TASK_ASYNC,
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&nfs_read_direct_ops, data);
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NFS_PROTO(inode)->read_setup(data);
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data->task.tk_cookie = (unsigned long) inode;
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rpc_execute(&data->task);
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dprintk("NFS: %5u initiated direct read call "
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"(req %s/%Ld, %zu bytes @ offset %Lu)\n",
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data->task.tk_pid,
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inode->i_sb->s_id,
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(long long)NFS_FILEID(inode),
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bytes,
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(unsigned long long)data->args.offset);
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started += bytes;
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user_addr += bytes;
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pos += bytes;
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/* FIXME: Remove this unnecessary math from final patch */
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pgbase += bytes;
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pgbase &= ~PAGE_MASK;
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BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
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count -= bytes;
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} while (count != 0);
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if (put_dreq(dreq))
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nfs_direct_complete(dreq);
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if (started)
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return 0;
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return result < 0 ? (ssize_t) result : -EFAULT;
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}
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static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size_t count, loff_t pos)
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{
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ssize_t result = 0;
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sigset_t oldset;
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struct inode *inode = iocb->ki_filp->f_mapping->host;
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struct rpc_clnt *clnt = NFS_CLIENT(inode);
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struct nfs_direct_req *dreq;
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dreq = nfs_direct_req_alloc();
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if (!dreq)
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return -ENOMEM;
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dreq->inode = inode;
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dreq->ctx = get_nfs_open_context((struct nfs_open_context *)iocb->ki_filp->private_data);
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if (!is_sync_kiocb(iocb))
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dreq->iocb = iocb;
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nfs_add_stats(inode, NFSIOS_DIRECTREADBYTES, count);
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rpc_clnt_sigmask(clnt, &oldset);
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result = nfs_direct_read_schedule(dreq, user_addr, count, pos);
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if (!result)
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result = nfs_direct_wait(dreq);
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rpc_clnt_sigunmask(clnt, &oldset);
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return result;
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}
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static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
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{
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while (!list_empty(&dreq->rewrite_list)) {
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struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
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list_del(&data->pages);
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nfs_direct_release_pages(data->pagevec, data->npages);
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nfs_writedata_release(data);
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}
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}
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#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
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static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
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{
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struct inode *inode = dreq->inode;
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struct list_head *p;
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struct nfs_write_data *data;
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dreq->count = 0;
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get_dreq(dreq);
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list_for_each(p, &dreq->rewrite_list) {
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data = list_entry(p, struct nfs_write_data, pages);
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get_dreq(dreq);
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/*
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* Reset data->res.
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*/
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nfs_fattr_init(&data->fattr);
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data->res.count = data->args.count;
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memset(&data->verf, 0, sizeof(data->verf));
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/*
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* Reuse data->task; data->args should not have changed
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* since the original request was sent.
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*/
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rpc_init_task(&data->task, NFS_CLIENT(inode), RPC_TASK_ASYNC,
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&nfs_write_direct_ops, data);
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NFS_PROTO(inode)->write_setup(data, FLUSH_STABLE);
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data->task.tk_priority = RPC_PRIORITY_NORMAL;
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data->task.tk_cookie = (unsigned long) inode;
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/*
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* We're called via an RPC callback, so BKL is already held.
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*/
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rpc_execute(&data->task);
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dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
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data->task.tk_pid,
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inode->i_sb->s_id,
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(long long)NFS_FILEID(inode),
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data->args.count,
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(unsigned long long)data->args.offset);
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}
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if (put_dreq(dreq))
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nfs_direct_write_complete(dreq, inode);
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}
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static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
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{
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struct nfs_write_data *data = calldata;
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struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
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/* Call the NFS version-specific code */
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if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
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return;
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if (unlikely(task->tk_status < 0)) {
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dreq->error = task->tk_status;
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dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
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}
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if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
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dprintk("NFS: %5u commit verify failed\n", task->tk_pid);
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dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
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}
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dprintk("NFS: %5u commit returned %d\n", task->tk_pid, task->tk_status);
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nfs_direct_write_complete(dreq, data->inode);
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}
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static const struct rpc_call_ops nfs_commit_direct_ops = {
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.rpc_call_done = nfs_direct_commit_result,
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.rpc_release = nfs_commit_release,
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};
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static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
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{
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struct nfs_write_data *data = dreq->commit_data;
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data->inode = dreq->inode;
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data->cred = dreq->ctx->cred;
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data->args.fh = NFS_FH(data->inode);
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data->args.offset = 0;
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data->args.count = 0;
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data->res.count = 0;
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data->res.fattr = &data->fattr;
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data->res.verf = &data->verf;
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rpc_init_task(&data->task, NFS_CLIENT(dreq->inode), RPC_TASK_ASYNC,
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&nfs_commit_direct_ops, data);
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NFS_PROTO(data->inode)->commit_setup(data, 0);
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data->task.tk_priority = RPC_PRIORITY_NORMAL;
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data->task.tk_cookie = (unsigned long)data->inode;
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/* Note: task.tk_ops->rpc_release will free dreq->commit_data */
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dreq->commit_data = NULL;
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dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
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rpc_execute(&data->task);
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}
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static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
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{
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int flags = dreq->flags;
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|
|
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_zap_mapping(inode, inode->i_mapping);
|
|
nfs_direct_complete(dreq);
|
|
}
|
|
}
|
|
|
|
static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
|
|
{
|
|
dreq->commit_data = nfs_commit_alloc();
|
|
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_zap_mapping(inode, inode->i_mapping);
|
|
nfs_direct_complete(dreq);
|
|
}
|
|
#endif
|
|
|
|
static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
|
|
{
|
|
struct nfs_write_data *data = calldata;
|
|
struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
|
|
int status = task->tk_status;
|
|
|
|
if (nfs_writeback_done(task, data) != 0)
|
|
return;
|
|
|
|
spin_lock(&dreq->lock);
|
|
|
|
if (unlikely(status < 0)) {
|
|
dreq->error = status;
|
|
goto out_unlock;
|
|
}
|
|
|
|
dreq->count += data->res.count;
|
|
|
|
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;
|
|
}
|
|
}
|
|
}
|
|
out_unlock:
|
|
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;
|
|
|
|
if (put_dreq(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_direct_write_release,
|
|
};
|
|
|
|
/*
|
|
* For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
|
|
* operation. If nfs_writedata_alloc() or get_user_pages() fails,
|
|
* bail and stop sending more writes. Write length accounting is
|
|
* handled automatically by nfs_direct_write_result(). Otherwise, if
|
|
* no requests have been sent, just return an error.
|
|
*/
|
|
static ssize_t nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned long user_addr, size_t count, loff_t pos, int sync)
|
|
{
|
|
struct nfs_open_context *ctx = dreq->ctx;
|
|
struct inode *inode = ctx->dentry->d_inode;
|
|
size_t wsize = NFS_SERVER(inode)->wsize;
|
|
unsigned int pgbase;
|
|
int result;
|
|
ssize_t started = 0;
|
|
|
|
get_dreq(dreq);
|
|
|
|
do {
|
|
struct nfs_write_data *data;
|
|
size_t bytes;
|
|
|
|
pgbase = user_addr & ~PAGE_MASK;
|
|
bytes = min(wsize,count);
|
|
|
|
result = -ENOMEM;
|
|
data = nfs_writedata_alloc(pgbase + bytes);
|
|
if (unlikely(!data))
|
|
break;
|
|
|
|
down_read(¤t->mm->mmap_sem);
|
|
result = get_user_pages(current, current->mm, user_addr,
|
|
data->npages, 0, 0, data->pagevec, NULL);
|
|
up_read(¤t->mm->mmap_sem);
|
|
if (unlikely(result < data->npages)) {
|
|
if (result > 0)
|
|
nfs_direct_release_pages(data->pagevec, result);
|
|
nfs_writedata_release(data);
|
|
break;
|
|
}
|
|
|
|
get_dreq(dreq);
|
|
|
|
list_move_tail(&data->pages, &dreq->rewrite_list);
|
|
|
|
data->req = (struct nfs_page *) dreq;
|
|
data->inode = inode;
|
|
data->cred = ctx->cred;
|
|
data->args.fh = NFS_FH(inode);
|
|
data->args.context = ctx;
|
|
data->args.offset = pos;
|
|
data->args.pgbase = pgbase;
|
|
data->args.pages = data->pagevec;
|
|
data->args.count = bytes;
|
|
data->res.fattr = &data->fattr;
|
|
data->res.count = bytes;
|
|
data->res.verf = &data->verf;
|
|
|
|
rpc_init_task(&data->task, NFS_CLIENT(inode), RPC_TASK_ASYNC,
|
|
&nfs_write_direct_ops, data);
|
|
NFS_PROTO(inode)->write_setup(data, sync);
|
|
|
|
data->task.tk_priority = RPC_PRIORITY_NORMAL;
|
|
data->task.tk_cookie = (unsigned long) inode;
|
|
|
|
rpc_execute(&data->task);
|
|
|
|
dprintk("NFS: %5u initiated direct write call "
|
|
"(req %s/%Ld, %zu bytes @ offset %Lu)\n",
|
|
data->task.tk_pid,
|
|
inode->i_sb->s_id,
|
|
(long long)NFS_FILEID(inode),
|
|
bytes,
|
|
(unsigned long long)data->args.offset);
|
|
|
|
started += bytes;
|
|
user_addr += bytes;
|
|
pos += bytes;
|
|
|
|
/* FIXME: Remove this useless math from the final patch */
|
|
pgbase += bytes;
|
|
pgbase &= ~PAGE_MASK;
|
|
BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
|
|
|
|
count -= bytes;
|
|
} while (count != 0);
|
|
|
|
if (put_dreq(dreq))
|
|
nfs_direct_write_complete(dreq, inode);
|
|
|
|
if (started)
|
|
return 0;
|
|
return result < 0 ? (ssize_t) result : -EFAULT;
|
|
}
|
|
|
|
static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, size_t count, loff_t pos)
|
|
{
|
|
ssize_t result = 0;
|
|
sigset_t oldset;
|
|
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_req_alloc();
|
|
if (!dreq)
|
|
return -ENOMEM;
|
|
nfs_alloc_commit_data(dreq);
|
|
|
|
if (dreq->commit_data == NULL || count < wsize)
|
|
sync = FLUSH_STABLE;
|
|
|
|
dreq->inode = inode;
|
|
dreq->ctx = get_nfs_open_context((struct nfs_open_context *)iocb->ki_filp->private_data);
|
|
if (!is_sync_kiocb(iocb))
|
|
dreq->iocb = iocb;
|
|
|
|
nfs_add_stats(inode, NFSIOS_DIRECTWRITTENBYTES, count);
|
|
|
|
nfs_begin_data_update(inode);
|
|
|
|
rpc_clnt_sigmask(clnt, &oldset);
|
|
result = nfs_direct_write_schedule(dreq, user_addr, count, pos, sync);
|
|
if (!result)
|
|
result = nfs_direct_wait(dreq);
|
|
rpc_clnt_sigunmask(clnt, &oldset);
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* nfs_file_direct_read - file direct read operation for NFS files
|
|
* @iocb: target I/O control block
|
|
* @iov: vector of user buffers into which to read data
|
|
* @nr_segs: size of iov vector
|
|
* @pos: byte offset in file where reading starts
|
|
*
|
|
* We use this function for direct reads instead of calling
|
|
* generic_file_aio_read() in order to avoid gfar's check to see if
|
|
* the request starts before the end of the file. For that check
|
|
* to work, we must generate a GETATTR before each direct read, and
|
|
* even then there is a window between the GETATTR and the subsequent
|
|
* READ where the file size could change. Our preference is simply
|
|
* to do all reads the application wants, and the server will take
|
|
* care of managing the end of file boundary.
|
|
*
|
|
* This function also eliminates unnecessarily updating the file's
|
|
* atime locally, as the NFS server sets the file's atime, and this
|
|
* client must read the updated atime from the server back into its
|
|
* cache.
|
|
*/
|
|
ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
|
|
unsigned long nr_segs, loff_t pos)
|
|
{
|
|
ssize_t retval = -EINVAL;
|
|
struct file *file = iocb->ki_filp;
|
|
struct address_space *mapping = file->f_mapping;
|
|
/* XXX: temporary */
|
|
const char __user *buf = iov[0].iov_base;
|
|
size_t count = iov[0].iov_len;
|
|
|
|
dprintk("nfs: direct read(%s/%s, %lu@%Ld)\n",
|
|
file->f_path.dentry->d_parent->d_name.name,
|
|
file->f_path.dentry->d_name.name,
|
|
(unsigned long) count, (long long) pos);
|
|
|
|
if (nr_segs != 1)
|
|
return -EINVAL;
|
|
|
|
if (count < 0)
|
|
goto out;
|
|
retval = -EFAULT;
|
|
if (!access_ok(VERIFY_WRITE, buf, count))
|
|
goto out;
|
|
retval = 0;
|
|
if (!count)
|
|
goto out;
|
|
|
|
retval = nfs_sync_mapping(mapping);
|
|
if (retval)
|
|
goto out;
|
|
|
|
retval = nfs_direct_read(iocb, (unsigned long) buf, count, pos);
|
|
if (retval > 0)
|
|
iocb->ki_pos = pos + retval;
|
|
|
|
out:
|
|
return retval;
|
|
}
|
|
|
|
/**
|
|
* nfs_file_direct_write - file direct write operation for NFS files
|
|
* @iocb: target I/O control block
|
|
* @iov: vector of user buffers from which to write data
|
|
* @nr_segs: size of iov vector
|
|
* @pos: byte offset in file where writing starts
|
|
*
|
|
* We use this function for direct writes instead of calling
|
|
* generic_file_aio_write() in order to avoid taking the inode
|
|
* semaphore and updating the i_size. The NFS server will set
|
|
* the new i_size and this client must read the updated size
|
|
* back into its cache. We let the server do generic write
|
|
* parameter checking and report problems.
|
|
*
|
|
* We also avoid an unnecessary invocation of generic_osync_inode(),
|
|
* as it is fairly meaningless to sync the metadata of an NFS file.
|
|
*
|
|
* We eliminate local atime updates, see direct read above.
|
|
*
|
|
* We avoid unnecessary page cache invalidations for normal cached
|
|
* readers of this file.
|
|
*
|
|
* Note that O_APPEND is not supported for NFS direct writes, as there
|
|
* is no atomic O_APPEND write facility in the NFS protocol.
|
|
*/
|
|
ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
|
|
unsigned long nr_segs, loff_t pos)
|
|
{
|
|
ssize_t retval;
|
|
struct file *file = iocb->ki_filp;
|
|
struct address_space *mapping = file->f_mapping;
|
|
/* XXX: temporary */
|
|
const char __user *buf = iov[0].iov_base;
|
|
size_t count = iov[0].iov_len;
|
|
|
|
dprintk("nfs: direct write(%s/%s, %lu@%Ld)\n",
|
|
file->f_path.dentry->d_parent->d_name.name,
|
|
file->f_path.dentry->d_name.name,
|
|
(unsigned long) count, (long long) pos);
|
|
|
|
if (nr_segs != 1)
|
|
return -EINVAL;
|
|
|
|
retval = generic_write_checks(file, &pos, &count, 0);
|
|
if (retval)
|
|
goto out;
|
|
|
|
retval = -EINVAL;
|
|
if ((ssize_t) count < 0)
|
|
goto out;
|
|
retval = 0;
|
|
if (!count)
|
|
goto out;
|
|
|
|
retval = -EFAULT;
|
|
if (!access_ok(VERIFY_READ, buf, count))
|
|
goto out;
|
|
|
|
retval = nfs_sync_mapping(mapping);
|
|
if (retval)
|
|
goto out;
|
|
|
|
retval = nfs_direct_write(iocb, (unsigned long) buf, count, pos);
|
|
|
|
if (retval > 0)
|
|
iocb->ki_pos = pos + retval;
|
|
|
|
out:
|
|
return retval;
|
|
}
|
|
|
|
/**
|
|
* nfs_init_directcache - create a slab cache for nfs_direct_req structures
|
|
*
|
|
*/
|
|
int __init nfs_init_directcache(void)
|
|
{
|
|
nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
|
|
sizeof(struct nfs_direct_req),
|
|
0, (SLAB_RECLAIM_ACCOUNT|
|
|
SLAB_MEM_SPREAD),
|
|
NULL, NULL);
|
|
if (nfs_direct_cachep == NULL)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
|
|
*
|
|
*/
|
|
void nfs_destroy_directcache(void)
|
|
{
|
|
kmem_cache_destroy(nfs_direct_cachep);
|
|
}
|