NFS: Eliminate nfs_get_user_pages()
Neil Brown observed that the kmalloc() in nfs_get_user_pages() is more likely to fail if the I/O is large enough to require the allocation of more than a single page to keep track of all the pinned pages in the user's buffer. Instead of tracking one large page array per dreq/iocb, track pages per nfs_read/write_data, just like the cached I/O path does. An array for pages is already allocated for us by nfs_readdata_alloc() (and the write and commit equivalents). This is also required for adding support for vectored I/O to the NFS direct I/O path. The original reason to pin the user buffer and allocate all the NFS data structures before trying to schedule I/O was to ensure all needed resources are allocated on the client before starting to send requests. This reduces the chance that resource exhaustion on the client will cause a short read or write. On the other hand, for an application making very large application I/O requests, this means that it will be nearly impossible for the application to make forward progress on a resource-limited client. Thus, moving the buffer pinning functionality into the I/O scheduling loops should be good for scalability. The next patch will do the same for NFS data structure allocation. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Chuck Lever
Trond Myklebust
parent
9c93ab7dff
commit
06cf6f2ed0
205
fs/nfs/direct.c
205
fs/nfs/direct.c
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@ -73,8 +73,6 @@ struct nfs_direct_req {
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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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struct page ** pages; /* pages in our buffer */
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unsigned int npages; /* count of pages */
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/* completion state */
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atomic_t io_count; /* i/os we're waiting for */
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@ -104,6 +102,20 @@ static inline int put_dreq(struct nfs_direct_req *dreq)
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return atomic_dec_and_test(&dreq->io_count);
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}
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/*
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* "size" is never larger than rsize or wsize.
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*/
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static inline int nfs_direct_count_pages(unsigned long user_addr, size_t size)
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{
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int page_count;
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page_count = (user_addr + size + PAGE_SIZE - 1) >> PAGE_SHIFT;
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page_count -= user_addr >> PAGE_SHIFT;
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BUG_ON(page_count < 0);
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return page_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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@ -143,40 +155,6 @@ static void nfs_direct_release_pages(struct page **pages, int npages)
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page_cache_release(pages[i]);
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}
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static inline int nfs_get_user_pages(int rw, unsigned long user_addr, size_t size, struct page ***pages)
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{
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int result = -ENOMEM;
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unsigned long page_count;
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size_t array_size;
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page_count = (user_addr + size + PAGE_SIZE - 1) >> PAGE_SHIFT;
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page_count -= user_addr >> PAGE_SHIFT;
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array_size = (page_count * sizeof(struct page *));
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*pages = kmalloc(array_size, GFP_KERNEL);
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if (*pages) {
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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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page_count, (rw == READ), 0,
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*pages, NULL);
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up_read(¤t->mm->mmap_sem);
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if (result != page_count) {
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/*
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* If we got fewer pages than expected from
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* get_user_pages(), the user buffer runs off the
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* end of a mapping; return EFAULT.
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*/
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if (result >= 0) {
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nfs_direct_release_pages(*pages, result);
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result = -EFAULT;
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} else
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kfree(*pages);
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*pages = NULL;
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}
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}
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return result;
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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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@ -233,13 +211,8 @@ static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
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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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* In addition, synchronous I/O uses a stack-allocated iocb. Thus we
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* can't trust the iocb is still valid here if this is a synchronous
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* request. If the waiter is woken prematurely, the iocb is long gone.
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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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@ -297,6 +270,11 @@ static struct nfs_direct_req *nfs_direct_read_alloc(size_t nbytes, size_t rsize)
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return dreq;
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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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@ -305,6 +283,9 @@ static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
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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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@ -314,11 +295,8 @@ static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
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spin_unlock(&dreq->lock);
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if (put_dreq(dreq)) {
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nfs_direct_dirty_pages(dreq->pages, dreq->npages);
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nfs_direct_release_pages(dreq->pages, dreq->npages);
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if (put_dreq(dreq))
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nfs_direct_complete(dreq);
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}
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}
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static const struct rpc_call_ops nfs_read_direct_ops = {
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@ -328,21 +306,23 @@ static const struct rpc_call_ops nfs_read_direct_ops = {
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/*
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* For each nfs_read_data struct that was allocated on the list, dispatch
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* an NFS READ operation
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* an NFS READ operation. If get_user_pages() fails, we stop sending reads.
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* Read length accounting is handled by nfs_direct_read_result().
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* Otherwise, if no requests have been sent, just return an error.
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*/
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static void nfs_direct_read_schedule(struct nfs_direct_req *dreq, unsigned long user_addr, size_t count, loff_t pos)
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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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struct list_head *list = &dreq->list;
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struct page **pages = dreq->pages;
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size_t rsize = NFS_SERVER(inode)->rsize;
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unsigned int curpage, pgbase;
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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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struct nfs_read_data *data;
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curpage = 0;
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pgbase = user_addr & ~PAGE_MASK;
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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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bytes = rsize;
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@ -353,13 +333,21 @@ static void nfs_direct_read_schedule(struct nfs_direct_req *dreq, unsigned long
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data = list_entry(list->next, struct nfs_read_data, pages);
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list_del_init(&data->pages);
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data->npages = nfs_direct_count_pages(user_addr, bytes);
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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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goto out_err;
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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 = &pages[curpage];
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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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@ -382,17 +370,36 @@ static void nfs_direct_read_schedule(struct nfs_direct_req *dreq, unsigned long
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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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pgbase += bytes;
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curpage += pgbase >> PAGE_SHIFT;
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pgbase &= ~PAGE_MASK;
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count -= bytes;
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} while (count != 0);
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BUG_ON(!list_empty(list));
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return 0;
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out_err:
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if (result > 0)
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nfs_direct_release_pages(data->pagevec, result);
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list_add(&data->pages, list);
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while (!list_empty(list)) {
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data = list_entry(list->next, struct nfs_read_data, pages);
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list_del(&data->pages);
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nfs_readdata_free(data);
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if (put_dreq(dreq))
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nfs_direct_complete(dreq);
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}
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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, struct page **pages, unsigned int nr_pages)
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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;
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sigset_t oldset;
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@ -404,8 +411,6 @@ static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size
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if (!dreq)
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return -ENOMEM;
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dreq->pages = pages;
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dreq->npages = nr_pages;
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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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@ -413,8 +418,9 @@ static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size
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nfs_add_stats(inode, NFSIOS_DIRECTREADBYTES, count);
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rpc_clnt_sigmask(clnt, &oldset);
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nfs_direct_read_schedule(dreq, user_addr, count, pos);
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result = nfs_direct_wait(dreq);
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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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@ -426,9 +432,9 @@ static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
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while (!list_empty(&dreq->list)) {
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struct nfs_write_data *data = list_entry(dreq->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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nfs_direct_release_pages(dreq->pages, dreq->npages);
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}
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#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
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@ -672,21 +678,23 @@ static const struct rpc_call_ops nfs_write_direct_ops = {
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/*
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* For each nfs_write_data struct that was allocated on the list, dispatch
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* an NFS WRITE operation
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* an NFS WRITE operation. If get_user_pages() fails, we stop sending writes.
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* Write length accounting is handled by nfs_direct_write_result().
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* Otherwise, if no requests have been sent, just return an error.
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*/
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static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned long user_addr, size_t count, loff_t pos, int sync)
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static ssize_t nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned long user_addr, size_t count, loff_t pos, int sync)
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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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struct list_head *list = &dreq->list;
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struct page **pages = dreq->pages;
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size_t wsize = NFS_SERVER(inode)->wsize;
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unsigned int curpage, pgbase;
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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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struct nfs_write_data *data;
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curpage = 0;
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pgbase = user_addr & ~PAGE_MASK;
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do {
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struct nfs_write_data *data;
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size_t bytes;
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bytes = wsize;
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@ -695,6 +703,15 @@ static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned long
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BUG_ON(list_empty(list));
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data = list_entry(list->next, struct nfs_write_data, pages);
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data->npages = nfs_direct_count_pages(user_addr, bytes);
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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, 0, 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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goto out_err;
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list_move_tail(&data->pages, &dreq->rewrite_list);
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data->inode = inode;
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@ -703,7 +720,7 @@ static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned long
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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 = &pages[curpage];
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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.count = bytes;
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@ -727,17 +744,36 @@ static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned long
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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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pgbase += bytes;
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curpage += pgbase >> PAGE_SHIFT;
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pgbase &= ~PAGE_MASK;
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count -= bytes;
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} while (count != 0);
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BUG_ON(!list_empty(list));
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return 0;
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out_err:
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if (result > 0)
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nfs_direct_release_pages(data->pagevec, result);
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list_add(&data->pages, list);
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while (!list_empty(list)) {
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data = list_entry(list->next, struct nfs_write_data, pages);
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list_del(&data->pages);
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nfs_writedata_free(data);
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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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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_write(struct kiocb *iocb, unsigned long user_addr, size_t count, loff_t pos, struct page **pages, int nr_pages)
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static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, size_t count, loff_t pos)
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{
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ssize_t result;
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sigset_t oldset;
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@ -753,8 +789,6 @@ static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, siz
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if (dreq->commit_data == NULL || count < wsize)
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sync = FLUSH_STABLE;
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dreq->pages = pages;
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dreq->npages = nr_pages;
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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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@ -765,8 +799,9 @@ static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, siz
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nfs_begin_data_update(inode);
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rpc_clnt_sigmask(clnt, &oldset);
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nfs_direct_write_schedule(dreq, user_addr, count, pos, sync);
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result = nfs_direct_wait(dreq);
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result = nfs_direct_write_schedule(dreq, user_addr, count, pos, sync);
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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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@ -796,8 +831,6 @@ static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, siz
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ssize_t nfs_file_direct_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
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{
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ssize_t retval = -EINVAL;
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int page_count;
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struct page **pages;
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struct file *file = iocb->ki_filp;
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struct address_space *mapping = file->f_mapping;
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@ -819,14 +852,7 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, char __user *buf, size_t count,
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if (retval)
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goto out;
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retval = nfs_get_user_pages(READ, (unsigned long) buf,
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count, &pages);
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if (retval < 0)
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goto out;
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page_count = retval;
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retval = nfs_direct_read(iocb, (unsigned long) buf, count, pos,
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pages, page_count);
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retval = nfs_direct_read(iocb, (unsigned long) buf, count, pos);
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if (retval > 0)
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iocb->ki_pos = pos + retval;
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@ -862,8 +888,6 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, char __user *buf, size_t count,
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ssize_t nfs_file_direct_write(struct kiocb *iocb, const char __user *buf, size_t count, loff_t pos)
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{
|
||||
ssize_t retval;
|
||||
int page_count;
|
||||
struct page **pages;
|
||||
struct file *file = iocb->ki_filp;
|
||||
struct address_space *mapping = file->f_mapping;
|
||||
|
||||
|
|
@ -891,14 +915,7 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, const char __user *buf, size_t
|
|||
if (retval)
|
||||
goto out;
|
||||
|
||||
retval = nfs_get_user_pages(WRITE, (unsigned long) buf,
|
||||
count, &pages);
|
||||
if (retval < 0)
|
||||
goto out;
|
||||
page_count = retval;
|
||||
|
||||
retval = nfs_direct_write(iocb, (unsigned long) buf, count,
|
||||
pos, pages, page_count);
|
||||
retval = nfs_direct_write(iocb, (unsigned long) buf, count, pos);
|
||||
|
||||
/*
|
||||
* XXX: nfs_end_data_update() already ensures this file's
|
||||
|
|
|
|||
|
|
@ -729,6 +729,7 @@ struct nfs_read_data {
|
|||
struct list_head pages; /* Coalesced read requests */
|
||||
struct nfs_page *req; /* multi ops per nfs_page */
|
||||
struct page **pagevec;
|
||||
unsigned int npages; /* active pages in pagevec */
|
||||
struct nfs_readargs args;
|
||||
struct nfs_readres res;
|
||||
#ifdef CONFIG_NFS_V4
|
||||
|
|
@ -747,6 +748,7 @@ struct nfs_write_data {
|
|||
struct list_head pages; /* Coalesced requests we wish to flush */
|
||||
struct nfs_page *req; /* multi ops per nfs_page */
|
||||
struct page **pagevec;
|
||||
unsigned int npages; /* active pages in pagevec */
|
||||
struct nfs_writeargs args; /* argument struct */
|
||||
struct nfs_writeres res; /* result struct */
|
||||
#ifdef CONFIG_NFS_V4
|
||||
|
|
|
|||
Loading…
Reference in New Issue