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Diffstat (limited to 'fs/nfs/direct.c')
| -rw-r--r-- | fs/nfs/direct.c | 1103 |
1 files changed, 1103 insertions, 0 deletions
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c new file mode 100644 index 000000000..6a4083d55 --- /dev/null +++ b/fs/nfs/direct.c @@ -0,0 +1,1103 @@ +/* + * linux/fs/nfs/direct.c + * + * Copyright (C) 2003 by Chuck Lever <cel@netapp.com> + * + * High-performance uncached I/O for the Linux NFS client + * + * There are important applications whose performance or correctness + * depends on uncached access to file data. Database clusters + * (multiple copies of the same instance running on separate hosts) + * implement their own cache coherency protocol that subsumes file + * system cache protocols. Applications that process datasets + * considerably larger than the client's memory do not always benefit + * from a local cache. A streaming video server, for instance, has no + * need to cache the contents of a file. + * + * When an application requests uncached I/O, all read and write requests + * are made directly to the server; data stored or fetched via these + * requests is not cached in the Linux page cache. The client does not + * correct unaligned requests from applications. All requested bytes are + * held on permanent storage before a direct write system call returns to + * an application. + * + * Solaris implements an uncached I/O facility called directio() that + * is used for backups and sequential I/O to very large files. Solaris + * also supports uncaching whole NFS partitions with "-o forcedirectio," + * an undocumented mount option. + * + * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with + * help from Andrew Morton. + * + * 18 Dec 2001 Initial implementation for 2.4 --cel + * 08 Jul 2002 Version for 2.4.19, with bug fixes --trondmy + * 08 Jun 2003 Port to 2.5 APIs --cel + * 31 Mar 2004 Handle direct I/O without VFS support --cel + * 15 Sep 2004 Parallel async reads --cel + * 04 May 2005 support O_DIRECT with aio --cel + * + */ + +#include <linux/errno.h> +#include <linux/sched.h> +#include <linux/kernel.h> +#include <linux/file.h> +#include <linux/pagemap.h> +#include <linux/kref.h> +#include <linux/slab.h> +#include <linux/task_io_accounting_ops.h> +#include <linux/module.h> + +#include <linux/nfs_fs.h> +#include <linux/nfs_page.h> +#include <linux/sunrpc/clnt.h> + +#include <linux/uaccess.h> +#include <linux/atomic.h> + +#include "internal.h" +#include "iostat.h" +#include "pnfs.h" + +#define NFSDBG_FACILITY NFSDBG_VFS + +static struct kmem_cache *nfs_direct_cachep; + +/* + * This represents a set of asynchronous requests that we're waiting on + */ +struct nfs_direct_mirror { + ssize_t count; +}; + +struct nfs_direct_req { + struct kref kref; /* release manager */ + + /* I/O parameters */ + struct nfs_open_context *ctx; /* file open context info */ + struct nfs_lock_context *l_ctx; /* Lock context info */ + struct kiocb * iocb; /* controlling i/o request */ + struct inode * inode; /* target file of i/o */ + + /* completion state */ + atomic_t io_count; /* i/os we're waiting for */ + spinlock_t lock; /* protect completion state */ + + struct nfs_direct_mirror mirrors[NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX]; + int mirror_count; + + loff_t io_start; /* Start offset for I/O */ + ssize_t count, /* bytes actually processed */ + max_count, /* max expected count */ + bytes_left, /* bytes left to be sent */ + error; /* any reported error */ + struct completion completion; /* wait for i/o completion */ + + /* commit state */ + struct nfs_mds_commit_info mds_cinfo; /* Storage for cinfo */ + struct pnfs_ds_commit_info ds_cinfo; /* Storage for cinfo */ + struct work_struct work; + int flags; + /* for write */ +#define NFS_ODIRECT_DO_COMMIT (1) /* an unstable reply was received */ +#define NFS_ODIRECT_RESCHED_WRITES (2) /* write verification failed */ + /* for read */ +#define NFS_ODIRECT_SHOULD_DIRTY (3) /* dirty user-space page after read */ + struct nfs_writeverf verf; /* unstable write verifier */ +}; + +static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops; +static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops; +static void nfs_direct_write_complete(struct nfs_direct_req *dreq); +static void nfs_direct_write_schedule_work(struct work_struct *work); + +static inline void get_dreq(struct nfs_direct_req *dreq) +{ + atomic_inc(&dreq->io_count); +} + +static inline int put_dreq(struct nfs_direct_req *dreq) +{ + return atomic_dec_and_test(&dreq->io_count); +} + +static void +nfs_direct_handle_truncated(struct nfs_direct_req *dreq, + const struct nfs_pgio_header *hdr, + ssize_t dreq_len) +{ + struct nfs_direct_mirror *mirror = &dreq->mirrors[hdr->pgio_mirror_idx]; + + if (!(test_bit(NFS_IOHDR_ERROR, &hdr->flags) || + test_bit(NFS_IOHDR_EOF, &hdr->flags))) + return; + if (dreq->max_count >= dreq_len) { + dreq->max_count = dreq_len; + if (dreq->count > dreq_len) + dreq->count = dreq_len; + + if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) + dreq->error = hdr->error; + else /* Clear outstanding error if this is EOF */ + dreq->error = 0; + } + if (mirror->count > dreq_len) + mirror->count = dreq_len; +} + +static void +nfs_direct_count_bytes(struct nfs_direct_req *dreq, + const struct nfs_pgio_header *hdr) +{ + struct nfs_direct_mirror *mirror = &dreq->mirrors[hdr->pgio_mirror_idx]; + loff_t hdr_end = hdr->io_start + hdr->good_bytes; + ssize_t dreq_len = 0; + + if (hdr_end > dreq->io_start) + dreq_len = hdr_end - dreq->io_start; + + nfs_direct_handle_truncated(dreq, hdr, dreq_len); + + if (dreq_len > dreq->max_count) + dreq_len = dreq->max_count; + + if (mirror->count < dreq_len) + mirror->count = dreq_len; + if (dreq->count < dreq_len) + dreq->count = dreq_len; +} + +/* + * nfs_direct_select_verf - select the right verifier + * @dreq - direct request possibly spanning multiple servers + * @ds_clp - nfs_client of data server or NULL if MDS / non-pnfs + * @commit_idx - commit bucket index for the DS + * + * returns the correct verifier to use given the role of the server + */ +static struct nfs_writeverf * +nfs_direct_select_verf(struct nfs_direct_req *dreq, + struct nfs_client *ds_clp, + int commit_idx) +{ + struct nfs_writeverf *verfp = &dreq->verf; + +#ifdef CONFIG_NFS_V4_1 + /* + * pNFS is in use, use the DS verf except commit_through_mds is set + * for layout segment where nbuckets is zero. + */ + if (ds_clp && dreq->ds_cinfo.nbuckets > 0) { + if (commit_idx >= 0 && commit_idx < dreq->ds_cinfo.nbuckets) + verfp = &dreq->ds_cinfo.buckets[commit_idx].direct_verf; + else + WARN_ON_ONCE(1); + } +#endif + return verfp; +} + + +/* + * nfs_direct_set_hdr_verf - set the write/commit verifier + * @dreq - direct request possibly spanning multiple servers + * @hdr - pageio header to validate against previously seen verfs + * + * Set the server's (MDS or DS) "seen" verifier + */ +static void nfs_direct_set_hdr_verf(struct nfs_direct_req *dreq, + struct nfs_pgio_header *hdr) +{ + struct nfs_writeverf *verfp; + + verfp = nfs_direct_select_verf(dreq, hdr->ds_clp, hdr->ds_commit_idx); + WARN_ON_ONCE(verfp->committed >= 0); + memcpy(verfp, &hdr->verf, sizeof(struct nfs_writeverf)); + WARN_ON_ONCE(verfp->committed < 0); +} + +static int nfs_direct_cmp_verf(const struct nfs_writeverf *v1, + const struct nfs_writeverf *v2) +{ + return nfs_write_verifier_cmp(&v1->verifier, &v2->verifier); +} + +/* + * nfs_direct_cmp_hdr_verf - compare verifier for pgio header + * @dreq - direct request possibly spanning multiple servers + * @hdr - pageio header to validate against previously seen verf + * + * set the server's "seen" verf if not initialized. + * returns result of comparison between @hdr->verf and the "seen" + * verf of the server used by @hdr (DS or MDS) + */ +static int nfs_direct_set_or_cmp_hdr_verf(struct nfs_direct_req *dreq, + struct nfs_pgio_header *hdr) +{ + struct nfs_writeverf *verfp; + + verfp = nfs_direct_select_verf(dreq, hdr->ds_clp, hdr->ds_commit_idx); + if (verfp->committed < 0) { + nfs_direct_set_hdr_verf(dreq, hdr); + return 0; + } + return nfs_direct_cmp_verf(verfp, &hdr->verf); +} + +/* + * nfs_direct_cmp_commit_data_verf - compare verifier for commit data + * @dreq - direct request possibly spanning multiple servers + * @data - commit data to validate against previously seen verf + * + * returns result of comparison between @data->verf and the verf of + * the server used by @data (DS or MDS) + */ +static int nfs_direct_cmp_commit_data_verf(struct nfs_direct_req *dreq, + struct nfs_commit_data *data) +{ + struct nfs_writeverf *verfp; + + verfp = nfs_direct_select_verf(dreq, data->ds_clp, + data->ds_commit_index); + + /* verifier not set so always fail */ + if (verfp->committed < 0 || data->res.verf->committed <= NFS_UNSTABLE) + return 1; + + return nfs_direct_cmp_verf(verfp, data->res.verf); +} + +/** + * nfs_direct_IO - NFS address space operation for direct I/O + * @iocb: target I/O control block + * @iter: I/O buffer + * + * The presence of this routine in the address space ops vector means + * the NFS client supports direct I/O. However, for most direct IO, we + * shunt off direct read and write requests before the VFS gets them, + * so this method is only ever called for swap. + */ +ssize_t nfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) +{ + struct inode *inode = iocb->ki_filp->f_mapping->host; + + /* we only support swap file calling nfs_direct_IO */ + if (!IS_SWAPFILE(inode)) + return 0; + + VM_BUG_ON(iov_iter_count(iter) != PAGE_SIZE); + + if (iov_iter_rw(iter) == READ) + return nfs_file_direct_read(iocb, iter, true); + return nfs_file_direct_write(iocb, iter, true); +} + +static void nfs_direct_release_pages(struct page **pages, unsigned int npages) +{ + unsigned int i; + for (i = 0; i < npages; i++) + put_page(pages[i]); +} + +void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo, + struct nfs_direct_req *dreq) +{ + cinfo->inode = dreq->inode; + cinfo->mds = &dreq->mds_cinfo; + cinfo->ds = &dreq->ds_cinfo; + cinfo->dreq = dreq; + cinfo->completion_ops = &nfs_direct_commit_completion_ops; +} + +static inline void nfs_direct_setup_mirroring(struct nfs_direct_req *dreq, + struct nfs_pageio_descriptor *pgio, + struct nfs_page *req) +{ + int mirror_count = 1; + + if (pgio->pg_ops->pg_get_mirror_count) + mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req); + + dreq->mirror_count = mirror_count; +} + +static inline struct nfs_direct_req *nfs_direct_req_alloc(void) +{ + struct nfs_direct_req *dreq; + + dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL); + if (!dreq) + return NULL; + + kref_init(&dreq->kref); + kref_get(&dreq->kref); + init_completion(&dreq->completion); + INIT_LIST_HEAD(&dreq->mds_cinfo.list); + dreq->verf.committed = NFS_INVALID_STABLE_HOW; /* not set yet */ + INIT_WORK(&dreq->work, nfs_direct_write_schedule_work); + dreq->mirror_count = 1; + spin_lock_init(&dreq->lock); + + return dreq; +} + +static void nfs_direct_req_free(struct kref *kref) +{ + struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref); + + nfs_free_pnfs_ds_cinfo(&dreq->ds_cinfo); + if (dreq->l_ctx != NULL) + nfs_put_lock_context(dreq->l_ctx); + if (dreq->ctx != NULL) + put_nfs_open_context(dreq->ctx); + kmem_cache_free(nfs_direct_cachep, dreq); +} + +static void nfs_direct_req_release(struct nfs_direct_req *dreq) +{ + kref_put(&dreq->kref, nfs_direct_req_free); +} + +ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq) +{ + return dreq->bytes_left; +} +EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left); + +/* + * Collects and returns the final error value/byte-count. + */ +static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq) +{ + ssize_t result = -EIOCBQUEUED; + + /* Async requests don't wait here */ + if (dreq->iocb) + goto out; + + result = wait_for_completion_killable(&dreq->completion); + + if (!result) { + result = dreq->count; + WARN_ON_ONCE(dreq->count < 0); + } + if (!result) + result = dreq->error; + +out: + return (ssize_t) result; +} + +/* + * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust + * the iocb is still valid here if this is a synchronous request. + */ +static void nfs_direct_complete(struct nfs_direct_req *dreq) +{ + struct inode *inode = dreq->inode; + + inode_dio_end(inode); + + if (dreq->iocb) { + long res = (long) dreq->error; + if (dreq->count != 0) { + res = (long) dreq->count; + WARN_ON_ONCE(dreq->count < 0); + } + dreq->iocb->ki_complete(dreq->iocb, res, 0); + } + + complete(&dreq->completion); + + nfs_direct_req_release(dreq); +} + +static void nfs_direct_read_completion(struct nfs_pgio_header *hdr) +{ + unsigned long bytes = 0; + struct nfs_direct_req *dreq = hdr->dreq; + + spin_lock(&dreq->lock); + if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) { + spin_unlock(&dreq->lock); + goto out_put; + } + + nfs_direct_count_bytes(dreq, hdr); + spin_unlock(&dreq->lock); + + while (!list_empty(&hdr->pages)) { + struct nfs_page *req = nfs_list_entry(hdr->pages.next); + struct page *page = req->wb_page; + + if (!PageCompound(page) && bytes < hdr->good_bytes && + (dreq->flags == NFS_ODIRECT_SHOULD_DIRTY)) + set_page_dirty(page); + bytes += req->wb_bytes; + nfs_list_remove_request(req); + nfs_release_request(req); + } +out_put: + if (put_dreq(dreq)) + nfs_direct_complete(dreq); + hdr->release(hdr); +} + +static void nfs_read_sync_pgio_error(struct list_head *head, int error) +{ + struct nfs_page *req; + + while (!list_empty(head)) { + req = nfs_list_entry(head->next); + nfs_list_remove_request(req); + nfs_release_request(req); + } +} + +static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr) +{ + get_dreq(hdr->dreq); +} + +static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = { + .error_cleanup = nfs_read_sync_pgio_error, + .init_hdr = nfs_direct_pgio_init, + .completion = nfs_direct_read_completion, +}; + +/* + * For each rsize'd chunk of the user's buffer, dispatch an NFS READ + * operation. If nfs_readdata_alloc() or get_user_pages() fails, + * bail and stop sending more reads. Read length accounting is + * handled automatically by nfs_direct_read_result(). Otherwise, if + * no requests have been sent, just return an error. + */ + +static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq, + struct iov_iter *iter, + loff_t pos) +{ + struct nfs_pageio_descriptor desc; + struct inode *inode = dreq->inode; + ssize_t result = -EINVAL; + size_t requested_bytes = 0; + size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE); + + nfs_pageio_init_read(&desc, dreq->inode, false, + &nfs_direct_read_completion_ops); + get_dreq(dreq); + desc.pg_dreq = dreq; + inode_dio_begin(inode); + + while (iov_iter_count(iter)) { + struct page **pagevec; + size_t bytes; + size_t pgbase; + unsigned npages, i; + + result = iov_iter_get_pages_alloc(iter, &pagevec, + rsize, &pgbase); + if (result < 0) + break; + + bytes = result; + iov_iter_advance(iter, bytes); + npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE; + for (i = 0; i < npages; i++) { + struct nfs_page *req; + unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase); + /* XXX do we need to do the eof zeroing found in async_filler? */ + req = nfs_create_request(dreq->ctx, pagevec[i], NULL, + pgbase, req_len); + if (IS_ERR(req)) { + result = PTR_ERR(req); + break; + } + req->wb_index = pos >> PAGE_SHIFT; + req->wb_offset = pos & ~PAGE_MASK; + if (!nfs_pageio_add_request(&desc, req)) { + result = desc.pg_error; + nfs_release_request(req); + break; + } + pgbase = 0; + bytes -= req_len; + requested_bytes += req_len; + pos += req_len; + dreq->bytes_left -= req_len; + } + nfs_direct_release_pages(pagevec, npages); + kvfree(pagevec); + if (result < 0) + break; + } + + nfs_pageio_complete(&desc); + + /* + * If no bytes were started, return the error, and let the + * generic layer handle the completion. + */ + if (requested_bytes == 0) { + inode_dio_end(inode); + nfs_direct_req_release(dreq); + return result < 0 ? result : -EIO; + } + + if (put_dreq(dreq)) + nfs_direct_complete(dreq); + return requested_bytes; +} + +/** + * nfs_file_direct_read - file direct read operation for NFS files + * @iocb: target I/O control block + * @iter: vector of user buffers into which to read data + * @swap: flag indicating this is swap IO, not O_DIRECT IO + * + * 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, struct iov_iter *iter, + bool swap) +{ + struct file *file = iocb->ki_filp; + struct address_space *mapping = file->f_mapping; + struct inode *inode = mapping->host; + struct nfs_direct_req *dreq; + struct nfs_lock_context *l_ctx; + ssize_t result = -EINVAL, requested; + size_t count = iov_iter_count(iter); + nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count); + + dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n", + file, count, (long long) iocb->ki_pos); + + result = 0; + if (!count) + goto out; + + task_io_account_read(count); + + result = -ENOMEM; + dreq = nfs_direct_req_alloc(); + if (dreq == NULL) + goto out; + + dreq->inode = inode; + dreq->bytes_left = dreq->max_count = count; + dreq->io_start = iocb->ki_pos; + dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp)); + l_ctx = nfs_get_lock_context(dreq->ctx); + if (IS_ERR(l_ctx)) { + result = PTR_ERR(l_ctx); + nfs_direct_req_release(dreq); + goto out_release; + } + dreq->l_ctx = l_ctx; + if (!is_sync_kiocb(iocb)) + dreq->iocb = iocb; + + if (iter_is_iovec(iter)) + dreq->flags = NFS_ODIRECT_SHOULD_DIRTY; + + if (!swap) + nfs_start_io_direct(inode); + + NFS_I(inode)->read_io += count; + requested = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos); + + if (!swap) + nfs_end_io_direct(inode); + + if (requested > 0) { + result = nfs_direct_wait(dreq); + if (result > 0) { + requested -= result; + iocb->ki_pos += result; + } + iov_iter_revert(iter, requested); + } else { + result = requested; + } + +out_release: + nfs_direct_req_release(dreq); +out: + return result; +} + +static void +nfs_direct_write_scan_commit_list(struct inode *inode, + struct list_head *list, + struct nfs_commit_info *cinfo) +{ + mutex_lock(&NFS_I(cinfo->inode)->commit_mutex); +#ifdef CONFIG_NFS_V4_1 + if (cinfo->ds != NULL && cinfo->ds->nwritten != 0) + NFS_SERVER(inode)->pnfs_curr_ld->recover_commit_reqs(list, cinfo); +#endif + nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0); + mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex); +} + +static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq) +{ + struct nfs_pageio_descriptor desc; + struct nfs_page *req, *tmp; + LIST_HEAD(reqs); + struct nfs_commit_info cinfo; + LIST_HEAD(failed); + int i; + + nfs_init_cinfo_from_dreq(&cinfo, dreq); + nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo); + + dreq->count = 0; + dreq->max_count = 0; + list_for_each_entry(req, &reqs, wb_list) + dreq->max_count += req->wb_bytes; + dreq->verf.committed = NFS_INVALID_STABLE_HOW; + nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo); + for (i = 0; i < dreq->mirror_count; i++) + dreq->mirrors[i].count = 0; + get_dreq(dreq); + + nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false, + &nfs_direct_write_completion_ops); + desc.pg_dreq = dreq; + + req = nfs_list_entry(reqs.next); + nfs_direct_setup_mirroring(dreq, &desc, req); + if (desc.pg_error < 0) { + list_splice_init(&reqs, &failed); + goto out_failed; + } + + list_for_each_entry_safe(req, tmp, &reqs, wb_list) { + if (!nfs_pageio_add_request(&desc, req)) { + nfs_list_move_request(req, &failed); + spin_lock(&cinfo.inode->i_lock); + dreq->flags = 0; + if (desc.pg_error < 0) + dreq->error = desc.pg_error; + else + dreq->error = -EIO; + spin_unlock(&cinfo.inode->i_lock); + } + nfs_release_request(req); + } + nfs_pageio_complete(&desc); + +out_failed: + while (!list_empty(&failed)) { + req = nfs_list_entry(failed.next); + nfs_list_remove_request(req); + nfs_unlock_and_release_request(req); + } + + if (put_dreq(dreq)) + nfs_direct_write_complete(dreq); +} + +static void nfs_direct_commit_complete(struct nfs_commit_data *data) +{ + struct nfs_direct_req *dreq = data->dreq; + struct nfs_commit_info cinfo; + struct nfs_page *req; + int status = data->task.tk_status; + + nfs_init_cinfo_from_dreq(&cinfo, dreq); + if (status < 0 || nfs_direct_cmp_commit_data_verf(dreq, data)) + dreq->flags = NFS_ODIRECT_RESCHED_WRITES; + + while (!list_empty(&data->pages)) { + req = nfs_list_entry(data->pages.next); + nfs_list_remove_request(req); + if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) { + /* Note the rewrite will go through mds */ + nfs_mark_request_commit(req, NULL, &cinfo, 0); + } else + nfs_release_request(req); + nfs_unlock_and_release_request(req); + } + + if (atomic_dec_and_test(&cinfo.mds->rpcs_out)) + nfs_direct_write_complete(dreq); +} + +static void nfs_direct_resched_write(struct nfs_commit_info *cinfo, + struct nfs_page *req) +{ + struct nfs_direct_req *dreq = cinfo->dreq; + + spin_lock(&dreq->lock); + dreq->flags = NFS_ODIRECT_RESCHED_WRITES; + spin_unlock(&dreq->lock); + nfs_mark_request_commit(req, NULL, cinfo, 0); +} + +static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = { + .completion = nfs_direct_commit_complete, + .resched_write = nfs_direct_resched_write, +}; + +static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq) +{ + int res; + struct nfs_commit_info cinfo; + LIST_HEAD(mds_list); + + nfs_init_cinfo_from_dreq(&cinfo, dreq); + nfs_scan_commit(dreq->inode, &mds_list, &cinfo); + res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo); + if (res < 0) /* res == -ENOMEM */ + nfs_direct_write_reschedule(dreq); +} + +static void nfs_direct_write_schedule_work(struct work_struct *work) +{ + struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work); + 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_zap_mapping(dreq->inode, dreq->inode->i_mapping); + nfs_direct_complete(dreq); + } +} + +static void nfs_direct_write_complete(struct nfs_direct_req *dreq) +{ + queue_work(nfsiod_workqueue, &dreq->work); /* Calls nfs_direct_write_schedule_work */ +} + +static void nfs_direct_write_completion(struct nfs_pgio_header *hdr) +{ + struct nfs_direct_req *dreq = hdr->dreq; + struct nfs_commit_info cinfo; + bool request_commit = false; + struct nfs_page *req = nfs_list_entry(hdr->pages.next); + + nfs_init_cinfo_from_dreq(&cinfo, dreq); + + spin_lock(&dreq->lock); + if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) { + spin_unlock(&dreq->lock); + goto out_put; + } + + nfs_direct_count_bytes(dreq, hdr); + if (hdr->good_bytes != 0) { + if (nfs_write_need_commit(hdr)) { + if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) + request_commit = true; + else if (dreq->flags == 0) { + nfs_direct_set_hdr_verf(dreq, hdr); + request_commit = true; + dreq->flags = NFS_ODIRECT_DO_COMMIT; + } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) { + request_commit = true; + if (nfs_direct_set_or_cmp_hdr_verf(dreq, hdr)) + dreq->flags = + NFS_ODIRECT_RESCHED_WRITES; + } + } + } + spin_unlock(&dreq->lock); + + while (!list_empty(&hdr->pages)) { + + req = nfs_list_entry(hdr->pages.next); + nfs_list_remove_request(req); + if (request_commit) { + kref_get(&req->wb_kref); + nfs_mark_request_commit(req, hdr->lseg, &cinfo, + hdr->ds_commit_idx); + } + nfs_unlock_and_release_request(req); + } + +out_put: + if (put_dreq(dreq)) + nfs_direct_write_complete(dreq); + hdr->release(hdr); +} + +static void nfs_write_sync_pgio_error(struct list_head *head, int error) +{ + struct nfs_page *req; + + while (!list_empty(head)) { + req = nfs_list_entry(head->next); + nfs_list_remove_request(req); + nfs_unlock_and_release_request(req); + } +} + +static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr) +{ + struct nfs_direct_req *dreq = hdr->dreq; + + spin_lock(&dreq->lock); + if (dreq->error == 0) { + dreq->flags = NFS_ODIRECT_RESCHED_WRITES; + /* fake unstable write to let common nfs resend pages */ + hdr->verf.committed = NFS_UNSTABLE; + hdr->good_bytes = hdr->args.count; + } + spin_unlock(&dreq->lock); +} + +static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = { + .error_cleanup = nfs_write_sync_pgio_error, + .init_hdr = nfs_direct_pgio_init, + .completion = nfs_direct_write_completion, + .reschedule_io = nfs_direct_write_reschedule_io, +}; + + +/* + * NB: Return the value of the first error return code. Subsequent + * errors after the first one are ignored. + */ +/* + * 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_iovec(struct nfs_direct_req *dreq, + struct iov_iter *iter, + loff_t pos, int ioflags) +{ + struct nfs_pageio_descriptor desc; + struct inode *inode = dreq->inode; + ssize_t result = 0; + size_t requested_bytes = 0; + size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE); + + nfs_pageio_init_write(&desc, inode, ioflags, false, + &nfs_direct_write_completion_ops); + desc.pg_dreq = dreq; + get_dreq(dreq); + inode_dio_begin(inode); + + NFS_I(inode)->write_io += iov_iter_count(iter); + while (iov_iter_count(iter)) { + struct page **pagevec; + size_t bytes; + size_t pgbase; + unsigned npages, i; + + result = iov_iter_get_pages_alloc(iter, &pagevec, + wsize, &pgbase); + if (result < 0) + break; + + bytes = result; + iov_iter_advance(iter, bytes); + npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE; + for (i = 0; i < npages; i++) { + struct nfs_page *req; + unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase); + + req = nfs_create_request(dreq->ctx, pagevec[i], NULL, + pgbase, req_len); + if (IS_ERR(req)) { + result = PTR_ERR(req); + break; + } + + nfs_direct_setup_mirroring(dreq, &desc, req); + if (desc.pg_error < 0) { + nfs_free_request(req); + result = desc.pg_error; + break; + } + + nfs_lock_request(req); + req->wb_index = pos >> PAGE_SHIFT; + req->wb_offset = pos & ~PAGE_MASK; + if (!nfs_pageio_add_request(&desc, req)) { + result = desc.pg_error; + nfs_unlock_and_release_request(req); + break; + } + pgbase = 0; + bytes -= req_len; + requested_bytes += req_len; + pos += req_len; + dreq->bytes_left -= req_len; + } + nfs_direct_release_pages(pagevec, npages); + kvfree(pagevec); + if (result < 0) + break; + } + nfs_pageio_complete(&desc); + + /* + * If no bytes were started, return the error, and let the + * generic layer handle the completion. + */ + if (requested_bytes == 0) { + inode_dio_end(inode); + nfs_direct_req_release(dreq); + return result < 0 ? result : -EIO; + } + + if (put_dreq(dreq)) + nfs_direct_write_complete(dreq); + return requested_bytes; +} + +/** + * nfs_file_direct_write - file direct write operation for NFS files + * @iocb: target I/O control block + * @iter: vector of user buffers from which to write data + * @swap: flag indicating this is swap IO, not O_DIRECT IO + * + * 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 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, struct iov_iter *iter, + bool swap) +{ + ssize_t result = -EINVAL, requested; + size_t count; + struct file *file = iocb->ki_filp; + struct address_space *mapping = file->f_mapping; + struct inode *inode = mapping->host; + struct nfs_direct_req *dreq; + struct nfs_lock_context *l_ctx; + loff_t pos, end; + + dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n", + file, iov_iter_count(iter), (long long) iocb->ki_pos); + + if (swap) + /* bypass generic checks */ + result = iov_iter_count(iter); + else + result = generic_write_checks(iocb, iter); + if (result <= 0) + return result; + count = result; + nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count); + + pos = iocb->ki_pos; + end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT; + + task_io_account_write(count); + + result = -ENOMEM; + dreq = nfs_direct_req_alloc(); + if (!dreq) + goto out; + + dreq->inode = inode; + dreq->bytes_left = dreq->max_count = count; + dreq->io_start = pos; + dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp)); + l_ctx = nfs_get_lock_context(dreq->ctx); + if (IS_ERR(l_ctx)) { + result = PTR_ERR(l_ctx); + nfs_direct_req_release(dreq); + goto out_release; + } + dreq->l_ctx = l_ctx; + if (!is_sync_kiocb(iocb)) + dreq->iocb = iocb; + + if (swap) { + requested = nfs_direct_write_schedule_iovec(dreq, iter, pos, + FLUSH_STABLE); + } else { + nfs_start_io_direct(inode); + + requested = nfs_direct_write_schedule_iovec(dreq, iter, pos, + FLUSH_COND_STABLE); + + if (mapping->nrpages) { + invalidate_inode_pages2_range(mapping, + pos >> PAGE_SHIFT, end); + } + + nfs_end_io_direct(inode); + } + + if (requested > 0) { + result = nfs_direct_wait(dreq); + if (result > 0) { + requested -= result; + iocb->ki_pos = pos + result; + /* XXX: should check the generic_write_sync retval */ + generic_write_sync(iocb, result); + } + iov_iter_revert(iter, requested); + } else { + result = requested; + } +out_release: + nfs_direct_req_release(dreq); +out: + return result; +} + +/** + * 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); + 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); +} |