From 8c5f9c1ab7cb45f6584ce312b14fb310a8fa28f3 Mon Sep 17 00:00:00 2001 From: Long Li Date: Wed, 31 Oct 2018 22:13:10 +0000 Subject: [PATCH] CIFS: Add support for direct I/O write With direct I/O write, user supplied buffers are pinned to the memory and data are transferred directly from user buffers to the transport layer. Change in v3: add support for kernel AIO Change in v4: Refactor common write code to __cifs_writev for direct and non-direct I/O. Retry on direct I/O failure. Signed-off-by: Long Li Signed-off-by: Steve French --- fs/cifs/cifsfs.h | 1 + fs/cifs/file.c | 204 +++++++++++++++++++++++++++++++++++++---------- 2 files changed, 164 insertions(+), 41 deletions(-) diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h index 3abea1a3f20c..4c3b5cfccc49 100644 --- a/fs/cifs/cifsfs.h +++ b/fs/cifs/cifsfs.h @@ -104,6 +104,7 @@ extern ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to); extern ssize_t cifs_direct_readv(struct kiocb *iocb, struct iov_iter *to); extern ssize_t cifs_strict_readv(struct kiocb *iocb, struct iov_iter *to); extern ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from); +extern ssize_t cifs_direct_writev(struct kiocb *iocb, struct iov_iter *from); extern ssize_t cifs_strict_writev(struct kiocb *iocb, struct iov_iter *from); extern int cifs_lock(struct file *, int, struct file_lock *); extern int cifs_fsync(struct file *, loff_t, loff_t, int); diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 1be36076e960..937ffa79066b 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -2537,6 +2537,61 @@ wdata_fill_from_iovec(struct cifs_writedata *wdata, struct iov_iter *from, return 0; } +static int +cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list, + struct cifs_aio_ctx *ctx) +{ + int wait_retry = 0; + unsigned int wsize, credits; + int rc; + struct TCP_Server_Info *server = + tlink_tcon(wdata->cfile->tlink)->ses->server; + + /* + * Try to resend this wdata, waiting for credits up to 3 seconds. + * Note: we are attempting to resend the whole wdata not in segments + */ + do { + rc = server->ops->wait_mtu_credits( + server, wdata->bytes, &wsize, &credits); + + if (rc) + break; + + if (wsize < wdata->bytes) { + add_credits_and_wake_if(server, credits, 0); + msleep(1000); + wait_retry++; + } + } while (wsize < wdata->bytes && wait_retry < 3); + + if (wsize < wdata->bytes) { + rc = -EBUSY; + goto out; + } + + rc = -EAGAIN; + while (rc == -EAGAIN) { + rc = 0; + if (wdata->cfile->invalidHandle) + rc = cifs_reopen_file(wdata->cfile, false); + if (!rc) + rc = server->ops->async_writev(wdata, + cifs_uncached_writedata_release); + } + + if (!rc) { + list_add_tail(&wdata->list, wdata_list); + return 0; + } + + add_credits_and_wake_if(server, wdata->credits, 0); +out: + kref_put(&wdata->refcount, cifs_uncached_writedata_release); + + return rc; +} + static int cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from, struct cifsFileInfo *open_file, @@ -2551,6 +2606,8 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from, loff_t saved_offset = offset; pid_t pid; struct TCP_Server_Info *server; + struct page **pagevec; + size_t start; if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD) pid = open_file->pid; @@ -2567,38 +2624,76 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from, if (rc) break; - nr_pages = get_numpages(wsize, len, &cur_len); - wdata = cifs_writedata_alloc(nr_pages, + if (ctx->direct_io) { + cur_len = iov_iter_get_pages_alloc( + from, &pagevec, wsize, &start); + if (cur_len < 0) { + cifs_dbg(VFS, + "direct_writev couldn't get user pages " + "(rc=%zd) iter type %d iov_offset %zd " + "count %zd\n", + cur_len, from->type, + from->iov_offset, from->count); + dump_stack(); + break; + } + iov_iter_advance(from, cur_len); + + nr_pages = + (cur_len + start + PAGE_SIZE - 1) / PAGE_SIZE; + + wdata = cifs_writedata_direct_alloc(pagevec, cifs_uncached_writev_complete); - if (!wdata) { - rc = -ENOMEM; - add_credits_and_wake_if(server, credits, 0); - break; - } + if (!wdata) { + rc = -ENOMEM; + add_credits_and_wake_if(server, credits, 0); + break; + } - rc = cifs_write_allocate_pages(wdata->pages, nr_pages); - if (rc) { - kfree(wdata); - add_credits_and_wake_if(server, credits, 0); - break; - } - num_pages = nr_pages; - rc = wdata_fill_from_iovec(wdata, from, &cur_len, &num_pages); - if (rc) { - for (i = 0; i < nr_pages; i++) - put_page(wdata->pages[i]); - kfree(wdata); - add_credits_and_wake_if(server, credits, 0); - break; - } + wdata->page_offset = start; + wdata->tailsz = + nr_pages > 1 ? + cur_len - (PAGE_SIZE - start) - + (nr_pages - 2) * PAGE_SIZE : + cur_len; + } else { + nr_pages = get_numpages(wsize, len, &cur_len); + wdata = cifs_writedata_alloc(nr_pages, + cifs_uncached_writev_complete); + if (!wdata) { + rc = -ENOMEM; + add_credits_and_wake_if(server, credits, 0); + break; + } - /* - * Bring nr_pages down to the number of pages we actually used, - * and free any pages that we didn't use. - */ - for ( ; nr_pages > num_pages; nr_pages--) - put_page(wdata->pages[nr_pages - 1]); + rc = cifs_write_allocate_pages(wdata->pages, nr_pages); + if (rc) { + kfree(wdata); + add_credits_and_wake_if(server, credits, 0); + break; + } + + num_pages = nr_pages; + rc = wdata_fill_from_iovec( + wdata, from, &cur_len, &num_pages); + if (rc) { + for (i = 0; i < nr_pages; i++) + put_page(wdata->pages[i]); + kfree(wdata); + add_credits_and_wake_if(server, credits, 0); + break; + } + + /* + * Bring nr_pages down to the number of pages we + * actually used, and free any pages that we didn't use. + */ + for ( ; nr_pages > num_pages; nr_pages--) + put_page(wdata->pages[nr_pages - 1]); + + wdata->tailsz = cur_len - ((nr_pages - 1) * PAGE_SIZE); + } wdata->sync_mode = WB_SYNC_ALL; wdata->nr_pages = nr_pages; @@ -2607,7 +2702,6 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from, wdata->pid = pid; wdata->bytes = cur_len; wdata->pagesz = PAGE_SIZE; - wdata->tailsz = cur_len - ((nr_pages - 1) * PAGE_SIZE); wdata->credits = credits; wdata->ctx = ctx; kref_get(&ctx->refcount); @@ -2682,13 +2776,18 @@ restart_loop: INIT_LIST_HEAD(&tmp_list); list_del_init(&wdata->list); - iov_iter_advance(&tmp_from, + if (ctx->direct_io) + rc = cifs_resend_wdata( + wdata, &tmp_list, ctx); + else { + iov_iter_advance(&tmp_from, wdata->offset - ctx->pos); - rc = cifs_write_from_iter(wdata->offset, + rc = cifs_write_from_iter(wdata->offset, wdata->bytes, &tmp_from, ctx->cfile, cifs_sb, &tmp_list, ctx); + } list_splice(&tmp_list, &ctx->list); @@ -2701,8 +2800,9 @@ restart_loop: kref_put(&wdata->refcount, cifs_uncached_writedata_release); } - for (i = 0; i < ctx->npages; i++) - put_page(ctx->bv[i].bv_page); + if (!ctx->direct_io) + for (i = 0; i < ctx->npages; i++) + put_page(ctx->bv[i].bv_page); cifs_stats_bytes_written(tcon, ctx->total_len); set_bit(CIFS_INO_INVALID_MAPPING, &CIFS_I(dentry->d_inode)->flags); @@ -2717,7 +2817,8 @@ restart_loop: complete(&ctx->done); } -ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from) +static ssize_t __cifs_writev( + struct kiocb *iocb, struct iov_iter *from, bool direct) { struct file *file = iocb->ki_filp; ssize_t total_written = 0; @@ -2726,13 +2827,18 @@ ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from) struct cifs_sb_info *cifs_sb; struct cifs_aio_ctx *ctx; struct iov_iter saved_from = *from; + size_t len = iov_iter_count(from); int rc; /* - * BB - optimize the way when signing is disabled. We can drop this - * extra memory-to-memory copying and use iovec buffers for constructing - * write request. + * iov_iter_get_pages_alloc doesn't work with ITER_KVEC. + * In this case, fall back to non-direct write function. + * this could be improved by getting pages directly in ITER_KVEC */ + if (direct && from->type & ITER_KVEC) { + cifs_dbg(FYI, "use non-direct cifs_writev for kvec I/O\n"); + direct = false; + } rc = generic_write_checks(iocb, from); if (rc <= 0) @@ -2756,10 +2862,16 @@ ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from) ctx->pos = iocb->ki_pos; - rc = setup_aio_ctx_iter(ctx, from, WRITE); - if (rc) { - kref_put(&ctx->refcount, cifs_aio_ctx_release); - return rc; + if (direct) { + ctx->direct_io = true; + ctx->iter = *from; + ctx->len = len; + } else { + rc = setup_aio_ctx_iter(ctx, from, WRITE); + if (rc) { + kref_put(&ctx->refcount, cifs_aio_ctx_release); + return rc; + } } /* grab a lock here due to read response handlers can access ctx */ @@ -2809,6 +2921,16 @@ ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from) return total_written; } +ssize_t cifs_direct_writev(struct kiocb *iocb, struct iov_iter *from) +{ + return __cifs_writev(iocb, from, true); +} + +ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from) +{ + return __cifs_writev(iocb, from, false); +} + static ssize_t cifs_writev(struct kiocb *iocb, struct iov_iter *from) { -- 2.30.2