From 6685c5e2d1acae8e7d3b63b1a205f58420ce7150 Mon Sep 17 00:00:00 2001 From: Pavel Shilovsky Date: Tue, 25 Apr 2017 11:52:30 -0700 Subject: CIFS: Add asynchronous read support through kernel AIO This patch adds support to process read calls passed by io_submit() asynchronously. It based on the previously introduced async context that allows to process i/o responses in a separate thread and return the caller immediately for asynchronous calls. This improves reading performance of single threaded applications with increasing of i/o queue depth size. Signed-off-by: Pavel Shilovsky Signed-off-by: Steve French --- fs/cifs/cifsglob.h | 1 + fs/cifs/file.c | 169 ++++++++++++++++++++++++++++++++++++++++------------- 2 files changed, 131 insertions(+), 39 deletions(-) (limited to 'fs/cifs') diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index bb412261d601..9438c7cd8dc7 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -1140,6 +1140,7 @@ struct cifs_readdata { struct completion done; struct cifsFileInfo *cfile; struct address_space *mapping; + struct cifs_aio_ctx *ctx; __u64 offset; unsigned int bytes; unsigned int got_bytes; diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 21d404535739..9564e2cb4a06 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -2859,6 +2859,7 @@ cifs_uncached_readdata_release(struct kref *refcount) struct cifs_readdata, refcount); unsigned int i; + kref_put(&rdata->ctx->refcount, cifs_aio_ctx_release); for (i = 0; i < rdata->nr_pages; i++) { put_page(rdata->pages[i]); rdata->pages[i] = NULL; @@ -2900,6 +2901,8 @@ cifs_readdata_to_iov(struct cifs_readdata *rdata, struct iov_iter *iter) return remaining ? -EFAULT : 0; } +static void collect_uncached_read_data(struct cifs_aio_ctx *ctx); + static void cifs_uncached_readv_complete(struct work_struct *work) { @@ -2907,6 +2910,8 @@ cifs_uncached_readv_complete(struct work_struct *work) struct cifs_readdata, work); complete(&rdata->done); + collect_uncached_read_data(rdata->ctx); + /* the below call can possibly free the last ref to aio ctx */ kref_put(&rdata->refcount, cifs_uncached_readdata_release); } @@ -2973,7 +2978,8 @@ cifs_uncached_copy_into_pages(struct TCP_Server_Info *server, static int cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file, - struct cifs_sb_info *cifs_sb, struct list_head *rdata_list) + struct cifs_sb_info *cifs_sb, struct list_head *rdata_list, + struct cifs_aio_ctx *ctx) { struct cifs_readdata *rdata; unsigned int npages, rsize, credits; @@ -3020,6 +3026,8 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file, rdata->read_into_pages = cifs_uncached_read_into_pages; rdata->copy_into_pages = cifs_uncached_copy_into_pages; rdata->credits = credits; + rdata->ctx = ctx; + kref_get(&ctx->refcount); if (!rdata->cfile->invalidHandle || !(rc = cifs_reopen_file(rdata->cfile, true))) @@ -3042,50 +3050,37 @@ error: return rc; } -ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to) +static void +collect_uncached_read_data(struct cifs_aio_ctx *ctx) { - struct file *file = iocb->ki_filp; - ssize_t rc; - size_t len; - ssize_t total_read = 0; - loff_t offset = iocb->ki_pos; + struct cifs_readdata *rdata, *tmp; + struct iov_iter *to = &ctx->iter; struct cifs_sb_info *cifs_sb; struct cifs_tcon *tcon; - struct cifsFileInfo *open_file; - struct cifs_readdata *rdata, *tmp; - struct list_head rdata_list; - - len = iov_iter_count(to); - if (!len) - return 0; + unsigned int i; + int rc; - INIT_LIST_HEAD(&rdata_list); - cifs_sb = CIFS_FILE_SB(file); - open_file = file->private_data; - tcon = tlink_tcon(open_file->tlink); + tcon = tlink_tcon(ctx->cfile->tlink); + cifs_sb = CIFS_SB(ctx->cfile->dentry->d_sb); - if (!tcon->ses->server->ops->async_readv) - return -ENOSYS; + mutex_lock(&ctx->aio_mutex); - if ((file->f_flags & O_ACCMODE) == O_WRONLY) - cifs_dbg(FYI, "attempting read on write only file instance\n"); - - rc = cifs_send_async_read(offset, len, open_file, cifs_sb, &rdata_list); - - /* if at least one read request send succeeded, then reset rc */ - if (!list_empty(&rdata_list)) - rc = 0; + if (list_empty(&ctx->list)) { + mutex_unlock(&ctx->aio_mutex); + return; + } - len = iov_iter_count(to); + rc = ctx->rc; /* the loop below should proceed in the order of increasing offsets */ again: - list_for_each_entry_safe(rdata, tmp, &rdata_list, list) { + list_for_each_entry_safe(rdata, tmp, &ctx->list, list) { if (!rc) { - /* FIXME: freezable sleep too? */ - rc = wait_for_completion_killable(&rdata->done); - if (rc) - rc = -EINTR; - else if (rdata->result == -EAGAIN) { + if (!try_wait_for_completion(&rdata->done)) { + mutex_unlock(&ctx->aio_mutex); + return; + } + + if (rdata->result == -EAGAIN) { /* resend call if it's a retryable error */ struct list_head tmp_list; unsigned int got_bytes = rdata->got_bytes; @@ -3111,9 +3106,9 @@ again: rdata->offset + got_bytes, rdata->bytes - got_bytes, rdata->cfile, cifs_sb, - &tmp_list); + &tmp_list, ctx); - list_splice(&tmp_list, &rdata_list); + list_splice(&tmp_list, &ctx->list); kref_put(&rdata->refcount, cifs_uncached_readdata_release); @@ -3131,14 +3126,110 @@ again: kref_put(&rdata->refcount, cifs_uncached_readdata_release); } - total_read = len - iov_iter_count(to); + for (i = 0; i < ctx->npages; i++) { + if (ctx->should_dirty) + set_page_dirty(ctx->bv[i].bv_page); + put_page(ctx->bv[i].bv_page); + } - cifs_stats_bytes_read(tcon, total_read); + ctx->total_len = ctx->len - iov_iter_count(to); + + cifs_stats_bytes_read(tcon, ctx->total_len); /* mask nodata case */ if (rc == -ENODATA) rc = 0; + ctx->rc = (rc == 0) ? ctx->total_len : rc; + + mutex_unlock(&ctx->aio_mutex); + + if (ctx->iocb && ctx->iocb->ki_complete) + ctx->iocb->ki_complete(ctx->iocb, ctx->rc, 0); + else + complete(&ctx->done); +} + +ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to) +{ + struct file *file = iocb->ki_filp; + ssize_t rc; + size_t len; + ssize_t total_read = 0; + loff_t offset = iocb->ki_pos; + struct cifs_sb_info *cifs_sb; + struct cifs_tcon *tcon; + struct cifsFileInfo *cfile; + struct cifs_aio_ctx *ctx; + + len = iov_iter_count(to); + if (!len) + return 0; + + cifs_sb = CIFS_FILE_SB(file); + cfile = file->private_data; + tcon = tlink_tcon(cfile->tlink); + + if (!tcon->ses->server->ops->async_readv) + return -ENOSYS; + + if ((file->f_flags & O_ACCMODE) == O_WRONLY) + cifs_dbg(FYI, "attempting read on write only file instance\n"); + + ctx = cifs_aio_ctx_alloc(); + if (!ctx) + return -ENOMEM; + + ctx->cfile = cifsFileInfo_get(cfile); + + if (!is_sync_kiocb(iocb)) + ctx->iocb = iocb; + + if (to->type & ITER_IOVEC) + ctx->should_dirty = true; + + rc = setup_aio_ctx_iter(ctx, to, READ); + if (rc) { + kref_put(&ctx->refcount, cifs_aio_ctx_release); + return rc; + } + + len = ctx->len; + + /* grab a lock here due to read response handlers can access ctx */ + mutex_lock(&ctx->aio_mutex); + + rc = cifs_send_async_read(offset, len, cfile, cifs_sb, &ctx->list, ctx); + + /* if at least one read request send succeeded, then reset rc */ + if (!list_empty(&ctx->list)) + rc = 0; + + mutex_unlock(&ctx->aio_mutex); + + if (rc) { + kref_put(&ctx->refcount, cifs_aio_ctx_release); + return rc; + } + + if (!is_sync_kiocb(iocb)) { + kref_put(&ctx->refcount, cifs_aio_ctx_release); + return -EIOCBQUEUED; + } + + rc = wait_for_completion_killable(&ctx->done); + if (rc) { + mutex_lock(&ctx->aio_mutex); + ctx->rc = rc = -EINTR; + total_read = ctx->total_len; + mutex_unlock(&ctx->aio_mutex); + } else { + rc = ctx->rc; + total_read = ctx->total_len; + } + + kref_put(&ctx->refcount, cifs_aio_ctx_release); + if (total_read) { iocb->ki_pos += total_read; return total_read; -- cgit