Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760622AbZC3UC3 (ORCPT ); Mon, 30 Mar 2009 16:02:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757971AbZC3UCT (ORCPT ); Mon, 30 Mar 2009 16:02:19 -0400 Received: from fxip-0047f.externet.hu ([88.209.222.127]:38061 "EHLO pomaz-ex.szeredi.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756724AbZC3UCR (ORCPT ); Mon, 30 Mar 2009 16:02:17 -0400 To: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org In-reply-to: (message from Miklos Szeredi on Mon, 30 Mar 2009 22:00:37 +0200) Subject: [patch 1/3] fuse: allow kernel to access "direct_io" files References: Message-Id: From: Miklos Szeredi Date: Mon, 30 Mar 2009 22:02:17 +0200 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5404 Lines: 162 From: Miklos Szeredi Allow the kernel read and write on "direct_io" files. This is necessary for nfs export and execute support. The implementation is simple: if an access from the kernel is detected, don't perform get_user_pages(), just use the kernel address provided by the requester to copy from/to the userspace filesystem. Signed-off-by: Miklos Szeredi --- fs/fuse/dir.c | 1 + fs/fuse/file.c | 53 ++++++++++++++++++++++++++++++++++++++++------------- 2 files changed, 41 insertions(+), 13 deletions(-) Index: linux-2.6/fs/fuse/file.c =================================================================== --- linux-2.6.orig/fs/fuse/file.c 2009-03-25 10:30:52.000000000 +0100 +++ linux-2.6/fs/fuse/file.c 2009-03-25 10:35:22.000000000 +0100 @@ -386,7 +386,6 @@ void fuse_read_fill(struct fuse_req *req req->in.numargs = 1; req->in.args[0].size = sizeof(struct fuse_read_in); req->in.args[0].value = inarg; - req->out.argpages = 1; req->out.argvar = 1; req->out.numargs = 1; req->out.args[0].size = count; @@ -453,6 +452,7 @@ static int fuse_readpage(struct file *fi attr_ver = fuse_get_attr_version(fc); req->out.page_zeroing = 1; + req->out.argpages = 1; req->num_pages = 1; req->pages[0] = page; num_read = fuse_send_read(req, file, inode, pos, count, NULL); @@ -510,6 +510,8 @@ static void fuse_send_readpages(struct f struct fuse_conn *fc = get_fuse_conn(inode); loff_t pos = page_offset(req->pages[0]); size_t count = req->num_pages << PAGE_CACHE_SHIFT; + + req->out.argpages = 1; req->out.page_zeroing = 1; fuse_read_fill(req, file, inode, pos, count, FUSE_READ); req->misc.read.attr_ver = fuse_get_attr_version(fc); @@ -621,7 +623,6 @@ static void fuse_write_fill(struct fuse_ inarg->flags = file ? file->f_flags : 0; req->in.h.opcode = FUSE_WRITE; req->in.h.nodeid = get_node_id(inode); - req->in.argpages = 1; req->in.numargs = 2; if (fc->minor < 9) req->in.args[0].size = FUSE_COMPAT_WRITE_IN_SIZE; @@ -695,6 +696,7 @@ static int fuse_buffered_write(struct fi if (IS_ERR(req)) return PTR_ERR(req); + req->in.argpages = 1; req->num_pages = 1; req->pages[0] = page; req->page_offset = offset; @@ -771,6 +773,7 @@ static ssize_t fuse_fill_write_pages(str size_t count = 0; int err; + req->in.argpages = 1; req->page_offset = offset; do { @@ -935,21 +938,28 @@ static void fuse_release_user_pages(stru } static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf, - unsigned nbytes, int write) + unsigned *nbytesp, int write) { + unsigned nbytes = *nbytesp; unsigned long user_addr = (unsigned long) buf; unsigned offset = user_addr & ~PAGE_MASK; int npages; - /* This doesn't work with nfsd */ - if (!current->mm) - return -EPERM; + /* Special case for kernel I/O: can copy directly into the buffer */ + if (segment_eq(get_fs(), KERNEL_DS)) { + if (write) + req->in.args[1].value = (void *) user_addr; + else + req->out.args[0].value = (void *) user_addr; + + return 0; + } nbytes = min(nbytes, (unsigned) FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT); npages = (nbytes + offset + PAGE_SIZE - 1) >> PAGE_SHIFT; npages = clamp(npages, 1, FUSE_MAX_PAGES_PER_REQ); down_read(¤t->mm->mmap_sem); - npages = get_user_pages(current, current->mm, user_addr, npages, write, + npages = get_user_pages(current, current->mm, user_addr, npages, !write, 0, req->pages, NULL); up_read(¤t->mm->mmap_sem); if (npages < 0) @@ -957,6 +967,15 @@ static int fuse_get_user_pages(struct fu req->num_pages = npages; req->page_offset = offset; + + if (write) + req->in.argpages = 1; + else + req->out.argpages = 1; + + nbytes = (req->num_pages << PAGE_SHIFT) - req->page_offset; + *nbytesp = min(*nbytesp, nbytes); + return 0; } @@ -979,15 +998,13 @@ static ssize_t fuse_direct_io(struct fil while (count) { size_t nres; - size_t nbytes_limit = min(count, nmax); - size_t nbytes; - int err = fuse_get_user_pages(req, buf, nbytes_limit, !write); + size_t nbytes = min(count, nmax); + int err = fuse_get_user_pages(req, buf, &nbytes, write); if (err) { res = err; break; } - nbytes = (req->num_pages << PAGE_SHIFT) - req->page_offset; - nbytes = min(nbytes_limit, nbytes); + if (write) nres = fuse_send_write(req, file, inode, pos, nbytes, current->files); @@ -1163,6 +1180,7 @@ static int fuse_writepage_locked(struct fuse_write_fill(req, NULL, ff, inode, page_offset(page), 0, 1); copy_highpage(tmp_page, page); + req->in.argpages = 1; req->num_pages = 1; req->pages[0] = tmp_page; req->page_offset = 0; Index: linux-2.6/fs/fuse/dir.c =================================================================== --- linux-2.6.orig/fs/fuse/dir.c 2009-03-25 10:31:06.000000000 +0100 +++ linux-2.6/fs/fuse/dir.c 2009-03-25 10:31:10.000000000 +0100 @@ -1032,6 +1032,7 @@ static int fuse_readdir(struct file *fil fuse_put_request(fc, req); return -ENOMEM; } + req->out.argpages = 1; req->num_pages = 1; req->pages[0] = page; fuse_read_fill(req, file, inode, file->f_pos, PAGE_SIZE, FUSE_READDIR); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/