From 7c190c8b9c0dd373cdd4d96e63306ec6e1a7115d Mon Sep 17 00:00:00 2001 From: Maxim Patlasov Date: Fri, 26 Oct 2012 19:50:29 +0400 Subject: fuse: optimize fuse_get_user_pages() Let fuse_get_user_pages() pack as many iov-s to a single fuse_req as possible. This is very beneficial in case of iov[] consisting of many iov-s of relatively small sizes (e.g. PAGE_SIZE). Signed-off-by: Maxim Patlasov Signed-off-by: Miklos Szeredi --- fs/fuse/file.c | 79 +++++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 51 insertions(+), 28 deletions(-) (limited to 'fs/fuse') diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 542ad97b103a..b2aa6c21e209 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -1047,29 +1047,37 @@ static void fuse_release_user_pages(struct fuse_req *req, int write) } } -static inline void fuse_page_descs_length_init(struct fuse_req *req) +static inline void fuse_page_descs_length_init(struct fuse_req *req, + unsigned index, unsigned nr_pages) { int i; - for (i = 0; i < req->num_pages; i++) + for (i = index; i < index + nr_pages; i++) req->page_descs[i].length = PAGE_SIZE - req->page_descs[i].offset; } +static inline unsigned long fuse_get_user_addr(const struct iov_iter *ii) +{ + return (unsigned long)ii->iov->iov_base + ii->iov_offset; +} + +static inline size_t fuse_get_frag_size(const struct iov_iter *ii, + size_t max_size) +{ + return min(iov_iter_single_seg_count(ii), max_size); +} + static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii, size_t *nbytesp, int write) { - size_t nbytes = *nbytesp; - size_t frag_size = min(iov_iter_single_seg_count(ii), nbytes); - unsigned long user_addr; - unsigned offset; - int npages; - - user_addr = (unsigned long)ii->iov->iov_base + ii->iov_offset; - offset = user_addr & ~PAGE_MASK; + size_t nbytes = 0; /* # bytes already packed in req */ /* Special case for kernel I/O: can copy directly into the buffer */ if (segment_eq(get_fs(), KERNEL_DS)) { + unsigned long user_addr = fuse_get_user_addr(ii); + size_t frag_size = fuse_get_frag_size(ii, *nbytesp); + if (write) req->in.args[1].value = (void *) user_addr; else @@ -1080,30 +1088,45 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii, return 0; } - nbytes = min_t(size_t, frag_size, FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT); - npages = (nbytes + offset + PAGE_SIZE - 1) >> PAGE_SHIFT; - npages = clamp(npages, 1, FUSE_MAX_PAGES_PER_REQ); - npages = get_user_pages_fast(user_addr, npages, !write, req->pages); - if (npages < 0) - return npages; + while (nbytes < *nbytesp && req->num_pages < FUSE_MAX_PAGES_PER_REQ) { + unsigned npages; + unsigned long user_addr = fuse_get_user_addr(ii); + unsigned offset = user_addr & ~PAGE_MASK; + size_t frag_size = fuse_get_frag_size(ii, *nbytesp - nbytes); + int ret; - req->num_pages = npages; - req->page_descs[0].offset = offset; - fuse_page_descs_length_init(req); + unsigned n = FUSE_MAX_PAGES_PER_REQ - req->num_pages; + frag_size = min_t(size_t, frag_size, n << PAGE_SHIFT); + + npages = (frag_size + offset + PAGE_SIZE - 1) >> PAGE_SHIFT; + npages = clamp(npages, 1U, n); + + ret = get_user_pages_fast(user_addr, npages, !write, + &req->pages[req->num_pages]); + if (ret < 0) + return ret; + + npages = ret; + frag_size = min_t(size_t, frag_size, + (npages << PAGE_SHIFT) - offset); + iov_iter_advance(ii, frag_size); + + req->page_descs[req->num_pages].offset = offset; + fuse_page_descs_length_init(req, req->num_pages, npages); + + req->num_pages += npages; + req->page_descs[req->num_pages - 1].length -= + (npages << PAGE_SHIFT) - offset - frag_size; + + nbytes += frag_size; + } if (write) req->in.argpages = 1; else req->out.argpages = 1; - nbytes = (req->num_pages << PAGE_SHIFT) - req->page_descs[0].offset; - - if (frag_size < nbytes) - req->page_descs[req->num_pages - 1].length -= - nbytes - frag_size; - - *nbytesp = min(frag_size, nbytes); - iov_iter_advance(ii, *nbytesp); + *nbytesp = nbytes; return 0; } @@ -1948,7 +1971,7 @@ long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg, } memcpy(req->pages, pages, sizeof(req->pages[0]) * num_pages); req->num_pages = num_pages; - fuse_page_descs_length_init(req); + fuse_page_descs_length_init(req, 0, req->num_pages); /* okay, let's send it to the client */ req->in.h.opcode = FUSE_IOCTL; -- cgit v1.2.3