From 38815b780285a4957852c5c9dbe94991c0b26c56 Mon Sep 17 00:00:00 2001 From: Sage Weil Date: Wed, 2 Mar 2011 16:55:21 -0800 Subject: [PATCH] libceph: fix handling of short returns from get_user_pages get_user_pages() can return fewer pages than we ask for. We were returning a bogus pointer/error code in that case. Instead, loop until we get all the pages we want or get an error we can return to the caller. Signed-off-by: Sage Weil --- net/ceph/pagevec.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/net/ceph/pagevec.c b/net/ceph/pagevec.c index 1a040e64c69f..cd9c21df87d1 100644 --- a/net/ceph/pagevec.c +++ b/net/ceph/pagevec.c @@ -16,22 +16,30 @@ struct page **ceph_get_direct_page_vector(const char __user *data, int num_pages, bool write_page) { struct page **pages; - int rc; + int got = 0; + int rc = 0; pages = kmalloc(sizeof(*pages) * num_pages, GFP_NOFS); if (!pages) return ERR_PTR(-ENOMEM); down_read(¤t->mm->mmap_sem); - rc = get_user_pages(current, current->mm, (unsigned long)data, - num_pages, write_page, 0, pages, NULL); + while (got < num_pages) { + rc = get_user_pages(current, current->mm, + (unsigned long)data + ((unsigned long)got * PAGE_SIZE), + num_pages - got, write_page, 0, pages + got, NULL); + if (rc < 0) + break; + BUG_ON(rc == 0); + got += rc; + } up_read(¤t->mm->mmap_sem); - if (rc < num_pages) + if (rc < 0) goto fail; return pages; fail: - ceph_put_page_vector(pages, rc > 0 ? rc : 0, false); + ceph_put_page_vector(pages, got, false); return ERR_PTR(rc); } EXPORT_SYMBOL(ceph_get_direct_page_vector); -- 2.30.2