From 91e0bc231805a4d47d620f0c0085f74f6f6030aa Mon Sep 17 00:00:00 2001 From: Pavel Shilovsky Date: Thu, 19 Jan 2017 13:53:15 -0800 Subject: [PATCH] CIFS: Fix splice read for non-cached files BugLink: http://bugs.launchpad.net/bugs/1672544 commit 9c25702cee1405099f982894c865c163de7909a8 upstream. Currently we call copy_page_to_iter() for uncached reading into a pipe. This is wrong because it treats pages as VFS cache pages and copies references rather than actual data. When we are trying to read from the pipe we end up calling page_cache_pipe_buf_confirm() which returns -ENODATA. This error is translated into 0 which is returned to a user. This issue is reproduced by running xfs-tests suite (generic test #249) against mount points with "cache=none". Fix it by mapping pages manually and calling copy_to_iter() that copies data into the pipe. Signed-off-by: Pavel Shilovsky Signed-off-by: Greg Kroah-Hartman Signed-off-by: Tim Gardner --- fs/cifs/file.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 2586ba1db551..98dc842e7245 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -2884,7 +2884,15 @@ cifs_readdata_to_iov(struct cifs_readdata *rdata, struct iov_iter *iter) for (i = 0; i < rdata->nr_pages; i++) { struct page *page = rdata->pages[i]; size_t copy = min_t(size_t, remaining, PAGE_SIZE); - size_t written = copy_page_to_iter(page, 0, copy, iter); + size_t written; + + if (unlikely(iter->type & ITER_PIPE)) { + void *addr = kmap_atomic(page); + + written = copy_to_iter(addr, copy, iter); + kunmap_atomic(addr); + } else + written = copy_page_to_iter(page, 0, copy, iter); remaining -= written; if (written < copy && iov_iter_count(iter) > 0) break; -- 2.39.2