From 9c25702cee1405099f982894c865c163de7909a8 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 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. Cc: Stable Signed-off-by: Pavel Shilovsky --- 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 18a1e1d6671f..1cd0e2eefc66 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; -- 2.20.1