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authorEryu Guan <guaneryu@gmail.com>2016-11-10 10:46:35 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-11-11 08:12:37 -0800
commit60da81ea61201f43387793d1cc3f501609d922ed (patch)
tree697971fb9078e743923e4a7a2f667e67f1b673ac /mm
parent96b96a96ddee4ba08ce4aeb8a558a3271fd4a7a7 (diff)
downloadlinux-60da81ea61201f43387793d1cc3f501609d922ed.tar.bz2
mm/filemap: don't allow partially uptodate page for pipes
Starting from 4.9-rc1 kernel, I started noticing some test failures of sendfile(2) and splice(2) (sendfile0N and splice01 from LTP) when testing on sub-page block size filesystems (tested both XFS and ext4), these syscalls start to return EIO in the tests. e.g. sendfile02 1 TFAIL : sendfile02.c:133: sendfile(2) failed to return expected value, expected: 26, got: -1 sendfile02 2 TFAIL : sendfile02.c:133: sendfile(2) failed to return expected value, expected: 24, got: -1 sendfile02 3 TFAIL : sendfile02.c:133: sendfile(2) failed to return expected value, expected: 22, got: -1 sendfile02 4 TFAIL : sendfile02.c:133: sendfile(2) failed to return expected value, expected: 20, got: -1 This is because that in sub-page block size cases, we don't need the whole page to be uptodate, only the part we care about is uptodate is OK (if fs has ->is_partially_uptodate defined). But page_cache_pipe_buf_confirm() doesn't have the ability to check the partially-uptodate case, it needs the whole page to be uptodate. So it returns EIO in this case. This is a regression introduced by commit 82c156f85384 ("switch generic_file_splice_read() to use of ->read_iter()"). Prior to the change, generic_file_splice_read() doesn't allow partially-uptodate page either, so it worked fine. Fix it by skipping the partially-uptodate check if we're working on a pipe in do_generic_file_read(), so we read the whole page from disk as long as the page is not uptodate. I think the other way to fix it is to add the ability to check & allow partially-uptodate page to page_cache_pipe_buf_confirm(), but that is much harder to do and seems gain little. Link: http://lkml.kernel.org/r/1477986187-12717-1-git-send-email-guaneryu@gmail.com Signed-off-by: Eryu Guan <guaneryu@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/filemap.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index c7fe2f16503f..50b52fe51937 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1732,6 +1732,9 @@ find_page:
if (inode->i_blkbits == PAGE_SHIFT ||
!mapping->a_ops->is_partially_uptodate)
goto page_not_up_to_date;
+ /* pipes can't handle partially uptodate pages */
+ if (unlikely(iter->type & ITER_PIPE))
+ goto page_not_up_to_date;
if (!trylock_page(page))
goto page_not_up_to_date;
/* Did it get truncated before we got the lock? */