| Message ID | 1477568519-7891-1-git-send-email-guaneryu@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
diff --git a/mm/filemap.c b/mm/filemap.c index 849f459..ae9ef9a 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1734,6 +1734,8 @@ static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos, if (inode->i_blkbits == PAGE_SHIFT || !mapping->a_ops->is_partially_uptodate) goto page_not_up_to_date; + 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? */
After commit 82c156f85384 ("switch generic_file_splice_read() to use of ->read_iter()") 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. 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. Signed-off-by: Eryu Guan <guaneryu@gmail.com> --- 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. mm/filemap.c | 2 ++ 1 file changed, 2 insertions(+)