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From: Daniel Gomez <da.gomez@samsung.com>
To: "viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
	"brauner@kernel.org" <brauner@kernel.org>, "jack@suse.cz" <jack@suse.cz>,
	"hughd@google.com" <hughd@google.com>, "akpm@linux-foundation.org"
	<akpm@linux-foundation.org>
CC: "dagmcr@gmail.com" <dagmcr@gmail.com>, "linux-fsdevel@vger.kernel.org"
	<linux-fsdevel@vger.kernel.org>, "linux-kernel@vger.kernel.org"
	<linux-kernel@vger.kernel.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>,
	"willy@infradead.org" <willy@infradead.org>, "hch@infradead.org"
	<hch@infradead.org>, "mcgrof@kernel.org" <mcgrof@kernel.org>, Pankaj Raghav
	<p.raghav@samsung.com>, "gost.dev@samsung.com" <gost.dev@samsung.com>,
	Daniel Gomez <da.gomez@samsung.com>
Subject: [RFC PATCH 1/9] splice: don't check for uptodate if partially
 uptodate is impl
Thread-Topic: [RFC PATCH 1/9] splice: don't check for uptodate if partially
	uptodate is impl
Thread-Index: AQHaW2RTk/uEtIw1W0yBH2EezPFdkg==
Date: Fri, 9 Feb 2024 14:29:02 +0000
Message-ID: <20240209142901.126894-2-da.gomez@samsung.com>
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References: <20240209142901.126894-1-da.gomez@samsung.com>
	<CGME20240209142903eucas1p17f73779c6b38276cd7cefbe0a40f355e@eucas1p1.samsung.com>

From: Pankaj Raghav <p.raghav@samsung.com>

When huge_page=3Dalways is set in tmpfs, it will zero out the whole page ev=
en
if only a small part of it is written, and it updates the uptodate flag of =
the
whole huge page.

Once the per-block uptodate tracking is implemented for tmpfs hugepages,
pipe_buf_confirm only needs to check the range it needs to splice to be
uptodate and not the whole folio as we don't set uptodate flag for partial
writes.

Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Daniel Gomez <da.gomez@samsung.com>
---

Other option here is to have a separate implementation of
page_cache_pipe_buf_ops  for tmpfs instead of changing the
page_cache_pipe_buf_confirm.

 fs/splice.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/fs/splice.c b/fs/splice.c
index 218e24b1ac40..e6ac57795590 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -120,7 +120,9 @@ static int page_cache_pipe_buf_confirm(struct pipe_inod=
e_info *pipe,
 				       struct pipe_buffer *buf)
 {
 	struct folio *folio =3D page_folio(buf->page);
+	const struct address_space_operations *ops;
 	int err;
+	off_t off =3D folio_page_idx(folio, buf->page) * PAGE_SIZE + buf->offset;
=20
 	if (!folio_test_uptodate(folio)) {
 		folio_lock(folio);
@@ -134,12 +136,21 @@ static int page_cache_pipe_buf_confirm(struct pipe_in=
ode_info *pipe,
 			goto error;
 		}
=20
+		ops =3D folio->mapping->a_ops;
 		/*
 		 * Uh oh, read-error from disk.
 		 */
-		if (!folio_test_uptodate(folio)) {
-			err =3D -EIO;
-			goto error;
+		if (!ops->is_partially_uptodate) {
+			if (!folio_test_uptodate(folio)) {
+				err =3D -EIO;
+				goto error;
+			}
+		} else {
+			if (!ops->is_partially_uptodate(folio, off,
+							buf->len)) {
+				err =3D -EIO;
+				goto error;
+			}
 		}
=20
 		/* Folio is ok after all, we are done */
--=20
2.43.0