linux-kernel - [f2fs-dev] [PATCH v5 2/2] f2fs: don't allow unaligned truncation to smaller/equal size on pinned file

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Message-ID: <20250630095454.3912441-2-wangzijie1@honor.com>
Date: Mon, 30 Jun 2025 17:54:54 +0800
From: wangzijie <wangzijie1@...or.com>
To: <jaegeuk@...nel.org>, <chao@...nel.org>
CC: <linux-f2fs-devel@...ts.sourceforge.net>, <linux-kernel@...r.kernel.org>,
	<bintian.wang@...or.com>, <feng.han@...or.com>, <niuzhiguo84@...il.com>,
	wangzijie <wangzijie1@...or.com>
Subject: [f2fs-dev] [PATCH v5 2/2] f2fs: don't allow unaligned truncation to smaller/equal size on pinned file

To prevent scattered pin block generation, don't allow non-section aligned truncation
to smaller or equal size on pinned file. But for truncation to larger size, after
commit 3fdd89b452c2("f2fs: prevent writing without fallocate() for pinned files"),
we only support overwrite IO to pinned file, so we don't need to consider
attr->ia_size > i_size case.
In addition, xfstests #494 assumes truncation on active swapfile(pinned) will return
ETXTBSY by setattr_prepare() -> inode_newsize_ok(), so we relocate this check after
setattr_prepare().

Signed-off-by: wangzijie <wangzijie1@...or.com>
---
v5:
- fix xfstests #494 fail
---
 fs/f2fs/file.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 78368b793..d4feea44b 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1070,6 +1070,23 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	if (err)
 		return err;
 
+	/*
+	 * To prevent scattered pin block generation, we don't allow
+	 * smaller/equal size unaligned truncation for pinned file.
+	 * We only support overwrite IO to pinned file, so don't
+	 * care about larger size truncation.
+	 * We need to check this after setattr_prepare() because xfstests
+	 * #494 assumes truncation on active swapfile(pinned) will
+	 * return ETXTBSY by setattr_prepare() -> inode_newsize_ok().
+	 */
+	if (attr->ia_valid & ATTR_SIZE) {
+		if (f2fs_is_pinned_file(inode) &&
+			attr->ia_size <= i_size_read(inode) &&
+			!IS_ALIGNED(attr->ia_size,
+			F2FS_BLK_TO_BYTES(CAP_BLKS_PER_SEC(sbi))))
+			return -EINVAL;
+	}
+
 	err = fscrypt_prepare_setattr(dentry, attr);
 	if (err)
 		return err;
-- 
2.25.1