From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794047689; b=z2Z64ts20alajsKnj4icLvst2pjgP8zfTc1yJEIBp9XYYeAkZiDz7ie4ymPnGvwEjz31 4VaIkXMn74dyjdkl7Ac53mqkDJ/cBFgrwN4hYbfFRhneuOS1ZR1L4qUjtRKPvu+gmMnmd 8zE5GOTogkwqj76o+qmvaRm95OyljfRUgJRrUAT9jgh+R6U0OI7OjsnvuD5orDA4FTYdB kePDilW3FpdnOSqasE96sKKYStFfVhwAyi/Djcghq0axNzOZgrSfEmmpQkwOkRSHeg3ZS nI1bQ+UBC7bzV6kt8+ZcvXcRjZisZMRyFTKLAr46EmIE0K/stdGXrgZlC8cIrYkXprg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794047689; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=6pjfbpmaIkZNT9Ie9TOBW4k1QfdABtMHSEwWsAxt7NU=; b=gAWqOsYaFgvIZBuk3T/G58rcVJDuFLrVzmk/OzVvqg5hMSFyBdLR/wF3r++5iEMc4pJI S7bkO90FPmGs3SaA93UxHcNOUOV0tvcvJshfWpOeGMcwbzNXt7tA0DSUXwN0hhpwXluXH 9EfDfhzryoXRXWWqOnoiajhVM7dTl55H5fMtbKLeCGyAeJTqtr6A3TUcKtwFZdB3B64y5 sSSK7dM+MDJDKc7zxJjY4AJBf42fALwA00M4rcuthm5bx2p2yjefWQWT+l4WxhjarJezZ nQUedh1eUdd9rXB1Uhs2g64/NxjDBml1381VJb1LZqGQSCLyAlsbRlT2zp7pyqc+t9g== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Nr8xCJat; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DE2EA606A32C for ; Sat, 7 Nov 2026 10:34:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Nr8xCJat Received: by smtp.kernel.org (Postfix) with ESMTPSA id 407761F0089F; Sat, 7 Nov 2026 10:34:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794047688; bh=6pjfbpmaIkZNT9Ie9TOBW4k1QfdABtMHSEwWsAxt7NU=; h=From:To:Cc:Subject:Date; b=Nr8xCJatgpKJn47+SxxV6xZUtvs8xy6obncp1RfJJ0r8Im8TO7w2rMPtrq5t9cLxb +qdtmgnWTklIPF9UcTibqfqHJrDcKABcGY9nvRziJfvj5n1xDlMj8Evn3OHZgKjSPf BtaWQ837vrYpCZky3YJbM5M/zWqa70mpTSUmjcRRKony7Ic1ODJ+vW67O06FwPYhGD n1hYmmNtuSyOREFQ9RUNv4/w/9k5hQPmbOVSE1UFUWZyVAGXtWKQoYA8r1OD6RjP/U ScBKvYb7FWXO9DB/Lib5+vvPDaRMWH0WBgca+Elk2VoBJj9raD4GgVrD3EACGKtetM r1PqpICcbzEaQ== From: Sasha Levin To: daehojeong@google.com, chao@kernel.org, jaegeuk@kernel.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] f2fs: disallow mmap write and data-modifying fallocate on atomic files" failed to apply to 6.6-stable tree Date: Sat, 7 Nov 2026 05:34:47 -0500 Message-ID: <20261107053447-failed-6.6-06dfe4a7eb69@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 06dfe4a7eb696d868b196c2a49873142f19bd862 # git commit -s git send-email --to '' --in-reply-to '20261107053447-failed-6.6-06dfe4a7eb69@kernel.org' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 06dfe4a7eb696d868b196c2a49873142f19bd862 Mon Sep 17 00:00:00 2001 From: Daeho Jeong Date: Sat, 10 Oct 2026 02:41:33 +0000 Subject: [PATCH] f2fs: disallow mmap write and data-modifying fallocate on atomic files Stores through a shared writable mapping and fallocate with FALLOC_FL_PUNCH_HOLE, FALLOC_FL_ZERO_RANGE, FALLOC_FL_COLLAPSE_RANGE or FALLOC_FL_INSERT_RANGE do not go through ->write_begin, so they bypass the COW inode and modify the original inode directly. Reject them while the file is in atomic write mode, as fallocate already does for pinned and compressed files. A write fault gets SIGBUS and fallocate gets -EOPNOTSUPP. fallocate without these flags only preallocates blocks and stays allowed. f2fs_vm_page_mkwrite() cannot take inode_lock, so check the flag under invalidate_lock, and hold invalidate_lock in f2fs_ioc_start_atomic_write() from the flush until the flag is set. Otherwise a fault could check the flag, then start_atomic_write could flush and set the flag, and the fault would dirty the folio afterwards. Cc: stable@kernel.org Fixes: 3db1de0e582c ("f2fs: change the current atomic write way") Signed-off-by: Daeho Jeong Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/file.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index d4d859dbef880..58599ab4937de 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -188,6 +188,17 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) file_update_time(vmf->vma->vm_file); filemap_invalidate_lock_shared(inode->i_mapping); + /* + * mmap stores bypass the COW inode and would break atomicity. Check + * under invalidate_lock: f2fs_ioc_start_atomic_write() holds it while + * flushing dirty folios and setting FI_ATOMIC_FILE, so either it sees + * our dirty folio and writes it back, or we see the flag. + */ + if (unlikely(f2fs_is_atomic_file(inode))) { + err = -EOPNOTSUPP; + goto out_sem; + } + folio_lock(folio); /* * A concurrent buffered write can extend isize, so we store isize in a @@ -2113,9 +2124,11 @@ static long f2fs_fallocate(struct file *file, int mode, /* * Pinned file should not support partial truncation since the block - * can be used by applications. + * can be used by applications. Atomic files should not either, since + * these modify the original inode directly and break atomicity. */ - if ((f2fs_compressed_file(inode) || f2fs_is_pinned_file(inode)) && + if ((f2fs_compressed_file(inode) || f2fs_is_pinned_file(inode) || + f2fs_is_atomic_file(inode)) && (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE | FALLOC_FL_INSERT_RANGE))) { ret = -EOPNOTSUPP; @@ -2403,6 +2416,8 @@ static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate) f2fs_down_write(&fi->i_gc_rwsem[WRITE]); f2fs_down_write(&fi->i_gc_rwsem[READ]); + /* serialize with f2fs_vm_page_mkwrite(), see the comment there */ + filemap_invalidate_lock(inode->i_mapping); /* * Should wait end_io to count F2FS_WB_CP_DATA correctly by @@ -2458,6 +2473,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate) f2fs_i_size_write(fi->cow_inode, isize); out_unlock: + filemap_invalidate_unlock(inode->i_mapping); f2fs_up_write(&fi->i_gc_rwsem[READ]); f2fs_up_write(&fi->i_gc_rwsem[WRITE]); if (ret) -- 2.53.0