From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EB2691FC4 for ; Sat, 3 Oct 2026 03:31:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790998299; cv=none; b=EMvlBmOJLu6JsZ34WQZZBXoEjEYfyA0DjebJ4/iYv1qxETs5OYkrB+HRYc2ZnJmA/E93Zq7TiG0Wi7wgX7weQokmAq8yPb2xMeDCdmbVa44SgpZsgcnga8dhphiRYKAz1xMiSiUCDyXZHVts0tR+iPg6Cdv4Qk7YcmV6rl2EEZ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790998299; c=relaxed/simple; bh=x+SyX/2UyUp5F/RathMEnkorgJUMPh4nptR11vCtD4Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jfS/1TY4L8LijU6BxHR72+f1gGDvYRouq3mkY/h5qPMUcRK7wuDOmezgDRodi/xk1jJt7Y7Sc2dvWL4wk1zjHgBn5LX/OcUMi0YI4cc/KhKYHouRjF6kIyeoYqTWJJoLTpcRTxdGPMfoaATWJP10ei84BK2xT39nhANWeiyJ0qM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=AQv1f6a/; arc=none smtp.client-ip=117.135.210.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="AQv1f6a/" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=pF RGHzIn+da/mBuHaNgxNy+G5bu/CnYpKU9A6UvT1V0=; b=AQv1f6a/n7FyhB74el 1OOX2CUHXhasxbGmDl6EiVnUHsEKvPf3OeGb+sK3y7ze+EXeaEQFrEv/zJkk2iPg sUdU9RCWndaaPpGx/7T+NeOZoa88dIAdqs/Py3iMLzsUK5CgFuVcZSVZBWfbMhNS oZY3P7dz+m40QQRQykhqjr3GY= Received: from czl-pc (unknown []) by gzga-smtp-mtada-g0-1 (Coremail) with SMTP id _____wCXTnLfdsBqOdNwCA--.32914S9; Sat, 03 Oct 2026 11:30:45 +0800 (CST) From: Chi Zhiling To: exfat@lists.linux.dev, linux-kernel@vger.kernel.org Cc: Yuezhang.Mo@sony.com, chenxiaosong@chenxiaosong.com, dxdt@dev.snart.me, hyc.lee@gmail.com, linkinjeon@kernel.org, liubaolin12138@163.com, sj1557.seo@samsung.com, Chi Zhiling Subject: [PATCH v2 7/7] exfat: drop i_rwsem from exfat_page_mkwrite Date: Sat, 3 Oct 2026 11:30:32 +0800 Message-ID: <20261003033032.1775311-8-chizhiling@163.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261003033032.1775311-1-chizhiling@163.com> References: <20261003033032.1775311-1-chizhiling@163.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wCXTnLfdsBqOdNwCA--.32914S9 X-Coremail-Antispam: 1Uf129KBjvJXoW7AF15Gw1UCF1UZFWkKrWDCFg_yoW8Kw4rpr y3G3yDGwsrX398Wrn7Grn5Z3WY93WrtrWxury5W3WvvrsrJ34xtFW8KrWkua1Yywn5Xw4j qF4YyrW8ZwnFg3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07UHyIUUUUUU= X-CM-SenderInfo: hfkl6xxlol0wi6rwjhhfrp/xtbC9wWhP2rAduVV+QAA35 From: Chi Zhiling exfat_page_mkwrite() takes i_rwsem with inode_trylock() and returns VM_FAULT_RETRY when that fails. The MM subsystem does not propagate VM_FAULT_RETRY from ->page_mkwrite(), so the fault still completes and the page becomes writable without exfat_page_mkwrite() ever advancing valid_size. Blocking on i_rwsem is not an option either: ->page_mkwrite() runs under mmap_lock, so waiting for i_rwsem would create an mmap_lock -> i_rwsem ordering that can deadlock. Now that valid_size is advanced under the folio lock, i_rwsem is no longer needed here. Take mapping->invalidate_lock shared, which serializes the fault against truncate, and advance valid_size after iomap_page_mkwrite() has returned the locked folio. Signed-off-by: Chi Zhiling --- fs/exfat/file.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/fs/exfat/file.c b/fs/exfat/file.c index d92997dc8eec..8eadaa7b9275 100644 --- a/fs/exfat/file.c +++ b/fs/exfat/file.c @@ -893,8 +893,9 @@ static vm_fault_t exfat_page_mkwrite(struct vm_fault *vmf) vm_fault_t ret; loff_t new_valid_size, mmap_valid_size, fault_page_start; - if (!inode_trylock(inode)) - return VM_FAULT_RETRY; + sb_start_pagefault(inode->i_sb); + file_update_time(vmf->vma->vm_file); + filemap_invalidate_lock_shared(inode->i_mapping); mmap_valid_size = ((loff_t)vmf->pgoff + 1) << PAGE_SHIFT; fault_page_start = ((loff_t)vmf->pgoff) << PAGE_SHIFT; @@ -914,8 +915,8 @@ static vm_fault_t exfat_page_mkwrite(struct vm_fault *vmf) err = exfat_zero_new_range(inode, zeroed_size, fault_page_start); if (err < 0) { - inode_unlock(inode); - return vmf_fs_error(err); + ret = vmf_fs_error(err); + goto out; } } @@ -929,17 +930,12 @@ static vm_fault_t exfat_page_mkwrite(struct vm_fault *vmf) mark_inode_dirty(inode); } - sb_start_pagefault(inode->i_sb); - file_update_time(vmf->vma->vm_file); - - filemap_invalidate_lock_shared(inode->i_mapping); ret = iomap_page_mkwrite(vmf, &exfat_iomap_ops, NULL); if (ret == VM_FAULT_LOCKED) exfat_advance_valid_size(ei, new_valid_size); - +out: filemap_invalidate_unlock_shared(inode->i_mapping); sb_end_pagefault(inode->i_sb); - inode_unlock(inode); return ret; } -- 2.53.0