From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:51088 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726116AbfGKOAT (ORCPT ); Thu, 11 Jul 2019 10:00:19 -0400 From: Jan Kara Subject: [PATCH 1/3] mm: Handle MADV_WILLNEED through vfs_fadvise() Date: Thu, 11 Jul 2019 16:00:10 +0200 Message-Id: <20190711140012.1671-2-jack@suse.cz> In-Reply-To: <20190711140012.1671-1-jack@suse.cz> References: <20190711140012.1671-1-jack@suse.cz> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: linux-fsdevel@vger.kernel.org Cc: linux-mm@kvack.org, linux-xfs@vger.kernel.org, Amir Goldstein , Boaz Harrosh , Jan Kara , stable@vger.kernel.org Currently handling of MADV_WILLNEED hint calls directly into readahead code. Handle it by calling vfs_fadvise() instead so that filesystem can use its ->fadvise() callback to acquire necessary locks or otherwise prepare for the request. Suggested-by: Amir Goldstein CC: stable@vger.kernel.org # Needed by "xfs: Fix stale data exposure when readahead races with hole punch" Signed-off-by: Jan Kara --- mm/madvise.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/mm/madvise.c b/mm/madvise.c index 628022e674a7..ae56d0ef337d 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include @@ -275,6 +276,7 @@ static long madvise_willneed(struct vm_area_struct *vma, unsigned long start, unsigned long end) { struct file *file = vma->vm_file; + loff_t offset; *prev = vma; #ifdef CONFIG_SWAP @@ -298,12 +300,20 @@ static long madvise_willneed(struct vm_area_struct *vma, return 0; } - start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; - if (end > vma->vm_end) - end = vma->vm_end; - end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; - - force_page_cache_readahead(file->f_mapping, file, start, end - start); + /* + * Filesystem's fadvise may need to take various locks. We need to + * explicitly grab a reference because the vma (and hence the + * vma's reference to the file) can go away as soon as we drop + * mmap_sem. + */ + *prev = NULL; /* tell sys_madvise we drop mmap_sem */ + get_file(file); + up_read(¤t->mm->mmap_sem); + offset = (loff_t)(start - vma->vm_start) + + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); + vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED); + fput(file); + down_read(¤t->mm->mmap_sem); return 0; } -- 2.16.4