From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f48.google.com (mail-pa0-f48.google.com [209.85.220.48]) by kanga.kvack.org (Postfix) with ESMTP id 7EF076B0255 for ; Mon, 17 Aug 2015 19:47:01 -0400 (EDT) Received: by pawq9 with SMTP id q9so20917525paw.3 for ; Mon, 17 Aug 2015 16:47:01 -0700 (PDT) Received: from mail-pa0-x22c.google.com (mail-pa0-x22c.google.com. [2607:f8b0:400e:c03::22c]) by mx.google.com with ESMTPS id ng6si26965700pdb.92.2015.08.17.16.47.00 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 17 Aug 2015 16:47:00 -0700 (PDT) Received: by pawq9 with SMTP id q9so20917309paw.3 for ; Mon, 17 Aug 2015 16:47:00 -0700 (PDT) Date: Mon, 17 Aug 2015 16:45:44 -0700 (PDT) From: Hugh Dickins Subject: [PATCH] shmem: recalculate file inode when fstat In-Reply-To: Message-ID: References: <1436558977-31712-1-git-send-email-yuzhao@google.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Yu Zhao , Hugh Dickins , linux-mm@kvack.org, linux-kernel@vger.kernel.org From: Yu Zhao Shmem uses shmem_recalc_inode to update i_blocks when it allocates page, undoes range or swaps. But mm can drop clean page without notifying shmem. This makes fstat sometimes return out-of-date block size. The problem can be partially solved when we add inode_operations->getattr which calls shmem_recalc_inode to update i_blocks for fstat. shmem_recalc_inode also updates counter used by statfs and vm_committed_as. For them the situation is not changed. They still suffer from the discrepancy after dropping clean page and before the function is called by aforementioned triggers. Signed-off-by: Yu Zhao Signed-off-by: Hugh Dickins --- mm/shmem.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/mm/shmem.c b/mm/shmem.c index 4caf8ed..37e7933 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -542,6 +542,21 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) } EXPORT_SYMBOL_GPL(shmem_truncate_range); +static int shmem_getattr(struct vfsmount *mnt, struct dentry *dentry, + struct kstat *stat) +{ + struct inode *inode = dentry->d_inode; + struct shmem_inode_info *info = SHMEM_I(inode); + + spin_lock(&info->lock); + shmem_recalc_inode(inode); + spin_unlock(&info->lock); + + generic_fillattr(inode, stat); + + return 0; +} + static int shmem_setattr(struct dentry *dentry, struct iattr *attr) { struct inode *inode = d_inode(dentry); @@ -3122,6 +3137,7 @@ static const struct file_operations shmem_file_operations = { }; static const struct inode_operations shmem_inode_operations = { + .getattr = shmem_getattr, .setattr = shmem_setattr, #ifdef CONFIG_TMPFS_XATTR .setxattr = shmem_setxattr, -- 2.4.3.573.g4eafbef -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org