Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752477AbaDAEJh (ORCPT ); Tue, 1 Apr 2014 00:09:37 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:53820 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752450AbaDAEJe (ORCPT ); Tue, 1 Apr 2014 00:09:34 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, John Sullivan , "Theodore Tso" , Linus Torvalds Subject: [PATCH 3.13 01/22] ext4: atomically set inode->i_flags in ext4_set_inode_flags() Date: Mon, 31 Mar 2014 21:08:31 -0700 Message-Id: <20140401040703.320575581@linuxfoundation.org> X-Mailer: git-send-email 1.9.0 In-Reply-To: <20140401040703.045139933@linuxfoundation.org> References: <20140401040703.045139933@linuxfoundation.org> User-Agent: quilt/0.60-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13-stable review patch. If anyone has any objections, please let me know. ------------------ From: Theodore Ts'o commit 00a1a053ebe5febcfc2ec498bd894f035ad2aa06 upstream. Use cmpxchg() to atomically set i_flags instead of clearing out the S_IMMUTABLE, S_APPEND, etc. flags and then setting them from the EXT4_IMMUTABLE_FL, EXT4_APPEND_FL flags, since this opens up a race where an immutable file has the immutable flag cleared for a brief window of time. Reported-by: John Sullivan Signed-off-by: "Theodore Ts'o" Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/ext4/inode.c | 15 +++++++++------ include/linux/bitops.h | 15 +++++++++++++++ 2 files changed, 24 insertions(+), 6 deletions(-) --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -38,6 +38,7 @@ #include #include #include +#include #include "ext4_jbd2.h" #include "xattr.h" @@ -3926,18 +3927,20 @@ int ext4_get_inode_loc(struct inode *ino void ext4_set_inode_flags(struct inode *inode) { unsigned int flags = EXT4_I(inode)->i_flags; + unsigned int new_fl = 0; - inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC); if (flags & EXT4_SYNC_FL) - inode->i_flags |= S_SYNC; + new_fl |= S_SYNC; if (flags & EXT4_APPEND_FL) - inode->i_flags |= S_APPEND; + new_fl |= S_APPEND; if (flags & EXT4_IMMUTABLE_FL) - inode->i_flags |= S_IMMUTABLE; + new_fl |= S_IMMUTABLE; if (flags & EXT4_NOATIME_FL) - inode->i_flags |= S_NOATIME; + new_fl |= S_NOATIME; if (flags & EXT4_DIRSYNC_FL) - inode->i_flags |= S_DIRSYNC; + new_fl |= S_DIRSYNC; + set_mask_bits(&inode->i_flags, + S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC, new_fl); } /* Propagate flags from i_flags to EXT4_I(inode)->i_flags */ --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -196,6 +196,21 @@ static inline unsigned long __ffs64(u64 #ifdef __KERNEL__ +#ifndef set_mask_bits +#define set_mask_bits(ptr, _mask, _bits) \ +({ \ + const typeof(*ptr) mask = (_mask), bits = (_bits); \ + typeof(*ptr) old, new; \ + \ + do { \ + old = ACCESS_ONCE(*ptr); \ + new = (old & ~mask) | bits; \ + } while (cmpxchg(ptr, old, new) != old); \ + \ + new; \ +}) +#endif + #ifndef find_last_bit /** * find_last_bit - find the last set bit in a memory region -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/