From 3cc79392558f1789e5e1d2fce44b681980f403c3 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Wed, 25 Jun 2014 22:36:02 +0100 Subject: [PATCH] Btrfs: atomically set inode->i_flags in btrfs_update_iflags This change is based on the corresponding recent change for ext4: ext4: atomically set inode->i_flags in ext4_set_inode_flags() That has the following commit message that applies to btrfs as well: "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." Replacing EXT4_IMMUTABLE_FL and EXT4_APPEND_FL with BTRFS_INODE_IMMUTABLE and BTRFS_INODE_APPEND, respectively. Reviewed-by: David Sterba Reviewed-by: Satoru Takeuchi Signed-off-by: Filipe David Borba Manana Signed-off-by: Chris Mason --- fs/btrfs/ioctl.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 6ea15469c63f..02dc64bbf1cb 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -136,19 +136,22 @@ static unsigned int btrfs_flags_to_ioctl(unsigned int flags) void btrfs_update_iflags(struct inode *inode) { struct btrfs_inode *ip = BTRFS_I(inode); - - inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC); + unsigned int new_fl = 0; if (ip->flags & BTRFS_INODE_SYNC) - inode->i_flags |= S_SYNC; + new_fl |= S_SYNC; if (ip->flags & BTRFS_INODE_IMMUTABLE) - inode->i_flags |= S_IMMUTABLE; + new_fl |= S_IMMUTABLE; if (ip->flags & BTRFS_INODE_APPEND) - inode->i_flags |= S_APPEND; + new_fl |= S_APPEND; if (ip->flags & BTRFS_INODE_NOATIME) - inode->i_flags |= S_NOATIME; + new_fl |= S_NOATIME; if (ip->flags & BTRFS_INODE_DIRSYNC) - 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); } /* -- 2.20.1