Filipe David Borba Manana
2014-Jun-25 21:36 UTC
[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.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
---
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 6ea1546..02dc64b 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);
}
/*
--
1.9.1
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