ext4: Save and restore state flags in EXT4_IOC_SETFLAGS.

From: Tao Ma <boyu.mt@taobao.com>

In commit 353eb83c we removes i_state_flags with 64-bit longs,
But in case we call EXT4_IOC_SETFLAGS, we fail to save the
high 32-bit state flags and only stores the low 32-bit back
to ei->i_flags. So the state flags are missing now in 64-bit
long architecture.

Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
---
 fs/ext4/ext4.h  |   21 +++++++++++++++++++++
 fs/ext4/ioctl.c |    3 +++
 2 files changed, 24 insertions(+), 0 deletions(-)

On 05/04/2012 11:37 PM, Tao Ma wrote:
> From: Tao Ma <boyu.mt@taobao.com>
> 
> In commit 353eb83c we removes i_state_flags with 64-bit longs,
> But in case we call EXT4_IOC_SETFLAGS, we fail to save the
> high 32-bit state flags and only stores the low 32-bit back
> to ei->i_flags. So the state flags are missing now in 64-bit
> long architecture.
> 
> Cc: "Theodore Ts'o" <tytso@mit.edu>
> Cc: stable <stable@vger.kernel.org>
> Signed-off-by: Tao Ma <boyu.mt@taobao.com>
ping?
> ---
>  fs/ext4/ext4.h  |   21 +++++++++++++++++++++
>  fs/ext4/ioctl.c |    3 +++
>  2 files changed, 24 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index ebec24a..855ddba 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1345,6 +1345,16 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
>  {
>  	(ei)->i_state_flags = 0;
>  }
> +
> +static inline unsigned long ext4_save_state_flags(struct ext4_inode_info *ei)
> +{
> +	return (ei)->i_state_flags;
> +}
> +
> +static inline void ext4_restore_state_flags(struct ext4_inode_info *ei,
> +					    unsigned long state)
> +{
> +}
>  #else
>  EXT4_INODE_BIT_FNS(state, flags, 32)
>  
> @@ -1352,6 +1362,17 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
>  {
>  	/* We depend on the fact that callers will set i_flags */
>  }
> +
> +static inline unsigned long ext4_save_state_flags(struct ext4_inode_info *ei)
> +{
> +	return (ei)->i_flags >> 32;
> +}
> +
> +static inline void ext4_restore_state_flags(struct ext4_inode_info *ei,
> +					    unsigned long state)
> +{
> +	(ei)->i_flags |= state << 32;
> +}
>  #endif
>  #else
>  /* Assume that user mode programs are passing in an ext4fs superblock, not
> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> index 6eee255..a2cc254 100644
> --- a/fs/ext4/ioctl.c
> +++ b/fs/ext4/ioctl.c
> @@ -40,6 +40,7 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>  		struct ext4_iloc iloc;
>  		unsigned int oldflags;
>  		unsigned int jflag;
> +		unsigned long state_flags;
>  
>  		if (!inode_owner_or_capable(inode))
>  			return -EACCES;
> @@ -60,6 +61,7 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>  			goto flags_out;
>  
>  		oldflags = ei->i_flags;
> +		state_flags = ext4_save_state_flags(ei);
>  
>  		/* The JOURNAL_DATA flag is modifiable only by root */
>  		jflag = flags & EXT4_JOURNAL_DATA_FL;
> @@ -118,6 +120,7 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>  		flags = flags & EXT4_FL_USER_MODIFIABLE;
>  		flags |= oldflags & ~EXT4_FL_USER_MODIFIABLE;
>  		ei->i_flags = flags;
> +		ext4_restore_state_flags(ei, state_flags);
>  
>  		ext4_set_inode_flags(inode);
>  		inode->i_ctime = ext4_current_time(inode);

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