linux-ext4 - Re: Correction to nanosecond timestamp patch for 64-bit arch

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Date:	Mon, 18 Jun 2007 15:39:39 +0530
From:	Kalpak Shah <kalpak@...sterfs.com>
To:	linux-ext4 <linux-ext4@...r.kernel.org>
Cc:	Andreas Dilger <adilger@...sterfs.com>,
	Mingming Cao <cmm@...ibm.com>
Subject: Re: Correction to nanosecond timestamp patch for 64-bit arch

On Sun, 2007-06-17 at 18:32 +0530, Kalpak Shah wrote:
> Index: linux-2.6.21/include/linux/ext4_fs.h
> ===================================================================
> --- linux-2.6.21.orig/include/linux/ext4_fs.h
> +++ linux-2.6.21/include/linux/ext4_fs.h
> @@ -366,9 +366,9 @@ static inline __le32 ext4_encode_extra_t
>  static inline void ext4_decode_extra_time(struct timespec *time, __le32 extra)
>  {
>         if (sizeof(time->tv_sec) > 4)
> -	       time->tv_sec |= (__u64)(le32_to_cpu(extra) & EXT4_EPOCH_MASK)
> -			       << 32;
> -       time->tv_nsec = (le32_to_cpu(extra) & EXT4_NSEC_MASK) >> 2;
> +	       time->tv_sec |= (__u64)((signed)le32_to_cpu(extra) &
> +				       EXT4_EPOCH_MASK) << 32;
> +       time->tv_nsec = ((signed)le32_to_cpu(extra) & EXT4_NSEC_MASK) >> 2;
>  }
>  

I am not too sure about the above hunk. tv_sec would not need any
(signed) cast since it is being ORed. And nsec should always lie between
0 and 1e9.

But the following patch is definitely correct and needs to be applied.

Index: linux-2.6.21/include/linux/ext4_fs.h
===================================================================
--- linux-2.6.21.orig/include/linux/ext4_fs.h
+++ linux-2.6.21/include/linux/ext4_fs.h
@@ -390,7 +390,7 @@ do {                                                                               \

 #define EXT4_INODE_GET_XTIME(xtime, inode, raw_inode)                         \
 do {                                                                          \
-       (inode)->xtime.tv_sec = le32_to_cpu((raw_inode)->xtime);               \
+       (inode)->xtime.tv_sec = (signed)le32_to_cpu((raw_inode)->xtime);       \
        if (EXT4_FITS_IN_INODE(raw_inode, EXT4_I(inode), xtime ## _extra))     \
                ext4_decode_extra_time(&(inode)->xtime,                        \
                                       raw_inode->xtime ## _extra);            \
@@ -399,7 +399,8 @@ do {                                                                               \
 #define EXT4_EINODE_GET_XTIME(xtime, einode, raw_inode)                               \
 do {                                                                          \
        if (EXT4_FITS_IN_INODE(raw_inode, einode, xtime))                      \
-               (einode)->xtime.tv_sec = le32_to_cpu((raw_inode)->xtime);      \
+               (einode)->xtime.tv_sec =                                       \
+                               (signed)le32_to_cpu((raw_inode)->xtime);       \
        if (EXT4_FITS_IN_INODE(raw_inode, einode, xtime ## _extra))            \
                ext4_decode_extra_time(&(einode)->xtime,                       \
                                       raw_inode->xtime ## _extra);            \

Thanks,
Kalpak.

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