* [PATCH] libext2fs: Always swab MMP block on BE machines
@ 2011-09-30 19:41 Darrick J. Wong
2011-09-30 21:09 ` Andreas Dilger
2011-09-30 23:03 ` Ted Ts'o
0 siblings, 2 replies; 3+ messages in thread
From: Darrick J. Wong @ 2011-09-30 19:41 UTC (permalink / raw)
To: Theodore Ts'o; +Cc: linux-ext4
The MMP code in libext2fs tries to gate MMP block swab'ing with this test:
#ifdef EXT2FS_ENABLE_SWAPFS
if (fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC))
However, EXT2FS_ENABLE_SWAPFS never seems to be defined anywhere (all possible
#define's were cleaned out of e2fsprogs ages ago), and even if any still
existed, the field fs->super->s_magic is always in host byteorder, so the test
always fails. So, we can change the #ifdef to WORDS_BIGENDIAN (which is
conditionally defined on BE platforms) and get rid of the broken if test.
(This fix came up while testing the metadata checksumming patchset)
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
---
lib/ext2fs/mmp.c | 15 ++++++---------
1 files changed, 6 insertions(+), 9 deletions(-)
diff --git a/lib/ext2fs/mmp.c b/lib/ext2fs/mmp.c
index ed6ee42..91f4fb2 100644
--- a/lib/ext2fs/mmp.c
+++ b/lib/ext2fs/mmp.c
@@ -91,9 +91,8 @@ errcode_t ext2fs_mmp_read(ext2_filsys fs, blk64_t mmp_blk, void *buf)
}
mmp_cmp = fs->mmp_cmp;
-#ifdef EXT2FS_ENABLE_SWAPFS
- if (fs->flags & EXT2_FLAG_SWAP_BYTES)
- ext2fs_swap_mmp(mmp_cmp);
+#ifdef WORDS_BIGENDIAN
+ ext2fs_swap_mmp(mmp_cmp);
#endif
if (buf != NULL && buf != fs->mmp_cmp)
@@ -122,18 +121,16 @@ errcode_t ext2fs_mmp_write(ext2_filsys fs, blk64_t mmp_blk, void *buf)
fs->super->s_mmp_block > ext2fs_blocks_count(fs->super))
return EXT2_ET_MMP_BAD_BLOCK;
-#ifdef EXT2FS_ENABLE_SWAPFS
- if (fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC))
- ext2fs_swap_mmp(mmp_s);
+#ifdef WORDS_BIGENDIAN
+ ext2fs_swap_mmp(mmp_s);
#endif
/* I was tempted to make this use O_DIRECT and the mmp_fd, but
* this caused no end of grief, while leaving it as-is works. */
retval = io_channel_write_blk64(fs->io, mmp_blk, -fs->blocksize, buf);
-#ifdef EXT2FS_ENABLE_SWAPFS
- if (fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC))
- ext2fs_swap_mmp(mmp_s);
+#ifdef WORDS_BIGENDIAN
+ ext2fs_swap_mmp(mmp_s);
#endif
/* Make sure the block gets to disk quickly */
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] libext2fs: Always swab MMP block on BE machines
2011-09-30 19:41 [PATCH] libext2fs: Always swab MMP block on BE machines Darrick J. Wong
@ 2011-09-30 21:09 ` Andreas Dilger
2011-09-30 23:03 ` Ted Ts'o
1 sibling, 0 replies; 3+ messages in thread
From: Andreas Dilger @ 2011-09-30 21:09 UTC (permalink / raw)
To: djwong; +Cc: Theodore Ts'o, linux-ext4
On 2011-09-30, at 1:41 PM, Darrick J. Wong wrote:
> The MMP code in libext2fs tries to gate MMP block swab'ing with this test:
>
> #ifdef EXT2FS_ENABLE_SWAPFS
> if (fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC))
We've never run Lustre on big-endian servers (clients generally work),
so it's possible this has been in our patch for years.
Thanks for the catch.
> However, EXT2FS_ENABLE_SWAPFS never seems to be defined anywhere (all possible
> #define's were cleaned out of e2fsprogs ages ago), and even if any still
> existed, the field fs->super->s_magic is always in host byteorder, so the test
> always fails. So, we can change the #ifdef to WORDS_BIGENDIAN (which is
> conditionally defined on BE platforms) and get rid of the broken if test.
>
> (This fix came up while testing the metadata checksumming patchset)
>
> Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
> ---
>
> lib/ext2fs/mmp.c | 15 ++++++---------
> 1 files changed, 6 insertions(+), 9 deletions(-)
>
> diff --git a/lib/ext2fs/mmp.c b/lib/ext2fs/mmp.c
> index ed6ee42..91f4fb2 100644
> --- a/lib/ext2fs/mmp.c
> +++ b/lib/ext2fs/mmp.c
> @@ -91,9 +91,8 @@ errcode_t ext2fs_mmp_read(ext2_filsys fs, blk64_t mmp_blk, void *buf)
> }
>
> mmp_cmp = fs->mmp_cmp;
> -#ifdef EXT2FS_ENABLE_SWAPFS
> - if (fs->flags & EXT2_FLAG_SWAP_BYTES)
> - ext2fs_swap_mmp(mmp_cmp);
> +#ifdef WORDS_BIGENDIAN
> + ext2fs_swap_mmp(mmp_cmp);
> #endif
>
> if (buf != NULL && buf != fs->mmp_cmp)
> @@ -122,18 +121,16 @@ errcode_t ext2fs_mmp_write(ext2_filsys fs, blk64_t mmp_blk, void *buf)
> fs->super->s_mmp_block > ext2fs_blocks_count(fs->super))
> return EXT2_ET_MMP_BAD_BLOCK;
>
> -#ifdef EXT2FS_ENABLE_SWAPFS
> - if (fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC))
> - ext2fs_swap_mmp(mmp_s);
> +#ifdef WORDS_BIGENDIAN
> + ext2fs_swap_mmp(mmp_s);
> #endif
>
> /* I was tempted to make this use O_DIRECT and the mmp_fd, but
> * this caused no end of grief, while leaving it as-is works. */
> retval = io_channel_write_blk64(fs->io, mmp_blk, -fs->blocksize, buf);
>
> -#ifdef EXT2FS_ENABLE_SWAPFS
> - if (fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC))
> - ext2fs_swap_mmp(mmp_s);
> +#ifdef WORDS_BIGENDIAN
> + ext2fs_swap_mmp(mmp_s);
> #endif
>
> /* Make sure the block gets to disk quickly */
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
Cheers, Andreas
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] libext2fs: Always swab MMP block on BE machines
2011-09-30 19:41 [PATCH] libext2fs: Always swab MMP block on BE machines Darrick J. Wong
2011-09-30 21:09 ` Andreas Dilger
@ 2011-09-30 23:03 ` Ted Ts'o
1 sibling, 0 replies; 3+ messages in thread
From: Ted Ts'o @ 2011-09-30 23:03 UTC (permalink / raw)
To: Darrick J. Wong; +Cc: linux-ext4
On Fri, Sep 30, 2011 at 12:41:26PM -0700, Darrick J. Wong wrote:
> The MMP code in libext2fs tries to gate MMP block swab'ing with this test:
>
> #ifdef EXT2FS_ENABLE_SWAPFS
> if (fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC))
>
> However, EXT2FS_ENABLE_SWAPFS never seems to be defined anywhere (all possible
> #define's were cleaned out of e2fsprogs ages ago), and even if any still
> existed, the field fs->super->s_magic is always in host byteorder, so the test
> always fails. So, we can change the #ifdef to WORDS_BIGENDIAN (which is
> conditionally defined on BE platforms) and get rid of the broken if test.
>
> (This fix came up while testing the metadata checksumming patchset)
>
> Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Applied, thanks.
- Ted
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2011-09-30 23:03 UTC | newest]
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2011-09-30 19:41 [PATCH] libext2fs: Always swab MMP block on BE machines Darrick J. Wong
2011-09-30 21:09 ` Andreas Dilger
2011-09-30 23:03 ` Ted Ts'o
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