[PATCH] ext3: Don't update superblock write time when filesystem is read-only

[PATCH] ext3: Don't update superblock write time when filesystem is read-only

[Theodore Ts'o]

This avoids updating the superblock write time when we are mounting
the root file system read/only but we need to replay the journal; at
that point, for people who are east of GMT and who make their clock
tick in localtime for Windows bug-for-bug compatibility, and this will
cause e2fsck to complain and force a full file system check.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
 fs/ext3/super.c |   13 ++++++++++++-
 1 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index a8d80a7..62c86af 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -2321,7 +2321,18 @@ static int ext3_commit_super(struct super_block *sb,
 
 	if (!sbh)
 		return error;
-	es->s_wtime = cpu_to_le32(get_seconds());
+	/*
+	 * If the file system is mounted read-only, don't update the
+	 * superblock write time.  This avoids updating the superblock
+	 * write time when we are mounting the root file system
+	 * read/only but we need to replay the journal; at that point,
+	 * for people who are east of GMT and who make their clock
+	 * tick in localtime for Windows bug-for-bug compatibility,
+	 * the clock is set in the future, and this will cause e2fsck
+	 * to complain and force a full file system check.
+	 */
+	if (!(sb->s_flags & MS_RDONLY))
+		es->s_wtime = cpu_to_le32(get_seconds());
 	es->s_free_blocks_count = cpu_to_le32(ext3_count_free_blocks(sb));
 	es->s_free_inodes_count = cpu_to_le32(ext3_count_free_inodes(sb));
 	BUFFER_TRACE(sbh, "marking dirty");
-- 
1.6.3.2.1.gb9f7d.dirty

Re: [PATCH] ext3: Don't update superblock write time when filesystem is read-only

[Jan Kara]

On Wed 16-09-09 11:21:13, Theodore Ts'o wrote:
> This avoids updating the superblock write time when we are mounting
> the root file system read/only but we need to replay the journal; at
> that point, for people who are east of GMT and who make their clock
> tick in localtime for Windows bug-for-bug compatibility, and this will
> cause e2fsck to complain and force a full file system check.
> 
> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  Thanks. Added to my tree.

									Honza
> ---
>  fs/ext3/super.c |   13 ++++++++++++-
>  1 files changed, 12 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/ext3/super.c b/fs/ext3/super.c
> index a8d80a7..62c86af 100644
> --- a/fs/ext3/super.c
> +++ b/fs/ext3/super.c
> @@ -2321,7 +2321,18 @@ static int ext3_commit_super(struct super_block *sb,
>  
>  	if (!sbh)
>  		return error;
> -	es->s_wtime = cpu_to_le32(get_seconds());
> +	/*
> +	 * If the file system is mounted read-only, don't update the
> +	 * superblock write time.  This avoids updating the superblock
> +	 * write time when we are mounting the root file system
> +	 * read/only but we need to replay the journal; at that point,
> +	 * for people who are east of GMT and who make their clock
> +	 * tick in localtime for Windows bug-for-bug compatibility,
> +	 * the clock is set in the future, and this will cause e2fsck
> +	 * to complain and force a full file system check.
> +	 */
> +	if (!(sb->s_flags & MS_RDONLY))
> +		es->s_wtime = cpu_to_le32(get_seconds());
>  	es->s_free_blocks_count = cpu_to_le32(ext3_count_free_blocks(sb));
>  	es->s_free_inodes_count = cpu_to_le32(ext3_count_free_inodes(sb));
>  	BUFFER_TRACE(sbh, "marking dirty");
> -- 
> 1.6.3.2.1.gb9f7d.dirty
> 
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

Re: [PATCH] ext3: Don't update superblock write time when filesystem is read-only

[Eric Sandeen]

Theodore Ts'o wrote:
> This avoids updating the superblock write time when we are mounting
> the root file system read/only but we need to replay the journal; at
> that point, for people who are east of GMT and who make their clock
> tick in localtime for Windows bug-for-bug compatibility, and this will
> cause e2fsck to complain and force a full file system check.

Just out of curiosity, why does e2fsck even care?  Why is a fairly
common & explainable time delta the trigger for a full fsck?

It seems like this solution may have some implications for forensics, etc.

Thanks,
-Eric

> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
> ---
>  fs/ext3/super.c |   13 ++++++++++++-
>  1 files changed, 12 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/ext3/super.c b/fs/ext3/super.c
> index a8d80a7..62c86af 100644
> --- a/fs/ext3/super.c
> +++ b/fs/ext3/super.c
> @@ -2321,7 +2321,18 @@ static int ext3_commit_super(struct super_block *sb,
>  
>  	if (!sbh)
>  		return error;
> -	es->s_wtime = cpu_to_le32(get_seconds());
> +	/*
> +	 * If the file system is mounted read-only, don't update the
> +	 * superblock write time.  This avoids updating the superblock
> +	 * write time when we are mounting the root file system
> +	 * read/only but we need to replay the journal; at that point,
> +	 * for people who are east of GMT and who make their clock
> +	 * tick in localtime for Windows bug-for-bug compatibility,
> +	 * the clock is set in the future, and this will cause e2fsck
> +	 * to complain and force a full file system check.
> +	 */
> +	if (!(sb->s_flags & MS_RDONLY))
> +		es->s_wtime = cpu_to_le32(get_seconds());
>  	es->s_free_blocks_count = cpu_to_le32(ext3_count_free_blocks(sb));
>  	es->s_free_inodes_count = cpu_to_le32(ext3_count_free_inodes(sb));
>  	BUFFER_TRACE(sbh, "marking dirty");