[PATCH] ecryptfs: set s_time_gran to get correct time granularity

[PATCH] ecryptfs: set s_time_gran to get correct time granularity

[Frank Hsiao 蕭法宣]

related to: https://bugs.launchpad.net/ecryptfs/+bug/1890486

This bug happens in the two following situations:
cp -p: copy a file and preserve its atime and mtime
touch -r: touch a file and use a ref file's time instead of current time

In fs/attr.c notify_change(), atime and mtime is truncated by timestamp_truncate(),
ecryptfs gets wrong s_time_gran (10^9 instead of original fs time granularity) and
truncates a/mtime to whole second. Setting s_time_gran when mounting ecryptfs
 solves the issue. 

Signed-off-by: Frank Hsiao 蕭法宣 <frankhsiao@qnap.com>

diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index b2f6a1937d239..19dbe9d1187e1 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -567,6 +567,7 @@ static struct dentry *ecryptfs_mount(struct file_system_type
 *fs_type, int flags
 	s->s_blocksize = path.dentry->d_sb->s_blocksize;
 	s->s_magic = ECRYPTFS_SUPER_MAGIC;
 	s->s_stack_depth = path.dentry->d_sb->s_stack_depth + 1;
+	s->s_time_gran = path.dentry->d_sb->s_time_gran;
 
 	rc = -EINVAL;
 	if (s->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {

Re: [PATCH] ecryptfs: set s_time_gran to get correct time granularity

[Bert Wesarg]

Hi,

On 17.05.24 12:09, Frank Hsiao 蕭法宣 wrote:
> related to: https://bugs.launchpad.net/ecryptfs/+bug/1890486
> 
> This bug happens in the two following situations:
> cp -p: copy a file and preserve its atime and mtime
> touch -r: touch a file and use a ref file's time instead of current time

was there some discussion for this solution. I came to the same conclusion but cannot test it right now.

Thanks
Bert

> 
> In fs/attr.c notify_change(), atime and mtime is truncated by timestamp_truncate(),
> ecryptfs gets wrong s_time_gran (10^9 instead of original fs time granularity) and
> truncates a/mtime to whole second. Setting s_time_gran when mounting ecryptfs
>   solves the issue.
> 
> Signed-off-by: Frank Hsiao 蕭法宣 <frankhsiao@qnap.com>
> 
> diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
> index b2f6a1937d239..19dbe9d1187e1 100644
> --- a/fs/ecryptfs/main.c
> +++ b/fs/ecryptfs/main.c
> @@ -567,6 +567,7 @@ static struct dentry *ecryptfs_mount(struct file_system_type
>   *fs_type, int flags
>   	s->s_blocksize = path.dentry->d_sb->s_blocksize;
>   	s->s_magic = ECRYPTFS_SUPER_MAGIC;
>   	s->s_stack_depth = path.dentry->d_sb->s_stack_depth + 1;
> +	s->s_time_gran = path.dentry->d_sb->s_time_gran;
>   
>   	rc = -EINVAL;
>   	if (s->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {

回覆: [PATCH] ecryptfs: set s_time_gran to get correct time granularity

[Frank Hsiao 蕭法宣]

Friendly ping, thanks.

________________________________________
寄件者: Frank Hsiao 蕭法宣 <frankhsiao@qnap.com>
寄件日期: 2024年5月17日 下午 06:09
收件者: code@tyhicks.com
副本: ecryptfs@vger.kernel.org
主旨: [PATCH] ecryptfs: set s_time_gran to get correct time granularity

related to: https://bugs.launchpad.net/ecryptfs/+bug/1890486

This bug happens in the two following situations:
cp -p: copy a file and preserve its atime and mtime
touch -r: touch a file and use a ref file's time instead of current time

In fs/attr.c notify_change(), atime and mtime is truncated by timestamp_truncate(),
ecryptfs gets wrong s_time_gran (10^9 instead of original fs time granularity) and
truncates a/mtime to whole second. Setting s_time_gran when mounting ecryptfs
 solves the issue.

Signed-off-by: Frank Hsiao 蕭法宣 <frankhsiao@qnap.com>

diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index b2f6a1937d239..19dbe9d1187e1 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -567,6 +567,7 @@ static struct dentry *ecryptfs_mount(struct file_system_type
 *fs_type, int flags
        s->s_blocksize = path.dentry->d_sb->s_blocksize;
        s->s_magic = ECRYPTFS_SUPER_MAGIC;
        s->s_stack_depth = path.dentry->d_sb->s_stack_depth + 1;
+       s->s_time_gran = path.dentry->d_sb->s_time_gran;

        rc = -EINVAL;
        if (s->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {