[PATCH] VFS: Handle lazytime in do_mount()

[PATCH] VFS: Handle lazytime in do_mount()

[Markus Trippelsdorf]

Since commit e462ec50cb5fa ("VFS: Differentiate mount flags (MS_*) from
internal superblock flags") the lazytime mount option doesn't get passed
on anymore.

Fix the issue by handling the option in do_mount().

Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Markus Trippelsdorf <markus@trippelsdorf.de>
---
 fs/namespace.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 54059b142d6b..b633838b8f02 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2823,7 +2823,8 @@ long do_mount(const char *dev_name, const char __user *dir_name,
 			    SB_MANDLOCK |
 			    SB_DIRSYNC |
 			    SB_SILENT |
-			    SB_POSIXACL);
+			    SB_POSIXACL |
+			    SB_LAZYTIME);
 
 	if (flags & MS_REMOUNT)
 		retval = do_remount(&path, flags, sb_flags, mnt_flags,
-- 
Markus

Re: [PATCH] VFS: Handle lazytime in do_mount()

[Goldwyn Rodrigues]

On 10/11/2017 12:01 AM, Markus Trippelsdorf wrote:
> Since commit e462ec50cb5fa ("VFS: Differentiate mount flags (MS_*) from
> internal superblock flags") the lazytime mount option doesn't get passed
> on anymore.
> 
> Fix the issue by handling the option in do_mount().
> 
> Reviewed-by: Lukas Czerner <lczerner@redhat.com>
> Signed-off-by: Markus Trippelsdorf <markus@trippelsdorf.de>

Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

> ---
>  fs/namespace.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/namespace.c b/fs/namespace.c
> index 54059b142d6b..b633838b8f02 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -2823,7 +2823,8 @@ long do_mount(const char *dev_name, const char __user *dir_name,
>  			    SB_MANDLOCK |
>  			    SB_DIRSYNC |
>  			    SB_SILENT |
> -			    SB_POSIXACL);
> +			    SB_POSIXACL |
> +			    SB_LAZYTIME);
>  
>  	if (flags & MS_REMOUNT)
>  		retval = do_remount(&path, flags, sb_flags, mnt_flags,
> 

-- 
Goldwyn

mounting with lazytime doesn't work on ext4

[Markus Trippelsdorf]

I switched back to ext4 yesterday, because my btrfs fs got corrupted.
However mounting with lazytime doesn't work, neither specifying it in
/etc/fstab nor a manual remount. It looks like the option is simply
ignored.

Strace shows, e.g.:

 # mount -o lazytime /boot
mount("/dev/sdc2", "/boot", "ext4", MS_LAZYTIME, NULL) = 0 
EXT4-fs (sdc2): mounted filesystem with ordered data mode. Opts: (null) 
/dev/sdc2 on /boot type ext4 (rw,relatime,data=ordered)

 # mount -o remount,lazytime /var
mount("/dev/sdb2", "/var", 0x12c4460, MS_REMOUNT|MS_NOATIME|MS_LAZYTIME, NULL) = 0 
EXT4-fs (sdb2): re-mounted. Opts: (null)
/dev/sdb2 on /var type ext4 (rw,noatime,data=ordered)

When I set "sb->s_flags |= MS_LAZYTIME;" unconditionally in
fs/ext4/super.c:5057 (just deleting the if statement), then lazytime
gets used when I remount.

I'm running the latest git tree (4.14.0-rc1).

-- 
Markus

Re: mounting with lazytime doesn't work on ext4

[Markus Trippelsdorf]

On 2017.09.18 at 21:26 +0200, Markus Trippelsdorf wrote:
> I switched back to ext4 yesterday, because my btrfs fs got corrupted.
> However mounting with lazytime doesn't work, neither specifying it in
> /etc/fstab nor a manual remount. It looks like the option is simply
> ignored.
> 
> Strace shows, e.g.:
> 
>  # mount -o lazytime /boot
> mount("/dev/sdc2", "/boot", "ext4", MS_LAZYTIME, NULL) = 0 
> EXT4-fs (sdc2): mounted filesystem with ordered data mode. Opts: (null) 
> /dev/sdc2 on /boot type ext4 (rw,relatime,data=ordered)
> 
>  # mount -o remount,lazytime /var
> mount("/dev/sdb2", "/var", 0x12c4460, MS_REMOUNT|MS_NOATIME|MS_LAZYTIME, NULL) = 0 
> EXT4-fs (sdb2): re-mounted. Opts: (null)
> /dev/sdb2 on /var type ext4 (rw,noatime,data=ordered)
> 
> When I set "sb->s_flags |= MS_LAZYTIME;" unconditionally in
> fs/ext4/super.c:5057 (just deleting the if statement), then lazytime
> gets used when I remount.
> 
> I'm running the latest git tree (4.14.0-rc1).

The following patch seems to fix the issue for remounts:

diff --git a/fs/namespace.c b/fs/namespace.c
index 54059b142d6b..d0b386706c5b 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2322,6 +2322,9 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags,
 	if (err)
 		return err;
 
+	if (mnt_flags & MS_LAZYTIME)
+		sb_flags |= MS_LAZYTIME;
+
 	down_write(&sb->s_umount);
 	if (ms_flags & MS_BIND)
 		err = change_mount_flags(path->mnt, ms_flags);
@@ -2809,6 +2812,8 @@ long do_mount(const char *dev_name, const char __user *dir_name,
 		mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME);
 	if (flags & SB_RDONLY)
 		mnt_flags |= MNT_READONLY;
+	if (flags & MS_LAZYTIME)
+		mnt_flags |= MS_LAZYTIME;
 
 	/* The default atime for remount is preservation */
 	if ((flags & MS_REMOUNT) &&

-- 
Markus

[PATCH] VFS: Handle lazytime in do_mount()

[Markus Trippelsdorf]

The lazytime option didn't get passed on when using current util-linux,
which passes MS_LAZYTIME in the mountflags directly.

Fix the issue by handling the option in do_mount().

Signed-off-by: Markus Trippelsdorf <markus@trippelsdorf.de>
---
 fs/namespace.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 54059b142d6b..b633838b8f02 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2823,7 +2823,8 @@ long do_mount(const char *dev_name, const char __user *dir_name,
 			    SB_MANDLOCK |
 			    SB_DIRSYNC |
 			    SB_SILENT |
-			    SB_POSIXACL);
+			    SB_POSIXACL |
+			    MS_LAZYTIME);
 
 	if (flags & MS_REMOUNT)
 		retval = do_remount(&path, flags, sb_flags, mnt_flags,
-- 
Markus