2022-01-21 20:03:23

by Anthony Iliopoulos

[permalink] [raw]
Subject: [PATCH RESEND] mount: warn only once about timestamp range expiration

Commit f8b92ba67c5d ("mount: Add mount warning for impending timestamp
expiry") introduced a mount warning regarding filesystem timestamp
limits, that is printed upon each writable mount or remount.

This can result in a lot of unnecessary messages in the kernel log in
setups where filesystems are being frequently remounted (or mounted
multiple times).

Avoid this by setting a superblock flag which indicates that the warning
has been emitted at least once for any particular mount, as suggested in
[1].

Signed-off-by: Anthony Iliopoulos <[email protected]>

[1] https://lore.kernel.org/CAHk-=wim6VGnxQmjfK_tDg6fbHYKL4EFkmnTjVr9QnRqjDBAeA@mail.gmail.com/
---
fs/namespace.c | 2 ++
include/linux/fs.h | 1 +
2 files changed, 3 insertions(+)

diff --git a/fs/namespace.c b/fs/namespace.c
index c6feb92209a6..fec0f79aa2eb 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2583,6 +2583,7 @@ static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount *
struct super_block *sb = mnt->mnt_sb;

if (!__mnt_is_readonly(mnt) &&
+ (!(sb->s_iflags & SB_I_TS_EXPIRY_WARNED)) &&
(ktime_get_real_seconds() + TIME_UPTIME_SEC_MAX > sb->s_time_max)) {
char *buf = (char *)__get_free_page(GFP_KERNEL);
char *mntpath = buf ? d_path(mountpoint, buf, PAGE_SIZE) : ERR_PTR(-ENOMEM);
@@ -2597,6 +2598,7 @@ static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount *
tm.tm_year+1900, (unsigned long long)sb->s_time_max);

free_page((unsigned long)buf);
+ sb->s_iflags |= SB_I_TS_EXPIRY_WARNED;
}
}

diff --git a/include/linux/fs.h b/include/linux/fs.h
index f3daaea16554..5c537cd9b006 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1435,6 +1435,7 @@ extern int send_sigurg(struct fown_struct *fown);

#define SB_I_SKIP_SYNC 0x00000100 /* Skip superblock at global sync */
#define SB_I_PERSB_BDI 0x00000200 /* has a per-sb bdi */
+#define SB_I_TS_EXPIRY_WARNED 0x00000400 /* warned about timestamp range expiry */

/* Possible states of 'frozen' field */
enum {
--
2.34.1


2022-01-21 21:12:16

by Christian Brauner

[permalink] [raw]
Subject: Re: [PATCH RESEND] mount: warn only once about timestamp range expiration

On Wed, Jan 19, 2022 at 09:29:34PM +0100, Anthony Iliopoulos wrote:
> Commit f8b92ba67c5d ("mount: Add mount warning for impending timestamp
> expiry") introduced a mount warning regarding filesystem timestamp
> limits, that is printed upon each writable mount or remount.
>
> This can result in a lot of unnecessary messages in the kernel log in
> setups where filesystems are being frequently remounted (or mounted
> multiple times).
>
> Avoid this by setting a superblock flag which indicates that the warning
> has been emitted at least once for any particular mount, as suggested in
> [1].
>
> Signed-off-by: Anthony Iliopoulos <[email protected]>
>
> [1] https://lore.kernel.org/CAHk-=wim6VGnxQmjfK_tDg6fbHYKL4EFkmnTjVr9QnRqjDBAeA@mail.gmail.com/
> ---

Acked-by: Christian Brauner <[email protected]>

2022-01-21 22:29:40

by Darrick J. Wong

[permalink] [raw]
Subject: Re: [PATCH RESEND] mount: warn only once about timestamp range expiration

On Wed, Jan 19, 2022 at 09:29:34PM +0100, Anthony Iliopoulos wrote:
> Commit f8b92ba67c5d ("mount: Add mount warning for impending timestamp
> expiry") introduced a mount warning regarding filesystem timestamp
> limits, that is printed upon each writable mount or remount.
>
> This can result in a lot of unnecessary messages in the kernel log in
> setups where filesystems are being frequently remounted (or mounted
> multiple times).
>
> Avoid this by setting a superblock flag which indicates that the warning
> has been emitted at least once for any particular mount, as suggested in
> [1].
>
> Signed-off-by: Anthony Iliopoulos <[email protected]>

I'm glad someone finally turned down the volume on this.
Reviewed-by: Darrick J. Wong <[email protected]>

--D

>
> [1] https://lore.kernel.org/CAHk-=wim6VGnxQmjfK_tDg6fbHYKL4EFkmnTjVr9QnRqjDBAeA@mail.gmail.com/
> ---
> fs/namespace.c | 2 ++
> include/linux/fs.h | 1 +
> 2 files changed, 3 insertions(+)
>
> diff --git a/fs/namespace.c b/fs/namespace.c
> index c6feb92209a6..fec0f79aa2eb 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -2583,6 +2583,7 @@ static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount *
> struct super_block *sb = mnt->mnt_sb;
>
> if (!__mnt_is_readonly(mnt) &&
> + (!(sb->s_iflags & SB_I_TS_EXPIRY_WARNED)) &&
> (ktime_get_real_seconds() + TIME_UPTIME_SEC_MAX > sb->s_time_max)) {
> char *buf = (char *)__get_free_page(GFP_KERNEL);
> char *mntpath = buf ? d_path(mountpoint, buf, PAGE_SIZE) : ERR_PTR(-ENOMEM);
> @@ -2597,6 +2598,7 @@ static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount *
> tm.tm_year+1900, (unsigned long long)sb->s_time_max);
>
> free_page((unsigned long)buf);
> + sb->s_iflags |= SB_I_TS_EXPIRY_WARNED;
> }
> }
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index f3daaea16554..5c537cd9b006 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1435,6 +1435,7 @@ extern int send_sigurg(struct fown_struct *fown);
>
> #define SB_I_SKIP_SYNC 0x00000100 /* Skip superblock at global sync */
> #define SB_I_PERSB_BDI 0x00000200 /* has a per-sb bdi */
> +#define SB_I_TS_EXPIRY_WARNED 0x00000400 /* warned about timestamp range expiry */
>
> /* Possible states of 'frozen' field */
> enum {
> --
> 2.34.1
>

2022-02-01 15:17:44

by Al Viro

[permalink] [raw]
Subject: Re: [PATCH RESEND] mount: warn only once about timestamp range expiration

On Wed, Jan 19, 2022 at 09:29:34PM +0100, Anthony Iliopoulos wrote:
> Commit f8b92ba67c5d ("mount: Add mount warning for impending timestamp
> expiry") introduced a mount warning regarding filesystem timestamp
> limits, that is printed upon each writable mount or remount.
>
> This can result in a lot of unnecessary messages in the kernel log in
> setups where filesystems are being frequently remounted (or mounted
> multiple times).
>
> Avoid this by setting a superblock flag which indicates that the warning
> has been emitted at least once for any particular mount, as suggested in
> [1].

Looks sane, except for the locking rules for ->s_iflags stores...

2022-02-08 01:50:44

by Christian Kujau

[permalink] [raw]
Subject: Re: [PATCH RESEND] mount: warn only once about timestamp range expiration

> On Wed, Jan 19, 2022 at 09:29:34PM +0100, Anthony Iliopoulos wrote:
> Commit f8b92ba67c5d ("mount: Add mount warning for impending timestamp
> expiry") introduced a mount warning regarding filesystem timestamp
> limits, that is printed upon each writable mount or remount.
>
> This can result in a lot of unnecessary messages in the kernel log in
> setups where filesystems are being frequently remounted (or mounted
> multiple times).
>
> Avoid this by setting a superblock flag which indicates that the warning
> has been emitted at least once for any particular mount, as suggested in

Great! I hope this lands in mainline soon. Applied this to 5.17.0-rc3 here
and it warns on mounts, but not on remounts. Yay!

Tested-by: Christian Kujau <[email protected]>

Thanks so much for not forgetting about this!
--
BOFH excuse #402:

Secretary sent chain letter to all 5000 employees.