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

From: Anthony Iliopoulos
Date: Wed Jan 19 2022 - 15:30:09 EST


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 <ailiop@xxxxxxxx>

[1] https://lore.kernel.org/CAHk-=wim6VGnxQmjfK_tDg6fbHYKL4EFkmnTjVr9QnRqjDBAeA@xxxxxxxxxxxxxx/
---
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