[017/227] mount: warn only once about timestamp range expiration

Commit Message

Andrew Morton March 22, 2022, 9:39 p.m. UTC

From: Anthony Iliopoulos <[e-mail]>
Subject: 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].

[1] https://lore.kernel.org/CAHk-=[e-mail]/

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Anthony Iliopoulos <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Acked-by: Christian Brauner <[e-mail]>
Reviewed-by: Darrick J. Wong <[e-mail]>
Cc: Alexander Viro <[e-mail]>
Cc: Deepa Dinamani <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 fs/namespace.c     |    2 ++
 include/linux/fs.h |    1 +
 2 files changed, 3 insertions(+)

Patch

--- a/fs/namespace.c~mount-warn-only-once-about-timestamp-range-expiration
+++ a/fs/namespace.c
@@ -2597,6 +2597,7 @@  static void mnt_warn_timestamp_expiry(st
 	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);
@@ -2611,6 +2612,7 @@  static void mnt_warn_timestamp_expiry(st
 			tm.tm_year+1900, (unsigned long long)sb->s_time_max);
 
 		free_page((unsigned long)buf);
+		sb->s_iflags |= SB_I_TS_EXPIRY_WARNED;
 	}
 }
 
--- a/include/linux/fs.h~mount-warn-only-once-about-timestamp-range-expiration
+++ a/include/linux/fs.h
@@ -1440,6 +1440,7 @@  extern int send_sigurg(struct fown_struc
 
 #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 {