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].

Link: https://lore.kernel.org/CAHk-=wim6VGnxQmjfK_tDg6fbHYKL4EFkmnTjVr9QnRqjDBAeA@mail.gmail.com/
Link: https://lkml.kernel.org/r/20220119202934.26495-1-ailiop@suse.com
Signed-off-by: Anthony Iliopoulos <ailiop@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/namespace.c b/fs/namespace.c
index de6fae8..0044fee 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2597,6 +2597,7 @@ 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);
@@ -2611,6 +2612,7 @@ 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 8b5c486..ca9445f 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1440,6 +1440,7 @@ 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 {