[PATCH] Allow relatime to update atime once a day

Matthew Garrett
2009-03-26T17:33:11Z

Allow atime to be updated once per day even with relatime. This lets
utilities like tmpreaper (which delete files based on last access time)
continue working, making relatime a plausible default for distributions.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Reviewed-by: Matthew Wilcox <willy@linux.intel.com>
Acked-by: Valerie Aurora Henson <vaurora@redhat.com>
Acked-by: Alan Cox <alan@redhat.com>
Acked-by: Ingo Molnar <mingo@elte.hu>

---

diff --git a/fs/inode.c b/fs/inode.c
index 0487ddb..057c92b 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1179,6 +1179,40 @@ sector_t bmap(struct inode * inode, sector_t block)
}
EXPORT_SYMBOL(bmap);

+/*
+ * With relative atime, only update atime if the previous atime is
+ * earlier than either the ctime or mtime or if at least a day has
+ * passed since the last atime update.
+ */
+static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
+ struct timespec now)
+{
+
+ if (!(mnt->mnt_flags & MNT_RELATIME))
+ return 1;
+ /*
+ * Is mtime younger than atime? If yes, update atime:
+ */
+ if (timespec_compare(&inode->i_mtime, &inode->i_atime) >= 0)
+ return 1;
+ /*
+ * Is ctime younger than atime? If yes, update atime:
+ */
+ if (timespec_compare(&inode->i_ctime, &inode->i_atime) >= 0)
+ return 1;
+
+ /*
+ * Is the previous atime value older than a day? If yes,
+ * update atime:
+ */
+ if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
+ return 1;
+ /*
+ * Good, we can skip the atime update:
+ */
+ return 0;
+}
+
/**
* touch_atime - update the access time
* @mnt: mount the inode is accessed on
@@ -1206,17 +1240,12 @@ void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
goto out;
if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
goto out;
- if (mnt->mnt_flags & MNT_RELATIME) {
- /*
- * With relative atime, only update atime if the previous
- * atime is earlier than either the ctime or mtime.
- */
- if (timespec_compare(&inode->i_mtime, &inode->i_atime) < 0 &&
- timespec_compare(&inode->i_ctime, &inode->i_atime) < 0)
- goto out;
- }

now = current_fs_time(inode->i_sb);
+
+ if (!relatime_need_update(mnt, inode, now))
+ goto out;
+
if (timespec_equal(&inode->i_atime, &now))
goto out;

--
Matthew Garrett | mjg59@srcf.ucam.org