On overlayfs relatime_need_update() needs inode times to be correct on overlay inode. But i_mtime and i_ctime are updated by filesystem code on underlying inode only, so they will be out-of-date on the overlay inode.
This patch copies the times from the underlying inode if needed. This can't be done if called from RCU lookup (link following) but link m/ctime are not updated by fs, so this is all right. This patch doesn't change functionality for anything but overlayfs. Signed-off-by: Miklos Szeredi <[email protected]> --- fs/inode.c | 38 ++++++++++++++++++++++++++++++++------ 1 file changed, 32 insertions(+), 6 deletions(-) diff --git a/fs/inode.c b/fs/inode.c index 4ccbc21b30ce..6a2d447c8775 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -1534,16 +1534,36 @@ sector_t bmap(struct inode *inode, sector_t block) EXPORT_SYMBOL(bmap); /* + * Update times in overlayed inode from underlying real inode + */ +static void update_ovl_inode_times(struct dentry *dentry, struct inode *inode, + bool rcu) +{ + if (!rcu) { + struct inode *realinode = d_real_inode(dentry); + + if (unlikely(inode != realinode)) { + inode->i_mtime = realinode->i_mtime; + inode->i_ctime = realinode->i_ctime; + WARN_ON_ONCE(!timespec_equal(&inode->i_atime, + &realinode->i_atime)); + } + } +} + +/* * 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) +static int relatime_need_update(const struct path *path, struct inode *inode, + struct timespec now, bool rcu) { - if (!(mnt->mnt_flags & MNT_RELATIME)) + if (!(path->mnt->mnt_flags & MNT_RELATIME)) return 1; + + update_ovl_inode_times(path->dentry, inode, rcu); /* * Is mtime younger than atime? If yes, update atime: */ @@ -1610,7 +1630,8 @@ static int update_time(struct inode *inode, struct timespec *time, int flags) * This function automatically handles read only file systems and media, * as well as the "noatime" flag and inode specific "noatime" markers. */ -bool atime_needs_update(const struct path *path, struct inode *inode) +static bool __atime_needs_update(const struct path *path, struct inode *inode, + bool rcu) { struct vfsmount *mnt = path->mnt; struct timespec now; @@ -1629,7 +1650,7 @@ bool atime_needs_update(const struct path *path, struct inode *inode) now = current_fs_time(inode->i_sb); - if (!relatime_need_update(mnt, inode, now)) + if (!relatime_need_update(path, inode, now, rcu)) return false; if (timespec_equal(&inode->i_atime, &now)) @@ -1638,13 +1659,18 @@ bool atime_needs_update(const struct path *path, struct inode *inode) return true; } +bool atime_needs_update(const struct path *path, struct inode *inode) +{ + return __atime_needs_update(path, inode, true); +} + void touch_atime(const struct path *path) { struct vfsmount *mnt = path->mnt; struct inode *inode = d_inode(path->dentry); struct timespec now; - if (!atime_needs_update(path, inode)) + if (!__atime_needs_update(path, inode, false)) return; if (!sb_start_write_trylock(inode->i_sb)) -- 2.5.5
