Commit 598e3c8f authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

vfs: update ovl inode before relatime check 



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underlying inode only, so they will be out-of-date on the overlay inode.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: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent f2b20f6e

fs/inode.c

+27 −6
Original line number Diff line number Diff line
@@ -1535,17 +1535,37 @@ 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) &&

		    (!timespec_equal(&inode->i_mtime, &realinode->i_mtime) ||

		     !timespec_equal(&inode->i_ctime, &realinode->i_ctime))) {

			inode->i_mtime = realinode->i_mtime;

			inode->i_ctime = realinode->i_ctime;

		}

	}

}



/*

 * 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:

	 */
@@ -1612,7 +1632,8 @@ 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)

bool __atime_needs_update(const struct path *path, struct inode *inode,

			  bool rcu)

{

	struct vfsmount *mnt = path->mnt;

	struct timespec now;
@@ -1638,7 +1659,7 @@ 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))
@@ -1653,7 +1674,7 @@ void touch_atime(const struct path *path) 
	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))

fs/internal.h

+9 −0
Original line number Diff line number Diff line
@@ -120,6 +120,15 @@ extern long prune_icache_sb(struct super_block *sb, struct shrink_control *sc); 
extern void inode_add_lru(struct inode *inode);

extern int dentry_needs_remove_privs(struct dentry *dentry);



extern bool __atime_needs_update(const struct path *, struct inode *, bool);

static inline bool atime_needs_update_rcu(const struct path *path,

					  struct inode *inode)

{

	return __atime_needs_update(path, inode, true);

}



extern bool atime_needs_update_rcu(const struct path *, struct inode *);



/*

 * fs-writeback.c

 */

fs/namei.c

+1 −1
Original line number Diff line number Diff line
@@ -1015,7 +1015,7 @@ const char *get_link(struct nameidata *nd) 
	if (!(nd->flags & LOOKUP_RCU)) {

		touch_atime(&last->link);

		cond_resched();

	} else if (atime_needs_update(&last->link, inode)) {

	} else if (atime_needs_update_rcu(&last->link, inode)) {

		if (unlikely(unlazy_walk(nd, NULL, 0)))

			return ERR_PTR(-ECHILD);

		touch_atime(&last->link);

include/linux/fs.h

+0 −1
Original line number Diff line number Diff line
@@ -2007,7 +2007,6 @@ enum file_time_flags { 
	S_VERSION = 8,

};



extern bool atime_needs_update(const struct path *, struct inode *);

extern void touch_atime(const struct path *);

static inline void file_accessed(struct file *file)

{

CRA Git | Maintained and supported by SUSTech CRA and CCSE