From: David Howells <dhowells@redhat.com>
To: viro@zeniv.linux.org.uk
Cc: dhowells@redhat.com, raven@themaw.net, mszeredi@redhat.com,
christian@brauner.io, linux-api@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 04/19] vfs: Add mount change counter [ver #16]
Date: Tue, 18 Feb 2020 17:05:28 +0000 [thread overview]
Message-ID: <158204552812.3299825.2343288163181726758.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <158204549488.3299825.3783690177353088425.stgit@warthog.procyon.org.uk>
Add a change counter on each mount object so that the user can easily check
to see if a mount has changed its attributes or its children.
Future patches will:
(1) Provide this value through fsinfo() attributes.
(2) Implement a watch_mount() system call to provide a notification
interface for userspace monitoring.
Signed-off-by: David Howells <dhowells@redhat.com>
---
fs/mount.h | 22 ++++++++++++++++++++++
fs/namespace.c | 11 +++++++++++
2 files changed, 33 insertions(+)
diff --git a/fs/mount.h b/fs/mount.h
index 711a4093e475..a1625924fe81 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -72,6 +72,7 @@ struct mount {
int mnt_expiry_mark; /* true if marked for expiry */
struct hlist_head mnt_pins;
struct hlist_head mnt_stuck_children;
+ atomic_t mnt_change_counter; /* Number of changed applied */
} __randomize_layout;
#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */
@@ -153,3 +154,24 @@ static inline bool is_anon_ns(struct mnt_namespace *ns)
{
return ns->seq == 0;
}
+
+/*
+ * Type of mount topology change notification.
+ */
+enum mount_notification_subtype {
+ NOTIFY_MOUNT_NEW_MOUNT = 0, /* New mount added */
+ NOTIFY_MOUNT_UNMOUNT = 1, /* Mount removed manually */
+ NOTIFY_MOUNT_EXPIRY = 2, /* Automount expired */
+ NOTIFY_MOUNT_READONLY = 3, /* Mount R/O state changed */
+ NOTIFY_MOUNT_SETATTR = 4, /* Mount attributes changed */
+ NOTIFY_MOUNT_MOVE_FROM = 5, /* Mount moved from here */
+ NOTIFY_MOUNT_MOVE_TO = 6, /* Mount moved to here (compare op_id) */
+};
+
+static inline void notify_mount(struct mount *changed,
+ struct mount *aux,
+ enum mount_notification_subtype subtype,
+ u32 info_flags)
+{
+ atomic_inc(&changed->mnt_change_counter);
+}
diff --git a/fs/namespace.c b/fs/namespace.c
index 85b5f7bea82e..5c84aadb6aa1 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -498,6 +498,8 @@ static int mnt_make_readonly(struct mount *mnt)
smp_wmb();
mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD;
unlock_mount_hash();
+ if (ret == 0)
+ notify_mount(mnt, NULL, NOTIFY_MOUNT_READONLY, 0x10000);
return ret;
}
@@ -506,6 +508,7 @@ static int __mnt_unmake_readonly(struct mount *mnt)
lock_mount_hash();
mnt->mnt.mnt_flags &= ~MNT_READONLY;
unlock_mount_hash();
+ notify_mount(mnt, NULL, NOTIFY_MOUNT_READONLY, 0);
return 0;
}
@@ -819,6 +822,7 @@ static struct mountpoint *unhash_mnt(struct mount *mnt)
*/
static void umount_mnt(struct mount *mnt)
{
+ notify_mount(mnt->mnt_parent, mnt, NOTIFY_MOUNT_UNMOUNT, 0);
put_mountpoint(unhash_mnt(mnt));
}
@@ -1453,6 +1457,7 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
p = list_first_entry(&tmp_list, struct mount, mnt_list);
list_del_init(&p->mnt_expire);
list_del_init(&p->mnt_list);
+
ns = p->mnt_ns;
if (ns) {
ns->mounts--;
@@ -2078,7 +2083,10 @@ static int attach_recursive_mnt(struct mount *source_mnt,
lock_mount_hash();
}
if (moving) {
+ notify_mount(source_mnt->mnt_parent, source_mnt,
+ NOTIFY_MOUNT_MOVE_FROM, 0);
unhash_mnt(source_mnt);
+ notify_mount(dest_mnt, source_mnt, NOTIFY_MOUNT_MOVE_TO, 0);
attach_mnt(source_mnt, dest_mnt, dest_mp);
touch_mnt_namespace(source_mnt->mnt_ns);
} else {
@@ -2087,6 +2095,7 @@ static int attach_recursive_mnt(struct mount *source_mnt,
list_del_init(&source_mnt->mnt_ns->list);
}
mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt);
+ notify_mount(dest_mnt, source_mnt, NOTIFY_MOUNT_NEW_MOUNT, 0);
commit_tree(source_mnt);
}
@@ -2464,6 +2473,7 @@ static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags)
mnt->mnt.mnt_flags = mnt_flags;
touch_mnt_namespace(mnt->mnt_ns);
unlock_mount_hash();
+ notify_mount(mnt, NULL, NOTIFY_MOUNT_SETATTR, 0);
}
static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount *mnt)
@@ -2898,6 +2908,7 @@ void mark_mounts_for_expiry(struct list_head *mounts)
if (!xchg(&mnt->mnt_expiry_mark, 1) ||
propagate_mount_busy(mnt, 1))
continue;
+ notify_mount(mnt, NULL, NOTIFY_MOUNT_EXPIRY, 0);
list_move(&mnt->mnt_expire, &graveyard);
}
while (!list_empty(&graveyard)) {
next prev parent reply other threads:[~2020-02-18 17:05 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 17:04 [PATCH 00/19] VFS: Filesystem information and notifications [ver #16] David Howells
2020-02-18 17:05 ` [PATCH 01/19] vfs: syscall: Add fsinfo() to query filesystem information " David Howells
2020-02-19 16:31 ` Darrick J. Wong
2020-02-19 20:07 ` Jann Horn
2020-02-20 10:34 ` David Howells
2020-02-20 15:48 ` Darrick J. Wong
2020-02-20 11:03 ` David Howells
2020-02-20 14:54 ` Jann Horn
2020-02-20 15:31 ` Darrick J. Wong
2020-02-18 17:05 ` [PATCH 02/19] fsinfo: Add syscalls to other arches " David Howells
2020-02-21 14:51 ` Christian Brauner
2020-02-21 18:10 ` Geert Uytterhoeven
2020-02-18 17:05 ` [PATCH 03/19] fsinfo: Provide a bitmap of supported features " David Howells
2020-02-19 16:37 ` Darrick J. Wong
2020-02-20 12:22 ` David Howells
2020-02-18 17:05 ` David Howells [this message]
2020-02-21 14:48 ` [PATCH 04/19] vfs: Add mount change counter " Christian Brauner
2020-02-18 17:05 ` [PATCH 05/19] vfs: Introduce a non-repeating system-unique superblock ID " David Howells
2020-02-19 16:53 ` Darrick J. Wong
2020-02-20 12:45 ` David Howells
2020-02-18 17:05 ` [PATCH 06/19] vfs: Allow fsinfo() to look up a mount object by " David Howells
2020-02-21 15:09 ` Christian Brauner
2020-02-18 17:05 ` [PATCH 07/19] vfs: Allow mount information to be queried by fsinfo() " David Howells
2020-02-18 17:05 ` [PATCH 08/19] vfs: fsinfo sample: Mount listing program " David Howells
2020-02-18 17:06 ` [PATCH 09/19] fsinfo: Allow the mount topology propogation flags to be retrieved " David Howells
2020-02-18 17:06 ` [PATCH 10/19] fsinfo: Add API documentation " David Howells
2020-02-18 17:06 ` [PATCH 11/19] afs: Support fsinfo() " David Howells
2020-02-19 21:01 ` Jann Horn
2020-02-20 12:58 ` David Howells
2020-02-20 14:58 ` Jann Horn
2020-02-21 13:26 ` David Howells
2020-02-18 17:06 ` [PATCH 12/19] security: Add hooks to rule on setting a superblock or mount watch " David Howells
2020-02-18 17:06 ` [PATCH 13/19] vfs: Add a mount-notification facility " David Howells
2020-02-19 22:40 ` Jann Horn
2020-02-19 22:55 ` Jann Horn
2020-02-21 12:24 ` David Howells
2020-02-21 15:49 ` Jann Horn
2020-02-21 17:06 ` David Howells
2020-02-21 17:36 ` seq_lock and lockdep_is_held() assertions Jann Horn
2020-02-21 18:02 ` John Stultz
2020-02-18 17:06 ` [PATCH 14/19] notifications: sample: Display mount tree change notifications [ver #16] David Howells
2020-02-18 17:06 ` [PATCH 15/19] vfs: Add superblock " David Howells
2020-02-19 23:08 ` Jann Horn
2020-02-21 14:23 ` David Howells
2020-02-21 15:44 ` Jann Horn
2020-02-21 16:33 ` David Howells
2020-02-21 16:41 ` Jann Horn
2020-02-21 17:11 ` David Howells
2020-02-18 17:06 ` [PATCH 16/19] fsinfo: Provide superblock notification counter " David Howells
2020-02-18 17:07 ` [PATCH 17/19] notifications: sample: Display superblock notifications " David Howells
2020-02-18 17:07 ` [PATCH 18/19] ext4: Add example fsinfo information " David Howells
2020-02-19 17:04 ` Darrick J. Wong
2020-02-20 0:53 ` kbuild test robot
2020-02-21 14:43 ` David Howells
2020-02-21 16:26 ` Darrick J. Wong
2020-02-18 17:07 ` [PATCH 19/19] nfs: Add example filesystem " David Howells
2020-02-20 2:13 ` kbuild test robot
2020-02-20 2:20 ` kbuild test robot
2020-02-18 18:12 ` David Howells
2020-02-19 10:23 ` [PATCH 00/19] VFS: Filesystem information and notifications " Stefan Metzmacher
2020-02-19 14:46 ` Christian Brauner
2020-02-19 15:50 ` Darrick J. Wong
2020-02-20 4:42 ` Ian Kent
2020-02-20 9:09 ` Christian Brauner
2020-02-20 11:30 ` Ian Kent
2020-02-19 16:16 ` David Howells
2020-02-21 12:57 ` David Howells
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