The commit is pushed to "branch-rh7-3.10.0-514.26.1.vz7.35.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-514.26.1.vz7.35.3
------>
commit 049382b868b944f91c154bab238eb94c45ce476a
Author: Konstantin Khorenko <khore...@virtuozzo.com>
Date: Fri Aug 11 18:50:12 2017 +0400
ve/fs/mount: pin mnt to a VE for correct number of mounts accounting
If a mount is done in one VE context and umount - in another,
counters ve->mnt_nr became unbalanced and this can cause denial
of new mounts due to per-VE numbre of mounts limit.
Additionally move related functions to fs/namespace.c to avoid adding
fs/mount.h into ve.h:
ve_mount_nr_inc()
ve_mount_nr_dec()
ve_mount_allowed()
Example: mount is done from inside a CT, umount - from host =>
ve->mnt_nr gets incorrectly increased for a CT.
https://jira.sw.ru/browse/PSBM-69880
Signed-off-by: Konstantin Khorenko <khore...@virtuozzo.com>
Reviewed-by: Kirill Tkhai <ktk...@virtuozzo.com>
---
fs/mount.h | 3 +++
fs/namespace.c | 41 ++++++++++++++++++++++++++++++++++++++---
include/linux/ve.h | 27 +--------------------------
3 files changed, 42 insertions(+), 29 deletions(-)
diff --git a/fs/mount.h b/fs/mount.h
index 013152b..77f50cc 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -41,6 +41,9 @@ struct mount {
struct mount *mnt_master; /* slave is on master->mnt_slave_list */
struct mnt_namespace *mnt_ns; /* containing namespace */
struct mountpoint *mnt_mp; /* where is it mounted */
+#ifdef CONFIG_VE
+ struct ve_struct *ve_owner; /* VE in which this mount was created */
+#endif /* CONFIG_VE */
#ifdef CONFIG_FSNOTIFY
struct hlist_head mnt_fsnotify_marks;
__u32 mnt_fsnotify_mask;
diff --git a/fs/namespace.c b/fs/namespace.c
index f2d1f84..2cf7f9a 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -163,6 +163,10 @@ unsigned int mnt_get_count(struct mount *mnt)
#endif
}
+static inline int ve_mount_allowed(void);
+static inline void ve_mount_nr_inc(struct mount *mnt);
+static inline void ve_mount_nr_dec(struct mount *mnt);
+
static struct mount *alloc_vfsmnt(const char *name)
{
struct mount *mnt;
@@ -211,7 +215,7 @@ static struct mount *alloc_vfsmnt(const char *name)
INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks);
#endif
}
- ve_mount_nr_inc();
+ ve_mount_nr_inc(mnt);
return mnt;
#ifdef CONFIG_SMP
@@ -552,7 +556,7 @@ int sb_prepare_remount_readonly(struct super_block *sb)
static void free_vfsmnt(struct mount *mnt)
{
- ve_mount_nr_dec();
+ ve_mount_nr_dec(mnt);
kfree(mnt->mnt_devname);
mnt_free_id(mnt);
#ifdef CONFIG_SMP
@@ -2012,7 +2016,38 @@ int ve_devmnt_process(struct ve_struct *ve, dev_t dev,
void **data_pp, int remou
return err;
}
-#endif
+
+static inline int ve_mount_allowed(void)
+{
+ struct ve_struct *ve = get_exec_env();
+
+ return ve_is_super(ve) ||
+ atomic_read(&ve->mnt_nr) < (int)sysctl_ve_mount_nr;
+}
+
+static inline void ve_mount_nr_inc(struct mount *mnt)
+{
+ struct ve_struct *ve = get_exec_env();
+
+ mnt->ve_owner = get_ve(ve);
+ atomic_inc(&ve->mnt_nr);
+}
+
+static inline void ve_mount_nr_dec(struct mount *mnt)
+{
+ struct ve_struct *ve = mnt->ve_owner;
+
+ atomic_dec(&ve->mnt_nr);
+ put_ve(ve);
+ mnt->ve_owner = NULL;
+}
+
+#else /* CONFIG_VE */
+
+static inline int ve_mount_allowed(void) { return 1; }
+static inline void ve_mount_nr_inc(struct mount *mnt) { }
+static inline void ve_mount_nr_dec(struct mount *mnt) { }
+#endif /* CONFIG_VE */
static int do_check_and_remount_sb(struct super_block *sb, int flags, void
*data)
{
diff --git a/include/linux/ve.h b/include/linux/ve.h
index f430ccd..c9b0af4 100644
--- a/include/linux/ve.h
+++ b/include/linux/ve.h
@@ -119,10 +119,7 @@ struct ve_struct {
int netns_max_nr;
atomic_t netif_avail_nr;
int netif_max_nr;
- /* Number of mounts. May become unbalanced if VE0 mounts something
- * and the VE unmounts it. This is acceptable.
- */
- atomic_t mnt_nr;
+ atomic_t mnt_nr; /* number of present VE mounts */
#ifdef CONFIG_COREDUMP
char core_pattern[CORENAME_MAX_SIZE];
#endif
@@ -228,24 +225,6 @@ extern void vtty_release(struct tty_struct *tty, struct
tty_struct *o_tty,
extern bool vtty_is_master(struct tty_struct *tty);
#endif /* CONFIG_TTY */
-static inline int ve_mount_allowed(void)
-{
- struct ve_struct *ve = get_exec_env();
-
- return ve_is_super(ve) ||
- atomic_read(&ve->mnt_nr) < (int)sysctl_ve_mount_nr;
-}
-
-static inline void ve_mount_nr_inc(void)
-{
- atomic_inc(&get_exec_env()->mnt_nr);
-}
-
-static inline void ve_mount_nr_dec(void)
-{
- atomic_dec(&get_exec_env()->mnt_nr);
-}
-
#else /* CONFIG_VE */
#define ve_uevent_seqnum uevent_seqnum
@@ -279,10 +258,6 @@ static inline void monotonic_abs_to_ve(clockid_t
which_clock,
struct timespec *tp) { }
static inline void monotonic_ve_to_abs(clockid_t which_clock,
struct timepsec *tp) { }
-
-static inline int ve_mount_allowed(void) { return 1; }
-static inline void ve_mount_nr_inc(void) { }
-static inline void ve_mount_nr_dec(void) { }
#endif /* CONFIG_VE */
struct seq_file;
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