From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Riabchun Date: Wed, 19 Aug 2026 09:07:40 +0000 Subject: [Devel] [PATCH VZ10 v6 3/9] ve/fs: Rework per-ve mount count In-Reply-To: References: Message-ID: <32a25abefb3fc3818b7bfb9d5d10f2a95ce88d0a.1787129389.git.vladimir.riabchun@virtuozzo.com> List-Id: Previous approach with current mounts counter had an issue: there was a gap between ve_mount_allowed check and ve_mount_nr_inc, which could allow CT to have more mounts than expected. Fix this by tracking the number of available mounts instead of current ones. This also makes resources accounting more consistent - we are using ***_avail_nr approach more. One more issue with inconsistent ve value is fixed: ve_mount_allowed always used ve from get_exec_env, but ve_mount_nr_inc operated with owner_ve. Now actual ve value is calculated in the beginning of alloc_vfsmnt. To avoid incorrect accounting when is_pseudosuper is changed, update avail_nr count without > 0 check if VE is ve0 or pseudosuper. This also simplifies ve_mount_put, since increment is now unconditional. https://virtuozzo.atlassian.net/browse/VSTOR-135520 Feature: per-ve failcounters Signed-off-by: Vladimir Riabchun --- fs/namespace.c | 71 +++++++++++++++++++++++++++------------------- include/linux/ve.h | 2 +- kernel/ve/ve.c | 12 ++++---- 3 files changed, 49 insertions(+), 36 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index 68e0efb73d7c..c9e2ab9b3b57 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -317,18 +317,21 @@ 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, struct ve_struct *ve); -static inline void ve_mount_nr_dec(struct mount *mnt); +static inline int ve_try_reserve_mount(struct ve_struct *ve); +static inline void ve_mount_put(struct mount *mnt, struct ve_struct *ve); static struct mount *alloc_vfsmnt(const char *name, struct ve_struct *owner_ve) { struct mount *mnt; + struct ve_struct *ve = owner_ve; - if (!ve_mount_allowed()) { + if (!ve) + ve = get_exec_env(); + + if (!ve_try_reserve_mount(ve)) { pr_warn_ratelimited( "CT#%s reached the limit on mounts.\n", - ve_name(get_exec_env())); + ve_name(ve)); return NULL; } @@ -336,6 +339,14 @@ static struct mount *alloc_vfsmnt(const char *name, struct ve_struct *owner_ve) if (mnt) { int err; +#ifdef CONFIG_VE + /* + * Got ve reference in ve_try_reserve_mount, set mnt ve data + * here, so in case of error ve_mount_put sees correct info. + */ + mnt->ve_owner = ve; +#endif + err = mnt_alloc_id(mnt); if (err) goto out_free_cache; @@ -370,7 +381,8 @@ static struct mount *alloc_vfsmnt(const char *name, struct ve_struct *owner_ve) INIT_LIST_HEAD(&mnt->mnt_umounting); INIT_HLIST_HEAD(&mnt->mnt_stuck_children); mnt->mnt.mnt_idmap = &nop_mnt_idmap; - ve_mount_nr_inc(mnt, owner_ve); + } else { + ve_mount_put(mnt, ve); } return mnt; @@ -381,6 +393,8 @@ static struct mount *alloc_vfsmnt(const char *name, struct ve_struct *owner_ve) out_free_id: mnt_free_id(mnt); out_free_cache: + /* Got ve reference in ve_try_reserve_mount */ + ve_mount_put(mnt, ve); kmem_cache_free(mnt_cache, mnt); return NULL; } @@ -750,7 +764,7 @@ int sb_prepare_remount_readonly(struct super_block *sb) static void free_vfsmnt(struct mount *mnt) { mnt_idmap_put(mnt_idmap(&mnt->mnt)); - ve_mount_nr_dec(mnt); + ve_mount_put(mnt, mnt->ve_owner); kfree_const(mnt->mnt_devname); #ifdef CONFIG_SMP free_percpu(mnt->mnt_pcp); @@ -3205,7 +3219,7 @@ int ve_devmnt_process(struct ve_struct *ve, dev_t dev, void **data_pp, int remou if (devmnt->dev == dev) { err = ve_devmnt_check(data, devmnt->allowed_options); /* - * In case of @is_pseudouser set, ie restore procedure, + * In case of @is_pseudosuper set, ie restore procedure, * we don't check for allowed options filtering, since * restore mode is special. */ @@ -3344,30 +3358,30 @@ int ve_devmnt_verify(struct ve_struct *ve, dev_t dev, char *opts, bool new_mount return err; } -static inline int ve_mount_allowed(void) +static inline int ve_try_reserve_mount(struct ve_struct *ve) { - struct ve_struct *ve = get_exec_env(); - - return ve_is_super(ve) || ve->is_pseudosuper || - atomic_read(&ve->mnt_nr) < (int)sysctl_ve_mount_nr; -} - -static inline void ve_mount_nr_inc(struct mount *mnt, struct ve_struct *ve) -{ - if (!ve) - ve = get_exec_env(); + int ret = ve_is_super(ve) || ve->is_pseudosuper; + /* Ignore limits in ve0 and pseudosuper cases, but still count. */ + if (ret) + atomic_dec(&ve->mnt_avail_nr); + else + ret = atomic_dec_if_positive(&ve->mnt_avail_nr) >= 0; - mnt->ve_owner = get_ve(ve); - atomic_inc(&ve->mnt_nr); + if (ret) + get_ve(ve); + return ret; } -static inline void ve_mount_nr_dec(struct mount *mnt) +static inline void ve_mount_put(struct mount *mnt, struct ve_struct *ve) { - struct ve_struct *ve = mnt->ve_owner; - - atomic_dec(&ve->mnt_nr); + /* + * ve argument is needed to reuse this function in alloc_vfsmnt error path. + * Other users should pass mnt->ve_owner value. + */ + atomic_inc(&ve->mnt_avail_nr); put_ve(ve); - mnt->ve_owner = NULL; + if (mnt) + mnt->ve_owner = NULL; } bool is_sb_ve_accessible(struct ve_struct *ve, struct super_block *sb) @@ -3389,9 +3403,8 @@ bool is_sb_ve_accessible(struct ve_struct *ve, struct super_block *sb) #else /* CONFIG_VE */ -static inline int ve_mount_allowed(void) { return 1; } -static inline void ve_mount_nr_inc(struct mount *mnt, struct ve_struct *ve) { } -static inline void ve_mount_nr_dec(struct mount *mnt) { } +static inline int ve_try_reserve_mount(struct ve_struct *ve) { return 1; } +static inline void ve_mount_put(struct mount *mnt, struct ve_struct *ve) { } #endif /* CONFIG_VE */ /* diff --git a/include/linux/ve.h b/include/linux/ve.h index 3facbd1759df..cca0a2bc1aac 100644 --- a/include/linux/ve.h +++ b/include/linux/ve.h @@ -88,7 +88,7 @@ struct ve_struct { atomic_t nd_neigh_nr; unsigned long meminfo_val; - atomic_t mnt_nr; /* number of present VE mounts */ + atomic_t mnt_avail_nr; /* number of available VE mounts */ #ifdef CONFIG_COREDUMP char core_pattern[CORENAME_MAX_SIZE]; diff --git a/kernel/ve/ve.c b/kernel/ve/ve.c index dffb35da22bd..42669a832993 100644 --- a/kernel/ve/ve.c +++ b/kernel/ve/ve.c @@ -81,7 +81,7 @@ struct ve_struct ve0 = { .arp_neigh_nr = ATOMIC_INIT(0), .nd_neigh_nr = ATOMIC_INIT(0), - .mnt_nr = ATOMIC_INIT(0), + .mnt_avail_nr = ATOMIC_INIT(INT_MAX), .meminfo_val = VE_MEMINFO_SYSTEM, .umh_running_helpers = ATOMIC_INIT(0), .umh_helpers_waitq = __WAIT_QUEUE_HEAD_INITIALIZER(ve0.umh_helpers_waitq), @@ -778,7 +778,7 @@ static struct cgroup_subsys_state *ve_create(struct cgroup_subsys_state *parent_ atomic_set(&ve->arp_neigh_nr, 0); atomic_set(&ve->nd_neigh_nr, 0); - atomic_set(&ve->mnt_nr, 0); + atomic_set(&ve->mnt_avail_nr, sysctl_ve_mount_nr); #ifdef CONFIG_COREDUMP strcpy(ve->core_pattern, "core"); @@ -1054,9 +1054,9 @@ static u64 ve_netns_avail_nr_read(struct cgroup_subsys_state *css, struct cftype return atomic_read(&css_to_ve(css)->netns_avail_nr); } -static u64 ve_mnt_nr_read(struct cgroup_subsys_state *css, struct cftype *cft) +static s64 ve_mnt_avail_nr_read(struct cgroup_subsys_state *css, struct cftype *cft) { - return atomic_read(&css_to_ve(css)->mnt_nr); + return atomic_read(&css_to_ve(css)->mnt_avail_nr); } static u64 ve_netif_max_nr_read(struct cgroup_subsys_state *css, struct cftype *cft) @@ -1616,8 +1616,8 @@ static struct cftype ve_cftypes[] = { .read_u64 = ve_netns_avail_nr_read, }, { - .name = "mnt_nr", - .read_u64 = ve_mnt_nr_read, + .name = "mnt_avail_nr", + .read_s64 = ve_mnt_avail_nr_read, }, { .name = "netif_max_nr", -- 2.47.1