If there are some mount points(not exported for nfs) under pseudo root,
after client's operation of those entry under the root, anyone *can't*
unmount those mount points until export cache expired.
# cat /etc/exports
/nfs/xfs *(rw,insecure,no_subtree_check,no_root_squash)
/nfs/pnfs *(rw,insecure,no_subtree_check,no_root_squash)
# ll /nfs/
total 0
drwxr-xr-x. 3 root root 84 Apr 21 22:27 pnfs
drwxr-xr-x. 3 root root 84 Apr 21 22:27 test
drwxr-xr-x. 2 root root 6 Apr 20 22:01 xfs
# mount /dev/sde /nfs/test
# df
Filesystem 1K-blocks Used Available Use% Mounted on
......
/dev/sdd 1038336 32944 1005392 4% /nfs/pnfs
/dev/sdc 10475520 32928 10442592 1% /nfs/xfs
/dev/sde 999320 1284 929224 1% /nfs/test
# mount -t nfs 127.0.0.1:/nfs/ /mnt
# ll /mnt/*/
/mnt/pnfs/:
total 0
-rw-r--r--. 1 root root 0 Apr 21 22:23 attr
drwxr-xr-x. 2 root root 6 Apr 21 22:19 tmp
/mnt/xfs/:
total 0
# umount /nfs/test/
umount: /nfs/test/: target is busy
(In some cases useful info about processes that
use the device is found by lsof(8) or fuser(1).)
I don't think that's user expect, they want umount /nfs/test/.
It's caused by exports cache of nfsd holds the reference of
the path (here is /nfs/test/), so, it can't be umounted.
The patch site using fs_pin instead of mntget for export cache,
user at nfs server can unmount any mount points includes exported
for nfs. Maybe, only umounted for unexported mount points is better?
Signed-off-by: Kinglong Mee <kinglongmee@xxxxxxxxx>
---
fs/nfsd/export.c | 37 ++++++++++++++++++++++++++++++-------
fs/nfsd/export.h | 10 +++++++++-
2 files changed, 39 insertions(+), 8 deletions(-)
diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index f79521a..80f82f5 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -42,10 +42,12 @@ static void expkey_put(struct kref *ref)
struct svc_expkey *key = container_of(ref, struct svc_expkey, h.ref);
if (test_bit(CACHE_VALID, &key->h.flags) &&
- !test_bit(CACHE_NEGATIVE, &key->h.flags))
- path_put(&key->ek_path);
+ !test_bit(CACHE_NEGATIVE, &key->h.flags)) {
+ dput(key->ek_path.dentry);
+ pin_remove(&key->ek_pin);
+ }
auth_domain_put(key->ek_client);
- kfree(key);
+ kfree_rcu(key, rcu_head);
}
static void expkey_request(struct cache_detail *cd,
@@ -120,6 +122,7 @@ static int expkey_parse(struct cache_detail *cd, char *mesg, int mlen)
goto out;
key.ek_client = dom;
+ key.cd = cd;
key.ek_fsidtype = fsidtype;
memcpy(key.ek_fsid, buf, len);
@@ -210,6 +213,13 @@ static inline void expkey_init(struct cache_head *cnew,
new->ek_fsidtype = item->ek_fsidtype;
memcpy(new->ek_fsid, item->ek_fsid, sizeof(new->ek_fsid));
+ new->cd = item->cd;
+}
+
+static void expkey_pin_kill(struct fs_pin *pin)
+{
+ struct svc_expkey *key = container_of(pin, struct svc_expkey, ek_pin);
+ cache_force_expire(key->cd, &key->h);
}
static inline void expkey_update(struct cache_head *cnew,
@@ -218,8 +228,10 @@ static inline void expkey_update(struct cache_head *cnew,
struct svc_expkey *new = container_of(cnew, struct svc_expkey, h);
struct svc_expkey *item = container_of(citem, struct svc_expkey, h);
+ init_fs_pin(&new->ek_pin, expkey_pin_kill);
new->ek_path = item->ek_path;
- path_get(&item->ek_path);
+ dget(item->ek_path.dentry);
+ pin_insert_group(&new->ek_pin, item->ek_path.mnt, NULL);
}
static struct cache_head *expkey_alloc(void)
@@ -309,11 +321,13 @@ static void nfsd4_fslocs_free(struct nfsd4_fs_locations *fsloc)
static void svc_export_put(struct kref *ref)
{
struct svc_export *exp = container_of(ref, struct svc_export, h.ref);
- path_put(&exp->ex_path);
+
+ dput(exp->ex_path.dentry);
+ pin_remove(&exp->ex_pin);
auth_domain_put(exp->ex_client);
nfsd4_fslocs_free(&exp->ex_fslocs);
kfree(exp->ex_uuid);
- kfree(exp);
+ kfree_rcu(exp, rcu_head);
}
static void svc_export_request(struct cache_detail *cd,
@@ -694,15 +708,23 @@ static int svc_export_match(struct cache_head *a, struct cache_head *b)
path_equal(&orig->ex_path, &new->ex_path);
}
+static void export_pin_kill(struct fs_pin *pin)
+{
+ struct svc_export *exp = container_of(pin, struct svc_export, ex_pin);
+ cache_force_expire(exp->cd, &exp->h);
+}
+
static void svc_export_init(struct cache_head *cnew, struct cache_head *citem)
{
struct svc_export *new = container_of(cnew, struct svc_export, h);
struct svc_export *item = container_of(citem, struct svc_export, h);
+ init_fs_pin(&new->ex_pin, export_pin_kill);
kref_get(&item->ex_client->ref);
new->ex_client = item->ex_client;
new->ex_path = item->ex_path;
- path_get(&item->ex_path);
+ dget(item->ex_path.dentry);
+ pin_insert_group(&new->ex_pin, item->ex_path.mnt, NULL);
new->ex_fslocs.locations = NULL;
new->ex_fslocs.locations_count = 0;
new->ex_fslocs.migrated = 0;
@@ -811,6 +833,7 @@ exp_find_key(struct cache_detail *cd, struct auth_domain *clp, int fsid_type,
key.ek_client = clp;
key.ek_fsidtype = fsid_type;
+ key.cd = cd;
memcpy(key.ek_fsid, fsidv, key_len(fsid_type));
ek = svc_expkey_lookup(cd, &key);
diff --git a/fs/nfsd/export.h b/fs/nfsd/export.h
index 1f52bfc..1cf6ada 100644
--- a/fs/nfsd/export.h
+++ b/fs/nfsd/export.h
@@ -4,6 +4,7 @@
#ifndef NFSD_EXPORT_H
#define NFSD_EXPORT_H
+#include <linux/fs_pin.h>
#include <linux/sunrpc/cache.h>
#include <uapi/linux/nfsd/export.h>
@@ -46,6 +47,8 @@ struct exp_flavor_info {
struct svc_export {
struct cache_head h;
+ struct cache_detail *cd;
+
struct auth_domain * ex_client;
int ex_flags;
struct path ex_path;
@@ -58,7 +61,9 @@ struct svc_export {
struct exp_flavor_info ex_flavors[MAX_SECINFO_LIST];
enum pnfs_layouttype ex_layout_type;
struct nfsd4_deviceid_map *ex_devid_map;
- struct cache_detail *cd;
+
+ struct fs_pin ex_pin;
+ struct rcu_head rcu_head;
};
/* an "export key" (expkey) maps a filehandlefragement to an
@@ -67,12 +72,15 @@ struct svc_export {
*/
struct svc_expkey {
struct cache_head h;
+ struct cache_detail *cd;
struct auth_domain * ek_client;
int ek_fsidtype;
u32 ek_fsid[6];
struct path ek_path;
+ struct fs_pin ek_pin;
+ struct rcu_head rcu_head;
};
#define EX_ISSYNC(exp) (!((exp)->ex_flags & NFSEXP_ASYNC))
--
2.4.0
--
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