Return-Path: Received: from mail-pa0-f50.google.com ([209.85.220.50]:33423 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750995AbbEFNVW (ORCPT ); Wed, 6 May 2015 09:21:22 -0400 Message-ID: <554A154B.6040103@gmail.com> Date: Wed, 06 May 2015 21:21:15 +0800 From: Kinglong Mee MIME-Version: 1.0 To: "J. Bruce Fields" , linux-fsdevel@vger.kernel.org, "linux-nfs@vger.kernel.org" CC: Al Viro , NeilBrown , Trond Myklebust , kinglongmee@gmail.com Subject: [PATCH 4/4] nfsd: Pin to vfsmnt instead of mntget References: <554A149B.5060102@gmail.com> In-Reply-To: <554A149B.5060102@gmail.com> Content-Type: text/plain; charset=utf-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: 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 --- 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 #include #include @@ -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