| Message ID | 55B5A186.7040004@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
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On Mon, 27 Jul 2015 11:12:06 +0800 Kinglong Mee <kinglongmee@gmail.com> wrote: > 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. > > /nfs/xfs *(rw,insecure,no_subtree_check,no_root_squash) > /nfs/pnfs *(rw,insecure,no_subtree_check,no_root_squash) > 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 > 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 > /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/: target is busy > (In some cases useful info about processes that > use the device is found by lsof(8) or fuser(1).) > > It's caused by exports cache of nfsd holds the reference of > the path (here is /nfs/test/), so, it can't be umounted. > > I don't think that's user expect, they want umount /nfs/test/. > Bruce think user can also umount /nfs/pnfs/ and /nfs/xfs. > > Also, using kzalloc for all memory allocating without kmalloc. > Thanks for Al Viro's commets for the logic of fs_pin. > > v3, > 1. using path_get_pin/path_put_unpin for path pin > 2. using kzalloc for memory allocating > > v5, v4, > 1. add a completion for pin_kill waiting the reference is decreased to zero. > 2. add a work_struct for pin_kill decreases the reference indirectly. > 3. free svc_export/svc_expkey in pin_kill, not svc_export_put/svc_expkey_put. > 4. svc_export_put/svc_expkey_put go though pin_kill logic. > > v6, > 1. Pin vfsmnt to mount point at first, when reference increace (==2), > grab a reference to vfsmnt by mntget. When decreace (==1), > drop the reference to vfsmnt, left pin. > 2. Delete cache_head directly from cache_detail. > > v7, > implement self reference increase and decrease for nfsd exports/expkey > > v8, > new method as, > > 1. There are only one outlet from each cache, exp_find_key() for expkey, > exp_get_by_name() for export. > 2. Any fsid to export or filehandle to export will call the function. > 3. exp_get()/exp_put() increase/decrease the reference of export. > > Call legitimize_mntget() in the only outlet function exp_find_key()/ > exp_get_by_name(), if fail return STALE, otherwise, any valid > expkey/export from the cache is validated (Have get the reference of vfsmnt). > > Add mntget() in exp_get() and mntput() in exp_put(), because the export > passed to exp_get/exp_put are returned from exp_find_key/exp_get_by_name. > > For expkey cache, > 1. At first, a fsid is passed to exp_find_key, and lookup a cache > in svc_expkey_lookup, if success, ekey->ek_path is pined to mount. > 2. Then call legitimize_mntget getting a reference of vfsmnt > before return from exp_find_key. > 3. Any calling exp_find_key with valid cache must put the vfsmnt. > > for export cache, > 1. At first, a path (returned from exp_find_key) with validate vfsmnt > is passed to exp_get_by_name, if success, exp->ex_path is pined to mount. > 2. Then call legitimize_mntget getting a reference of vfsmnt > before return from exp_get_by_name. > 3. Any calling exp_get_by_name with valid cache must put the vfsmnt > by exp_put(); > 4. Any using the exp returned from exp_get_by_name must call exp_get(), > will increase the reference of vfsmnt. > > So that, > a. After getting the reference in 2, any umount of filesystem will get -EBUSY. > b. After put all reference after 4, or before get the reference in 2, > any umount of filesystem will call pin_kill, and delete the cache directly, > also unpin the vfsmount. > c. Between 1 and 2, have get the reference of exp/key cache, with invalidate vfsmnt. > As you said, umount of filesystem only wait exp_find_key/exp_get_by_name > put the reference of cache when legitimize_mntget fail. > > Signed-off-by: Kinglong Mee <kinglongmee@gmail.com> > --- > fs/nfsd/export.c | 136 +++++++++++++++++++++++++++++++++++++++++++++---------- > fs/nfsd/export.h | 22 ++++++++- > 2 files changed, 132 insertions(+), 26 deletions(-) > > diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c > index b4d84b5..7f4816d 100644 > --- a/fs/nfsd/export.c > +++ b/fs/nfsd/export.c > @@ -37,15 +37,23 @@ > #define EXPKEY_HASHMAX (1 << EXPKEY_HASHBITS) > #define EXPKEY_HASHMASK (EXPKEY_HASHMAX -1) > > +static void expkey_destroy(struct svc_expkey *key) > +{ > + auth_domain_put(key->ek_client); > + kfree_rcu(key, rcu_head); > +} > + > 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); > - auth_domain_put(key->ek_client); > - kfree(key); > + !test_bit(CACHE_NEGATIVE, &key->h.flags)) { > + rcu_read_lock(); > + complete(&key->ek_done); > + pin_kill(&key->ek_pin); > + } else > + expkey_destroy(key); > } > > static void expkey_request(struct cache_detail *cd, > @@ -83,7 +91,7 @@ static int expkey_parse(struct cache_detail *cd, char *mesg, int mlen) > return -EINVAL; > mesg[mlen-1] = 0; > > - buf = kmalloc(PAGE_SIZE, GFP_KERNEL); > + buf = kzalloc(PAGE_SIZE, GFP_KERNEL); Why this change? There are certainly times when kzmalloc is appropriate but I don't see that this is one of them, or that the change has anything to do with the rest of the patch. > err = -ENOMEM; > if (!buf) > goto out; > @@ -119,6 +127,7 @@ static int expkey_parse(struct cache_detail *cd, char *mesg, int mlen) > if (key.h.expiry_time == 0) > goto out; > > + key.cd = cd; > key.ek_client = dom; > key.ek_fsidtype = fsidtype; > memcpy(key.ek_fsid, buf, len); > @@ -181,7 +190,11 @@ static int expkey_show(struct seq_file *m, > if (test_bit(CACHE_VALID, &h->flags) && > !test_bit(CACHE_NEGATIVE, &h->flags)) { > seq_printf(m, " "); > - seq_path(m, &ek->ek_path, "\\ \t\n"); > + if (legitimize_mntget(ek->ek_path.mnt)) { > + seq_path(m, &ek->ek_path, "\\ \t\n"); > + mntput(ek->ek_path.mnt); > + } else > + seq_printf(m, "Dir umounting"); This "Dir umounting" needs to parse as a single word, so having a space in there is bad. Maybe "Dir-unmounting". > } > seq_printf(m, "\n"); > return 0; > @@ -210,6 +223,26 @@ 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); > + > + if (!completion_done(&key->ek_done)) { > + schedule_work(&key->ek_work); > + wait_for_completion(&key->ek_done); > + } > + > + path_put_unpin(&key->ek_path, &key->ek_pin); > + expkey_destroy(key); > +} > + > +static void expkey_close_work(struct work_struct *work) > +{ > + struct svc_expkey *key = container_of(work, struct svc_expkey, ek_work); > + cache_delete_entry(key->cd, &key->h); > } I'm perplexed by this separate scheduled work. You say: > 2. add a work_struct for pin_kill decreases the reference indirectly. above. cache_delete_entry() can call cache_put() which would call expkey_put() which calls pin_kill(), which will block until path_put_unpin calls pin_remove() which of course now cannot happen. So I can see why you have it, but I really really don't like it. :-( I'll post a patch to make a change to fs_pin so this sort of thing should be much easier. > > static inline void expkey_update(struct cache_head *cnew, > @@ -218,16 +251,19 @@ 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); > + path_get_pin(&new->ek_path, &new->ek_pin); > } > > static struct cache_head *expkey_alloc(void) > { > - struct svc_expkey *i = kmalloc(sizeof(*i), GFP_KERNEL); > - if (i) > + struct svc_expkey *i = kzalloc(sizeof(*i), GFP_KERNEL); > + if (i) { > + INIT_WORK(&i->ek_work, expkey_close_work); > + init_completion(&i->ek_done); > return &i->h; > - else > + } else > return NULL; > } I'm slightly less offended by this kzalloc, but I still think it needs to be justified if it is going to remain. > > @@ -306,14 +342,21 @@ static void nfsd4_fslocs_free(struct nfsd4_fs_locations *fsloc) > fsloc->locations = NULL; > } > > -static void svc_export_put(struct kref *ref) > +static void svc_export_destroy(struct svc_export *exp) > { > - struct svc_export *exp = container_of(ref, struct svc_export, h.ref); > - path_put(&exp->ex_path); > 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_put(struct kref *ref) > +{ > + struct svc_export *exp = container_of(ref, struct svc_export, h.ref); > + > + rcu_read_lock(); > + complete(&exp->ex_done); > + pin_kill(&exp->ex_pin); > } > > static void svc_export_request(struct cache_detail *cd, > @@ -520,7 +563,7 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen) > return -EINVAL; > mesg[mlen-1] = 0; > > - buf = kmalloc(PAGE_SIZE, GFP_KERNEL); > + buf = kzalloc(PAGE_SIZE, GFP_KERNEL); > if (!buf) > return -ENOMEM; > > @@ -636,7 +679,7 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen) > if (expp == NULL) > err = -ENOMEM; > else > - exp_put(expp); > + cache_put(&expp->h, expp->cd); > out4: > nfsd4_fslocs_free(&exp.ex_fslocs); > kfree(exp.ex_uuid); > @@ -664,7 +707,12 @@ static int svc_export_show(struct seq_file *m, > return 0; > } > exp = container_of(h, struct svc_export, h); > - seq_path(m, &exp->ex_path, " \t\n\\"); > + if (legitimize_mntget(exp->ex_path.mnt)) { > + seq_path(m, &exp->ex_path, " \t\n\\"); > + mntput(exp->ex_path.mnt); > + } else > + seq_printf(m, "Dir umounting"); > + again, "Dir-umounting" .. or even "Dir-unmounting" with the 'n'. > seq_putc(m, '\t'); > seq_escape(m, exp->ex_client->name, " \t\n\\"); > seq_putc(m, '('); > @@ -694,15 +742,35 @@ 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); > + > + if (!completion_done(&exp->ex_done)) { > + schedule_work(&exp->ex_work); > + wait_for_completion(&exp->ex_done); > + } > + > + path_put_unpin(&exp->ex_path, &exp->ex_pin); > + svc_export_destroy(exp); > +} > + > +static void export_close_work(struct work_struct *work) > +{ > + struct svc_export *exp = container_of(work, struct svc_export, ex_work); > + cache_delete_entry(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); > + path_get_pin(&new->ex_path, &new->ex_pin); > new->ex_fslocs.locations = NULL; > new->ex_fslocs.locations_count = 0; > new->ex_fslocs.migrated = 0; > @@ -740,10 +808,12 @@ static void export_update(struct cache_head *cnew, struct cache_head *citem) > > static struct cache_head *svc_export_alloc(void) > { > - struct svc_export *i = kmalloc(sizeof(*i), GFP_KERNEL); > - if (i) > + struct svc_export *i = kzalloc(sizeof(*i), GFP_KERNEL); > + if (i) { > + INIT_WORK(&i->ex_work, export_close_work); > + init_completion(&i->ex_done); > return &i->h; > - else > + } else > return NULL; > } > > @@ -798,6 +868,11 @@ svc_export_update(struct svc_export *new, struct svc_export *old) > return NULL; > } > > +static void exp_put_key(struct svc_expkey *key) > +{ > + mntput(key->ek_path.mnt); > + cache_put(&key->h, key->cd); > +} This is only called in one place. Does it really help clarity to make it a separate function? > > static struct svc_expkey * > exp_find_key(struct cache_detail *cd, struct auth_domain *clp, int fsid_type, > @@ -809,6 +884,7 @@ exp_find_key(struct cache_detail *cd, struct auth_domain *clp, int fsid_type, > if (!clp) > return ERR_PTR(-ENOENT); > > + key.cd = cd; > key.ek_client = clp; > key.ek_fsidtype = fsid_type; > memcpy(key.ek_fsid, fsidv, key_len(fsid_type)); > @@ -819,6 +895,12 @@ exp_find_key(struct cache_detail *cd, struct auth_domain *clp, int fsid_type, > err = cache_check(cd, &ek->h, reqp); > if (err) > return ERR_PTR(err); > + > + if (!legitimize_mntget(ek->ek_path.mnt)) { > + cache_put(&ek->h, ek->cd); > + return ERR_PTR(-ESTALE); > + } > + I think -ENOENT would be a better error code here. Just pretend that the entry doesn't exist - because in a moment it won't. > return ek; > } > > @@ -842,6 +924,12 @@ exp_get_by_name(struct cache_detail *cd, struct auth_domain *clp, > err = cache_check(cd, &exp->h, reqp); > if (err) > return ERR_PTR(err); > + > + if (!legitimize_mntget(exp->ex_path.mnt)) { > + cache_put(&exp->h, exp->cd); > + return ERR_PTR(-ESTALE); > + } > + > return exp; > } You *really* don't need this legitimize_mntget() here, just mntget(). You already have a legitimate reference to the mnt here. I think this patch is mostly good - there only serious problem is the "Dir umounting" string that you use in place of a pathname, and which contains a space. But I'd really like to get rid of the completion and work struct if I can... Thanks, NeilBrown > > @@ -928,7 +1016,7 @@ static struct svc_export *exp_find(struct cache_detail *cd, > return ERR_CAST(ek); > > exp = exp_get_by_name(cd, clp, &ek->ek_path, reqp); > - cache_put(&ek->h, nn->svc_expkey_cache); > + exp_put_key(ek); > > if (IS_ERR(exp)) > return ERR_CAST(exp); > @@ -1195,10 +1283,10 @@ static int e_show(struct seq_file *m, void *p) > return 0; > } > > - exp_get(exp); > + cache_get(&exp->h); > if (cache_check(cd, &exp->h, NULL)) > return 0; > - exp_put(exp); > + cache_put(&exp->h, exp->cd); > return svc_export_show(m, cd, cp); > } > > diff --git a/fs/nfsd/export.h b/fs/nfsd/export.h > index 1f52bfc..52210fb 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> > > @@ -46,9 +47,10 @@ 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; > kuid_t ex_anon_uid; > kgid_t ex_anon_gid; > int ex_fsid; > @@ -58,7 +60,14 @@ 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 path ex_path; > + struct fs_pin ex_pin; > + struct rcu_head rcu_head; > + > + /* For svc_export_put and fs umounting window */ > + struct completion ex_done; > + struct work_struct ex_work; > }; > > /* an "export key" (expkey) maps a filehandlefragement to an > @@ -67,12 +76,19 @@ 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; > + > + /* For expkey_put and fs umounting window */ > + struct completion ek_done; > + struct work_struct ek_work; > }; > > #define EX_ISSYNC(exp) (!((exp)->ex_flags & NFSEXP_ASYNC)) > @@ -100,12 +116,14 @@ __be32 nfserrno(int errno); > > static inline void exp_put(struct svc_export *exp) > { > + mntput(exp->ex_path.mnt); > cache_put(&exp->h, exp->cd); > } > > static inline struct svc_export *exp_get(struct svc_export *exp) > { > cache_get(&exp->h); > + mntget(exp->ex_path.mnt); > return exp; > } > struct svc_export * rqst_exp_find(struct svc_rqst *, int, u32 *); -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 7/29/2015 11:56, NeilBrown wrote: > On Mon, 27 Jul 2015 11:12:06 +0800 Kinglong Mee <kinglongmee@gmail.com> > wrote: > >> 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. >> ... snip... >> >> static void expkey_request(struct cache_detail *cd, >> @@ -83,7 +91,7 @@ static int expkey_parse(struct cache_detail *cd, char *mesg, int mlen) >> return -EINVAL; >> mesg[mlen-1] = 0; >> >> - buf = kmalloc(PAGE_SIZE, GFP_KERNEL); >> + buf = kzalloc(PAGE_SIZE, GFP_KERNEL); > > Why this change? There are certainly times when kzmalloc is > appropriate but I don't see that this is one of them, or that the > change has anything to do with the rest of the patch. It is for [1/9] at first, without zalloc of memory, the fs_pin->done maybe a bad value for use. If applying [1/9], change to kzalloc is not needed here. Maybe it should be a separated patch. I will drop the change in the next version is true. > > >> err = -ENOMEM; >> if (!buf) >> goto out; >> @@ -119,6 +127,7 @@ static int expkey_parse(struct cache_detail *cd, char *mesg, int mlen) >> if (key.h.expiry_time == 0) >> goto out; >> >> + key.cd = cd; >> key.ek_client = dom; >> key.ek_fsidtype = fsidtype; >> memcpy(key.ek_fsid, buf, len); >> @@ -181,7 +190,11 @@ static int expkey_show(struct seq_file *m, >> if (test_bit(CACHE_VALID, &h->flags) && >> !test_bit(CACHE_NEGATIVE, &h->flags)) { >> seq_printf(m, " "); >> - seq_path(m, &ek->ek_path, "\\ \t\n"); >> + if (legitimize_mntget(ek->ek_path.mnt)) { >> + seq_path(m, &ek->ek_path, "\\ \t\n"); >> + mntput(ek->ek_path.mnt); >> + } else >> + seq_printf(m, "Dir umounting"); > > This "Dir umounting" needs to parse as a single word, so having a space > in there is bad. Maybe "Dir-unmounting". Thanks. > > >> } >> seq_printf(m, "\n"); >> return 0; >> @@ -210,6 +223,26 @@ 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); >> + >> + if (!completion_done(&key->ek_done)) { >> + schedule_work(&key->ek_work); >> + wait_for_completion(&key->ek_done); >> + } >> + >> + path_put_unpin(&key->ek_path, &key->ek_pin); >> + expkey_destroy(key); >> +} >> + >> +static void expkey_close_work(struct work_struct *work) >> +{ >> + struct svc_expkey *key = container_of(work, struct svc_expkey, ek_work); >> + cache_delete_entry(key->cd, &key->h); >> } > > I'm perplexed by this separate scheduled work. > You say: > >> 2. add a work_struct for pin_kill decreases the reference indirectly. > > above. > cache_delete_entry() can call cache_put() which would call expkey_put() > which calls pin_kill(), which will block until path_put_unpin calls > pin_remove() which of course now cannot happen. > > So I can see why you have it, but I really really don't like it. :-( > > I'll post a patch to make a change to fs_pin so this sort of thing > should be much easier. I will review your patch, and try to update the new resolve. > >> >> static inline void expkey_update(struct cache_head *cnew, >> @@ -218,16 +251,19 @@ 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); >> + path_get_pin(&new->ek_path, &new->ek_pin); >> } >> >> static struct cache_head *expkey_alloc(void) >> { >> - struct svc_expkey *i = kmalloc(sizeof(*i), GFP_KERNEL); >> - if (i) >> + struct svc_expkey *i = kzalloc(sizeof(*i), GFP_KERNEL); >> + if (i) { >> + INIT_WORK(&i->ek_work, expkey_close_work); >> + init_completion(&i->ek_done); >> return &i->h; >> - else >> + } else >> return NULL; >> } > > I'm slightly less offended by this kzalloc, but I still think it needs > to be justified if it is going to remain. > > >> >> @@ -306,14 +342,21 @@ static void nfsd4_fslocs_free(struct nfsd4_fs_locations *fsloc) >> fsloc->locations = NULL; >> } >> >> -static void svc_export_put(struct kref *ref) >> +static void svc_export_destroy(struct svc_export *exp) >> { >> - struct svc_export *exp = container_of(ref, struct svc_export, h.ref); >> - path_put(&exp->ex_path); >> 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_put(struct kref *ref) >> +{ >> + struct svc_export *exp = container_of(ref, struct svc_export, h.ref); >> + >> + rcu_read_lock(); >> + complete(&exp->ex_done); >> + pin_kill(&exp->ex_pin); >> } >> >> static void svc_export_request(struct cache_detail *cd, >> @@ -520,7 +563,7 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen) >> return -EINVAL; >> mesg[mlen-1] = 0; >> >> - buf = kmalloc(PAGE_SIZE, GFP_KERNEL); >> + buf = kzalloc(PAGE_SIZE, GFP_KERNEL); >> if (!buf) >> return -ENOMEM; >> >> @@ -636,7 +679,7 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen) >> if (expp == NULL) >> err = -ENOMEM; >> else >> - exp_put(expp); >> + cache_put(&expp->h, expp->cd); >> out4: >> nfsd4_fslocs_free(&exp.ex_fslocs); >> kfree(exp.ex_uuid); >> @@ -664,7 +707,12 @@ static int svc_export_show(struct seq_file *m, >> return 0; >> } >> exp = container_of(h, struct svc_export, h); >> - seq_path(m, &exp->ex_path, " \t\n\\"); >> + if (legitimize_mntget(exp->ex_path.mnt)) { >> + seq_path(m, &exp->ex_path, " \t\n\\"); >> + mntput(exp->ex_path.mnt); >> + } else >> + seq_printf(m, "Dir umounting"); >> + > > again, "Dir-umounting" .. or even "Dir-unmounting" with the 'n'. > > >> seq_putc(m, '\t'); >> seq_escape(m, exp->ex_client->name, " \t\n\\"); >> seq_putc(m, '('); >> @@ -694,15 +742,35 @@ 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); >> + >> + if (!completion_done(&exp->ex_done)) { >> + schedule_work(&exp->ex_work); >> + wait_for_completion(&exp->ex_done); >> + } >> + >> + path_put_unpin(&exp->ex_path, &exp->ex_pin); >> + svc_export_destroy(exp); >> +} >> + >> +static void export_close_work(struct work_struct *work) >> +{ >> + struct svc_export *exp = container_of(work, struct svc_export, ex_work); >> + cache_delete_entry(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); >> + path_get_pin(&new->ex_path, &new->ex_pin); >> new->ex_fslocs.locations = NULL; >> new->ex_fslocs.locations_count = 0; >> new->ex_fslocs.migrated = 0; >> @@ -740,10 +808,12 @@ static void export_update(struct cache_head *cnew, struct cache_head *citem) >> >> static struct cache_head *svc_export_alloc(void) >> { >> - struct svc_export *i = kmalloc(sizeof(*i), GFP_KERNEL); >> - if (i) >> + struct svc_export *i = kzalloc(sizeof(*i), GFP_KERNEL); >> + if (i) { >> + INIT_WORK(&i->ex_work, export_close_work); >> + init_completion(&i->ex_done); >> return &i->h; >> - else >> + } else >> return NULL; >> } >> >> @@ -798,6 +868,11 @@ svc_export_update(struct svc_export *new, struct svc_export *old) >> return NULL; >> } >> >> +static void exp_put_key(struct svc_expkey *key) >> +{ >> + mntput(key->ek_path.mnt); >> + cache_put(&key->h, key->cd); >> +} > > This is only called in one place. Does it really help clarity to make > it a separate function? I will update it with your next comments about legitimize_mntget() in exp_get_by_name(). > >> >> static struct svc_expkey * >> exp_find_key(struct cache_detail *cd, struct auth_domain *clp, int fsid_type, >> @@ -809,6 +884,7 @@ exp_find_key(struct cache_detail *cd, struct auth_domain *clp, int fsid_type, >> if (!clp) >> return ERR_PTR(-ENOENT); >> >> + key.cd = cd; >> key.ek_client = clp; >> key.ek_fsidtype = fsid_type; >> memcpy(key.ek_fsid, fsidv, key_len(fsid_type)); >> @@ -819,6 +895,12 @@ exp_find_key(struct cache_detail *cd, struct auth_domain *clp, int fsid_type, >> err = cache_check(cd, &ek->h, reqp); >> if (err) >> return ERR_PTR(err); >> + >> + if (!legitimize_mntget(ek->ek_path.mnt)) { >> + cache_put(&ek->h, ek->cd); >> + return ERR_PTR(-ESTALE); >> + } >> + > > I think -ENOENT would be a better error code here. > Just pretend that the entry doesn't exist - because in a moment it > won't. Yes, -ESTALE is for filehandle. -ENOENT is better for cache entry. > > >> return ek; >> } >> >> @@ -842,6 +924,12 @@ exp_get_by_name(struct cache_detail *cd, struct auth_domain *clp, >> err = cache_check(cd, &exp->h, reqp); >> if (err) >> return ERR_PTR(err); >> + >> + if (!legitimize_mntget(exp->ex_path.mnt)) { >> + cache_put(&exp->h, exp->cd); >> + return ERR_PTR(-ESTALE); >> + } >> + >> return exp; >> } > > You *really* don't need this legitimize_mntget() here, just mntget(). > You already have a legitimate reference to the mnt here. Got it! > > > I think this patch is mostly good - there only serious problem is the > "Dir umounting" string that you use in place of a pathname, and which > contains a space. > > But I'd really like to get rid of the completion and work struct if I > can... Thanks again for your comments. I will update those patches later! thanks, Kinglong Mee -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c index b4d84b5..7f4816d 100644 --- a/fs/nfsd/export.c +++ b/fs/nfsd/export.c @@ -37,15 +37,23 @@ #define EXPKEY_HASHMAX (1 << EXPKEY_HASHBITS) #define EXPKEY_HASHMASK (EXPKEY_HASHMAX -1) +static void expkey_destroy(struct svc_expkey *key) +{ + auth_domain_put(key->ek_client); + kfree_rcu(key, rcu_head); +} + 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); - auth_domain_put(key->ek_client); - kfree(key); + !test_bit(CACHE_NEGATIVE, &key->h.flags)) { + rcu_read_lock(); + complete(&key->ek_done); + pin_kill(&key->ek_pin); + } else + expkey_destroy(key); } static void expkey_request(struct cache_detail *cd, @@ -83,7 +91,7 @@ static int expkey_parse(struct cache_detail *cd, char *mesg, int mlen) return -EINVAL; mesg[mlen-1] = 0; - buf = kmalloc(PAGE_SIZE, GFP_KERNEL); + buf = kzalloc(PAGE_SIZE, GFP_KERNEL); err = -ENOMEM; if (!buf) goto out; @@ -119,6 +127,7 @@ static int expkey_parse(struct cache_detail *cd, char *mesg, int mlen) if (key.h.expiry_time == 0) goto out; + key.cd = cd; key.ek_client = dom; key.ek_fsidtype = fsidtype; memcpy(key.ek_fsid, buf, len); @@ -181,7 +190,11 @@ static int expkey_show(struct seq_file *m, if (test_bit(CACHE_VALID, &h->flags) && !test_bit(CACHE_NEGATIVE, &h->flags)) { seq_printf(m, " "); - seq_path(m, &ek->ek_path, "\\ \t\n"); + if (legitimize_mntget(ek->ek_path.mnt)) { + seq_path(m, &ek->ek_path, "\\ \t\n"); + mntput(ek->ek_path.mnt); + } else + seq_printf(m, "Dir umounting"); } seq_printf(m, "\n"); return 0; @@ -210,6 +223,26 @@ 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); + + if (!completion_done(&key->ek_done)) { + schedule_work(&key->ek_work); + wait_for_completion(&key->ek_done); + } + + path_put_unpin(&key->ek_path, &key->ek_pin); + expkey_destroy(key); +} + +static void expkey_close_work(struct work_struct *work) +{ + struct svc_expkey *key = container_of(work, struct svc_expkey, ek_work); + cache_delete_entry(key->cd, &key->h); } static inline void expkey_update(struct cache_head *cnew, @@ -218,16 +251,19 @@ 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); + path_get_pin(&new->ek_path, &new->ek_pin); } static struct cache_head *expkey_alloc(void) { - struct svc_expkey *i = kmalloc(sizeof(*i), GFP_KERNEL); - if (i) + struct svc_expkey *i = kzalloc(sizeof(*i), GFP_KERNEL); + if (i) { + INIT_WORK(&i->ek_work, expkey_close_work); + init_completion(&i->ek_done); return &i->h; - else + } else return NULL; } @@ -306,14 +342,21 @@ static void nfsd4_fslocs_free(struct nfsd4_fs_locations *fsloc) fsloc->locations = NULL; } -static void svc_export_put(struct kref *ref) +static void svc_export_destroy(struct svc_export *exp) { - struct svc_export *exp = container_of(ref, struct svc_export, h.ref); - path_put(&exp->ex_path); 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_put(struct kref *ref) +{ + struct svc_export *exp = container_of(ref, struct svc_export, h.ref); + + rcu_read_lock(); + complete(&exp->ex_done); + pin_kill(&exp->ex_pin); } static void svc_export_request(struct cache_detail *cd, @@ -520,7 +563,7 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen) return -EINVAL; mesg[mlen-1] = 0; - buf = kmalloc(PAGE_SIZE, GFP_KERNEL); + buf = kzalloc(PAGE_SIZE, GFP_KERNEL); if (!buf) return -ENOMEM; @@ -636,7 +679,7 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen) if (expp == NULL) err = -ENOMEM; else - exp_put(expp); + cache_put(&expp->h, expp->cd); out4: nfsd4_fslocs_free(&exp.ex_fslocs); kfree(exp.ex_uuid); @@ -664,7 +707,12 @@ static int svc_export_show(struct seq_file *m, return 0; } exp = container_of(h, struct svc_export, h); - seq_path(m, &exp->ex_path, " \t\n\\"); + if (legitimize_mntget(exp->ex_path.mnt)) { + seq_path(m, &exp->ex_path, " \t\n\\"); + mntput(exp->ex_path.mnt); + } else + seq_printf(m, "Dir umounting"); + seq_putc(m, '\t'); seq_escape(m, exp->ex_client->name, " \t\n\\"); seq_putc(m, '('); @@ -694,15 +742,35 @@ 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); + + if (!completion_done(&exp->ex_done)) { + schedule_work(&exp->ex_work); + wait_for_completion(&exp->ex_done); + } + + path_put_unpin(&exp->ex_path, &exp->ex_pin); + svc_export_destroy(exp); +} + +static void export_close_work(struct work_struct *work) +{ + struct svc_export *exp = container_of(work, struct svc_export, ex_work); + cache_delete_entry(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); + path_get_pin(&new->ex_path, &new->ex_pin); new->ex_fslocs.locations = NULL; new->ex_fslocs.locations_count = 0; new->ex_fslocs.migrated = 0; @@ -740,10 +808,12 @@ static void export_update(struct cache_head *cnew, struct cache_head *citem) static struct cache_head *svc_export_alloc(void) { - struct svc_export *i = kmalloc(sizeof(*i), GFP_KERNEL); - if (i) + struct svc_export *i = kzalloc(sizeof(*i), GFP_KERNEL); + if (i) { + INIT_WORK(&i->ex_work, export_close_work); + init_completion(&i->ex_done); return &i->h; - else + } else return NULL; } @@ -798,6 +868,11 @@ svc_export_update(struct svc_export *new, struct svc_export *old) return NULL; } +static void exp_put_key(struct svc_expkey *key) +{ + mntput(key->ek_path.mnt); + cache_put(&key->h, key->cd); +} static struct svc_expkey * exp_find_key(struct cache_detail *cd, struct auth_domain *clp, int fsid_type, @@ -809,6 +884,7 @@ exp_find_key(struct cache_detail *cd, struct auth_domain *clp, int fsid_type, if (!clp) return ERR_PTR(-ENOENT); + key.cd = cd; key.ek_client = clp; key.ek_fsidtype = fsid_type; memcpy(key.ek_fsid, fsidv, key_len(fsid_type)); @@ -819,6 +895,12 @@ exp_find_key(struct cache_detail *cd, struct auth_domain *clp, int fsid_type, err = cache_check(cd, &ek->h, reqp); if (err) return ERR_PTR(err); + + if (!legitimize_mntget(ek->ek_path.mnt)) { + cache_put(&ek->h, ek->cd); + return ERR_PTR(-ESTALE); + } + return ek; } @@ -842,6 +924,12 @@ exp_get_by_name(struct cache_detail *cd, struct auth_domain *clp, err = cache_check(cd, &exp->h, reqp); if (err) return ERR_PTR(err); + + if (!legitimize_mntget(exp->ex_path.mnt)) { + cache_put(&exp->h, exp->cd); + return ERR_PTR(-ESTALE); + } + return exp; } @@ -928,7 +1016,7 @@ static struct svc_export *exp_find(struct cache_detail *cd, return ERR_CAST(ek); exp = exp_get_by_name(cd, clp, &ek->ek_path, reqp); - cache_put(&ek->h, nn->svc_expkey_cache); + exp_put_key(ek); if (IS_ERR(exp)) return ERR_CAST(exp); @@ -1195,10 +1283,10 @@ static int e_show(struct seq_file *m, void *p) return 0; } - exp_get(exp); + cache_get(&exp->h); if (cache_check(cd, &exp->h, NULL)) return 0; - exp_put(exp); + cache_put(&exp->h, exp->cd); return svc_export_show(m, cd, cp); } diff --git a/fs/nfsd/export.h b/fs/nfsd/export.h index 1f52bfc..52210fb 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> @@ -46,9 +47,10 @@ 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; kuid_t ex_anon_uid; kgid_t ex_anon_gid; int ex_fsid; @@ -58,7 +60,14 @@ 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 path ex_path; + struct fs_pin ex_pin; + struct rcu_head rcu_head; + + /* For svc_export_put and fs umounting window */ + struct completion ex_done; + struct work_struct ex_work; }; /* an "export key" (expkey) maps a filehandlefragement to an @@ -67,12 +76,19 @@ 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; + + /* For expkey_put and fs umounting window */ + struct completion ek_done; + struct work_struct ek_work; }; #define EX_ISSYNC(exp) (!((exp)->ex_flags & NFSEXP_ASYNC)) @@ -100,12 +116,14 @@ __be32 nfserrno(int errno); static inline void exp_put(struct svc_export *exp) { + mntput(exp->ex_path.mnt); cache_put(&exp->h, exp->cd); } static inline struct svc_export *exp_get(struct svc_export *exp) { cache_get(&exp->h); + mntget(exp->ex_path.mnt); return exp; } struct svc_export * rqst_exp_find(struct svc_rqst *, int, u32 *);
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. /nfs/xfs *(rw,insecure,no_subtree_check,no_root_squash) /nfs/pnfs *(rw,insecure,no_subtree_check,no_root_squash) 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 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 /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/: target is busy (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1).) It's caused by exports cache of nfsd holds the reference of the path (here is /nfs/test/), so, it can't be umounted. I don't think that's user expect, they want umount /nfs/test/. Bruce think user can also umount /nfs/pnfs/ and /nfs/xfs. Also, using kzalloc for all memory allocating without kmalloc. Thanks for Al Viro's commets for the logic of fs_pin. v3, 1. using path_get_pin/path_put_unpin for path pin 2. using kzalloc for memory allocating v5, v4, 1. add a completion for pin_kill waiting the reference is decreased to zero. 2. add a work_struct for pin_kill decreases the reference indirectly. 3. free svc_export/svc_expkey in pin_kill, not svc_export_put/svc_expkey_put. 4. svc_export_put/svc_expkey_put go though pin_kill logic. v6, 1. Pin vfsmnt to mount point at first, when reference increace (==2), grab a reference to vfsmnt by mntget. When decreace (==1), drop the reference to vfsmnt, left pin. 2. Delete cache_head directly from cache_detail. v7, implement self reference increase and decrease for nfsd exports/expkey v8, new method as, 1. There are only one outlet from each cache, exp_find_key() for expkey, exp_get_by_name() for export. 2. Any fsid to export or filehandle to export will call the function. 3. exp_get()/exp_put() increase/decrease the reference of export. Call legitimize_mntget() in the only outlet function exp_find_key()/ exp_get_by_name(), if fail return STALE, otherwise, any valid expkey/export from the cache is validated (Have get the reference of vfsmnt). Add mntget() in exp_get() and mntput() in exp_put(), because the export passed to exp_get/exp_put are returned from exp_find_key/exp_get_by_name. For expkey cache, 1. At first, a fsid is passed to exp_find_key, and lookup a cache in svc_expkey_lookup, if success, ekey->ek_path is pined to mount. 2. Then call legitimize_mntget getting a reference of vfsmnt before return from exp_find_key. 3. Any calling exp_find_key with valid cache must put the vfsmnt. for export cache, 1. At first, a path (returned from exp_find_key) with validate vfsmnt is passed to exp_get_by_name, if success, exp->ex_path is pined to mount. 2. Then call legitimize_mntget getting a reference of vfsmnt before return from exp_get_by_name. 3. Any calling exp_get_by_name with valid cache must put the vfsmnt by exp_put(); 4. Any using the exp returned from exp_get_by_name must call exp_get(), will increase the reference of vfsmnt. So that, a. After getting the reference in 2, any umount of filesystem will get -EBUSY. b. After put all reference after 4, or before get the reference in 2, any umount of filesystem will call pin_kill, and delete the cache directly, also unpin the vfsmount. c. Between 1 and 2, have get the reference of exp/key cache, with invalidate vfsmnt. As you said, umount of filesystem only wait exp_find_key/exp_get_by_name put the reference of cache when legitimize_mntget fail. Signed-off-by: Kinglong Mee <kinglongmee@gmail.com> --- fs/nfsd/export.c | 136 +++++++++++++++++++++++++++++++++++++++++++++---------- fs/nfsd/export.h | 22 ++++++++- 2 files changed, 132 insertions(+), 26 deletions(-)