nfsd4: acquire only one lease per file

Instead of acquiring one lease each time another client opens a file,
nfsd can acquire just one lease to represent all of them, and reference
count it to determine when to release it.

This fixes a regression introduced by
c45821d263a8a5109d69a9e8942b8d65bcd5f31a "locks: eliminate fl_mylease
callback": after that patch, only the struct file * is used to determine
who owns a given lease.  But since we recently converted the server to
share a single struct file per open, if we acquire multiple leases on
the same file from nfsd, it then becomes impossible on unlocking a lease
to determine which of those leases (all of whom share the same struct
file *) we meant to remove.

Thanks to Takashi Iwai <tiwai@suse.de> for catching a bug in a previous
version of this patch.

Tested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 55 insertions, 40 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 8b6cd3cf4835..54b60bfceb8d 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -230,9 +230,6 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_stateid *stp, struct svc_f
         dp->dl_client = clp;
         get_nfs4_file(fp);
         dp->dl_file = fp;
-        dp->dl_vfs_file = find_readable_file(fp);
-        get_file(dp->dl_vfs_file);
-        dp->dl_flock = NULL;
         dp->dl_type = type;
         dp->dl_stateid.si_boot = boot_time;
         dp->dl_stateid.si_stateownerid = current_delegid++;
@@ -241,8 +238,6 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_stateid *stp, struct svc_f
         fh_copy_shallow(&dp->dl_fh, &current_fh->fh_handle);
         dp->dl_time = 0;
         atomic_set(&dp->dl_count, 1);
-        list_add(&dp->dl_perfile, &fp->fi_delegations);
-        list_add(&dp->dl_perclnt, &clp->cl_delegations);
         INIT_WORK(&dp->dl_recall.cb_work, nfsd4_do_callback_rpc);
         return dp;
 }
@@ -253,24 +248,18 @@ nfs4_put_delegation(struct nfs4_delegation *dp)
         if (atomic_dec_and_test(&dp->dl_count)) {
                 dprintk("NFSD: freeing dp %p\n",dp);
                 put_nfs4_file(dp->dl_file);
-                fput(dp->dl_vfs_file);
                 kmem_cache_free(deleg_slab, dp);
                 num_delegations--;
         }
 }
 
-/* Remove the associated file_lock first, then remove the delegation.
- * lease_modify() is called to remove the FS_LEASE file_lock from
- * the i_flock list, eventually calling nfsd's lock_manager
- * fl_release_callback.
- */
-static void
-nfs4_close_delegation(struct nfs4_delegation *dp)
+static void nfs4_put_deleg_lease(struct nfs4_file *fp)
 {
-        dprintk("NFSD: close_delegation dp %p\n",dp);
-        /* XXX: do we even need this check?: */
-        if (dp->dl_flock)
-                vfs_setlease(dp->dl_vfs_file, F_UNLCK, &dp->dl_flock);
+        if (atomic_dec_and_test(&fp->fi_delegees)) {
+                vfs_setlease(fp->fi_deleg_file, F_UNLCK, &fp->fi_lease);
+                fp->fi_lease = NULL;
+                fp->fi_deleg_file = NULL;
+        }
 }
 
 /* Called under the state lock. */
@@ -282,7 +271,7 @@ unhash_delegation(struct nfs4_delegation *dp)
         list_del_init(&dp->dl_perfile);
         list_del_init(&dp->dl_recall_lru);
         spin_unlock(&recall_lock);
-        nfs4_close_delegation(dp);
+        nfs4_put_deleg_lease(dp->dl_file);
         nfs4_put_delegation(dp);
 }
 
@@ -2076,6 +2065,7 @@ alloc_init_file(struct inode *ino)
                 fp->fi_inode = igrab(ino);
                 fp->fi_id = current_fileid++;
                 fp->fi_had_conflict = false;
+                fp->fi_lease = NULL;
                 memset(fp->fi_fds, 0, sizeof(fp->fi_fds));
                 memset(fp->fi_access, 0, sizeof(fp->fi_access));
                 spin_lock(&recall_lock);
@@ -2344,26 +2334,26 @@ static void nfsd_break_one_deleg(struct nfs4_delegation *dp)
         nfsd4_cb_recall(dp);
 }
 
-/*
- * Called from break_lease() with lock_flocks() held.
- * Note: we assume break_lease will only call this *once* for any given
- * lease.
- */
+/* Called from break_lease() with lock_flocks() held. */
 static void nfsd_break_deleg_cb(struct file_lock *fl)
 {
-        struct nfs4_delegation *dp = (struct nfs4_delegation *)fl->fl_owner;
+        struct nfs4_file *fp = (struct nfs4_file *)fl->fl_owner;
+        struct nfs4_delegation *dp;
 
-        BUG_ON(!dp);
+        BUG_ON(!fp);
+        /* We assume break_lease is only called once per lease: */
+        BUG_ON(fp->fi_had_conflict);
         /*
          * We don't want the locks code to timeout the lease for us;
-         * we'll remove it ourself if the delegation isn't returned
+         * we'll remove it ourself if a delegation isn't returned
          * in time:
          */
         fl->fl_break_time = 0;
 
         spin_lock(&recall_lock);
-        dp->dl_file->fi_had_conflict = true;
-        nfsd_break_one_deleg(dp);
+        fp->fi_had_conflict = true;
+        list_for_each_entry(dp, &fp->fi_delegations, dl_perfile)
+                nfsd_break_one_deleg(dp);
         spin_unlock(&recall_lock);
 }
 
@@ -2455,13 +2445,15 @@ nfs4_check_delegmode(struct nfs4_delegation *dp, int flags)
 static struct nfs4_delegation *
 find_delegation_file(struct nfs4_file *fp, stateid_t *stid)
 {
-        struct nfs4_delegation *dp;
+        struct nfs4_delegation *dp = NULL;
 
+        spin_lock(&recall_lock);
         list_for_each_entry(dp, &fp->fi_delegations, dl_perfile) {
                 if (dp->dl_stateid.si_stateownerid == stid->si_stateownerid)
-                        return dp;
+                        break;
         }
-        return NULL;
+        spin_unlock(&recall_lock);
+        return dp;
 }
 
 int share_access_to_flags(u32 share_access)
@@ -2649,28 +2641,51 @@ static struct file_lock *nfs4_alloc_init_lease(struct nfs4_delegation *dp, int f
         fl->fl_flags = FL_LEASE;
         fl->fl_type = flag == NFS4_OPEN_DELEGATE_READ? F_RDLCK: F_WRLCK;
         fl->fl_end = OFFSET_MAX;
-        fl->fl_owner = (fl_owner_t)dp;
-        fl->fl_file = dp->dl_vfs_file;
-        BUG_ON(!fl->fl_file);
+        fl->fl_owner = (fl_owner_t)(dp->dl_file);
         fl->fl_pid = current->tgid;
-        dp->dl_flock = fl;
         return fl;
 }
 
 static int nfs4_setlease(struct nfs4_delegation *dp, int flag)
 {
+        struct nfs4_file *fp = dp->dl_file;
         struct file_lock *fl;
         int status;
 
         fl = nfs4_alloc_init_lease(dp, flag);
         if (!fl)
                 return -ENOMEM;
-        status = vfs_setlease(dp->dl_vfs_file, fl->fl_type, &fl);
+        fl->fl_file = find_readable_file(fp);
+        list_add(&dp->dl_perclnt, &dp->dl_client->cl_delegations);
+        status = vfs_setlease(fl->fl_file, fl->fl_type, &fl);
         if (status) {
-                dp->dl_flock = NULL;
+                list_del_init(&dp->dl_perclnt);
                 locks_free_lock(fl);
                 return -ENOMEM;
         }
+        fp->fi_lease = fl;
+        fp->fi_deleg_file = fl->fl_file;
+        get_file(fp->fi_deleg_file);
+        atomic_set(&fp->fi_delegees, 1);
+        list_add(&dp->dl_perfile, &fp->fi_delegations);
+        return 0;
+}
+
+static int nfs4_set_delegation(struct nfs4_delegation *dp, int flag)
+{
+        struct nfs4_file *fp = dp->dl_file;
+
+        if (!fp->fi_lease)
+                return nfs4_setlease(dp, flag);
+        spin_lock(&recall_lock);
+        if (fp->fi_had_conflict) {
+                spin_unlock(&recall_lock);
+                return -EAGAIN;
+        }
+        atomic_inc(&fp->fi_delegees);
+        list_add(&dp->dl_perfile, &fp->fi_delegations);
+        spin_unlock(&recall_lock);
+        list_add(&dp->dl_perclnt, &dp->dl_client->cl_delegations);
         return 0;
 }
 
@@ -2715,7 +2730,7 @@ nfs4_open_delegation(struct svc_fh *fh, struct nfsd4_open *open, struct nfs4_sta
         dp = alloc_init_deleg(sop->so_client, stp, fh, flag);
         if (dp == NULL)
                 goto out_no_deleg;
-        status = nfs4_setlease(dp, flag);
+        status = nfs4_set_delegation(dp, flag);
         if (status)
                 goto out_free;
 
@@ -2731,7 +2746,7 @@ out:
         open->op_delegate_type = flag;
         return;
 out_free:
-        unhash_delegation(dp);
+        nfs4_put_delegation(dp);
 out_no_deleg:
         flag = NFS4_OPEN_DELEGATE_NONE;
         goto out;
@@ -3139,7 +3154,7 @@ nfs4_preprocess_stateid_op(struct nfsd4_compound_state *cstate,
                         goto out;
                 renew_client(dp->dl_client);
                 if (filpp) {
-                        *filpp = find_readable_file(dp->dl_file);
+                        *filpp = dp->dl_file->fi_deleg_file;
                         BUG_ON(!*filpp);
                 }
         } else { /* open or lock stateid */