dht:remember locked subvol and send unlock to the same

During locking we send lock request to cached subvol,
and normally we unlock to the cached subvol
But with parallel fresh lookup on a directory, there
is a race window where the cached subvol can change
and the unlock can go into a different subvol from
which we took lock.

This will result in a stale lock held on one of the
subvol.

So we will store the details of subvol which we took the lock
and will unlock from the same subvol

Change-Id: I47df99491671b10624eb37d1d17e40bacf0b15eb
BUG: 1311002
Signed-off-by: Mohammed Rafi KC <rkavunga@redhat.com>
Reviewed-on: http://review.gluster.org/13492
Reviewed-by: N Balachandran <nbalacha@redhat.com>
Smoke: Gluster Build System <jenkins@build.gluster.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Raghavendra G <rgowdapp@redhat.com>
CentOS-regression: Gluster Build System <jenkins@build.gluster.com>

5 files changed, 218 insertions, 21 deletions

diff --git a/xlators/cluster/dht/src/dht-common.c b/xlators/cluster/dht/src/dht-common.c
index b3e30392c29..e8d7401c474 100644
--- a/xlators/cluster/dht/src/dht-common.c
+++ b/xlators/cluster/dht/src/dht-common.c
@@ -8404,7 +8404,10 @@ dht_entrylk_cbk (call_frame_t *frame, void *cookie,
         return 0;
 }
 
-
+/* TODO
+ * Sending entrylk to cached subvol can result in stale lock
+ * as described in the bug 1311002.
+ */
 int
 dht_entrylk (call_frame_t *frame, xlator_t *this,
              const char *volume, loc_t *loc, const char *basename,
diff --git a/xlators/cluster/dht/src/dht-common.h b/xlators/cluster/dht/src/dht-common.h
index b2e9df68996..9a71c46c8e4 100644
--- a/xlators/cluster/dht/src/dht-common.h
+++ b/xlators/cluster/dht/src/dht-common.h
@@ -101,6 +101,7 @@ typedef struct dht_stat_time dht_stat_time_t;
 struct dht_inode_ctx {
         dht_layout_t    *layout;
         dht_stat_time_t  time;
+        xlator_t        *lock_subvol;
 };
 
 typedef struct dht_inode_ctx dht_inode_ctx_t;
@@ -285,6 +286,8 @@ struct dht_local {
                 int                 op_errno;
         } lock;
 
+        short           lock_type;
+
         call_stub_t *stub;
         int32_t      parent_disk_layout[4];
 };
@@ -1218,4 +1221,12 @@ dht_release (xlator_t *this, fd_t *fd);
 
 int32_t
 dht_set_fixed_dir_stat (struct iatt *stat);
+
+xlator_t*
+dht_get_lock_subvolume (xlator_t *this, struct gf_flock *lock,
+                        dht_local_t *local);
+
+int
+dht_lk_inode_unref (call_frame_t *frame, int32_t op_ret);
+
 #endif/* _DHT_H */
diff --git a/xlators/cluster/dht/src/dht-helper.c b/xlators/cluster/dht/src/dht-helper.c
index 0384c2a4cc4..0a5e1128db1 100644
--- a/xlators/cluster/dht/src/dht-helper.c
+++ b/xlators/cluster/dht/src/dht-helper.c
@@ -2298,3 +2298,158 @@ dht_heal_full_path_done (int op_ret, call_frame_t *heal_frame, void *data)
         DHT_STACK_DESTROY (heal_frame);
         return 0;
 }
+
+/* This function must be called inside an inode lock */
+int
+__dht_lock_subvol_set (inode_t *inode, xlator_t *this,
+                       xlator_t *lock_subvol)
+{
+        dht_inode_ctx_t         *ctx            = NULL;
+        int                      ret            = -1;
+        uint64_t                 value          = 0;
+
+        GF_VALIDATE_OR_GOTO (this->name, inode, out);
+
+        ret = __inode_ctx_get0 (inode, this, &value);
+        if (ret || !value) {
+                return -1;
+        }
+
+        ctx = (dht_inode_ctx_t *) value;
+        ctx->lock_subvol = lock_subvol;
+out:
+        return ret;
+}
+
+xlator_t*
+dht_get_lock_subvolume (xlator_t *this, struct gf_flock *lock,
+                        dht_local_t *local)
+{
+        xlator_t                *subvol                  = NULL;
+        inode_t                 *inode                   = NULL;
+        int32_t                  ret                     = -1;
+        uint64_t                 value                   = 0;
+        xlator_t                *cached_subvol           = NULL;
+        dht_inode_ctx_t         *ctx                     = NULL;
+        char                     gfid[GF_UUID_BUF_SIZE]  = {0};
+
+        GF_VALIDATE_OR_GOTO (this->name, lock, out);
+        GF_VALIDATE_OR_GOTO (this->name, local, out);
+
+        cached_subvol = local->cached_subvol;
+
+        if (local->loc.inode || local->fd) {
+                inode = local->loc.inode ? local->loc.inode : local->fd->inode;
+        }
+
+        if (!inode)
+                goto out;
+
+        if (!(IA_ISDIR (inode->ia_type) || IA_ISINVAL (inode->ia_type))) {
+                /*
+                 * We may get non-linked inode for directories as part
+                 * of the selfheal code path. So checking  for IA_INVAL
+                 * type also. This will only happen for directory.
+                 */
+                subvol = local->cached_subvol;
+                goto out;
+        }
+
+        if (lock->l_type != F_UNLCK) {
+                /*
+                 * inode purging might happen on NFS between a lk
+                 * and unlk. Due to this lk and unlk might be sent
+                 * to different subvols.
+                 * So during a lock request, taking a ref on inode
+                 * to prevent inode purging. inode unref will happen
+                 * in unlock cbk code path.
+                 */
+                inode_ref (inode);
+        }
+
+        LOCK (&inode->lock);
+                ret = __inode_ctx_get0 (inode, this, &value);
+                if (!ret && value) {
+                        ctx = (dht_inode_ctx_t *) value;
+                        subvol = ctx->lock_subvol;
+                }
+                if (!subvol && lock->l_type != F_UNLCK && cached_subvol) {
+                        ret = __dht_lock_subvol_set (inode, this,
+                                                     cached_subvol);
+                        if (ret) {
+                                gf_uuid_unparse(inode->gfid, gfid);
+                                gf_msg (this->name, GF_LOG_WARNING, 0,
+                                        DHT_MSG_SET_INODE_CTX_FAILED,
+                                        "Failed to set lock_subvol in "
+                                        "inode ctx for gfid %s",
+                                        gfid);
+                                goto unlock;
+                        }
+                        subvol = cached_subvol;
+                }
+unlock:
+        UNLOCK (&inode->lock);
+        if (!subvol && inode && lock->l_type != F_UNLCK) {
+                inode_unref (inode);
+        }
+out:
+        return subvol;
+}
+
+int
+dht_lk_inode_unref (call_frame_t *frame, int32_t op_ret)
+{
+        int                     ret                     = -1;
+        dht_local_t            *local                   = NULL;
+        inode_t                *inode                   = NULL;
+        xlator_t               *this                    = NULL;
+        char                    gfid[GF_UUID_BUF_SIZE]  = {0};
+
+        local = frame->local;
+        this = frame->this;
+
+        if (local->loc.inode || local->fd) {
+                inode = local->loc.inode ? local->loc.inode : local->fd->inode;
+        }
+        if (!inode) {
+                gf_msg (this->name, GF_LOG_WARNING, 0,
+                        DHT_MSG_LOCK_INODE_UNREF_FAILED,
+                        "Found a NULL inode. Failed to unref the inode");
+                goto out;
+        }
+
+        if (!(IA_ISDIR (inode->ia_type) || IA_ISINVAL (inode->ia_type))) {
+                ret = 0;
+                goto out;
+        }
+
+        switch (local->lock_type) {
+        case F_RDLCK:
+        case F_WRLCK:
+                if (op_ret) {
+                        gf_uuid_unparse(inode->gfid, gfid);
+                        gf_msg_debug (this->name, 0,
+                                "lock request failed for gfid %s", gfid);
+                        inode_unref (inode);
+                        goto out;
+                }
+                break;
+
+        case F_UNLCK:
+                if (!op_ret) {
+                        inode_unref (inode);
+                } else {
+                        gf_uuid_unparse(inode->gfid, gfid);
+                        gf_msg (this->name, GF_LOG_WARNING, 0,
+                                DHT_MSG_LOCK_INODE_UNREF_FAILED,
+                                "Unlock request failed for gfid %s."
+                                "Failed to unref the inode", gfid);
+                        goto out;
+                }
+        default:
+                break;
+        }
+        ret = 0;
+out:
+        return ret;
+}
diff --git a/xlators/cluster/dht/src/dht-inode-read.c b/xlators/cluster/dht/src/dht-inode-read.c
index 16a82cd5b98..549f1b9ea7e 100644
--- a/xlators/cluster/dht/src/dht-inode-read.c
+++ b/xlators/cluster/dht/src/dht-inode-read.c
@@ -997,6 +997,7 @@ dht_lk_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         }
 
 out:
+        dht_lk_inode_unref (frame, op_ret);
         DHT_STACK_UNWIND (lk, frame, op_ret, op_errno, flock, xdata);
 
         return 0;
@@ -1035,7 +1036,7 @@ int
 dht_lk (call_frame_t *frame, xlator_t *this,
         fd_t *fd, int cmd, struct gf_flock *flock, dict_t *xdata)
 {
-        xlator_t        *subvol         = NULL;
+        xlator_t        *lock_subvol    = NULL;
         int             op_errno        = -1;
         dht_local_t     *local          = NULL;
 
@@ -1044,11 +1045,16 @@ dht_lk (call_frame_t *frame, xlator_t *this,
         VALIDATE_OR_GOTO (fd, err);
 
         local = dht_local_init (frame, NULL, fd, GF_FOP_LK);
+        if (!local) {
+                op_errno = ENOMEM;
+                goto err;
+        }
 
-        subvol = dht_subvol_get_cached (this, fd->inode);
-        if (!subvol) {
+        local->lock_type = flock->l_type;
+        lock_subvol = dht_get_lock_subvolume (this, flock, local);
+        if (!lock_subvol) {
                 gf_msg_debug (this->name, 0,
-                              "no cached subvolume for fd=%p", fd);
+                              "no lock subvolume for path=%p", fd);
                 op_errno = EINVAL;
                 goto err;
         }
@@ -1058,7 +1064,7 @@ dht_lk (call_frame_t *frame, xlator_t *this,
 
         local->call_cnt = 1;
 
-        STACK_WIND (frame, dht_lk_cbk, subvol, subvol->fops->lk, fd,
+        STACK_WIND (frame, dht_lk_cbk, lock_subvol, lock_subvol->fops->lk, fd,
                     cmd, flock, xdata);
 
         return 0;
@@ -1283,6 +1289,7 @@ dht_inodelk_cbk (call_frame_t *frame, void *cookie,
                  xlator_t *this, int32_t op_ret, int32_t op_errno, dict_t *xdata)
 
 {
+        dht_lk_inode_unref (frame, op_ret);
         DHT_STACK_UNWIND (inodelk, frame, op_ret, op_errno, xdata);
         return 0;
 }
@@ -1292,9 +1299,9 @@ int32_t
 dht_inodelk (call_frame_t *frame, xlator_t *this, const char *volume,
              loc_t *loc, int32_t cmd, struct gf_flock *lock, dict_t *xdata)
 {
-        xlator_t     *subvol = NULL;
-        int           op_errno = -1;
-        dht_local_t  *local = NULL;
+        xlator_t        *lock_subvol            = NULL;
+        int              op_errno               = -1;
+        dht_local_t     *local                  = NULL;
 
 
         VALIDATE_OR_GOTO (frame, err);
@@ -1308,10 +1315,11 @@ dht_inodelk (call_frame_t *frame, xlator_t *this, const char *volume,
                 goto err;
         }
 
-        subvol = local->cached_subvol;
-        if (!subvol) {
+        local->lock_type = lock->l_type;
+        lock_subvol = dht_get_lock_subvolume (this, lock, local);
+        if (!lock_subvol) {
                 gf_msg_debug (this->name, 0,
-                              "no cached subvolume for path=%s", loc->path);
+                              "no lock subvolume for path=%s", loc->path);
                 op_errno = EINVAL;
                 goto err;
         }
@@ -1320,7 +1328,7 @@ dht_inodelk (call_frame_t *frame, xlator_t *this, const char *volume,
 
         STACK_WIND (frame,
                     dht_inodelk_cbk,
-                    subvol, subvol->fops->inodelk,
+                    lock_subvol, lock_subvol->fops->inodelk,
                     volume, loc, cmd, lock, xdata);
 
         return 0;
@@ -1332,12 +1340,13 @@ err:
         return 0;
 }
 
-
 int
 dht_finodelk_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
                   int32_t op_ret, int32_t op_errno, dict_t *xdata)
 
 {
+
+        dht_lk_inode_unref (frame, op_ret);
         DHT_STACK_UNWIND (finodelk, frame, op_ret, op_errno, xdata);
         return 0;
 }
@@ -1347,23 +1356,35 @@ int
 dht_finodelk (call_frame_t *frame, xlator_t *this, const char *volume,
               fd_t *fd, int32_t cmd, struct gf_flock *lock, dict_t *xdata)
 {
-        xlator_t     *subvol = NULL;
-        int           op_errno = -1;
+        xlator_t     *lock_subvol       = NULL;
+        dht_local_t  *local             = NULL;
+        int           op_errno          = -1;
+
 
         VALIDATE_OR_GOTO (frame, err);
         VALIDATE_OR_GOTO (this, err);
         VALIDATE_OR_GOTO (fd, err);
 
-        subvol = dht_subvol_get_cached (this, fd->inode);
-        if (!subvol) {
+        local = dht_local_init (frame, NULL, fd, GF_FOP_INODELK);
+        if (!local) {
+                op_errno = ENOMEM;
+                goto err;
+        }
+
+        local->call_cnt = 1;
+        local->lock_type = lock->l_type;
+
+        lock_subvol = dht_get_lock_subvolume (this, lock, local);
+        if (!lock_subvol) {
                 gf_msg_debug (this->name, 0,
-                              "no cached subvolume for fd=%p", fd);
+                              "no lock subvolume for fd=%p", fd);
                 op_errno = EINVAL;
                 goto err;
         }
 
 
-        STACK_WIND (frame, dht_finodelk_cbk, subvol, subvol->fops->finodelk,
+        STACK_WIND (frame, dht_finodelk_cbk, lock_subvol,
+                    lock_subvol->fops->finodelk,
                     volume, fd, cmd, lock, xdata);
 
         return 0;
diff --git a/xlators/cluster/dht/src/dht-messages.h b/xlators/cluster/dht/src/dht-messages.h
index 044292d86ca..8c0b9103df1 100644
--- a/xlators/cluster/dht/src/dht-messages.h
+++ b/xlators/cluster/dht/src/dht-messages.h
@@ -40,7 +40,7 @@
  */
 
 #define GLFS_DHT_BASE                   GLFS_MSGID_COMP_DHT
-#define GLFS_DHT_NUM_MESSAGES           114
+#define GLFS_DHT_NUM_MESSAGES           116
 #define GLFS_MSGID_END          (GLFS_DHT_BASE + GLFS_DHT_NUM_MESSAGES + 1)
 
 /* Messages with message IDs */
@@ -1064,5 +1064,12 @@
  */
 #define DHT_MSG_LOCK_MIGRATION_FAILED  (GLFS_DHT_BASE + 115)
 
+/*
+ * @messageid 109116
+ * @diagnosis
+ * @recommendedaction None
+ */
+#define DHT_MSG_LOCK_INODE_UNREF_FAILED  (GLFS_DHT_BASE + 116)
+
 #define glfs_msg_end_x GLFS_MSGID_END, "Invalid: End of messages"
 #endif /* _DHT_MESSAGES_H_ */