Add functions to check whether a client is allowed to reclaim, and
update its timestamp in the DB if so. We do this with an UPDATE OR
FAIL SQL statement. If the update fails for any reason (like, say
the record doesn't exist), then the kernel can disallow the reclaim.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
utils/clstated/clstated.c | 32 ++++++++++++++++++++++++
utils/clstated/sqlite.c | 58 +++++++++++++++++++++++++++++++++++++++++++++
utils/clstated/sqlite.h | 1 +
3 files changed, 91 insertions(+), 0 deletions(-)
diff --git a/utils/clstated/clstated.c b/utils/clstated/clstated.c
index 54214cb..885e302 100644
--- a/utils/clstated/clstated.c
+++ b/utils/clstated/clstated.c
@@ -177,6 +177,36 @@ clstate_remove(struct clstate_client *clnt)
}
static void
+clstate_check(struct clstate_client *clnt)
+{
+ int ret;
+ ssize_t bsize, wsize;
+ struct clstate_msg *cmsg = &clnt->cl_msg;
+
+ xlog(D_GENERAL, "%s: check client record. cm_addr=%s", __func__,
+ cmsg->cm_addr);
+
+ ret = clstate_check_client(cmsg->cm_addr, cmsg->cm_u.cm_id,
+ cmsg->cm_len);
+
+ /* set up reply */
+ cmsg->cm_status = ret ? -EACCES : ret;
+ cmsg->cm_len = 0;
+ memset(cmsg->cm_addr, 0, sizeof(cmsg->cm_addr) +
+ sizeof(cmsg->cm_u.cm_id));
+
+ bsize = sizeof(*cmsg);
+
+ xlog(D_GENERAL, "Doing downcall with status %d", cmsg->cm_status);
+ wsize = atomicio((void *)write, clnt->cl_fd, cmsg, bsize);
+ if (wsize != bsize) {
+ xlog(L_ERROR, "%s: problem writing to clstate pipe (%ld): %m",
+ __func__, wsize);
+ clstate_pipe_reopen(clnt);
+ }
+}
+
+static void
clstatecb(int UNUSED(fd), short which, void *data)
{
ssize_t len;
@@ -201,6 +231,8 @@ clstatecb(int UNUSED(fd), short which, void *data)
clstate_remove(clnt);
break;
case Cl_Allow:
+ clstate_check(clnt);
+ break;
case Cl_NrToReclaim:
case Cl_GraceDone:
xlog_warn("%s: command %u is not yet implemented", __func__,
diff --git a/utils/clstated/sqlite.c b/utils/clstated/sqlite.c
index 78ce6b4..d6f6a90 100644
--- a/utils/clstated/sqlite.c
+++ b/utils/clstated/sqlite.c
@@ -403,3 +403,61 @@ out_detach:
clstate_db_detach(dbname);
return ret;
}
+
+/*
+ * Update a client's timestamp. Return an error if the update fails. On error,
+ * the kernel can infer that reclaim should be denied.
+ */
+int
+clstate_check_client(const unsigned char *addr, const unsigned char *clname,
+ const size_t namelen)
+{
+ int ret;
+ char *err = NULL;
+ char dbname[CLSTATE_MAX_ADDRESS_LEN];
+ sqlite3_stmt *stmt = NULL;
+
+ addr_to_dbname((const char *)addr, dbname);
+
+ ret = clstate_db_attach(dbname);
+ if (ret != SQLITE_OK)
+ return ret;
+
+ ret = snprintf(buf, sizeof(buf),
+ "UPDATE OR FAIL '%s'.clients SET time=strftime('%%s', "
+ "'now') WHERE id==?", dbname);
+ if (ret < 0) {
+ goto out_detach;
+ } else if ((size_t)ret >= sizeof(buf)) {
+ ret = -EINVAL;
+ goto out_detach;
+ }
+
+ ret = sqlite3_prepare_v2(dbh, buf, -1, &stmt, NULL);
+ if (ret != SQLITE_OK) {
+ xlog(D_GENERAL, "Unable to prepare update statement: %d", ret);
+ goto out_err;
+ }
+
+ ret = sqlite3_bind_blob(stmt, 1, (const void *)clname, namelen,
+ SQLITE_STATIC);
+ if (ret != SQLITE_OK) {
+ xlog(D_GENERAL, "Bind blob failed: %d", ret);
+ goto out_err;
+ }
+
+ ret = sqlite3_step(stmt);
+ if (ret == SQLITE_DONE)
+ ret = SQLITE_OK;
+ else
+ xlog(D_GENERAL, "Unexpected return code from update: %s",
+ sqlite3_errmsg(dbh));
+
+out_err:
+ xlog(D_GENERAL, "%s returning %d", __func__, ret);
+ sqlite3_finalize(stmt);
+ sqlite3_free(err);
+out_detach:
+ clstate_db_detach(dbname);
+ return ret;
+}
diff --git a/utils/clstated/sqlite.h b/utils/clstated/sqlite.h
index 6f5637f..46d2f24 100644
--- a/utils/clstated/sqlite.h
+++ b/utils/clstated/sqlite.h
@@ -24,5 +24,6 @@ void clstate_set_topdir(char *topdir);
int clstate_maindb_init(void);
int clstate_insert_client(const unsigned char *addr, const unsigned char *clname, const size_t namelen);
int clstate_remove_client(const unsigned char *addr, const unsigned char *clname, const size_t namelen);
+int clstate_check_client(const unsigned char *addr, const unsigned char *clname, const size_t namelen);
#endif /* _SQLITE_H */
--
1.7.1
--
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