features/bit-rot: Implementation of bit-rot xlator

This is the "Signer" -- responsible for signing files with their
checksums upon last file descriptor close (last release()).
The event notification facility provided by the changelog xlator
is made use of.

Moreover, checksums are as of now SHA256 hash of the object data
and is the only available hash at this point of time. Therefore,
there is no special "what hash to use" type check, although it's
does not take much to add various hashing algorithms to sign
objects with. Signatures are stored in extended attributes of the
objects along with the the type of hashing used to calculate the
signature. This makes thing future proof when other hash types
are added. The signature  infrastructure is provided by bitrot
stub: a little piece of code that sits over the POSIX xlator
providing interfaces to "get or set" objects signature and it's
staleness.

Since objects are signed upon receiving release() notification,
pre-existing data which are "never" modified would never be
signed. To counter this, an initial crawler thread is spawned
The crawler scans the entire brick for objects that are unsigned
or "missed" signing due to the server going offline (node reboots,
crashes, etc..) and triggers an explicit sign. This would also
sign objects when bit-rot is enabled for a volume and/or after
upgrade.

Change-Id: I1d9a98bee6cad1c39c35c53c8fb0fc4bad2bf67b
BUG: 1170075
Original-Author: Raghavendra Bhat <raghavendra@redhat.com>
Signed-off-by: Venky Shankar <vshankar@redhat.com>
Reviewed-on: http://review.gluster.org/9711
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 126 insertions, 0 deletions

diff --git a/xlators/features/bit-rot/src/bitd/bit-rot.h b/xlators/features/bit-rot/src/bitd/bit-rot.h
new file mode 100644
index 00000000000..ab9fd806232
--- /dev/null
+++ b/xlators/features/bit-rot/src/bitd/bit-rot.h
@@ -0,0 +1,126 @@
+/*
+   Copyright (c) 2015 Red Hat, Inc. <http://www.redhat.com>
+   This file is part of GlusterFS.
+
+   This file is licensed to you under your choice of the GNU Lesser
+   General Public License, version 3 or any later version (LGPLv3 or
+   later), or the GNU General Public License, version 2 (GPLv2), in all
+   cases as published by the Free Software Foundation.
+*/
+#ifndef __BIT_ROT_H__
+#define __BIT_ROT_H__
+
+#ifndef _CONFIG_H
+#define _CONFIG_H
+#include "config.h"
+#endif
+
+#include "glusterfs.h"
+#include "logging.h"
+#include "dict.h"
+#include "xlator.h"
+#include "defaults.h"
+#include "syncop.h"
+#include "syncop-utils.h"
+#include "changelog.h"
+#include "timer-wheel.h"
+
+#include "bit-rot-common.h"
+#include "bit-rot-stub-mem-types.h"
+
+#include <openssl/sha.h>
+
+/* TODO: make this configurable */
+#define BR_WORKERS 8
+
+#define signature_size(hl) (sizeof (br_isignature_t) + hl + 1)
+
+struct br_child {
+        char child_up;                /* Indicates whether this child is
+                                         up or not */
+        xlator_t *xl;                 /* client xlator corresponding to
+                                         this child */
+        inode_table_t *table;         /* inode table for this child */
+        char brick_path[PATH_MAX];    /* brick export directory of this
+                                         child */
+        struct list_head list;        /* hook to attach to the list of
+                                         UP children */
+        xlator_t *this;               /* Bit rot xlator */
+
+        pthread_t thread;             /* initial crawler for unsigned
+                                         object(s) */
+        int threadrunning;            /* active thread */
+
+        struct mem_pool *timer_pool;  /* timer-wheel's timer mem-pool */
+
+        struct timeval tv;
+};
+
+typedef struct br_child br_child_t;
+
+struct br_obj_n_workers {
+        struct list_head objects;         /* queue of objects expired from the
+                                             timer wheel and ready to be picked
+                                             up for signing */
+        pthread_t workers[BR_WORKERS];    /* Threads which pick up the objects
+                                             from the above queue and start
+                                             signing each object */
+};
+
+typedef struct br_obj_n_workers br_obj_n_workers_t;
+
+struct br_private {
+        pthread_mutex_t lock;
+
+        struct list_head bricks;          /* list of bricks from which CHILD_UP
+                                             has been received */
+
+        pthread_cond_t cond;              /* handling CHILD_UP notifications */
+        pthread_cond_t object_cond;       /* handling signing of objects */
+        int child_count;
+        br_child_t *children;             /* list of subvolumes */
+        int up_children;
+        pthread_t thread;                 /* thread for connecting each UP
+                                             child with changelog */
+        struct tvec_base *timer_wheel;    /* timer wheel where the objects which
+                                             changelog has sent sits and waits
+                                             for expiry */
+        br_obj_n_workers_t *obj_queue;    /* place holder for all the objects
+                                             that are expired from timer wheel
+                                             and ready to be picked up for
+                                             signing and the workers which sign
+                                             the objects */
+        int32_t expiry_time;              /* objects "wait" time */
+};
+
+typedef struct br_private br_private_t;
+
+struct br_object {
+        xlator_t *this;
+
+        uuid_t gfid;
+
+        unsigned long signedversion;    /* version aginst which this object will
+                                           be signed */
+        br_child_t *child;              /* object's subvolume */
+
+        struct list_head list;          /* hook to add to the queue once the
+                                           object is expired from timer wheel */
+        void *data;
+};
+
+typedef struct br_object br_object_t;
+
+void
+br_log_object (xlator_t *, char *, uuid_t, int32_t);
+
+void
+br_log_object_path (xlator_t *, char *, const char *, int32_t);
+
+int32_t
+br_object_checksum (unsigned char *, br_object_t *, fd_t *, struct iatt *);
+
+int32_t
+br_prepare_loc (xlator_t *, br_child_t *, loc_t *, gf_dirent_t *, loc_t *);
+
+#endif /* __BIT_ROT_H__ */