features/changelog: Crash consistency of changelog wrt snapshot

This patch introduces call-path fop details logging for data operations
in CHANGELOG.SNAP. This feature is enabled with barrier-enable
notification and disabled with barrier-disable notification.

BUG: 1138952
Change-Id: Ic418dd70b0a0b369202c5b79a6f7f96512821065
Signed-off-by: Ajeet Jha <ajha@redhat.com>
Reviewed-on: http://review.gluster.org/8533
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>
Reviewed-on: http://review.gluster.org/8648

4 files changed, 232 insertions, 0 deletions

diff --git a/xlators/features/changelog/src/changelog-helpers.c b/xlators/features/changelog/src/changelog-helpers.c
index 07c6096dce5..9dccf45187c 100644
--- a/xlators/features/changelog/src/changelog-helpers.c
+++ b/xlators/features/changelog/src/changelog-helpers.c
@@ -337,6 +337,101 @@ out:
         return ret;
 }
 
+/* Description:
+ *      Opens the snap changelog to log call path fops in it.
+ *      This changelos name is "CHANGELOG.SNAP", stored in
+ *      path ".glusterfs/changelogs/csnap".
+ * Returns:
+ *       0  : On success.
+ *      -1  : On failure.
+ */
+int
+changelog_snap_open (xlator_t *this,
+                         changelog_priv_t *priv)
+{
+        int fd                        = -1;
+        int ret                       = 0;
+        int flags                     = 0;
+        char buffer[1024]             = {0,};
+        char c_snap_path[PATH_MAX]    = {0,};
+        char csnap_dir_path[PATH_MAX] = {0,};
+
+        CHANGELOG_FILL_CSNAP_DIR(priv->changelog_dir, csnap_dir_path);
+
+        (void) snprintf (c_snap_path, PATH_MAX,
+                        "%s/"CSNAP_FILE_NAME,
+                        csnap_dir_path);
+
+        flags |= (O_CREAT | O_RDWR | O_TRUNC);
+
+        fd = open (c_snap_path, flags,
+                        S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+        if (fd < 0) {
+                gf_log (this->name, GF_LOG_ERROR,
+                                "unable to open %s file "
+                                "reason:(%s)", c_snap_path, strerror (errno));
+                ret = -1;
+                goto out;
+        }
+        priv->c_snap_fd = fd;
+
+        (void) snprintf (buffer, 1024, CHANGELOG_HEADER,
+                        CHANGELOG_VERSION_MAJOR,
+                        CHANGELOG_VERSION_MINOR,
+                        priv->ce->encoder);
+        ret = changelog_snap_write_change (priv, buffer, strlen (buffer));
+        if (ret < 0) {
+                close (priv->c_snap_fd);
+                priv->c_snap_fd = -1;
+                goto out;
+        }
+
+out:
+        return ret;
+}
+
+/*
+ * Description:
+ *      Starts logging fop details in CSNAP journal.
+ * Returns:
+ *       0 : On success.
+ *      -1 : On Failure.
+ */
+int
+changelog_snap_logging_start (xlator_t *this,
+                                  changelog_priv_t *priv)
+{
+        int ret = 0;
+
+        ret = changelog_snap_open (this, priv);
+        gf_log (this->name, GF_LOG_INFO,
+                        "Now starting to log in call path");
+
+        return ret;
+}
+
+/*
+ * Description:
+ *      Stops logging fop details in CSNAP journal.
+ * Returns:
+ *       0 : On success.
+ *      -1 : On Failure.
+ */
+int
+changelog_snap_logging_stop (xlator_t *this,
+                changelog_priv_t *priv)
+{
+        int ret         = 0;
+
+        close (priv->c_snap_fd);
+        priv->c_snap_fd = -1;
+
+        gf_log (this->name, GF_LOG_INFO,
+                        "Stopped to log in call path");
+
+        return ret;
+}
+
 int
 changelog_open (xlator_t *this,
                 changelog_priv_t *priv)
@@ -424,11 +519,72 @@ changelog_fill_rollover_data (changelog_log_data_t *cld, gf_boolean_t is_last)
 }
 
 int
+changelog_snap_write_change (changelog_priv_t *priv, char *buffer, size_t len)
+{
+        return changelog_write (priv->c_snap_fd, buffer, len);
+}
+
+int
 changelog_write_change (changelog_priv_t *priv, char *buffer, size_t len)
 {
         return changelog_write (priv->changelog_fd, buffer, len);
 }
 
+/*
+ * Descriptions:
+ *      Writes fop details in ascii format to CSNAP.
+ * Issues:
+ *      Not Encoding agnostic.
+ * Returns:
+ *      0 : On Success.
+ *     -1 : On Failure.
+ */
+int
+changelog_snap_handle_ascii_change (xlator_t *this,
+                                    changelog_log_data_t *cld)
+{
+        size_t            off      = 0;
+        size_t            gfid_len = 0;
+        char             *gfid_str = NULL;
+        char             *buffer   = NULL;
+        changelog_priv_t *priv     = NULL;
+        int               ret      = 0;
+
+        if (this == NULL) {
+                ret = -1;
+                goto out;
+        }
+
+        priv = this->private;
+
+        if (priv == NULL) {
+                ret = -1;
+                goto out;
+        }
+
+        gfid_str = uuid_utoa (cld->cld_gfid);
+        gfid_len = strlen (gfid_str);
+
+        /*  extra bytes for decorations */
+        buffer = alloca (gfid_len + cld->cld_ptr_len + 10);
+        CHANGELOG_STORE_ASCII (priv, buffer,
+                        off, gfid_str, gfid_len, cld);
+
+        CHANGELOG_FILL_BUFFER (buffer, off, "\0", 1);
+
+        ret = changelog_snap_write_change (priv, buffer, off);
+
+        if (ret < 0) {
+                gf_log (this->name, GF_LOG_ERROR,
+                                "error writing csnap to disk");
+        }
+        gf_log (this->name, GF_LOG_INFO,
+                        "Successfully wrote to csnap");
+        ret = 0;
+out:
+        return ret;
+}
+
 inline int
 changelog_handle_change (xlator_t *this,
                          changelog_priv_t *priv, changelog_log_data_t *cld)
diff --git a/xlators/features/changelog/src/changelog-helpers.h b/xlators/features/changelog/src/changelog-helpers.h
index 95f369bf936..d4af1ff3445 100644
--- a/xlators/features/changelog/src/changelog-helpers.h
+++ b/xlators/features/changelog/src/changelog-helpers.h
@@ -212,11 +212,17 @@ struct changelog_priv {
         /* htime fd for current changelog session */
         int htime_fd;
 
+        /*  c_snap_fd is fd for call-path changelog */
+        int c_snap_fd;
+
         /* rollover_count used by htime */
         int  rollover_count;
 
         gf_lock_t lock;
 
+        /*  lock to synchronize CSNAP updation */
+        gf_lock_t c_snap_lock;
+
         /* writen end of the pipe */
         int wfd;
 
@@ -431,6 +437,18 @@ changelog_drain_white_fops (xlator_t *this, changelog_priv_t *priv);
 void
 changelog_drain_black_fops (xlator_t *this, changelog_priv_t *priv);
 
+/* Crash consistency of changelog wrt snapshot */
+int
+changelog_snap_logging_stop ( xlator_t *this, changelog_priv_t *priv);
+int
+changelog_snap_logging_start ( xlator_t *this, changelog_priv_t *priv);
+int
+changelog_snap_open ( xlator_t *this, changelog_priv_t *priv);
+int
+changelog_snap_handle_ascii_change (xlator_t *this,
+                changelog_log_data_t *cld);
+int
+changelog_snap_write_change (changelog_priv_t *priv, char *buffer, size_t len);
 /* Changelog barrier routines */
 void __chlog_barrier_enqueue (xlator_t *this, call_stub_t *stub);
 void __chlog_barrier_disable (xlator_t *this, struct list_head *queue);
diff --git a/xlators/features/changelog/src/changelog-misc.h b/xlators/features/changelog/src/changelog-misc.h
index 257c1f34218..58b10961463 100644
--- a/xlators/features/changelog/src/changelog-misc.h
+++ b/xlators/features/changelog/src/changelog-misc.h
@@ -17,6 +17,7 @@
 #define CHANGELOG_MAX_TYPE  3
 #define CHANGELOG_FILE_NAME "CHANGELOG"
 #define HTIME_FILE_NAME "HTIME"
+#define CSNAP_FILE_NAME "CHANGELOG.SNAP"
 #define HTIME_KEY "trusted.glusterfs.htime"
 #define HTIME_INITIAL_VALUE "0:0"
 
@@ -71,6 +72,11 @@
                 strcpy (path, changelog_dir);                   \
                 strcat (path, "/htime");                        \
         } while(0)
+
+#define CHANGELOG_FILL_CSNAP_DIR(changelog_dir, path) do {      \
+                strcpy (path, changelog_dir);                   \
+                strcat (path, "/csnap");                        \
+        } while(0)
 /**
  * everything after 'CHANGELOG_TYPE_ENTRY' are internal types
  * (ie. none of the fops trigger this type of event), hence
diff --git a/xlators/features/changelog/src/changelog.c b/xlators/features/changelog/src/changelog.c
index bbf05ba48c1..04e48b9ef08 100644
--- a/xlators/features/changelog/src/changelog.c
+++ b/xlators/features/changelog/src/changelog.c
@@ -1152,6 +1152,16 @@ changelog_truncate (call_frame_t *frame,
 
         CHANGELOG_INIT (this, frame->local,
                         loc->inode, loc->inode->gfid, 0);
+        LOCK(&priv->c_snap_lock);
+        {
+                if (priv->c_snap_fd != -1 &&
+                    priv->barrier_enabled == _gf_true) {
+                        changelog_snap_handle_ascii_change (this,
+                              &( ((changelog_local_t *)(frame->local))->cld));
+                }
+        }
+        UNLOCK(&priv->c_snap_lock);
+
 
  wind:
         changelog_color_fop_and_inc_cnt (this, priv, frame->local);
@@ -1195,6 +1205,15 @@ changelog_ftruncate (call_frame_t *frame,
 
         CHANGELOG_INIT (this, frame->local,
                         fd->inode, fd->inode->gfid, 0);
+        LOCK(&priv->c_snap_lock);
+        {
+                if (priv->c_snap_fd != -1 &&
+                    priv->barrier_enabled == _gf_true) {
+                        changelog_snap_handle_ascii_change (this,
+                              &( ((changelog_local_t *)(frame->local))->cld));
+                }
+        }
+        UNLOCK(&priv->c_snap_lock);
 
  wind:
         changelog_color_fop_and_inc_cnt (this, priv, frame->local);
@@ -1242,6 +1261,15 @@ changelog_writev (call_frame_t *frame,
 
         CHANGELOG_INIT (this, frame->local,
                         fd->inode, fd->inode->gfid, 0);
+        LOCK(&priv->c_snap_lock);
+        {
+                if (priv->c_snap_fd != -1 &&
+                    priv->barrier_enabled == _gf_true) {
+                        changelog_snap_handle_ascii_change (this,
+                              &( ((changelog_local_t *)(frame->local))->cld));
+                }
+        }
+        UNLOCK(&priv->c_snap_lock);
 
  wind:
         changelog_color_fop_and_inc_cnt (this, priv, frame->local);
@@ -1470,6 +1498,11 @@ notify (xlator_t *this, int event, void *data, ...)
                                 "Barrier off notification");
 
                         CHANGELOG_NOT_ON_THEN_GOTO(priv, ret, out);
+                        LOCK(&priv->c_snap_lock);
+                        {
+                                changelog_snap_logging_stop (this, priv);
+                        }
+                        UNLOCK(&priv->c_snap_lock);
 
                         LOCK (&priv->bflags.lock);
                         {
@@ -1519,6 +1552,11 @@ notify (xlator_t *this, int event, void *data, ...)
                                 "Barrier on notification");
 
                         CHANGELOG_NOT_ON_THEN_GOTO(priv, ret, out);
+                        LOCK(&priv->c_snap_lock);
+                        {
+                                changelog_snap_logging_start (this, priv);
+                        }
+                        UNLOCK(&priv->c_snap_lock);
 
                         LOCK (&priv->bflags.lock);
                         {
@@ -1799,6 +1837,7 @@ reconfigure (xlator_t *this, dict_t *options)
         changelog_time_slice_t *slice          = NULL;
         changelog_log_data_t    cld            = {0,};
         char    htime_dir[PATH_MAX]            = {0,};
+        char    csnap_dir[PATH_MAX]            = {0,};
         struct timeval          tv             = {0,};
         uint32_t                timeout        = 0;
 
@@ -1834,6 +1873,12 @@ reconfigure (xlator_t *this, dict_t *options)
         if (ret)
                 goto out;
 
+        CHANGELOG_FILL_CSNAP_DIR(priv->changelog_dir, csnap_dir);
+        ret = mkdir_p (csnap_dir, 0600, _gf_true);
+
+        if (ret)
+                goto out;
+
         GF_OPTION_RECONF ("changelog", active_now, options, bool, out);
 
         /**
@@ -1916,6 +1961,7 @@ init (xlator_t *this)
         changelog_priv_t        *priv                   = NULL;
         gf_boolean_t            cond_lock_init          = _gf_false;
         char                    htime_dir[PATH_MAX]     = {0,};
+        char                    csnap_dir[PATH_MAX]     = {0,};
         uint32_t                timeout                 = 0;
 
         GF_VALIDATE_OR_GOTO ("changelog", this, out);
@@ -1944,6 +1990,7 @@ init (xlator_t *this)
         }
 
         LOCK_INIT (&priv->lock);
+        LOCK_INIT (&priv->c_snap_lock);
 
         GF_OPTION_INIT ("changelog-brick", tmp, str, out);
         if (!tmp) {
@@ -1983,6 +2030,11 @@ init (xlator_t *this)
         if (ret)
                 goto out;
 
+        CHANGELOG_FILL_CSNAP_DIR(priv->changelog_dir, csnap_dir);
+        ret = mkdir_p (csnap_dir, 0600, _gf_true);
+        if (ret)
+                goto out;
+
         GF_OPTION_INIT ("changelog", priv->active, bool, out);
 
         GF_OPTION_INIT ("op-mode", tmp, str, out);