libgfapi: Store and restore THIS in every API exposed by libgfapi

        Backport of http://review.gluster.org/#/c/9797

Storing and restoring THIS:
When the APIs exposed by libgfapi are called by other xlators like
snapview server etc. the THIS value is overwritten to contain the
THIS of libgfapi(viz libgfapi master xlator). Hence using 'THIS'
in any xlator after calling libgfapi API will lead to issues.
One such issue was uncovered in snapview and the patch
http://review.gluster.org/#/c/9469/ was sent to workaround this issue.

Hence, storing and restoring THIS, at the entry and exit of every API
exposed by libgfapi.

Change-Id: I6f330dde25e7700fb26339d667a7ccd193ec6ba0
BUG: 1210934
Signed-off-by: Poornima G <pgurusid@redhat.com>
Reviewed-on: http://review.gluster.org/9797
Reviewed-by: Raghavendra Talur <rtalur@redhat.com>
Reviewed-by: soumya k <skoduri@redhat.com>
Reviewed-by: Niels de Vos <ndevos@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
(cherry picked from commit 1162bb36108ab8dba8303b86927a99835b791d79)
Reviewed-on: http://review.gluster.org/10414
Reviewed-by: Shyamsundar Ranganathan <srangana@redhat.com>

1 files changed, 88 insertions, 31 deletions

diff --git a/api/src/glfs.c b/api/src/glfs.c
index 23377f651d1..d6a6fe9c850 100644
--- a/api/src/glfs.c
+++ b/api/src/glfs.c
@@ -303,6 +303,9 @@ pub_glfs_set_xlator_option (struct glfs *fs, const char *xlator,
 {
 	xlator_cmdline_option_t *option = NULL;
 
+        DECLARE_OLD_THIS;
+        __GLFS_ENTRY_VALIDATE_FS (fs, invalid_fs);
+
 	option = GF_CALLOC (1, sizeof (*option),
 			    glfs_mt_xlator_cmdline_option_t);
 	if (!option)
@@ -322,18 +325,25 @@ pub_glfs_set_xlator_option (struct glfs *fs, const char *xlator,
 
 	list_add (&option->cmd_args, &fs->ctx->cmd_args.xlator_options);
 
+        __GLFS_EXIT_FS;
+
 	return 0;
 enomem:
 	errno = ENOMEM;
 
-	if (!option)
+	if (!option) {
+                __GLFS_EXIT_FS;
 		return -1;
+        }
 
 	GF_FREE (option->volume);
 	GF_FREE (option->key);
 	GF_FREE (option->value);
 	GF_FREE (option);
 
+        __GLFS_EXIT_FS;
+
+invalid_fs:
 	return -1;
 }
 
@@ -353,6 +363,9 @@ pub_glfs_unset_volfile_server (struct glfs *fs, const char *transport,
                 return ret;
         }
 
+        DECLARE_OLD_THIS;
+        __GLFS_ENTRY_VALIDATE_FS (fs, invalid_fs);
+
         cmd_args = &fs->ctx->cmd_args;
         list_for_each_entry(server, &cmd_args->curr_server->list, list) {
                 if ((!strcmp(server->volfile_server, host) &&
@@ -365,6 +378,9 @@ pub_glfs_unset_volfile_server (struct glfs *fs, const char *transport,
         }
 
 out:
+        __GLFS_EXIT_FS;
+
+invalid_fs:
         return ret;
 }
 
@@ -385,6 +401,9 @@ pub_glfs_set_volfile_server (struct glfs *fs, const char *transport,
                 return ret;
         }
 
+        DECLARE_OLD_THIS;
+        __GLFS_ENTRY_VALIDATE_FS (fs, invalid_fs);
+
         cmd_args = &fs->ctx->cmd_args;
 
         cmd_args->max_connect_attempts = 1;
@@ -444,6 +463,9 @@ out:
                 }
         }
 
+        __GLFS_EXIT_FS;
+
+invalid_fs:
         return ret;
 }
 
@@ -453,6 +475,9 @@ GFAPI_SYMVER_PUBLIC_DEFAULT(glfs_set_volfile_server, 3.4.0);
 int
 pub_glfs_setfsuid (uid_t fsuid)
 {
+         /* TODO:
+         * - Set the THIS and restore it appropriately
+         */
 	return syncopctx_setfsuid (&fsuid);
 }
 
@@ -462,6 +487,9 @@ GFAPI_SYMVER_PUBLIC_DEFAULT(glfs_setfsuid, 3.4.2);
 int
 pub_glfs_setfsgid (gid_t fsgid)
 {
+         /* TODO:
+         * - Set the THIS and restore it appropriately
+         */
 	return syncopctx_setfsgid (&fsgid);
 }
 
@@ -471,6 +499,9 @@ GFAPI_SYMVER_PUBLIC_DEFAULT(glfs_setfsgid, 3.4.2);
 int
 pub_glfs_setfsgroups (size_t size, const gid_t *list)
 {
+         /* TODO:
+         * - Set the THIS and restore it appropriately
+         */
 	return syncopctx_setfsgroups(size, list);
 }
 
@@ -563,7 +594,7 @@ pub_glfs_new (const char *volname)
 	struct glfs     *fs             = NULL;
 	int              ret            = -1;
 	glusterfs_ctx_t *ctx            = NULL;
-        gf_boolean_t     cleanup_fini   = _gf_false;
+        xlator_t        *old_THIS       = NULL;
 
         if (!volname) {
                 errno = EINVAL;
@@ -590,47 +621,49 @@ pub_glfs_new (const char *volname)
         if (ret != 0)
                 goto cond_child_destroy;
 
-        cleanup_fini = _gf_true;
-
         ctx = glusterfs_ctx_new ();
         if (!ctx)
-                goto freefs;
+                goto fini;
 
         /* first globals init, for gf_mem_acct_enable_set () */
 
         ret = glusterfs_globals_init (ctx);
         if (ret)
-                goto freefs;
+                goto fini;
 
-        if (!THIS->ctx)
-                THIS->ctx = ctx;
+        old_THIS = THIS;
+        /* THIS is set to NULL so that we do not modify the caller xlators'
+         * ctx, instead we set the global_xlator->ctx
+         */
+        THIS = NULL;
+        THIS->ctx = ctx;
 
         /* then ctx_defaults_init, for xlator_mem_acct_init(THIS) */
 
         ret = glusterfs_ctx_defaults_init (ctx);
         if (ret)
-                goto freefs;
+                goto fini;
 
         fs->ctx = ctx;
 
         ret = glfs_set_logging (fs, "/dev/null", 0);
         if (ret)
-                goto freefs;
+                goto fini;
 
         fs->ctx->cmd_args.volfile_id = gf_strdup (volname);
         if (!(fs->ctx->cmd_args.volfile_id))
-                goto freefs;
+                goto fini;
 
         fs->volname = strdup (volname);
         if (!fs->volname)
-                goto freefs;
+                goto fini;
 
         INIT_LIST_HEAD (&fs->openfds);
         INIT_LIST_HEAD (&fs->upcall_list);
 
         fs->pin_refcnt = 0;
 
-        return fs;
+        goto out;
 
 cond_child_destroy:
         pthread_cond_destroy (&fs->child_down_cond);
@@ -642,7 +675,10 @@ mutex_destroy:
         pthread_mutex_destroy (&fs->mutex);
 
 freefs:
-
+        FREE (fs);
+        fs = NULL;
+        goto out;
+fini:
         /*
          * When pthread_*init() fails there is no way for other cleanup
          * funtions (glfs_fini/glfs_free_from_ctx) to know which of them succeded
@@ -651,14 +687,13 @@ freefs:
          * directly call glfs_fini() to cleanup the resources.
          */
 
-        if (!cleanup_fini)
-                FREE(fs);
-        else
-                glfs_fini (fs);
-        fs = NULL;
+         glfs_fini (fs);
+         fs = NULL;
+out:
+        if (old_THIS)
+                THIS = old_THIS;
 
         return fs;
-
 }
 
 GFAPI_SYMVER_PUBLIC_DEFAULT(glfs_new, 3.4.0);
@@ -750,9 +785,12 @@ GFAPI_SYMVER_PUBLIC_DEFAULT(glfs_set_volfile, 3.4.0);
 int
 pub_glfs_set_logging (struct glfs *fs, const char *logfile, int loglevel)
 {
-        int  ret = 0;
+        int  ret = -1;
         char *tmplog = NULL;
 
+        DECLARE_OLD_THIS;
+        __GLFS_ENTRY_VALIDATE_FS (fs, invalid_fs);
+
         if (!logfile) {
                 ret = gf_set_log_file_path (&fs->ctx->cmd_args);
                 if (ret)
@@ -775,6 +813,9 @@ pub_glfs_set_logging (struct glfs *fs, const char *logfile, int loglevel)
                 goto out;
 
 out:
+        __GLFS_EXIT_FS;
+
+invalid_fs:
         return ret;
 }
 
@@ -882,6 +923,8 @@ pub_glfs_init (struct glfs *fs)
 {
 	int  ret = -1;
 
+        DECLARE_OLD_THIS;
+
 	if (!fs || !fs->ctx) {
 		gf_msg ("glfs", GF_LOG_ERROR, EINVAL, API_MSG_INVALID_ENTRY,
 			"fs is not properly initialized.");
@@ -889,17 +932,22 @@ pub_glfs_init (struct glfs *fs)
 		return ret;
 	}
 
+        __GLFS_ENTRY_VALIDATE_FS (fs, invalid_fs);
+
 	ret = glfs_init_common (fs);
 	if (ret)
-		return ret;
+		goto out;
 
 	ret = glfs_init_wait (fs);
+out:
+        __GLFS_EXIT_FS;
 
         /* Set the initial current working directory to "/" */
         if (ret >= 0) {
                 ret = glfs_chdir (fs, "/");
         }
 
+invalid_fs:
 	return ret;
 }
 
@@ -985,19 +1033,15 @@ pub_glfs_fini (struct glfs *fs)
         int                fs_init = 0;
         int                err = -1;
 
+        DECLARE_OLD_THIS;
 
-        if (!fs) {
-                errno = EINVAL;
-                return 0;
-        }
+        __GLFS_ENTRY_VALIDATE_FS (fs, invalid_fs);
 
         ctx = fs->ctx;
         if (!ctx) {
                 goto free_fs;
         }
 
-        __glfs_entry_fs (fs);
-
         if (ctx->mgmt) {
                 rpc_clnt_disable (ctx->mgmt);
                 ctx->mgmt = NULL;
@@ -1141,6 +1185,9 @@ fail:
         if (!ret)
                 ret = err;
 
+        __GLFS_EXIT_FS;
+
+invalid_fs:
         return ret;
 }
 
@@ -1150,7 +1197,10 @@ GFAPI_SYMVER_PUBLIC_DEFAULT(glfs_fini, 3.4.0);
 ssize_t
 pub_glfs_get_volfile (struct glfs *fs, void *buf, size_t len)
 {
-        ssize_t         res;
+        ssize_t         res = -1;
+
+        DECLARE_OLD_THIS;
+        __GLFS_ENTRY_VALIDATE_FS (fs, invalid_fs);
 
         glfs_lock(fs);
         if (len >= fs->oldvollen) {
@@ -1164,6 +1214,9 @@ pub_glfs_get_volfile (struct glfs *fs, void *buf, size_t len)
         }
         glfs_unlock(fs);
 
+        __GLFS_EXIT_FS;
+
+invalid_fs:
         return res;
 }
 
@@ -1173,9 +1226,10 @@ int
 pub_glfs_ipc (struct glfs *fs, int opcode)
 {
 	xlator_t        *subvol = NULL;
-        int             ret;
+        int             ret = -1;
 
-	__glfs_entry_fs (fs);
+	DECLARE_OLD_THIS;
+        __GLFS_ENTRY_VALIDATE_FS (fs, invalid_fs);
 
 	subvol = glfs_active_subvol (fs);
 	if (!subvol) {
@@ -1189,6 +1243,9 @@ pub_glfs_ipc (struct glfs *fs, int opcode)
 
 out:
         glfs_subvol_done (fs, subvol);
+        __GLFS_EXIT_FS;
+
+invalid_fs:
         return ret;
 }