DAOS-16932 dfuse: do not flush dentries at fs stop

This operation will never succeed since the file system is already
unmounted. Therefore it always returns EBADF from libfuse.

Actually, it should not attempt to do that since dentries will be
cleared by kernel at the time of unmounting.

Change-Id: I18eaffc0437d05e5ccc50d0a548451c4837cb1f9
Signed-off-by: Jinshan Xiong <[email protected]>

src/client/dfuse/dfuse_core.c

@@ -1,5 +1,6 @@
 /**
  * (C) Copyright 2016-2024 Intel Corporation.
+ * (C) Copyright 2025 Google LLC.
  *
  * SPDX-License-Identifier: BSD-2-Clause-Patent
  */
@@ -78,11 +79,11 @@ dfuse_progress_thread(void *arg)
 static int
 dfuse_parse_time(char *buff, size_t len, unsigned int *_out)
 {
-	int		matched;
-	unsigned int	out = 0;
-	int		count0 = 0;
-	int		count1 = 0;
-	char		c = '\0';
+	int          matched;
+	unsigned int out    = 0;
+	int          count0 = 0;
+	int          count1 = 0;
+	char         c      = '\0';
 
 	matched = sscanf(buff, "%u%n%c%n", &out, &count0, &c, &count1);
 
@@ -536,7 +537,7 @@ dfuse_pool_connect(struct dfuse_info *dfuse_info, const char *label, struct dfus
 err_disconnect:
 	ret = daos_pool_disconnect(dfp->dfp_poh, NULL);
 	if (ret)
-		DFUSE_TRA_WARNING(dfp, "Failed to disconnect pool: "DF_RC, DP_RC(ret));
+		DFUSE_TRA_WARNING(dfp, "Failed to disconnect pool: " DF_RC, DP_RC(ret));
 err_free:
 	D_FREE(dfp);
 err:
@@ -1377,20 +1378,20 @@ dfuse_event_release(void *arg)
 int
 dfuse_fs_start(struct dfuse_info *dfuse_info, struct dfuse_cont *dfs)
 {
-	struct fuse_args          args     = {0};
+	struct fuse_args          args = {0};
 	struct dfuse_inode_entry *ie;
-	struct d_slab_reg         read_slab  = {.sr_init    = dfuse_event_init,
-						.sr_reset   = dfuse_read_event_reset,
-						.sr_release = dfuse_event_release,
-						POOL_TYPE_INIT(dfuse_event, de_list)};
+	struct d_slab_reg         read_slab     = {.sr_init    = dfuse_event_init,
+						   .sr_reset   = dfuse_read_event_reset,
+						   .sr_release = dfuse_event_release,
+						   POOL_TYPE_INIT(dfuse_event, de_list)};
 	struct d_slab_reg         pre_read_slab = {.sr_init    = dfuse_event_init,
 						   .sr_reset   = dfuse_pre_read_event_reset,
 						   .sr_release = dfuse_event_release,
 						   POOL_TYPE_INIT(dfuse_event, de_list)};
-	struct d_slab_reg         write_slab = {.sr_init    = dfuse_event_init,
-						.sr_reset   = dfuse_write_event_reset,
-						.sr_release = dfuse_event_release,
-						POOL_TYPE_INIT(dfuse_event, de_list)};
+	struct d_slab_reg         write_slab    = {.sr_init    = dfuse_event_init,
+						   .sr_reset   = dfuse_write_event_reset,
+						   .sr_release = dfuse_event_release,
+						   POOL_TYPE_INIT(dfuse_event, de_list)};
 	int                       rc;
 	int                       idx = 0;
 
@@ -1580,41 +1581,6 @@ ino_dfs_flush_nr(d_list_t *rlink, void *arg)
 	return -DER_SUCCESS;
 }
 
-static int
-ino_kernel_flush(d_list_t *rlink, void *arg)
-{
-	struct dfuse_info        *dfuse_info = arg;
-	struct dfuse_inode_entry *ie = container_of(rlink, struct dfuse_inode_entry, ie_htl);
-	int                       rc;
-
-	/* Only evict entries that are direct children of the root, the kernel
-	 * will walk the tree for us
-	 */
-	if (ie->ie_parent != 1)
-		return 0;
-
-	/* Do not evict root itself */
-	if (ie->ie_stat.st_ino == 1)
-		return 0;
-
-	rc = fuse_lowlevel_notify_inval_entry(dfuse_info->di_session, ie->ie_parent, ie->ie_name,
-					      strlen(ie->ie_name));
-	if (rc != 0 && rc != -EBADF)
-		DHS_WARN(ie, -rc, "%#lx %#lx " DF_DE, ie->ie_parent, ie->ie_stat.st_ino,
-			 DP_DE(ie->ie_name));
-	else
-		DHS_INFO(ie, -rc, "%#lx %#lx " DF_DE, ie->ie_parent, ie->ie_stat.st_ino,
-			 DP_DE(ie->ie_name));
-
-	/* If the FUSE connection is dead then do not traverse further, it
-	 * doesn't matter what gets returned here, as long as it's negative
-	 */
-	if (rc == -EBADF)
-		return -DER_NO_HDL;
-
-	return -DER_SUCCESS;
-}
-
 static int
 dfuse_cont_close_cb(d_list_t *rlink, void *handle)
 {
@@ -1638,10 +1604,10 @@ dfuse_cont_close_cb(d_list_t *rlink, void *handle)
 static int
 dfuse_pool_close_cb(d_list_t *rlink, void *handle)
 {
-	struct dfuse_info *dfuse_info = handle;
+	struct dfuse_info      *dfuse_info = handle;
 	struct dfuse_cont_core *dfcc, *dfccn;
-	struct dfuse_pool *dfp;
-	int                rc;
+	struct dfuse_pool      *dfp;
+	int                     rc;
 
 	dfp = container_of(rlink, struct dfuse_pool, dfp_entry);
 
@@ -1703,13 +1669,6 @@ dfuse_fs_stop(struct dfuse_info *dfuse_info)
 		sem_destroy(&eqt->de_sem);
 	}
 
-	/* First flush, instruct the kernel to forget items.  This will run and work in ideal cases
-	 * but often if the filesystem is unmounted it'll abort part-way through.
-	 */
-	rc = d_hash_table_traverse(&dfuse_info->dpi_iet, ino_kernel_flush, dfuse_info);
-
-	DHL_INFO(dfuse_info, rc, "Kernel flush complete");
-
 	/* At this point there's a number of inodes which are in memory, traverse these and free
 	 * them, along with any resources.
 	 * The reference count on inodes match kernel references but the fuse module is disconnected