From: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Date: Thu, 20 Aug 2015 14:46:56 +0000 (+0900)
Subject: sys/vfs/hammer: Adjust hammer_debug_general
X-Git-Tag: v4.5.0~748
X-Git-Url: https://gitweb.dragonflybsd.org/~tuxillo/dragonfly.git/commitdiff_plain/4af7f53747c5cfc504b9ec89242b7a195fbfb933

sys/vfs/hammer: Adjust hammer_debug_general

Change hammer_debug_general in hammer_blockmap_getfree()
to 0x4000 which is the same value as those in
sys/vfs/hammer/hammer_reblock.c.

This is better since hammer_blockmap_getfree() is made
for reblock and only used by reblock (0x0800 picks up
other debug kprintfs that aren't related to reblock).

Also note that hammer_debug_general values are randomly
picked based on use cases rather than fixed value for
each file/etc.

Add some comments on the conditionals that are used to
start data/node reblock since this part is not too easy
to understand.
---

diff --git a/sys/vfs/hammer/hammer_blockmap.c b/sys/vfs/hammer/hammer_blockmap.c
index d537da57ce..ee7a91a93b 100644
--- a/sys/vfs/hammer/hammer_blockmap.c
+++ b/sys/vfs/hammer/hammer_blockmap.c
@@ -1387,15 +1387,19 @@ hammer_blockmap_getfree(hammer_mount_t hmp, hammer_off_t zone_offset,
 
 	bytes = layer2->bytes_free;
 
+	/*
+	 * *curp becomes 1 only when no error and,
+	 * next_offset and zone_offset are in the same big-block.
+	 */
 	if ((blockmap->next_offset ^ zone_offset) & ~HAMMER_BIGBLOCK_MASK64)
-		*curp = 0;
+		*curp = 0;  /* not same */
 	else
 		*curp = 1;
 failed:
 	if (buffer)
 		hammer_rel_buffer(buffer, 0);
 	hammer_rel_volume(root_volume, 0);
-	if (hammer_debug_general & 0x0800) {
+	if (hammer_debug_general & 0x4000) {
 		kprintf("hammer_blockmap_getfree: %016llx -> %d\n",
 			(long long)zone_offset, bytes);
 	}
diff --git a/sys/vfs/hammer/hammer_reblock.c b/sys/vfs/hammer/hammer_reblock.c
index e6968805c8..de4f85641d 100644
--- a/sys/vfs/hammer/hammer_reblock.c
+++ b/sys/vfs/hammer/hammer_reblock.c
@@ -306,6 +306,15 @@ hammer_reblock_helper(struct hammer_ioc_reblock *reblock,
 		bytes = hammer_blockmap_getfree(hmp, tmp_offset, &cur, &error);
 		if (hammer_debug_general & 0x4000)
 			kprintf("D %6d/%d\n", bytes, reblock->free_level);
+		/*
+		 * Start data reblock if
+		 * 1. there is no error
+		 * 2. the data and allocator offset are not in the same
+		 *    big-block, or free level threshold is 0
+		 * 3. free bytes in the data's big-block is larger than
+		 *    free level threshold (means if threshold is 0 then
+		 *    do reblock no matter what).
+		 */
 		if (error == 0 && (cur == 0 || reblock->free_level == 0) &&
 		    bytes >= reblock->free_level) {
 			/*
@@ -371,6 +380,15 @@ skip:
 		bytes = hammer_blockmap_getfree(hmp, tmp_offset, &cur, &error);
 		if (hammer_debug_general & 0x4000)
 			kprintf("B %6d/%d\n", bytes, reblock->free_level);
+		/*
+		 * Start node reblock if
+		 * 1. there is no error
+		 * 2. the node and allocator offset are not in the same
+		 *    big-block, or free level threshold is 0
+		 * 3. free bytes in the node's big-block is larger than
+		 *    free level threshold (means if threshold is 0 then
+		 *    do reblock no matter what).
+		 */
 		if (error == 0 && (cur == 0 || reblock->free_level == 0) &&
 		    bytes >= reblock->free_level) {
 			error = hammer_cursor_upgrade(cursor);
diff --git a/sys/vfs/hammer/hammer_volume.c b/sys/vfs/hammer/hammer_volume.c
index 2d1add95fb..c452b369dc 100644
--- a/sys/vfs/hammer/hammer_volume.c
+++ b/sys/vfs/hammer/hammer_volume.c
@@ -323,8 +323,8 @@ hammer_do_reblock(hammer_transaction_t trans, hammer_inode_t ip)
 	reblock.key_end.localization = HAMMER_MAX_LOCALIZATION;
 	reblock.key_end.obj_id = HAMMER_MAX_OBJID;
 	reblock.head.flags = HAMMER_IOC_DO_FLAGS;
-	reblock.free_level = 0;
-	reblock.allpfs = 1;
+	reblock.free_level = 0;	/* reblock all big-blocks */
+	reblock.allpfs = 1;	/* reblock all PFS */
 
 	kprintf("reblock started\n");
 	error = hammer_ioc_reblock(trans, ip, &reblock);