ext3-ialloc-2.6.patch

非常经典的一个分布式系统

Index: linux-2.6.5-SLES9_SP1_BRANCH_2004111114454891/fs/ext3/ialloc.c
===================================================================
--- linux-2.6.5-SLES9_SP1_BRANCH_2004111114454891.orig/fs/ext3/ialloc.c	2005-05-16 14:10:54.000000000 -0600
+++ linux-2.6.5-SLES9_SP1_BRANCH_2004111114454891/fs/ext3/ialloc.c	2005-05-16 14:18:29.000000000 -0600
@@ -352,13 +352,17 @@
 	return -1;
 }
 
-static int find_group_other(struct super_block *sb, struct inode *parent)
+static int find_group_other(struct super_block *sb, struct inode *parent,
+			    int mode)
 {
 	int parent_group = EXT3_I(parent)->i_block_group;
+	struct ext3_sb_info *sbi = EXT3_SB(sb);
 	int ngroups = EXT3_SB(sb)->s_groups_count;
 	struct ext3_group_desc *desc;
 	struct buffer_head *bh;
 	int group, i;
+	int best_group = -1;
+	int avefreeb, freeb, best_group_freeb = 0;
 
 	/*
 	 * Try to place the inode in its parent directory
@@ -366,9 +370,9 @@
 	group = parent_group;
 	desc = ext3_get_group_desc (sb, group, &bh);
 	if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
-			le16_to_cpu(desc->bg_free_blocks_count))
+	    (!S_ISREG(mode) || le16_to_cpu(desc->bg_free_blocks_count)))
 		return group;
-
+	avefreeb = le32_to_cpu(sbi->s_es->s_free_blocks_count) / ngroups;
 	/*
 	 * We're going to place this inode in a different blockgroup from its
 	 * parent.  We want to cause files in a common directory to all land in
@@ -381,33 +385,47 @@
 	group = (group + parent->i_ino) % ngroups;
 
 	/*
-	 * Use a quadratic hash to find a group with a free inode and some free
-	 * blocks.
+	 * Use a quadratic hash to find a group with a free inode and
+	 * average number of free blocks.
 	 */
 	for (i = 1; i < ngroups; i <<= 1) {
 		group += i;
 		if (group >= ngroups)
 			group -= ngroups;
 		desc = ext3_get_group_desc (sb, group, &bh);
-		if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
-				le16_to_cpu(desc->bg_free_blocks_count))
+		if (!desc || !desc->bg_free_inodes_count)
+			continue;
+		if (!S_ISREG(mode))
+			return group;
+		if (le16_to_cpu(desc->bg_free_blocks_count) >= avefreeb)
 			return group;
 	}
 
 	/*
-	 * That failed: try linear search for a free inode, even if that group
-	 * has no free blocks.
+	 * That failed: start from last group used to allocate inode
+	 * try linear search for a free inode and prefereably
+	 * free blocks.
 	 */
-	group = parent_group;
+	group = sbi->s_last_alloc_group;
+	if (group == -1)
+		group = parent_group;
+
 	for (i = 0; i < ngroups; i++) {
 		if (++group >= ngroups)
 			group = 0;
 		desc = ext3_get_group_desc (sb, group, &bh);
-		if (desc && le16_to_cpu(desc->bg_free_inodes_count))
-			return group;
+		if (!desc || !desc->bg_free_inodes_count)
+			continue;
+		freeb = le16_to_cpu(desc->bg_free_blocks_count);
+		if (freeb > best_group_freeb) {
+			best_group_freeb = freeb;
+			best_group = group;
+			if (freeb >= avefreeb || !S_ISREG(mode))
+				break;
+		}
 	}
-
-	return -1;
+	sbi->s_last_alloc_group = best_group;
+	return best_group;
 }
 
 /*
@@ -454,7 +472,7 @@
 		else
 			group = find_group_orlov(sb, dir);
 	} else 
-		group = find_group_other(sb, dir);
+		group = find_group_other(sb, dir, mode);
 
 	err = -ENOSPC;
 	if (group == -1)
Index: linux-2.6.5-SLES9_SP1_BRANCH_2004111114454891/fs/ext3/super.c
===================================================================
--- linux-2.6.5-SLES9_SP1_BRANCH_2004111114454891.orig/fs/ext3/super.c	2005-05-16 14:10:54.000000000 -0600
+++ linux-2.6.5-SLES9_SP1_BRANCH_2004111114454891/fs/ext3/super.c	2005-05-16 14:17:14.000000000 -0600
@@ -1297,6 +1297,7 @@
 	percpu_counter_init(&sbi->s_dirs_counter);
 	bgl_lock_init(&sbi->s_blockgroup_lock);
 
+	sbi->s_last_alloc_group = -1;
 	for (i = 0; i < db_count; i++) {
 		block = descriptor_loc(sb, logic_sb_block, i);
 		sbi->s_group_desc[i] = sb_bread(sb, block);
Index: linux-2.6.5-SLES9_SP1_BRANCH_2004111114454891/include/linux/ext3_fs_sb.h
===================================================================
--- linux-2.6.5-SLES9_SP1_BRANCH_2004111114454891.orig/include/linux/ext3_fs_sb.h	2005-05-16 14:10:54.000000000 -0600
+++ linux-2.6.5-SLES9_SP1_BRANCH_2004111114454891/include/linux/ext3_fs_sb.h	2005-05-16 14:17:14.000000000 -0600
@@ -59,6 +59,8 @@
 	struct percpu_counter s_freeinodes_counter;
 	struct percpu_counter s_dirs_counter;
 	struct blockgroup_lock s_blockgroup_lock;
+	/* Last group used to allocate inode */
+	int s_last_alloc_group;
 
 	/* root of the per fs reservation window tree */
 	spinlock_t s_rsv_window_lock;