ext4_grpnum_t: fix negative groups

Ext4: fixes to block group descriptor being set to a negative value
from: [email protected]

This patch fixes various places where the block group is set to -1.

---
fs/ext4/ialloc.c | 96 +++++++++++++++++++++++++++++--------------------------

1 file changed, 51 insertions(+), 45 deletions(-)

Index: linux-2.6.23-rc8-new/fs/ext4/ialloc.c
===================================================================
@@ -260,13 +260,15 @@
 * For other inodes, search forward from the parent directory\'s block
 * group to find a free inode.
 */
-static ext4_grpnum_t find_group_dir(struct super_block *sb, struct inode *parent)
+static int find_group_dir(struct super_block *sb, struct inode *parent,
+			  ext4_grpnum_t *best_group)

{
	ext4_grpnum_t ngroups = EXT4_SB(sb)->s_groups_count;
	unsigned int freei, avefreei;
	struct ext4_group_desc *desc, *best_desc = NULL;
	struct buffer_head *bh;

- ext4_grpnum_t group, best_group = -1;
+ ext4_grpnum_t group;
+ int ret = -1;

	freei = percpu_counter_read_positive(&EXT4_SB(sb)->s_freeinodes_counter);
	avefreei = freei / ngroups;
@@ -280,11 +282,12 @@
		if (!best_desc ||
		    (le16_to_cpu(desc->bg_free_blocks_count) >
		     le16_to_cpu(best_desc->bg_free_blocks_count))) {
-			best_group = group;
+			*best_group = group;
			best_desc = desc;
+			ret = 0;
		}
	}

- return best_group;
+ return ret;
}

/*
@@ -315,7 +318,8 @@
#define INODE_COST 64
#define BLOCK_COST 256

-static ext4_grpnum_t find_group_orlov(struct super_block *sb, struct inode *parent) +static int find_group_orlov(struct super_block *sb, struct inode *parent,
+ ext4_grpnum_t *group)

{
	ext4_grpnum_t parent_group = EXT4_I(parent)->i_block_group;
	struct ext4_sb_info *sbi = EXT4_SB(sb);
@@ -328,7 +332,7 @@
	unsigned int ndirs;
	int max_debt, max_dirs, min_inodes;
	ext4_grpblk_t min_blocks;
-	ext4_grpnum_t group = -1, i;
+	ext4_grpnum_t i;
	struct ext4_group_desc *desc;
	struct buffer_head *bh;

@@ -342,13 +346,14 @@

	if ((parent == sb->s_root->d_inode) ||
	    (EXT4_I(parent)->i_flags & EXT4_TOPDIR_FL)) {
		int best_ndir = inodes_per_group;

- ext4_grpnum_t best_group = -1;
+ ext4_grpnum_t grp;
+ int ret = -1;

- get_random_bytes(&group, sizeof(group));
- parent_group = (unsigned)group % ngroups;
+ get_random_bytes(&grp, sizeof(grp));

+		parent_group = (unsigned)grp % ngroups;
		for (i = 0; i < ngroups; i++) {
-			group = (parent_group + i) % ngroups;
-			desc = ext4_get_group_desc (sb, group, &bh);
+			grp = (parent_group + i) % ngroups;
+			desc = ext4_get_group_desc(sb, grp, &bh);
			if (!desc || !desc->bg_free_inodes_count)
				continue;
			if (le16_to_cpu(desc->bg_used_dirs_count) >= best_ndir)
@@ -357,11 +362,12 @@
				continue;
			if (le16_to_cpu(desc->bg_free_blocks_count) < avefreeb)
				continue;
-			best_group = group;
+			*group = grp;
+			ret = 0;
			best_ndir = le16_to_cpu(desc->bg_used_dirs_count);
		}
-		if (best_group >= 0)
-			return best_group;
+		if (ret == 0)
+			return ret;
		goto fallback;
	}

@@ -382,8 +388,8 @@

		max_debt = 1;

	for (i = 0; i < ngroups; i++) {
-		group = (parent_group + i) % ngroups;
-		desc = ext4_get_group_desc (sb, group, &bh);
+		*group = (parent_group + i) % ngroups;
+		desc = ext4_get_group_desc(sb, *group, &bh);
		if (!desc || !desc->bg_free_inodes_count)
			continue;
		if (le16_to_cpu(desc->bg_used_dirs_count) >= max_dirs)
@@ -392,17 +398,16 @@
			continue;
		if (le16_to_cpu(desc->bg_free_blocks_count) < min_blocks)
			continue;
-		return group;
+		return 0;
	}

fallback:

	for (i = 0; i < ngroups; i++) {

- group = (parent_group + i) % ngroups;
- desc = ext4_get_group_desc (sb, group, &bh);
- if (!desc || !desc->bg_free_inodes_count)
- continue;
- if (le16_to_cpu(desc->bg_free_inodes_count) >= avefreei)
- return group;
+ *group = (parent_group + i) % ngroups;
+ desc = ext4_get_group_desc(sb, *group, &bh);
+ if (desc && desc->bg_free_inodes_count &&
+ le16_to_cpu(desc->bg_free_inodes_count) >= avefreei)

+			return 0;
	}

	if (avefreei) {
@@ -417,22 +422,23 @@
	return -1;
}

-static ext4_grpnum_t find_group_other(struct super_block *sb, struct inode *parent) +static int find_group_other(struct super_block *sb, struct inode *parent,
+ ext4_grpnum_t *group)

{
	ext4_grpnum_t parent_group = EXT4_I(parent)->i_block_group;
	ext4_grpnum_t ngroups = EXT4_SB(sb)->s_groups_count;
	struct ext4_group_desc *desc;
	struct buffer_head *bh;

- ext4_grpnum_t group, i;
+ ext4_grpnum_t i;

	/*
	 * Try to place the inode in its parent directory
	 */
-	group = parent_group;
-	desc = ext4_get_group_desc (sb, group, &bh);
+	*group = parent_group;
+	desc = ext4_get_group_desc(sb, *group, &bh);
	if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
			le16_to_cpu(desc->bg_free_blocks_count))

- return group;
+ return 0;

	/*
	 * We're going to place this inode in a different blockgroup from its
@@ -443,33 +449,33 @@
	 *
	 * So add our directory's i_ino into the starting point for the hash.
	 */

- group = (group + parent->i_ino) % ngroups;
+ *group = (*group + parent->i_ino) % ngroups;

	/*
	 * Use a quadratic hash to find a group with a free inode and some free
	 * blocks.
	 */
	for (i = 1; i < ngroups; i <<= 1) {

- group += i;
- if (group >= ngroups)
- group -= ngroups;
- desc = ext4_get_group_desc (sb, group, &bh);
+ *group += i;
+ if (*group >= ngroups)
+ *group -= ngroups;

+		desc = ext4_get_group_desc(sb, *group, &bh);
		if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
				le16_to_cpu(desc->bg_free_blocks_count))
-			return group;
+			return 0;
	}

	/*
	 * That failed: try linear search for a free inode, even if that group
	 * has no free blocks.
	 */
-	group = parent_group;
+	*group = parent_group;
	for (i = 0; i < ngroups; i++) {

- if (++group >= ngroups)
- group = 0;
- desc = ext4_get_group_desc (sb, group, &bh);
+ if (++*group >= ngroups)
+ *group = 0;

+		desc = ext4_get_group_desc(sb, *group, &bh);
		if (desc && le16_to_cpu(desc->bg_free_inodes_count))
-			return group;
+			return 0;
	}

	return -1;
@@ -490,14 +496,14 @@
	struct super_block *sb;
	struct buffer_head *bitmap_bh = NULL;
	struct buffer_head *bh2;
-	ext4_grpnum_t group;
+	ext4_grpnum_t group = 0;
	unsigned long ino = 0;
	struct inode * inode;
	struct ext4_group_desc * gdp = NULL;
	struct ext4_super_block * es;
	struct ext4_inode_info *ei;
	struct ext4_sb_info *sbi;
-	int err = 0;
+	int ret2, err = 0;
	struct inode *ret;
	int i, free = 0;

@@ -515,14 +521,14 @@

	es = sbi->s_es;
	if (S_ISDIR(mode)) {
		if (test_opt (sb, OLDALLOC))

- group = find_group_dir(sb, dir);
+ ret2 = find_group_dir(sb, dir, &group);
else
- group = find_group_orlov(sb, dir);

+			ret2 = find_group_orlov(sb, dir, &group);
	} else

- group = find_group_other(sb, dir);
+ ret2 = find_group_other(sb, dir, &group);

	err = -ENOSPC;
-	if (group == -1)
+	if (ret2 == -1)
		goto out;

	for (i = 0; i < sbi->s_groups_count; i++) {