ext4: fixes block group number being set to a negative value

This patch fixes various places where the group number is set to a negative
value.

Signed-off-by: Avantika Mathur <mathur@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 64dea86..7b5cfa6 100644 (file)
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -260,12 +260,14 @@ error_return:
  * For other inodes, search forward from the parent directory\'s block
  * group to find a free inode.
  */
-static ext4_group_t find_group_dir(struct super_block *sb, struct inode *parent)
+static int find_group_dir(struct super_block *sb, struct inode *parent,
+                               ext4_group_t *best_group)
 {
        ext4_group_t ngroups = EXT4_SB(sb)->s_groups_count;
        unsigned int freei, avefreei;
        struct ext4_group_desc *desc, *best_desc = NULL;
-       ext4_group_t group, best_group = -1;
+       ext4_group_t group;
+       int ret = -1;
 
        freei = percpu_counter_read_positive(&EXT4_SB(sb)->s_freeinodes_counter);
        avefreei = freei / ngroups;
@@ -279,11 +281,12 @@ static ext4_group_t find_group_dir(struct super_block *sb, struct inode *parent)
                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;
 }
 
 /*
@@ -314,8 +317,8 @@ static ext4_group_t find_group_dir(struct super_block *sb, struct inode *parent)
 #define INODE_COST 64
 #define BLOCK_COST 256
 
-static ext4_group_t find_group_orlov(struct super_block *sb,
-                                     struct inode *parent)
+static int find_group_orlov(struct super_block *sb, struct inode *parent,
+                               ext4_group_t *group)
 {
        ext4_group_t parent_group = EXT4_I(parent)->i_block_group;
        struct ext4_sb_info *sbi = EXT4_SB(sb);
@@ -328,7 +331,7 @@ static ext4_group_t find_group_orlov(struct super_block *sb,
        unsigned int ndirs;
        int max_debt, max_dirs, min_inodes;
        ext4_grpblk_t min_blocks;
-       ext4_group_t group = -1, i;
+       ext4_group_t i;
        struct ext4_group_desc *desc;
 
        freei = percpu_counter_read_positive(&sbi->s_freeinodes_counter);
@@ -341,13 +344,14 @@ static ext4_group_t find_group_orlov(struct super_block *sb,
        if ((parent == sb->s_root->d_inode) ||
            (EXT4_I(parent)->i_flags & EXT4_TOPDIR_FL)) {
                int best_ndir = inodes_per_group;
-               ext4_group_t best_group = -1;
+               ext4_group_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, NULL);
+                       grp = (parent_group + i) % ngroups;
+                       desc = ext4_get_group_desc(sb, grp, NULL);
                        if (!desc || !desc->bg_free_inodes_count)
                                continue;
                        if (le16_to_cpu(desc->bg_used_dirs_count) >= best_ndir)
@@ -356,11 +360,12 @@ static ext4_group_t find_group_orlov(struct super_block *sb,
                                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;
        }
 
@@ -381,8 +386,8 @@ static ext4_group_t find_group_orlov(struct super_block *sb,
                max_debt = 1;
 
        for (i = 0; i < ngroups; i++) {
-               group = (parent_group + i) % ngroups;
-               desc = ext4_get_group_desc (sb, group, NULL);
+               *group = (parent_group + i) % ngroups;
+               desc = ext4_get_group_desc(sb, *group, NULL);
                if (!desc || !desc->bg_free_inodes_count)
                        continue;
                if (le16_to_cpu(desc->bg_used_dirs_count) >= max_dirs)
@@ -391,17 +396,16 @@ static ext4_group_t find_group_orlov(struct super_block *sb,
                        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, NULL);
-               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, NULL);
+               if (desc && desc->bg_free_inodes_count &&
+                       le16_to_cpu(desc->bg_free_inodes_count) >= avefreei)
+                       return 0;
        }
 
        if (avefreei) {
@@ -416,22 +420,22 @@ fallback:
        return -1;
 }
 
-static ext4_group_t find_group_other(struct super_block *sb,
-                                       struct inode *parent)
+static int find_group_other(struct super_block *sb, struct inode *parent,
+                               ext4_group_t *group)
 {
        ext4_group_t parent_group = EXT4_I(parent)->i_block_group;
        ext4_group_t ngroups = EXT4_SB(sb)->s_groups_count;
        struct ext4_group_desc *desc;
-       ext4_group_t group, i;
+       ext4_group_t i;
 
        /*
         * Try to place the inode in its parent directory
         */
-       group = parent_group;
-       desc = ext4_get_group_desc (sb, group, NULL);
+       *group = parent_group;
+       desc = ext4_get_group_desc(sb, *group, NULL);
        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
@@ -442,33 +446,33 @@ static ext4_group_t find_group_other(struct super_block *sb,
         *
         * 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, NULL);
+               *group += i;
+               if (*group >= ngroups)
+                       *group -= ngroups;
+               desc = ext4_get_group_desc(sb, *group, NULL);
                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, NULL);
+               if (++*group >= ngroups)
+                       *group = 0;
+               desc = ext4_get_group_desc(sb, *group, NULL);
                if (desc && le16_to_cpu(desc->bg_free_inodes_count))
-                       return group;
+                       return 0;
        }
 
        return -1;
@@ -489,16 +493,17 @@ struct inode *ext4_new_inode(handle_t *handle, struct inode * dir, int mode)
        struct super_block *sb;
        struct buffer_head *bitmap_bh = NULL;
        struct buffer_head *bh2;
-       ext4_group_t group;
+       ext4_group_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;
+       ext4_group_t i;
+       int free = 0;
 
        /* Cannot create files in a deleted directory */
        if (!dir || !dir->i_nlink)
@@ -514,14 +519,14 @@ struct inode *ext4_new_inode(handle_t *handle, struct inode * dir, int mode)
        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++) {