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>

1 files changed, 53 insertions, 48 deletions

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 64dea8689e1f..7b5cfa62b663 100644
--- 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++) {