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    Subject[PATCH 06/49] ext4: fixes block group number being set to a negative value
    Date
    From: Avantika Mathur <mathur@us.ibm.com>

    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>
    ---
    fs/ext4/ialloc.c | 101 ++++++++++++++++++++++++++++-------------------------
    1 files changed, 53 insertions(+), 48 deletions(-)

    diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
    index 64dea86..7b5cfa6 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++) {
    --
    1.5.4.rc3.31.g1271-dirty


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