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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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