ext4: use atomic64_t for the per-flexbg free_clusters count

Orabug: 17488415

commit 90ba983 upstream.

A user who was using a 8TB+ file system and with a very large flexbg
size (> 65536) could cause the atomic_t used in the struct flex_groups
to overflow.  This was detected by PaX security patchset:

http://forums.grsecurity.net/viewtopic.php?f=3&t=3289&p=12551#p12551

This bug was introduced in commit 9f24e42, so it's been around
since 2.6.30.  :-(

Fix this by using an atomic64_t for struct orlav_stats's
free_clusters.

[Backported for 3.0-stable. Renamed free_clusters back to free_blocks;
fixed a few more atomic_read's of free_blocks left in 3.0.]

Signed-off-by: "Theodore Ts'o" <[email protected]>
Reviewed-by: Lukas Czerner <[email protected]>
Signed-off-by: Lingzhu Xiang <[email protected]>
Reviewed-by: CAI Qian <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

(cherry picked from commit 503f4bdcc078e7abee273a85ce322de81b18a224)

Signed-off-by: Todd Vierling <[email protected]>
Acked-by: John Haxby <[email protected]>
Signed-off-by: Brian Maly <[email protected]>

Author: tytso

fs/ext4/ext4.h

@@ -289,9 +289,9 @@ struct ext4_group_desc
  */
 
 struct flex_groups {
-	atomic_t free_inodes;
-	atomic_t free_blocks;
-	atomic_t used_dirs;
+	atomic64_t	free_blocks;
+	atomic_t	free_inodes;
+	atomic_t	used_dirs;
 };
 
 #define EXT4_BG_INODE_UNINIT	0x0001 /* Inode table/bitmap not in use */

fs/ext4/ialloc.c

@@ -345,8 +345,8 @@ static int find_group_flex(struct super_block *sb, struct inode *parent,
 	ext4_group_t ngroups = ext4_get_groups_count(sb);
 	int flex_size = ext4_flex_bg_size(sbi);
 	ext4_group_t best_flex = parent_fbg_group;
-	int blocks_per_flex = sbi->s_blocks_per_group * flex_size;
-	int flexbg_free_blocks;
+	ext4_fsblk_t blocks_per_flex = sbi->s_blocks_per_group * flex_size;
+	ext4_fsblk_t flexbg_free_blocks;
 	int flex_freeb_ratio;
 	ext4_group_t n_fbg_groups;
 	ext4_group_t i;
@@ -355,7 +355,7 @@ static int find_group_flex(struct super_block *sb, struct inode *parent,
 		sbi->s_log_groups_per_flex;
 
 find_close_to_parent:
-	flexbg_free_blocks = atomic_read(&flex_group[best_flex].free_blocks);
+	flexbg_free_blocks = atomic64_read(&flex_group[best_flex].free_blocks);
 	flex_freeb_ratio = flexbg_free_blocks * 100 / blocks_per_flex;
 	if (atomic_read(&flex_group[best_flex].free_inodes) &&
 	    flex_freeb_ratio > free_block_ratio)
@@ -370,7 +370,7 @@ static int find_group_flex(struct super_block *sb, struct inode *parent,
 		if (i == parent_fbg_group || i == parent_fbg_group - 1)
 			continue;
 
-		flexbg_free_blocks = atomic_read(&flex_group[i].free_blocks);
+		flexbg_free_blocks = atomic64_read(&flex_group[i].free_blocks);
 		flex_freeb_ratio = flexbg_free_blocks * 100 / blocks_per_flex;
 
 		if (flex_freeb_ratio > free_block_ratio &&
@@ -380,14 +380,14 @@ static int find_group_flex(struct super_block *sb, struct inode *parent,
 		}
 
 		if ((atomic_read(&flex_group[best_flex].free_inodes) == 0) ||
-		    ((atomic_read(&flex_group[i].free_blocks) >
-		      atomic_read(&flex_group[best_flex].free_blocks)) &&
+		    ((atomic64_read(&flex_group[i].free_blocks) >
+		      atomic64_read(&flex_group[best_flex].free_blocks)) &&
 		     atomic_read(&flex_group[i].free_inodes)))
 			best_flex = i;
 	}
 
 	if (!atomic_read(&flex_group[best_flex].free_inodes) ||
-	    !atomic_read(&flex_group[best_flex].free_blocks))
+	    !atomic64_read(&flex_group[best_flex].free_blocks))
 		return -1;
 
 found_flexbg:
@@ -406,8 +406,8 @@ static int find_group_flex(struct super_block *sb, struct inode *parent,
 }
 
 struct orlov_stats {
+	__u64 free_blocks;
 	__u32 free_inodes;
-	__u32 free_blocks;
 	__u32 used_dirs;
 };
 
@@ -424,7 +424,7 @@ static void get_orlov_stats(struct super_block *sb, ext4_group_t g,
 
 	if (flex_size > 1) {
 		stats->free_inodes = atomic_read(&flex_group[g].free_inodes);
-		stats->free_blocks = atomic_read(&flex_group[g].free_blocks);
+		stats->free_blocks = atomic64_read(&flex_group[g].free_blocks);
 		stats->used_dirs = atomic_read(&flex_group[g].used_dirs);
 		return;
 	}

fs/ext4/mballoc.c

@@ -2814,8 +2814,8 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
 	if (sbi->s_log_groups_per_flex) {
 		ext4_group_t flex_group = ext4_flex_group(sbi,
 							  ac->ac_b_ex.fe_group);
-		atomic_sub(ac->ac_b_ex.fe_len,
-			   &sbi->s_flex_groups[flex_group].free_blocks);
+		atomic64_sub(ac->ac_b_ex.fe_len,
+			     &sbi->s_flex_groups[flex_group].free_blocks);
 	}
 
 	err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
@@ -4614,7 +4614,7 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode,
 
 	if (sbi->s_log_groups_per_flex) {
 		ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
-		atomic_add(count, &sbi->s_flex_groups[flex_group].free_blocks);
+		atomic64_add(count, &sbi->s_flex_groups[flex_group].free_blocks);
 	}
 
 	ext4_mb_unload_buddy(&e4b);
@@ -4745,8 +4745,8 @@ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
 
 	if (sbi->s_log_groups_per_flex) {
 		ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
-		atomic_add(blocks_freed,
-			   &sbi->s_flex_groups[flex_group].free_blocks);
+		atomic64_add(blocks_freed,
+			     &sbi->s_flex_groups[flex_group].free_blocks);
 	}
 
 	ext4_mb_unload_buddy(&e4b);

fs/ext4/resize.c

@@ -929,8 +929,8 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
 	    sbi->s_log_groups_per_flex) {
 		ext4_group_t flex_group;
 		flex_group = ext4_flex_group(sbi, input->group);
-		atomic_add(input->free_blocks_count,
-			   &sbi->s_flex_groups[flex_group].free_blocks);
+		atomic64_add(input->free_blocks_count,
+			     &sbi->s_flex_groups[flex_group].free_blocks);
 		atomic_add(EXT4_INODES_PER_GROUP(sb),
 			   &sbi->s_flex_groups[flex_group].free_inodes);
 	}

fs/ext4/super.c

@@ -1992,8 +1992,8 @@ static int ext4_fill_flex_info(struct super_block *sb)
 		flex_group = ext4_flex_group(sbi, i);
 		atomic_add(ext4_free_inodes_count(sb, gdp),
 			   &sbi->s_flex_groups[flex_group].free_inodes);
-		atomic_add(ext4_free_blks_count(sb, gdp),
-			   &sbi->s_flex_groups[flex_group].free_blocks);
+		atomic64_add(ext4_free_blks_count(sb, gdp),
+			     &sbi->s_flex_groups[flex_group].free_blocks);
 		atomic_add(ext4_used_dirs_count(sb, gdp),
 			   &sbi->s_flex_groups[flex_group].used_dirs);
 	}