+ fs/ext3/balloc.c | 99 ++++++++++++++++++++++++++++++++++++++++++++----------
+ 1 files changed, 81 insertions(+), 18 deletions(-)
+diff --git a/fs/ext3/balloc.c b/fs/ext3/balloc.c
+index ff3428e..a9140ea 100644
+Index: linux-stage/fs/ext3/balloc.c
+===================================================================
+--- linux-stage.orig/fs/ext3/balloc.c
++++ linux-stage/fs/ext3/balloc.c
+@@ -144,9 +144,96 @@ unsigned ext3_init_block_bitmap(struct s
+ return free_blocks - sbi->s_itb_per_group - 2;
+ }
+
+-/*
+- * Read the bitmap for a given block_group, reading into the specified
+- * slot in the superblock's bitmap cache.
++/**
++* bh_uptodate_or_lock: Test whether the buffer is uptodate
++* @bh: struct buffer_head
++*
++* Return true if the buffer is up-to-date and false,
++* with the buffer locked, if not.
++*/
++int bh_uptodate_or_lock(struct buffer_head *bh)
++{
++ if (!buffer_uptodate(bh)) {
++ lock_buffer(bh);
++ if (!buffer_uptodate(bh))
++ return 0;
++ unlock_buffer(bh);
++ }
++ return 1;
++}
++
++/**
++* bh_submit_read: Submit a locked buffer for reading
++* @bh: struct buffer_head
++*
++* Returns a negative error
++*/
++int bh_submit_read(struct buffer_head *bh)
++{
++ if (!buffer_locked(bh))
++ lock_buffer(bh);
++ if (buffer_uptodate(bh))
++ return 0;
++ get_bh(bh);
++ bh->b_end_io = end_buffer_read_sync;
++ submit_bh(READ, bh);
++ wait_on_buffer(bh);
++ if (buffer_uptodate(bh))
++ return 0;
++ return -EIO;
++}
++
++static int ext3_valid_block_bitmap(struct super_block *sb,
++ struct ext3_group_desc *desc,
++ unsigned int block_group,
++ struct buffer_head *bh)
++{
++ unsigned long long offset;
++ unsigned long long next_zero_bit;
++ unsigned long long bitmap_blk;
++ unsigned long long group_first_block;
++
++ group_first_block = ext3_group_first_block_no(sb, block_group);
++
++ /* check whether block bitmap block number is set */
++ bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
++ offset = bitmap_blk - group_first_block;
++ if (!ext3_test_bit(offset, bh->b_data))
++ /* bad block bitmap */
++ goto err_out;
++
++ /* check whether the inode bitmap block number is set */
++ bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);
++ offset = bitmap_blk - group_first_block;
++ if (!ext3_test_bit(offset, bh->b_data))
++ /* bad block bitmap */
++ goto err_out;
++
++ /* check whether the inode table block number is set */
++ bitmap_blk = le32_to_cpu(desc->bg_inode_table);
++ offset = bitmap_blk - group_first_block;
++ next_zero_bit = ext3_find_next_zero_bit(bh->b_data,
++ offset + EXT3_SB(sb)->s_itb_per_group,
++ offset);
++ if (next_zero_bit >= offset + EXT3_SB(sb)->s_itb_per_group)
++ /* good bitmap for inode tables */
++ return 1;
++
++err_out:
++ ext3_error(sb, __FUNCTION__,
++ "Invalid block bitmap - "
++ "block_group = %d, block = %llu",
++ block_group, bitmap_blk);
++ return 0;
++}
++
++/**
++ * read_block_bitmap()
++ * @sb: super block
++ * @block_group: given block group
++ *
++ * Read the bitmap for a given block_group,and validate the
++ * bits for block/inode/inode tables are set in the bitmaps.
+ *
+ * Return buffer_head on success or NULL in case of failure.
+ */
+@@ -155,29 +242,42 @@ read_block_bitmap(struct super_block *sb
+ {
+ struct ext3_group_desc * desc;
+ struct buffer_head * bh = NULL;
++ unsigned long long bitmap_blk;
+
+ desc = ext3_get_group_desc (sb, block_group, NULL);
+ if (!desc)
+- goto error_out;
++ return NULL;
++ bitmap_blk = desc->bg_block_bitmap;
++ bh = sb_getblk(sb, bitmap_blk);
++ if (unlikely(!bh)) {
++ ext3_error(sb, __FUNCTION__,
++ "Can not read block bitmap - "
++ "block group = %d, block_bitmap = %llu",
++ (int)block_group, bitmap_blk);
++ return NULL;
++ }
++ if (bh_uptodate_or_lock(bh))
++ return bh;
++
+ if (desc->bg_flags & cpu_to_le16(EXT3_BG_BLOCK_UNINIT)) {
+- bh = sb_getblk(sb, le32_to_cpu(desc->bg_block_bitmap));
+- if (!buffer_uptodate(bh)) {
+- lock_buffer(bh);
+- if (!buffer_uptodate(bh)) {
+- ext3_init_block_bitmap(sb, bh,block_group,desc);
+- set_buffer_uptodate(bh);
+- }
+- unlock_buffer(bh);
+- }
+- } else {
+- bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap));
++ ext3_init_block_bitmap(sb, bh, block_group, desc);
++ set_buffer_uptodate(bh);
++ unlock_buffer(bh);
++ return bh;
++ }
++ if (bh_submit_read(bh) < 0) {
++ brelse(bh);
++ ext3_error(sb, __FUNCTION__,
++ "Cannot read block bitmap - "
++ "block group = %d block_bitmap = %llu",
++ (int)block_group, bitmap_blk);
++ return NULL;
+ }
+- if (!bh)
+- ext3_error (sb, "read_block_bitmap",
+- "Cannot read block bitmap - "
+- "block_group = %d, block_bitmap = %u",
+- block_group, le32_to_cpu(desc->bg_block_bitmap));
+-error_out:
++ if (!ext3_valid_block_bitmap(sb, desc, block_group, bh)) {
++ brelse(bh);
++ return NULL;
++ }
++
+ return bh;
+ }
+ /*
+Index: linux-stage/include/linux/ext3_fs.h
+===================================================================
+--- linux-stage.orig/include/linux/ext3_fs.h
++++ linux-stage/include/linux/ext3_fs.h
+@@ -872,6 +872,14 @@ struct dir_private_info {
+ __u32 next_hash;
+ };
+
++/* calculate the first block number of the group */
++static inline long long
++ext3_group_first_block_no(struct super_block *sb, unsigned long group_no)
++{
++ return group_no * (long long)EXT3_BLOCKS_PER_GROUP(sb) +
++ le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block);
++}
++
+ /*
+ * Special error return code only used by dx_probe() and its callers.
+ */