Fix ext4 block group descriptor sizing

Ext4 allows for arbitrarily sized block group descriptors when 64-bit
addressing is enabled, which was previously not properly supported. This
patch dynamically allocates a chunk of memory of the correct size.

Signed-off-by: Benjamin Lim <jarsp.ctf@gmail.com>

diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
index feffbfa9a9ebbd61b3c83fe69005f9a5ddaeaab0..464c33d0d74ccbc7c1746b69632f0bdbd73d454a 100644 (file)
--- a/fs/ext4/ext4_common.c
+++ b/fs/ext4/ext4_common.c
@@ -1587,7 +1587,7 @@ static int ext4fs_blockgroup
 
 int ext4fs_read_inode(struct ext2_data *data, int ino, struct ext2_inode *inode)
 {
-       struct ext2_block_group blkgrp;
+       struct ext2_block_group *blkgrp;
        struct ext2_sblock *sblock = &data->sblock;
        struct ext_filesystem *fs = get_fs();
        int log2blksz = get_fs()->dev_desc->log2blksz;
@@ -1595,17 +1595,28 @@ int ext4fs_read_inode(struct ext2_data *data, int ino, struct ext2_inode *inode)
        long int blkno;
        unsigned int blkoff;
 
+       /* Allocate blkgrp based on gdsize (for 64-bit support). */
+       blkgrp = zalloc(get_fs()->gdsize);
+       if (!blkgrp)
+               return 0;
+
        /* It is easier to calculate if the first inode is 0. */
        ino--;
        status = ext4fs_blockgroup(data, ino / le32_to_cpu
-                                  (sblock->inodes_per_group), &blkgrp);
-       if (status == 0)
+                                  (sblock->inodes_per_group), blkgrp);
+       if (status == 0) {
+               free(blkgrp);
                return 0;
+       }
 
        inodes_per_block = EXT2_BLOCK_SIZE(data) / fs->inodesz;
-       blkno = ext4fs_bg_get_inode_table_id(&blkgrp, fs) +
+       blkno = ext4fs_bg_get_inode_table_id(blkgrp, fs) +
            (ino % le32_to_cpu(sblock->inodes_per_group)) / inodes_per_block;
        blkoff = (ino % inodes_per_block) * fs->inodesz;
+
+       /* Free blkgrp as it is no longer required. */
+       free(blkgrp);
+
        /* Read the inode. */
        status = ext4fs_devread((lbaint_t)blkno << (LOG2_BLOCK_SIZE(data) -
                                log2blksz), blkoff,