From: Eric Sandeen <sandeen@redhat.com>
Subject: [RHEL5 PATCH] - fix ext2 overflows on filesystems > 8T
Date: Wed, 23 May 2007 11:40:55 -0500
Bugzilla: 237188
Message-Id: <46546E97.4020709@redhat.com>
Changelog: [fs] fix ext2 overflows on filesystems > 8T


Since we want to fully support ext3 at 16T in RHEL5, we should also
make sure ext2 won't fall down on large filesystems - today, there are
overflows above 8T (31 bits of blocks) in the ext2 allocator code.

This has had some basic testing, and should get further testing as we
shake out ext[23] at 16T for formal support.

This one isn't upstream, because 
ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.22-rc2/2.6.22-rc2-mm1/broken-out/ext2-reservations.patch
makes it irrelevant, by significantly reworking the allocator, and
introducing ext2_fsblk_t as appropriate to fix overflows in the new
allocation code.

Thanks,
-Eric

Index: linux-2.6.18-20.EL/fs/ext2/balloc.c
===================================================================
--- linux-2.6.18-20.EL.orig/fs/ext2/balloc.c
+++ linux-2.6.18-20.EL/fs/ext2/balloc.c
@@ -323,7 +323,7 @@ got_it:
  * bitmap, and then for any free bit if that fails.
  * This function also updates quota and i_blocks field.
  */
-int ext2_new_block(struct inode *inode, unsigned long goal,
+unsigned long ext2_new_block(struct inode *inode, unsigned long goal,
 			u32 *prealloc_count, u32 *prealloc_block, int *err)
 {
 	struct buffer_head *bitmap_bh = NULL;
@@ -332,8 +332,8 @@ int ext2_new_block(struct inode *inode, 
 	int group_no;			/* i */
 	int ret_block;			/* j */
 	int group_idx;			/* k */
-	int target_block;		/* tmp */
-	int block = 0;
+	unsigned long target_block;	/* tmp */
+	unsigned long block = 0;
 	struct super_block *sb = inode->i_sb;
 	struct ext2_sb_info *sbi = EXT2_SB(sb);
 	struct ext2_super_block *es = sbi->s_es;
@@ -460,7 +460,7 @@ got_block:
 		      sbi->s_itb_per_group))
 		ext2_error (sb, "ext2_new_block",
 			    "Allocating block in system zone - "
-			    "block = %u", target_block);
+			    "block = %lu", target_block);
 
 	if (target_block >= le32_to_cpu(es->s_blocks_count)) {
 		ext2_error (sb, "ext2_new_block",
Index: linux-2.6.18-20.EL/fs/ext2/ext2.h
===================================================================
--- linux-2.6.18-20.EL.orig/fs/ext2/ext2.h
+++ linux-2.6.18-20.EL/fs/ext2/ext2.h
@@ -91,7 +91,7 @@ static inline struct ext2_inode_info *EX
 /* balloc.c */
 extern int ext2_bg_has_super(struct super_block *sb, int group);
 extern unsigned long ext2_bg_num_gdb(struct super_block *sb, int group);
-extern int ext2_new_block (struct inode *, unsigned long,
+extern unsigned long ext2_new_block (struct inode *, unsigned long,
 			   __u32 *, __u32 *, int *);
 extern void ext2_free_blocks (struct inode *, unsigned long,
 			      unsigned long);
Index: linux-2.6.18-20.EL/fs/ext2/inode.c
===================================================================
--- linux-2.6.18-20.EL.orig/fs/ext2/inode.c
+++ linux-2.6.18-20.EL/fs/ext2/inode.c
@@ -107,7 +107,7 @@ void ext2_discard_prealloc (struct inode
 #endif
 }
 
-static int ext2_alloc_block (struct inode * inode, unsigned long goal, int *err)
+static unsigned long ext2_alloc_block (struct inode * inode, unsigned long goal, int *err)
 {
 #ifdef EXT2FS_DEBUG
 	static unsigned long alloc_hits, alloc_attempts;
@@ -425,13 +425,13 @@ static int ext2_alloc_branch(struct inod
 	int n = 0;
 	int err;
 	int i;
-	int parent = ext2_alloc_block(inode, goal, &err);
+	unsigned long parent = ext2_alloc_block(inode, goal, &err);
 
 	branch[0].key = cpu_to_le32(parent);
 	if (parent) for (n = 1; n < num; n++) {
 		struct buffer_head *bh;
 		/* Allocate the next block */
-		int nr = ext2_alloc_block(inode, parent, &err);
+		unsigned long nr = ext2_alloc_block(inode, parent, &err);
 		if (!nr)
 			break;
 		branch[n].key = cpu_to_le32(nr);