Re: Boot failure with ext2 and initrds

[Andrew Morton]

On Tue, 14 Nov 2006 19:11:22 +0000 (GMT)
Hugh Dickins <hugh@xxxxxxxxxxx> wrote:

> On Tue, 14 Nov 2006, Mel Gorman wrote:
> > 2.6.19-rc5-mm2
> > 
> > Am seeing errors with systems using ext2. First machine is a plan old x86
> > using initramfs. Console output looks like;
> > ...
> > Configuring network interfaces...BUG: soft lockup detected on CPU#3!
> > ...
> >  [<c01b3b80>] ext2_try_to_allocate+0xdb/0x152
> >  [<c01b3e72>] ext2_try_to_allocate_with_rsv+0x4b/0x1b2
> > 
> > I've not investigated yet what patches might be at fault.
> 
> I expect you'll find it's
> ext2-reservations-bring-ext2-reservations-code-in-line-with-latest-ext3.patch
> which gets stuck in a loop there for me too: back it out and all seems fine.
> 
> It's not obvious which part of the patch is to blame: mostly it's
> cleanup, but a few variables do change size: I'm currently narrowing
> down to where a fix is needed.
> 

Doing s/-Wall/-W/ tends to shake out bugs in this stuff.

The below might help.

Sorry, I tested this well, then the cleanup patch was merged and I didn't
get onto retesting :(



From: Andrew Morton <akpm@xxxxxxxx>

Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---

 fs/ext2/balloc.c |   33 +++++++++++++++------------------
 1 files changed, 15 insertions(+), 18 deletions(-)

diff -puN fs/ext2/balloc.c~ext2-reservations-bring-ext2-reservations-code-in-line-with-latest-ext3-fix fs/ext2/balloc.c
--- a/fs/ext2/balloc.c~ext2-reservations-bring-ext2-reservations-code-in-line-with-latest-ext3-fix
+++ a/fs/ext2/balloc.c
@@ -1155,9 +1155,10 @@ int ext2_new_blocks(struct inode *inode,
 	struct buffer_head *gdp_bh;
 	int group_no;
 	int goal_group;
+	ext2_grpblk_t grp_target_blk;	/* blockgroup relative goal block */
+	ext2_grpblk_t grp_alloc_blk;	/* blockgroup-relative allocated block*/
 	ext2_fsblk_t ret_block;		/* filesyetem-wide allocated block */
 	int bgi;			/* blockgroup iteration index */
-	int target_block;
 	int performed_allocation = 0;
 	ext2_grpblk_t free_blocks;	/* number of free blocks in a group */
 	struct super_block *sb;
@@ -1230,14 +1231,15 @@ retry_alloc:
 		my_rsv = NULL;
 
 	if (free_blocks > 0) {
-		ret_block = ((goal - le32_to_cpu(es->s_first_data_block)) %
+		grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
 				EXT2_BLOCKS_PER_GROUP(sb));
 		bitmap_bh = read_block_bitmap(sb, group_no);
 		if (!bitmap_bh)
 			goto io_error;
-		ret_block = ext2_try_to_allocate_with_rsv(sb, group_no,
-					bitmap_bh, ret_block, my_rsv, &num);
-		if (ret_block >= 0)
+		grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
+					bitmap_bh, grp_target_blk,
+					my_rsv, &num);
+		if (grp_alloc_blk >= 0)
 			goto allocated;
 	}
 
@@ -1273,9 +1275,9 @@ retry_alloc:
 		/*
 		 * try to allocate block(s) from this group, without a goal(-1).
 		 */
-		ret_block = ext2_try_to_allocate_with_rsv(sb, group_no,
+		grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
 					bitmap_bh, -1, my_rsv, &num);
-		if (ret_block >= 0)
+		if (grp_alloc_blk >= 0)
 			goto allocated;
 	}
 	/*
@@ -1299,25 +1301,20 @@ allocated:
 	ext2_debug("using block group %d(%d)\n",
 			group_no, gdp->bg_free_blocks_count);
 
-	target_block = ret_block + group_no * EXT2_BLOCKS_PER_GROUP(sb)
-				+ le32_to_cpu(es->s_first_data_block);
+	ret_block = grp_alloc_blk + ext2_group_first_block_no(sb, group_no);
 
-	if (in_range(le32_to_cpu(gdp->bg_block_bitmap), target_block, num) ||
-	    in_range(le32_to_cpu(gdp->bg_inode_bitmap), target_block, num) ||
-	    in_range(target_block, le32_to_cpu(gdp->bg_inode_table),
+	if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
+	    in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
+	    in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
 		      EXT2_SB(sb)->s_itb_per_group) ||
-	    in_range(target_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
+	    in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
 		      EXT2_SB(sb)->s_itb_per_group))
 		ext2_error(sb, "ext2_new_blocks",
 			    "Allocating block in system zone - "
-			    "blocks from %u, length %lu", target_block, num);
+			    "blocks from %u, length %lu", ret_block, num);
 
 	performed_allocation = 1;
 
-
-	/* ret_block was blockgroup-relative.  Now it becomes fs-relative */
-	ret_block = target_block;
-
 	if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
 		ext2_error(sb, "ext2_new_blocks",
 			    "block("E2FSBLK") >= blocks count(%d) - "
_

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