linux-ext4 - [PATCH] e2fsck: blk64_t to blk

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Date:	Mon, 2 Dec 2013 15:47:36 -0500
From:	Kit Westneat <kwestneat@....com>
To:	Theodore Ts'o <tytso@....edu>
CC:	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
	"Dilger, Andreas" <andreas.dilger@...el.com>
Subject: [PATCH] e2fsck: blk64_t to blk_t truncation

Hello,

We recently ran into an issue where e2fsck was claiming to clear 
deleted/unused inodes, but was not actually doing it. We tracked it down 
to a bad blk64_t to blk_t conversion in pass2 where 
ext2fs_write_dir_block is being called instead of 
ext2fs_write_dir_block3. There is another similar call in 
allocate_dir_block. These appear to be fixed in master as part of the 
move to adding checksums to the end of directory leaf nodes, but it's 
still an issue on maint.

I ran gcc with -Wconversion and found a number of other places that have 
blk64_t to blk_t truncations, but I'm not sure how many of them are 
actually problems. For example in block_iterate_ind, block_nr is blk_t 
but it seems to be a specific choice, since there is also the blk64 
variable. Another instance is with the EA refcounting, which is all 
32-bit. In expand_dir_proc in pass3.c, it uses the 32-bit 
ext2fs_write_dir_block. Against 1.42.7, gcc reports 103 blk64_t to blk_t 
conversions, so this is just a small sample.

I'm sure most of these are not problems, but I thought I'd raise the 
issue since we did run into problems with deleted/unused inodes.

Signed-off-by: Kit Westneat <kwestneat@....com>

diff --git a/e2fsck/pass2.c b/e2fsck/pass2.c
index 78740c0..e8d0b47 100644
--- a/e2fsck/pass2.c
+++ b/e2fsck/pass2.c
@@ -1216,7 +1216,7 @@ out_htree:
  		}
  	}
  	if (dir_modified) {
-		cd->pctx.errcode = ext2fs_write_dir_block(fs, block_nr, buf);
+		cd->pctx.errcode = ext2fs_write_dir_block3(fs, block_nr, buf, 0);
  		if (cd->pctx.errcode) {
  			if (!fix_problem(ctx, PR_2_WRITE_DIRBLOCK,
  					 &cd->pctx))
@@ -1595,7 +1595,7 @@ static int allocate_dir_block(e2fsck_t ctx,
  		return 1;
  	}

-	pctx->errcode = ext2fs_write_dir_block(fs, blk, block);
+	pctx->errcode = ext2fs_write_dir_block3(fs, blk, block, 0);
  	ext2fs_free_mem(&block);
  	if (pctx->errcode) {
  		pctx->str = "ext2fs_write_dir_block";

---
Kit Westneat
L3 Lustre Support, DDN
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