Re: extents in e2fsprogs

On Jun 15, 2006  18:50 +0200, Alexandre Ratchov wrote:
> > > @@ -83,10 +84,26 @@ errcode_t ext2fs_mkdir(ext2_filsys fs, e
> > > +	if (fs->super->s_feature_ro_compat & EXT2_FEATURE_RO_COMPAT_64BIT) {
> > > +		struct ext3_extent_header *eh = (struct ext3_extent_header *)inode.i_block;
> > > +		struct ext3_extent *ex = EXT_FIRST_EXTENT(eh);
> > > +
> > > +		 eh->eh_magic = EXT3_EXT_MAGIC;
> > > +		 eh->eh_depth = 0;
> > > +		 eh->eh_entries = 1;
> > > +		 eh->eh_max = (sizeof(inode.i_block) - sizeof(struct ext3_extent_header))
> > > +			 / sizeof(struct ext3_extent);
> > > +		 ex->ee_block = 0;
> > > +		 ex->ee_start = blk;
> > > +		 ex->ee_len = 1;
> > > +
> > > +		 inode.i_flags = EXT3_EXTENTS_FL;
> > > +	} else {
> > > +		inode.i_block[0] = blk;
> > > +	}
> > 
> > This relates to 64-bit support...
> > 
> 
> the EXT2_FEATURE_RO_COMPAT_64BIT flag is wrong;
> 
> however, if the file system is using extents then we can create the new
> directory using extents; is it ok?

While this is possible, it definitely isn't desirable.  There is a
bug in e2fsck that breaks the walking of directories that are extent
mapped.  This is because the htree code is assuming that i_blocks[0]
is directly mapping to the first logical block of the directory, but
of extent-mapped files this is a struct ext3_extent_hdr.

Patch below to do correct logical->physical mapping for the index root
block 0 (though CFS doesn't need this currently, since we don't use
extent-mapped directories anymore):


============================================================================
diff -rup e2fsprogs/e2fsck/pass1.c e2fsprogs-lustre-hg/e2fsck/pass1.c
--- e2fsprogs/e2fsck/pass1.c	2006-02-09 14:08:12.000000000 -0700
+++ e2fsprogs-lustre-hg/e2fsck/pass1.c	2006-06-08 11:52:01.000000000 -0600
@@ -1309,10 +1346,23 @@ clear_extattr:
 	return 0;
 }
 
+static int htree_blk_iter_cb(ext2_filsys fs EXT2FS_ATTR((unused)),
+			     blk_t *blocknr,
+			     e2_blkcnt_t blockcnt EXT2FS_ATTR((unused)),
+			     blk_t ref_blk EXT2FS_ATTR((unused)),
+			     int ref_offset EXT2FS_ATTR((unused)),
+			     void *priv_data)
+{
+	blk_t *blk = priv_data;
+
+	*blk = *blocknr;
+
+	return BLOCK_ABORT;
+}
+
 /* Returns 1 if bad htree, 0 if OK */
 static int handle_htree(e2fsck_t ctx, struct problem_context *pctx,
-			ext2_ino_t ino EXT2FS_ATTR((unused)),
-			struct ext2_inode *inode,
+			ext2_ino_t ino, struct ext2_inode *inode,
 			char *block_buf)
 {
 	struct ext2_dx_root_info	*root;
@@ -1326,7 +1376,8 @@ static int handle_htree(e2fsck_t ctx, st
 	     fix_problem(ctx, PR_1_HTREE_SET, pctx)))
 		return 1;
 
-	blk = inode->i_block[0];
+	ext2fs_block_iterate2(fs, ino, BLOCK_FLAG_DATA_ONLY | BLOCK_FLAG_HOLE,
+			      block_buf, htree_blk_iter_cb, &blk);
 	if (((blk == 0) ||
 	     (blk < fs->super->s_first_data_block) ||
 	     (blk >= fs->super->s_blocks_count)) &&


Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.