linux-ext4 - [PATCH -V3 2/3] tune2fs: Handle fs meta-data blocks during inode resize

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Date:	Thu,  6 Aug 2009 11:42:30 +0530
From:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:	tytso@....edu
Cc:	linux-ext4@...r.kernel.org,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Subject: [PATCH -V3 2/3] tune2fs: Handle fs meta-data blocks during inode resize

With file system formated for RAID arrays we can have inode bitmap
and block bitmap after inode table. Make sure we move them around
properly when doing inode resize.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
---

Changes from v2:
	o Set proper retval when we failed to get a mapping block in 
	  the same group. This make sure inode resize fails if we failed
	  to get a mapping fs meta data block in the same group.


 misc/tune2fs.c |   85 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 84 insertions(+), 1 deletions(-)

diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index 08fff29..966738b 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -1003,10 +1003,39 @@ static int get_move_bitmaps(ext2_filsys fs, int new_ino_blks_per_grp,
 	return 0;
 }
 
+static int ext2fs_is_meta_block(ext2_filsys fs, blk_t blk)
+{
+	dgrp_t group;
+	group = ext2fs_group_of_blk(fs, blk);
+	if (fs->group_desc[group].bg_block_bitmap == blk)
+		return 1;
+	if (fs->group_desc[group].bg_inode_bitmap == blk)
+		return 1;
+	return 0;
+}
+
+static int ext2fs_is_block_in_group(ext2_filsys fs, dgrp_t group, blk_t blk)
+{
+	blk_t start_blk, end_blk;
+	start_blk = fs->super->s_first_data_block +
+			EXT2_BLOCKS_PER_GROUP(fs->super) * group;
+	/*
+	 * We cannot get new block beyond end_blk for for the last block group
+	 * so we can check with EXT2_BLOCKS_PER_GROUP even for last block group
+	 */
+	end_blk   = start_blk + EXT2_BLOCKS_PER_GROUP(fs->super);
+	if (blk >= start_blk && blk <= end_blk)
+		return 1;
+	return 0;
+}
+
 static int move_block(ext2_filsys fs, ext2fs_block_bitmap bmap)
 {
+
 	char *buf;
+	dgrp_t group;
 	errcode_t retval;
+	int meta_data = 0;
 	blk_t blk, new_blk, goal;
 	struct blk_move *bmv;
 
@@ -1019,11 +1048,31 @@ static int move_block(ext2_filsys fs, ext2fs_block_bitmap bmap)
 		if (!ext2fs_test_block_bitmap(bmap, blk))
 			continue;
 
-		goal = new_blk;
+		if (ext2fs_is_meta_block(fs, blk)) {
+			/*
+			 * If the block is mapping a fs meta data block
+			 * like group desc/block bitmap/inode bitmap. We
+			 * should find a block in the same group and fix
+			 * the respective fs metadata pointers. Otherwise
+			 * fail
+			 */
+			group = ext2fs_group_of_blk(fs, blk);
+			goal = ext2fs_group_first_block(fs, group);
+			meta_data = 1;
+
+		} else {
+			goal = new_blk;
+		}
 		retval = ext2fs_new_block(fs, goal, NULL, &new_blk);
 		if (retval)
 			goto err_out;
 
+		/* new fs meta data block should be in the same group */
+		if (meta_data && !ext2fs_is_block_in_group(fs, group, new_blk)) {
+			retval = ENOSPC;
+			goto err_out;
+		}
+
 		/* Mark this block as allocated */
 		ext2fs_mark_block_bitmap(fs->block_map, new_blk);
 
@@ -1158,6 +1207,36 @@ err_out:
 	return retval;
 }
 
+/*
+ * We need to scan for inode and block bitmaps that may need to be
+ * moved.  This can take place if the filesystem was formatted for
+ * RAID arrays using the mke2fs's extended option "stride".
+ */
+static int group_desc_scan_and_fix(ext2_filsys fs, ext2fs_block_bitmap bmap)
+{
+	dgrp_t i;
+	blk_t blk, new_blk;
+
+	for (i = 0; i < fs->group_desc_count; i++) {
+		blk = fs->group_desc[i].bg_block_bitmap;
+		if (ext2fs_test_block_bitmap(bmap, blk)) {
+			new_blk = translate_block(blk);
+			if (!new_blk)
+				continue;
+			fs->group_desc[i].bg_block_bitmap = new_blk;
+		}
+
+		blk = fs->group_desc[i].bg_inode_bitmap;
+		if (ext2fs_test_block_bitmap(bmap, blk)) {
+			new_blk = translate_block(blk);
+			if (!new_blk)
+				continue;
+			fs->group_desc[i].bg_inode_bitmap = new_blk;
+		}
+	}
+	return 0;
+}
+
 static int expand_inode_table(ext2_filsys fs, unsigned long new_ino_size)
 {
 	dgrp_t i;
@@ -1349,6 +1428,10 @@ static int resize_inode(ext2_filsys fs, unsigned long new_size)
 	if (retval)
 		goto err_out_undo;
 
+	retval = group_desc_scan_and_fix(fs, bmap);
+	if (retval)
+		goto err_out_undo;
+
 	retval = expand_inode_table(fs, new_size);
 	if (retval)
 		goto err_out_undo;
-- 
1.6.4.13.ge6580

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