linux-ext4 - [PATCH 2/7] e2fsck: Fix indexed dir rehash failure with metadata

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Date:   Thu, 13 Feb 2020 11:15:57 +0100
From:   Jan Kara <jack@...e.cz>
To:     Ted Tso <tytso@....edu>
Cc:     <linux-ext4@...r.kernel.org>, Jan Kara <jack@...e.cz>
Subject: [PATCH 2/7] e2fsck: Fix indexed dir rehash failure with metadata_csum enabled

E2fsck directory rehashing code can fail with ENOSPC due to a bug in
ext2fs_htree_intnode_maxrecs() which fails to take metadata checksum
into account and thus e.g. e2fsck can decide to create 1 indirect level
of index tree when two are actually needed. Fix the logic to account for
metadata checksum.

Signed-off-by: Jan Kara <jack@...e.cz>
---
 lib/ext2fs/ext2fs.h | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 93ecf29c568d..5fde3343b1f1 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -1783,7 +1783,6 @@ extern blk_t ext2fs_group_first_block(ext2_filsys fs, dgrp_t group);
 extern blk_t ext2fs_group_last_block(ext2_filsys fs, dgrp_t group);
 extern blk_t ext2fs_inode_data_blocks(ext2_filsys fs,
 				      struct ext2_inode *inode);
-extern int ext2fs_htree_intnode_maxrecs(ext2_filsys fs, int blocks);
 extern unsigned int ext2fs_div_ceil(unsigned int a, unsigned int b);
 extern __u64 ext2fs_div64_ceil(__u64 a, __u64 b);
 extern int ext2fs_dirent_name_len(const struct ext2_dir_entry *entry);
@@ -2015,9 +2014,14 @@ _INLINE_ blk_t ext2fs_inode_data_blocks(ext2_filsys fs,
 	return (blk_t) ext2fs_inode_data_blocks2(fs, inode);
 }
 
-_INLINE_ int ext2fs_htree_intnode_maxrecs(ext2_filsys fs, int blocks)
+static inline int ext2fs_htree_intnode_maxrecs(ext2_filsys fs, int blocks)
 {
-	return blocks * ((fs->blocksize - 8) / sizeof(struct ext2_dx_entry));
+	int csum_size = 0;
+
+	if (ext2fs_has_feature_metadata_csum(fs->super))
+		csum_size = sizeof(struct ext2_dx_tail);
+	return blocks * ((fs->blocksize - (8 + csum_size)) /
+						sizeof(struct ext2_dx_entry));
 }
 
 /*
-- 
2.16.4