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Message-ID: <20130927000334.17889.54958.stgit@birch.djwong.org>
Date: Thu, 26 Sep 2013 17:03:34 -0700
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: tytso@....edu, darrick.wong@...cle.com
Cc: linux-ext4@...r.kernel.org
Subject: [PATCH 2/2] ext4: Spot-check block group sub-table locations
Perform a quick sanity check of bitmap and inode table block numbers when
loading them, and if there's something suspicious, mark the block group
corrupt.
Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
---
fs/ext4/balloc.c | 5 +++++
fs/ext4/ext4.h | 2 ++
fs/ext4/ialloc.c | 4 ++++
fs/ext4/inode.c | 6 ++++++
fs/ext4/super.c | 21 +++++++++++++++++++++
5 files changed, 38 insertions(+)
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 4390f9f..3d79bfe 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -396,11 +396,16 @@ ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
struct ext4_group_desc *desc;
struct buffer_head *bh;
ext4_fsblk_t bitmap_blk;
+ struct ext4_group_info *grp;
desc = ext4_get_group_desc(sb, block_group, NULL);
if (!desc)
return NULL;
bitmap_blk = ext4_block_bitmap(sb, desc);
+ if (!ext4_is_sane_bgdata_location(sb, block_group, bitmap_blk)) {
+ grp = ext4_get_group_info(sb, block_group);
+ set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
+ }
bh = sb_getblk(sb, bitmap_blk);
if (unlikely(!bh)) {
ext4_error(sb, "Cannot get buffer for block bitmap - "
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index af815ea..afb1bb2 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2531,6 +2531,8 @@ static inline void ext4_unlock_group(struct super_block *sb,
spin_unlock(ext4_group_lock_ptr(sb, group));
}
+int ext4_is_sane_bgdata_location(struct super_block *sb, ext4_group_t grp,
+ ext4_fsblk_t blk);
/*
* Block validity checking
*/
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 137193f..242250d 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -122,6 +122,10 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
return NULL;
bitmap_blk = ext4_inode_bitmap(sb, desc);
+ if (!ext4_is_sane_bgdata_location(sb, block_group, bitmap_blk)) {
+ grp = ext4_get_group_info(sb, block_group);
+ set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
+ }
bh = sb_getblk(sb, bitmap_blk);
if (unlikely(!bh)) {
ext4_error(sb, "Cannot read inode bitmap - "
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0d424d7..c5af22e 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3795,6 +3795,7 @@ static int __ext4_get_inode_loc(struct inode *inode,
struct super_block *sb = inode->i_sb;
ext4_fsblk_t block;
int inodes_per_block, inode_offset;
+ struct ext4_group_info *grp;
iloc->bh = NULL;
if (!ext4_valid_inum(sb, inode->i_ino))
@@ -3814,6 +3815,11 @@ static int __ext4_get_inode_loc(struct inode *inode,
block = ext4_inode_table(sb, gdp) + (inode_offset / inodes_per_block);
iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);
+ if (!ext4_is_sane_bgdata_location(sb, iloc->block_group, block)) {
+ grp = ext4_get_group_info(sb, iloc->block_group);
+ set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
+ return -EIO;
+ }
bh = sb_getblk(sb, block);
if (unlikely(!bh))
return -ENOMEM;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 2c2e6cb..d22248e 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2049,6 +2049,27 @@ void ext4_group_desc_csum_set(struct super_block *sb, __u32 block_group,
gdp->bg_checksum = ext4_group_desc_csum(EXT4_SB(sb), block_group, gdp);
}
+/* returns 1 if the location of a blockgroup data item seems sane */
+int ext4_is_sane_bgdata_location(struct super_block *sb, ext4_group_t grp,
+ ext4_fsblk_t blk)
+{
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+ ext4_fsblk_t first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
+ ext4_fsblk_t last_block;
+
+ if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
+ last_block = ext4_blocks_count(sbi->s_es) - 1;
+ else {
+ first_block += grp * sbi->s_blocks_per_group;
+ last_block = first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
+ }
+
+ if (last_block >= ext4_blocks_count(sbi->s_es))
+ last_block = ext4_blocks_count(sbi->s_es) - 1;
+
+ return blk >= first_block && blk <= last_block;
+}
+
/* Called at mount-time, super-block is locked */
static int ext4_check_descriptors(struct super_block *sb,
ext4_group_t *first_not_zeroed)
--
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