[PATCH 0/6 v3] ext4: Check journal inode extents more carefully

[PATCH 0/6 v3] ext4: Check journal inode extents more carefully

[Jan Kara]

Hello!

This series changes ext4 to properly check extent tree blocks of journal inode.
Omitting these (which is a limitation of block validity checks) leads to crash
in ext4_cache_extents() in case the extent tree of the journal inode is
suitably corrupted. 

Changes since v1:
* Added Reviewed-by tags from Lukas
* Fixed two more unrelated minor bugs in block validity testing spotted by
  Lukas

Changes since v2:
* Add more Reviewed-by tags from Lukas
* Fix intermediate compilation failure in patch 3/6

								Honza

[PATCH 1/6] ext4: Handle error of ext4_setup_system_zone() on remount

[Jan Kara]

ext4_setup_system_zone() can fail. Handle the failure in ext4_remount().

Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/super.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 330957ed1f05..8e055ec57a2c 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -5653,7 +5653,10 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 		ext4_register_li_request(sb, first_not_zeroed);
 	}
 
-	ext4_setup_system_zone(sb);
+	err = ext4_setup_system_zone(sb);
+	if (err)
+		goto restore_opts;
+
 	if (sbi->s_journal == NULL && !(old_sb_flags & SB_RDONLY)) {
 		err = ext4_commit_super(sb, 1);
 		if (err)
-- 
2.16.4

[PATCH 2/6] ext4: Don't allow overlapping system zones

[Jan Kara]

Currently, add_system_zone() just silently merges two added system zones
that overlap. However the overlap should not happen and it generally
suggests that some unrelated metadata overlap which indicates the fs is
corrupted. We should have caught such problems earlier (e.g. in
ext4_check_descriptors()) but add this check as another line of defense.
In later patch we also use this for stricter checking of journal inode
extent tree.

Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/block_validity.c | 36 +++++++++++++-----------------------
 1 file changed, 13 insertions(+), 23 deletions(-)

diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index 16e9b2fda03a..b394a50ebbe3 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -68,7 +68,7 @@ static int add_system_zone(struct ext4_system_blocks *system_blks,
 			   ext4_fsblk_t start_blk,
 			   unsigned int count)
 {
-	struct ext4_system_zone *new_entry = NULL, *entry;
+	struct ext4_system_zone *new_entry, *entry;
 	struct rb_node **n = &system_blks->root.rb_node, *node;
 	struct rb_node *parent = NULL, *new_node = NULL;
 
@@ -79,30 +79,20 @@ static int add_system_zone(struct ext4_system_blocks *system_blks,
 			n = &(*n)->rb_left;
 		else if (start_blk >= (entry->start_blk + entry->count))
 			n = &(*n)->rb_right;
-		else {
-			if (start_blk + count > (entry->start_blk +
-						 entry->count))
-				entry->count = (start_blk + count -
-						entry->start_blk);
-			new_node = *n;
-			new_entry = rb_entry(new_node, struct ext4_system_zone,
-					     node);
-			break;
-		}
+		else	/* Unexpected overlap of system zones. */
+			return -EFSCORRUPTED;
 	}
 
-	if (!new_entry) {
-		new_entry = kmem_cache_alloc(ext4_system_zone_cachep,
-					     GFP_KERNEL);
-		if (!new_entry)
-			return -ENOMEM;
-		new_entry->start_blk = start_blk;
-		new_entry->count = count;
-		new_node = &new_entry->node;
-
-		rb_link_node(new_node, parent, n);
-		rb_insert_color(new_node, &system_blks->root);
-	}
+	new_entry = kmem_cache_alloc(ext4_system_zone_cachep,
+				     GFP_KERNEL);
+	if (!new_entry)
+		return -ENOMEM;
+	new_entry->start_blk = start_blk;
+	new_entry->count = count;
+	new_node = &new_entry->node;
+
+	rb_link_node(new_node, parent, n);
+	rb_insert_color(new_node, &system_blks->root);
 
 	/* Can we merge to the left? */
 	node = rb_prev(new_node);
-- 
2.16.4

[PATCH 3/6] ext4: Check journal inode extents more carefully

[Jan Kara]

Currently, system zones just track ranges of block, that are "important"
fs metadata (bitmaps, group descriptors, journal blocks, etc.). This
however complicates how extent tree (or indirect blocks) can be checked
for inodes that actually track such metadata - currently the journal
inode but arguably we should be treating quota files or resize inode
similarly. We cannot run __ext4_ext_check() on such metadata inodes when
loading their extents as that would immediately trigger the validity
checks and so we just hack around that and special-case the journal
inode. This however leads to a situation that a journal inode which has
extent tree of depth at least one can have invalid extent tree that gets
unnoticed until ext4_cache_extents() crashes.

To overcome this limitation, track inode number each system zone belongs
to (0 is used for zones not belonging to any inode). We can then verify
inode number matches the expected one when verifying extent tree and
thus avoid the false errors. With this there's no need to to
special-case journal inode during extent tree checking anymore so remove
it.

Fixes: 0a944e8a6c66 ("ext4: don't perform block validity checks on the journal inode")
Reported-by: Wolfgang Frisch <wolfgang.frisch@suse.com>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/block_validity.c | 51 ++++++++++++++++++++++++------------------------
 fs/ext4/ext4.h           |  6 +++---
 fs/ext4/extents.c        | 16 ++++++---------
 fs/ext4/indirect.c       |  6 ++----
 fs/ext4/inode.c          |  5 ++---
 fs/ext4/mballoc.c        |  4 ++--
 6 files changed, 41 insertions(+), 47 deletions(-)

diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index b394a50ebbe3..e830a9d4e10d 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -24,6 +24,7 @@ struct ext4_system_zone {
 	struct rb_node	node;
 	ext4_fsblk_t	start_blk;
 	unsigned int	count;
+	u32		ino;
 };
 
 static struct kmem_cache *ext4_system_zone_cachep;
@@ -45,7 +46,8 @@ void ext4_exit_system_zone(void)
 static inline int can_merge(struct ext4_system_zone *entry1,
 		     struct ext4_system_zone *entry2)
 {
-	if ((entry1->start_blk + entry1->count) == entry2->start_blk)
+	if ((entry1->start_blk + entry1->count) == entry2->start_blk &&
+	    entry1->ino == entry2->ino)
 		return 1;
 	return 0;
 }
@@ -66,7 +68,7 @@ static void release_system_zone(struct ext4_system_blocks *system_blks)
  */
 static int add_system_zone(struct ext4_system_blocks *system_blks,
 			   ext4_fsblk_t start_blk,
-			   unsigned int count)
+			   unsigned int count, u32 ino)
 {
 	struct ext4_system_zone *new_entry, *entry;
 	struct rb_node **n = &system_blks->root.rb_node, *node;
@@ -89,6 +91,7 @@ static int add_system_zone(struct ext4_system_blocks *system_blks,
 		return -ENOMEM;
 	new_entry->start_blk = start_blk;
 	new_entry->count = count;
+	new_entry->ino = ino;
 	new_node = &new_entry->node;
 
 	rb_link_node(new_node, parent, n);
@@ -149,7 +152,7 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
 static int ext4_data_block_valid_rcu(struct ext4_sb_info *sbi,
 				     struct ext4_system_blocks *system_blks,
 				     ext4_fsblk_t start_blk,
-				     unsigned int count)
+				     unsigned int count, ino_t ino)
 {
 	struct ext4_system_zone *entry;
 	struct rb_node *n;
@@ -170,7 +173,7 @@ static int ext4_data_block_valid_rcu(struct ext4_sb_info *sbi,
 		else if (start_blk >= (entry->start_blk + entry->count))
 			n = n->rb_right;
 		else
-			return 0;
+			return entry->ino == ino;
 	}
 	return 1;
 }
@@ -204,19 +207,18 @@ static int ext4_protect_reserved_inode(struct super_block *sb,
 		if (n == 0) {
 			i++;
 		} else {
-			if (!ext4_data_block_valid_rcu(sbi, system_blks,
-						map.m_pblk, n)) {
-				err = -EFSCORRUPTED;
-				__ext4_error(sb, __func__, __LINE__, -err,
-					     map.m_pblk, "blocks %llu-%llu "
-					     "from inode %u overlap system zone",
-					     map.m_pblk,
-					     map.m_pblk + map.m_len - 1, ino);
+			err = add_system_zone(system_blks, map.m_pblk, n, ino);
+			if (err < 0) {
+				if (err == -EFSCORRUPTED) {
+					__ext4_error(sb, __func__, __LINE__,
+						     -err, map.m_pblk,
+						     "blocks %llu-%llu from inode %u overlap system zone",
+						     map.m_pblk,
+						     map.m_pblk + map.m_len - 1,
+						     ino);
+				}
 				break;
 			}
-			err = add_system_zone(system_blks, map.m_pblk, n);
-			if (err < 0)
-				break;
 			i += n;
 		}
 	}
@@ -270,19 +272,19 @@ int ext4_setup_system_zone(struct super_block *sb)
 		    ((i < 5) || ((i % flex_size) == 0)))
 			add_system_zone(system_blks,
 					ext4_group_first_block_no(sb, i),
-					ext4_bg_num_gdb(sb, i) + 1);
+					ext4_bg_num_gdb(sb, i) + 1, 0);
 		gdp = ext4_get_group_desc(sb, i, NULL);
 		ret = add_system_zone(system_blks,
-				ext4_block_bitmap(sb, gdp), 1);
+				ext4_block_bitmap(sb, gdp), 1, 0);
 		if (ret)
 			goto err;
 		ret = add_system_zone(system_blks,
-				ext4_inode_bitmap(sb, gdp), 1);
+				ext4_inode_bitmap(sb, gdp), 1, 0);
 		if (ret)
 			goto err;
 		ret = add_system_zone(system_blks,
 				ext4_inode_table(sb, gdp),
-				sbi->s_itb_per_group);
+				sbi->s_itb_per_group, 0);
 		if (ret)
 			goto err;
 	}
@@ -331,7 +333,7 @@ void ext4_release_system_zone(struct super_block *sb)
 		call_rcu(&system_blks->rcu, ext4_destroy_system_zone);
 }
 
-int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk,
+int ext4_inode_block_valid(struct inode *inode, ext4_fsblk_t start_blk,
 			  unsigned int count)
 {
 	struct ext4_system_blocks *system_blks;
@@ -343,9 +345,9 @@ int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk,
 	 * mount option.
 	 */
 	rcu_read_lock();
-	system_blks = rcu_dereference(sbi->system_blks);
-	ret = ext4_data_block_valid_rcu(sbi, system_blks, start_blk,
-					count);
+	system_blks = rcu_dereference(EXT4_SB(inode->i_sb)->system_blks);
+	ret = ext4_data_block_valid_rcu(EXT4_SB(inode->i_sb), system_blks,
+					start_blk, count, inode->i_ino);
 	rcu_read_unlock();
 	return ret;
 }
@@ -364,8 +366,7 @@ int ext4_check_blockref(const char *function, unsigned int line,
 	while (bref < p+max) {
 		blk = le32_to_cpu(*bref++);
 		if (blk &&
-		    unlikely(!ext4_data_block_valid(EXT4_SB(inode->i_sb),
-						    blk, 1))) {
+		    unlikely(!ext4_inode_block_valid(inode, blk, 1))) {
 			ext4_error_inode(inode, function, line, blk,
 					 "invalid block");
 			return -EFSCORRUPTED;
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 42f5060f3cdf..42815304902b 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3363,9 +3363,9 @@ extern void ext4_release_system_zone(struct super_block *sb);
 extern int ext4_setup_system_zone(struct super_block *sb);
 extern int __init ext4_init_system_zone(void);
 extern void ext4_exit_system_zone(void);
-extern int ext4_data_block_valid(struct ext4_sb_info *sbi,
-				 ext4_fsblk_t start_blk,
-				 unsigned int count);
+extern int ext4_inode_block_valid(struct inode *inode,
+				  ext4_fsblk_t start_blk,
+				  unsigned int count);
 extern int ext4_check_blockref(const char *, unsigned int,
 			       struct inode *, __le32 *, unsigned int);
 
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 221f240eae60..d75054570e44 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -340,7 +340,7 @@ static int ext4_valid_extent(struct inode *inode, struct ext4_extent *ext)
 	 */
 	if (lblock + len <= lblock)
 		return 0;
-	return ext4_data_block_valid(EXT4_SB(inode->i_sb), block, len);
+	return ext4_inode_block_valid(inode, block, len);
 }
 
 static int ext4_valid_extent_idx(struct inode *inode,
@@ -348,7 +348,7 @@ static int ext4_valid_extent_idx(struct inode *inode,
 {
 	ext4_fsblk_t block = ext4_idx_pblock(ext_idx);
 
-	return ext4_data_block_valid(EXT4_SB(inode->i_sb), block, 1);
+	return ext4_inode_block_valid(inode, block, 1);
 }
 
 static int ext4_valid_extent_entries(struct inode *inode,
@@ -507,14 +507,10 @@ __read_extent_tree_block(const char *function, unsigned int line,
 	}
 	if (buffer_verified(bh) && !(flags & EXT4_EX_FORCE_CACHE))
 		return bh;
-	if (!ext4_has_feature_journal(inode->i_sb) ||
-	    (inode->i_ino !=
-	     le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum))) {
-		err = __ext4_ext_check(function, line, inode,
-				       ext_block_hdr(bh), depth, pblk);
-		if (err)
-			goto errout;
-	}
+	err = __ext4_ext_check(function, line, inode,
+			       ext_block_hdr(bh), depth, pblk);
+	if (err)
+		goto errout;
 	set_buffer_verified(bh);
 	/*
 	 * If this is a leaf block, cache all of its entries
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index be2b66eb65f7..402641825712 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -858,8 +858,7 @@ static int ext4_clear_blocks(handle_t *handle, struct inode *inode,
 	else if (ext4_should_journal_data(inode))
 		flags |= EXT4_FREE_BLOCKS_FORGET;
 
-	if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), block_to_free,
-				   count)) {
+	if (!ext4_inode_block_valid(inode, block_to_free, count)) {
 		EXT4_ERROR_INODE(inode, "attempt to clear invalid "
 				 "blocks %llu len %lu",
 				 (unsigned long long) block_to_free, count);
@@ -1004,8 +1003,7 @@ static void ext4_free_branches(handle_t *handle, struct inode *inode,
 			if (!nr)
 				continue;		/* A hole */
 
-			if (!ext4_data_block_valid(EXT4_SB(inode->i_sb),
-						   nr, 1)) {
+			if (!ext4_inode_block_valid(inode, nr, 1)) {
 				EXT4_ERROR_INODE(inode,
 						 "invalid indirect mapped "
 						 "block %lu (level %d)",
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 10dd470876b3..92573f8540ab 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -394,8 +394,7 @@ static int __check_block_validity(struct inode *inode, const char *func,
 	    (inode->i_ino ==
 	     le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum)))
 		return 0;
-	if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), map->m_pblk,
-				   map->m_len)) {
+	if (!ext4_inode_block_valid(inode, map->m_pblk, map->m_len)) {
 		ext4_error_inode(inode, func, line, map->m_pblk,
 				 "lblock %lu mapped to illegal pblock %llu "
 				 "(length %d)", (unsigned long) map->m_lblk,
@@ -4760,7 +4759,7 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
 
 	ret = 0;
 	if (ei->i_file_acl &&
-	    !ext4_data_block_valid(EXT4_SB(sb), ei->i_file_acl, 1)) {
+	    !ext4_inode_block_valid(inode, ei->i_file_acl, 1)) {
 		ext4_error_inode(inode, function, line, 0,
 				 "iget: bad extended attribute block %llu",
 				 ei->i_file_acl);
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index c0a331e2feb0..38719c156573 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3090,7 +3090,7 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
 	block = ext4_grp_offs_to_block(sb, &ac->ac_b_ex);
 
 	len = EXT4_C2B(sbi, ac->ac_b_ex.fe_len);
-	if (!ext4_data_block_valid(sbi, block, len)) {
+	if (!ext4_inode_block_valid(ac->ac_inode, block, len)) {
 		ext4_error(sb, "Allocating blocks %llu-%llu which overlap "
 			   "fs metadata", block, block+len);
 		/* File system mounted not to panic on error
@@ -4915,7 +4915,7 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode,
 
 	sbi = EXT4_SB(sb);
 	if (!(flags & EXT4_FREE_BLOCKS_VALIDATED) &&
-	    !ext4_data_block_valid(sbi, block, count)) {
+	    !ext4_inode_block_valid(inode, block, count)) {
 		ext4_error(sb, "Freeing blocks not in datazone - "
 			   "block = %llu, count = %lu", block, count);
 		goto error_return;
-- 
2.16.4

[PATCH 4/6] ext4: Fold ext4_data_block_valid_rcu() into the caller

[Jan Kara]

After the previous patch, ext4_data_block_valid_rcu() has a single
caller. Fold it into it.

Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/block_validity.c | 69 ++++++++++++++++++++++--------------------------
 1 file changed, 31 insertions(+), 38 deletions(-)

diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index e830a9d4e10d..9c40214f31f9 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -144,40 +144,6 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
 	printk(KERN_CONT "\n");
 }
 
-/*
- * Returns 1 if the passed-in block region (start_blk,
- * start_blk+count) is valid; 0 if some part of the block region
- * overlaps with filesystem metadata blocks.
- */
-static int ext4_data_block_valid_rcu(struct ext4_sb_info *sbi,
-				     struct ext4_system_blocks *system_blks,
-				     ext4_fsblk_t start_blk,
-				     unsigned int count, ino_t ino)
-{
-	struct ext4_system_zone *entry;
-	struct rb_node *n;
-
-	if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
-	    (start_blk + count < start_blk) ||
-	    (start_blk + count > ext4_blocks_count(sbi->s_es)))
-		return 0;
-
-	if (system_blks == NULL)
-		return 1;
-
-	n = system_blks->root.rb_node;
-	while (n) {
-		entry = rb_entry(n, struct ext4_system_zone, node);
-		if (start_blk + count - 1 < entry->start_blk)
-			n = n->rb_left;
-		else if (start_blk >= (entry->start_blk + entry->count))
-			n = n->rb_right;
-		else
-			return entry->ino == ino;
-	}
-	return 1;
-}
-
 static int ext4_protect_reserved_inode(struct super_block *sb,
 				       struct ext4_system_blocks *system_blks,
 				       u32 ino)
@@ -333,11 +299,24 @@ void ext4_release_system_zone(struct super_block *sb)
 		call_rcu(&system_blks->rcu, ext4_destroy_system_zone);
 }
 
+/*
+ * Returns 1 if the passed-in block region (start_blk,
+ * start_blk+count) is valid; 0 if some part of the block region
+ * overlaps with some other filesystem metadata blocks.
+ */
 int ext4_inode_block_valid(struct inode *inode, ext4_fsblk_t start_blk,
 			  unsigned int count)
 {
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 	struct ext4_system_blocks *system_blks;
-	int ret;
+	struct ext4_system_zone *entry;
+	struct rb_node *n;
+	int ret = 1;
+
+	if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
+	    (start_blk + count < start_blk) ||
+	    (start_blk + count > ext4_blocks_count(sbi->s_es)))
+		return 0;
 
 	/*
 	 * Lock the system zone to prevent it being released concurrently
@@ -345,9 +324,23 @@ int ext4_inode_block_valid(struct inode *inode, ext4_fsblk_t start_blk,
 	 * mount option.
 	 */
 	rcu_read_lock();
-	system_blks = rcu_dereference(EXT4_SB(inode->i_sb)->system_blks);
-	ret = ext4_data_block_valid_rcu(EXT4_SB(inode->i_sb), system_blks,
-					start_blk, count, inode->i_ino);
+	system_blks = rcu_dereference(sbi->system_blks);
+	if (system_blks == NULL)
+		goto out_rcu;
+
+	n = system_blks->root.rb_node;
+	while (n) {
+		entry = rb_entry(n, struct ext4_system_zone, node);
+		if (start_blk + count - 1 < entry->start_blk)
+			n = n->rb_left;
+		else if (start_blk >= (entry->start_blk + entry->count))
+			n = n->rb_right;
+		else {
+			ret = (entry->ino == inode->i_ino);
+			break;
+		}
+	}
+out_rcu:
 	rcu_read_unlock();
 	return ret;
 }
-- 
2.16.4

[PATCH 5/6] ext4: Handle add_system_zone() failure in ext4_setup_system_zone()

[Jan Kara]

There's one place that fails to handle error from add_system_zone() call
and thus we can fail to protect superblock and group-descriptor blocks
properly in case of ENOMEM. Fix it.

Reported-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/block_validity.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index 9c40214f31f9..2d008c1b58f2 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -235,10 +235,13 @@ int ext4_setup_system_zone(struct super_block *sb)
 	for (i=0; i < ngroups; i++) {
 		cond_resched();
 		if (ext4_bg_has_super(sb, i) &&
-		    ((i < 5) || ((i % flex_size) == 0)))
-			add_system_zone(system_blks,
+		    ((i < 5) || ((i % flex_size) == 0))) {
+			ret = add_system_zone(system_blks,
 					ext4_group_first_block_no(sb, i),
 					ext4_bg_num_gdb(sb, i) + 1, 0);
+			if (ret)
+				goto err;
+		}
 		gdp = ext4_get_group_desc(sb, i, NULL);
 		ret = add_system_zone(system_blks,
 				ext4_block_bitmap(sb, gdp), 1, 0);
-- 
2.16.4

[PATCH 6/6] ext4: Correctly restore system zone info when remount fails

[Jan Kara]

When remounting filesystem fails late during remount handling and
block_validity mount option is also changed during the remount, we fail
to restore system zone information to a state matching the mount option.
This is mostly harmless, just the block validity checking will not match
the situation described by the mount option. Make sure these two are always
consistent.

Reported-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/block_validity.c |  8 --------
 fs/ext4/super.c          | 29 +++++++++++++++++++++--------
 2 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index 2d008c1b58f2..c54ba52f2dd4 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -220,14 +220,6 @@ int ext4_setup_system_zone(struct super_block *sb)
 	int flex_size = ext4_flex_bg_size(sbi);
 	int ret;
 
-	if (!test_opt(sb, BLOCK_VALIDITY)) {
-		if (sbi->system_blks)
-			ext4_release_system_zone(sb);
-		return 0;
-	}
-	if (sbi->system_blks)
-		return 0;
-
 	system_blks = kzalloc(sizeof(*system_blks), GFP_KERNEL);
 	if (!system_blks)
 		return -ENOMEM;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 8e055ec57a2c..37f09ecca0df 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4698,11 +4698,13 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 
 	ext4_set_resv_clusters(sb);
 
-	err = ext4_setup_system_zone(sb);
-	if (err) {
-		ext4_msg(sb, KERN_ERR, "failed to initialize system "
-			 "zone (%d)", err);
-		goto failed_mount4a;
+	if (test_opt(sb, BLOCK_VALIDITY)) {
+		err = ext4_setup_system_zone(sb);
+		if (err) {
+			ext4_msg(sb, KERN_ERR, "failed to initialize system "
+				 "zone (%d)", err);
+			goto failed_mount4a;
+		}
 	}
 
 	ext4_ext_init(sb);
@@ -5653,9 +5655,16 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 		ext4_register_li_request(sb, first_not_zeroed);
 	}
 
-	err = ext4_setup_system_zone(sb);
-	if (err)
-		goto restore_opts;
+	/*
+	 * Handle creation of system zone data early because it can fail.
+	 * Releasing of existing data is done when we are sure remount will
+	 * succeed.
+	 */
+	if (test_opt(sb, BLOCK_VALIDITY) && !sbi->system_blks) {
+		err = ext4_setup_system_zone(sb);
+		if (err)
+			goto restore_opts;
+	}
 
 	if (sbi->s_journal == NULL && !(old_sb_flags & SB_RDONLY)) {
 		err = ext4_commit_super(sb, 1);
@@ -5677,6 +5686,8 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 		}
 	}
 #endif
+	if (!test_opt(sb, BLOCK_VALIDITY) && sbi->system_blks)
+		ext4_release_system_zone(sb);
 
 	*flags = (*flags & ~SB_LAZYTIME) | (sb->s_flags & SB_LAZYTIME);
 	ext4_msg(sb, KERN_INFO, "re-mounted. Opts: %s", orig_data);
@@ -5692,6 +5703,8 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 	sbi->s_commit_interval = old_opts.s_commit_interval;
 	sbi->s_min_batch_time = old_opts.s_min_batch_time;
 	sbi->s_max_batch_time = old_opts.s_max_batch_time;
+	if (!test_opt(sb, BLOCK_VALIDITY) && sbi->system_blks)
+		ext4_release_system_zone(sb);
 #ifdef CONFIG_QUOTA
 	sbi->s_jquota_fmt = old_opts.s_jquota_fmt;
 	for (i = 0; i < EXT4_MAXQUOTAS; i++) {
-- 
2.16.4

Re: [PATCH 0/6 v3] ext4: Check journal inode extents more carefully

[tytso]

On Tue, Jul 28, 2020 at 03:04:31PM +0200, Jan Kara wrote:
> Hello!
> 
> This series changes ext4 to properly check extent tree blocks of journal inode.
> Omitting these (which is a limitation of block validity checks) leads to crash
> in ext4_cache_extents() in case the extent tree of the journal inode is
> suitably corrupted.

Thanks, I've applied this series.

					- Ted