summaryrefslogtreecommitdiffstats
path: root/fs/ext4/block_validity.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/ext4/block_validity.c')
-rw-r--r--fs/ext4/block_validity.c371
1 files changed, 371 insertions, 0 deletions
diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
new file mode 100644
index 0000000000..6fe3c941b5
--- /dev/null
+++ b/fs/ext4/block_validity.c
@@ -0,0 +1,371 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/fs/ext4/block_validity.c
+ *
+ * Copyright (C) 2009
+ * Theodore Ts'o (tytso@mit.edu)
+ *
+ * Track which blocks in the filesystem are metadata blocks that
+ * should never be used as data blocks by files or directories.
+ */
+
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/quotaops.h>
+#include <linux/buffer_head.h>
+#include <linux/swap.h>
+#include <linux/pagemap.h>
+#include <linux/blkdev.h>
+#include <linux/slab.h>
+#include "ext4.h"
+
+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;
+
+int __init ext4_init_system_zone(void)
+{
+ ext4_system_zone_cachep = KMEM_CACHE(ext4_system_zone, 0);
+ if (ext4_system_zone_cachep == NULL)
+ return -ENOMEM;
+ return 0;
+}
+
+void ext4_exit_system_zone(void)
+{
+ rcu_barrier();
+ kmem_cache_destroy(ext4_system_zone_cachep);
+}
+
+static inline int can_merge(struct ext4_system_zone *entry1,
+ struct ext4_system_zone *entry2)
+{
+ if ((entry1->start_blk + entry1->count) == entry2->start_blk &&
+ entry1->ino == entry2->ino)
+ return 1;
+ return 0;
+}
+
+static void release_system_zone(struct ext4_system_blocks *system_blks)
+{
+ struct ext4_system_zone *entry, *n;
+
+ rbtree_postorder_for_each_entry_safe(entry, n,
+ &system_blks->root, node)
+ kmem_cache_free(ext4_system_zone_cachep, entry);
+}
+
+/*
+ * Mark a range of blocks as belonging to the "system zone" --- that
+ * is, filesystem metadata blocks which should never be used by
+ * inodes.
+ */
+static int add_system_zone(struct ext4_system_blocks *system_blks,
+ ext4_fsblk_t start_blk,
+ unsigned int count, u32 ino)
+{
+ 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;
+
+ while (*n) {
+ parent = *n;
+ entry = rb_entry(parent, struct ext4_system_zone, node);
+ if (start_blk < entry->start_blk)
+ n = &(*n)->rb_left;
+ else if (start_blk >= (entry->start_blk + entry->count))
+ n = &(*n)->rb_right;
+ else /* Unexpected overlap of system zones. */
+ return -EFSCORRUPTED;
+ }
+
+ 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_entry->ino = ino;
+ 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);
+ if (node) {
+ entry = rb_entry(node, struct ext4_system_zone, node);
+ if (can_merge(entry, new_entry)) {
+ new_entry->start_blk = entry->start_blk;
+ new_entry->count += entry->count;
+ rb_erase(node, &system_blks->root);
+ kmem_cache_free(ext4_system_zone_cachep, entry);
+ }
+ }
+
+ /* Can we merge to the right? */
+ node = rb_next(new_node);
+ if (node) {
+ entry = rb_entry(node, struct ext4_system_zone, node);
+ if (can_merge(new_entry, entry)) {
+ new_entry->count += entry->count;
+ rb_erase(node, &system_blks->root);
+ kmem_cache_free(ext4_system_zone_cachep, entry);
+ }
+ }
+ return 0;
+}
+
+static void debug_print_tree(struct ext4_sb_info *sbi)
+{
+ struct rb_node *node;
+ struct ext4_system_zone *entry;
+ struct ext4_system_blocks *system_blks;
+ int first = 1;
+
+ printk(KERN_INFO "System zones: ");
+ rcu_read_lock();
+ system_blks = rcu_dereference(sbi->s_system_blks);
+ node = rb_first(&system_blks->root);
+ while (node) {
+ entry = rb_entry(node, struct ext4_system_zone, node);
+ printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ",
+ entry->start_blk, entry->start_blk + entry->count - 1);
+ first = 0;
+ node = rb_next(node);
+ }
+ rcu_read_unlock();
+ printk(KERN_CONT "\n");
+}
+
+static int ext4_protect_reserved_inode(struct super_block *sb,
+ struct ext4_system_blocks *system_blks,
+ u32 ino)
+{
+ struct inode *inode;
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+ struct ext4_map_blocks map;
+ u32 i = 0, num;
+ int err = 0, n;
+
+ if ((ino < EXT4_ROOT_INO) ||
+ (ino > le32_to_cpu(sbi->s_es->s_inodes_count)))
+ return -EINVAL;
+ inode = ext4_iget(sb, ino, EXT4_IGET_SPECIAL);
+ if (IS_ERR(inode))
+ return PTR_ERR(inode);
+ num = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
+ while (i < num) {
+ cond_resched();
+ map.m_lblk = i;
+ map.m_len = num - i;
+ n = ext4_map_blocks(NULL, inode, &map, 0);
+ if (n < 0) {
+ err = n;
+ break;
+ }
+ if (n == 0) {
+ i++;
+ } else {
+ err = add_system_zone(system_blks, map.m_pblk, n, ino);
+ if (err < 0) {
+ if (err == -EFSCORRUPTED) {
+ EXT4_ERROR_INODE_ERR(inode, -err,
+ "blocks %llu-%llu from inode overlap system zone",
+ map.m_pblk,
+ map.m_pblk + map.m_len - 1);
+ }
+ break;
+ }
+ i += n;
+ }
+ }
+ iput(inode);
+ return err;
+}
+
+static void ext4_destroy_system_zone(struct rcu_head *rcu)
+{
+ struct ext4_system_blocks *system_blks;
+
+ system_blks = container_of(rcu, struct ext4_system_blocks, rcu);
+ release_system_zone(system_blks);
+ kfree(system_blks);
+}
+
+/*
+ * Build system zone rbtree which is used for block validity checking.
+ *
+ * The update of system_blks pointer in this function is protected by
+ * sb->s_umount semaphore. However we have to be careful as we can be
+ * racing with ext4_inode_block_valid() calls reading system_blks rbtree
+ * protected only by RCU. That's why we first build the rbtree and then
+ * swap it in place.
+ */
+int ext4_setup_system_zone(struct super_block *sb)
+{
+ ext4_group_t ngroups = ext4_get_groups_count(sb);
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+ struct ext4_system_blocks *system_blks;
+ struct ext4_group_desc *gdp;
+ ext4_group_t i;
+ int ret;
+
+ system_blks = kzalloc(sizeof(*system_blks), GFP_KERNEL);
+ if (!system_blks)
+ return -ENOMEM;
+
+ for (i=0; i < ngroups; i++) {
+ unsigned int meta_blks = ext4_num_base_meta_blocks(sb, i);
+
+ cond_resched();
+ if (meta_blks != 0) {
+ ret = add_system_zone(system_blks,
+ ext4_group_first_block_no(sb, i),
+ meta_blks, 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);
+ if (ret)
+ goto err;
+ ret = add_system_zone(system_blks,
+ 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, 0);
+ if (ret)
+ goto err;
+ }
+ if (ext4_has_feature_journal(sb) && sbi->s_es->s_journal_inum) {
+ ret = ext4_protect_reserved_inode(sb, system_blks,
+ le32_to_cpu(sbi->s_es->s_journal_inum));
+ if (ret)
+ goto err;
+ }
+
+ /*
+ * System blks rbtree complete, announce it once to prevent racing
+ * with ext4_inode_block_valid() accessing the rbtree at the same
+ * time.
+ */
+ rcu_assign_pointer(sbi->s_system_blks, system_blks);
+
+ if (test_opt(sb, DEBUG))
+ debug_print_tree(sbi);
+ return 0;
+err:
+ release_system_zone(system_blks);
+ kfree(system_blks);
+ return ret;
+}
+
+/*
+ * Called when the filesystem is unmounted or when remounting it with
+ * noblock_validity specified.
+ *
+ * The update of system_blks pointer in this function is protected by
+ * sb->s_umount semaphore. However we have to be careful as we can be
+ * racing with ext4_inode_block_valid() calls reading system_blks rbtree
+ * protected only by RCU. So we first clear the system_blks pointer and
+ * then free the rbtree only after RCU grace period expires.
+ */
+void ext4_release_system_zone(struct super_block *sb)
+{
+ struct ext4_system_blocks *system_blks;
+
+ system_blks = rcu_dereference_protected(EXT4_SB(sb)->s_system_blks,
+ lockdep_is_held(&sb->s_umount));
+ rcu_assign_pointer(EXT4_SB(sb)->s_system_blks, NULL);
+
+ if (system_blks)
+ call_rcu(&system_blks->rcu, ext4_destroy_system_zone);
+}
+
+int ext4_sb_block_valid(struct super_block *sb, struct inode *inode,
+ ext4_fsblk_t start_blk, unsigned int count)
+{
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+ struct ext4_system_blocks *system_blks;
+ 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
+ * when doing a remount which inverse current "[no]block_validity"
+ * mount option.
+ */
+ rcu_read_lock();
+ system_blks = rcu_dereference(sbi->s_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 = 0;
+ if (inode)
+ ret = (entry->ino == inode->i_ino);
+ break;
+ }
+ }
+out_rcu:
+ rcu_read_unlock();
+ return ret;
+}
+
+/*
+ * 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)
+{
+ return ext4_sb_block_valid(inode->i_sb, inode, start_blk, count);
+}
+
+int ext4_check_blockref(const char *function, unsigned int line,
+ struct inode *inode, __le32 *p, unsigned int max)
+{
+ __le32 *bref = p;
+ unsigned int blk;
+
+ if (ext4_has_feature_journal(inode->i_sb) &&
+ (inode->i_ino ==
+ le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum)))
+ return 0;
+
+ while (bref < p+max) {
+ blk = le32_to_cpu(*bref++);
+ if (blk &&
+ unlikely(!ext4_inode_block_valid(inode, blk, 1))) {
+ ext4_error_inode(inode, function, line, blk,
+ "invalid block");
+ return -EFSCORRUPTED;
+ }
+ }
+ return 0;
+}
+