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363 lines
9.3 KiB
363 lines
9.3 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* linux/fs/ext4/block_validity.c |
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* |
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* Copyright (C) 2009 |
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* Theodore Ts'o ([email protected]) |
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* |
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* Track which blocks in the filesystem are metadata blocks that |
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* should never be used as data blocks by files or directories. |
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*/ |
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#include <linux/time.h> |
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#include <linux/fs.h> |
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#include <linux/namei.h> |
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#include <linux/quotaops.h> |
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#include <linux/buffer_head.h> |
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#include <linux/swap.h> |
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#include <linux/pagemap.h> |
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#include <linux/blkdev.h> |
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#include <linux/slab.h> |
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#include "ext4.h" |
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struct ext4_system_zone { |
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struct rb_node node; |
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ext4_fsblk_t start_blk; |
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unsigned int count; |
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u32 ino; |
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}; |
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static struct kmem_cache *ext4_system_zone_cachep; |
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int __init ext4_init_system_zone(void) |
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{ |
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ext4_system_zone_cachep = KMEM_CACHE(ext4_system_zone, 0); |
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if (ext4_system_zone_cachep == NULL) |
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return -ENOMEM; |
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return 0; |
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} |
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void ext4_exit_system_zone(void) |
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{ |
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rcu_barrier(); |
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kmem_cache_destroy(ext4_system_zone_cachep); |
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} |
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static inline int can_merge(struct ext4_system_zone *entry1, |
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struct ext4_system_zone *entry2) |
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{ |
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if ((entry1->start_blk + entry1->count) == entry2->start_blk && |
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entry1->ino == entry2->ino) |
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return 1; |
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return 0; |
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} |
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static void release_system_zone(struct ext4_system_blocks *system_blks) |
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{ |
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struct ext4_system_zone *entry, *n; |
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rbtree_postorder_for_each_entry_safe(entry, n, |
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&system_blks->root, node) |
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kmem_cache_free(ext4_system_zone_cachep, entry); |
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} |
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/* |
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* Mark a range of blocks as belonging to the "system zone" --- that |
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* is, filesystem metadata blocks which should never be used by |
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* inodes. |
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*/ |
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static int add_system_zone(struct ext4_system_blocks *system_blks, |
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ext4_fsblk_t start_blk, |
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unsigned int count, u32 ino) |
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{ |
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struct ext4_system_zone *new_entry, *entry; |
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struct rb_node **n = &system_blks->root.rb_node, *node; |
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struct rb_node *parent = NULL, *new_node = NULL; |
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while (*n) { |
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parent = *n; |
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entry = rb_entry(parent, struct ext4_system_zone, node); |
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if (start_blk < entry->start_blk) |
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n = &(*n)->rb_left; |
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else if (start_blk >= (entry->start_blk + entry->count)) |
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n = &(*n)->rb_right; |
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else /* Unexpected overlap of system zones. */ |
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return -EFSCORRUPTED; |
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} |
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new_entry = kmem_cache_alloc(ext4_system_zone_cachep, |
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GFP_KERNEL); |
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if (!new_entry) |
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return -ENOMEM; |
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new_entry->start_blk = start_blk; |
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new_entry->count = count; |
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new_entry->ino = ino; |
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new_node = &new_entry->node; |
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rb_link_node(new_node, parent, n); |
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rb_insert_color(new_node, &system_blks->root); |
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/* Can we merge to the left? */ |
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node = rb_prev(new_node); |
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if (node) { |
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entry = rb_entry(node, struct ext4_system_zone, node); |
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if (can_merge(entry, new_entry)) { |
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new_entry->start_blk = entry->start_blk; |
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new_entry->count += entry->count; |
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rb_erase(node, &system_blks->root); |
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kmem_cache_free(ext4_system_zone_cachep, entry); |
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} |
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} |
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/* Can we merge to the right? */ |
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node = rb_next(new_node); |
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if (node) { |
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entry = rb_entry(node, struct ext4_system_zone, node); |
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if (can_merge(new_entry, entry)) { |
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new_entry->count += entry->count; |
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rb_erase(node, &system_blks->root); |
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kmem_cache_free(ext4_system_zone_cachep, entry); |
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} |
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} |
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return 0; |
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} |
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static void debug_print_tree(struct ext4_sb_info *sbi) |
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{ |
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struct rb_node *node; |
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struct ext4_system_zone *entry; |
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struct ext4_system_blocks *system_blks; |
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int first = 1; |
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printk(KERN_INFO "System zones: "); |
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rcu_read_lock(); |
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system_blks = rcu_dereference(sbi->s_system_blks); |
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node = rb_first(&system_blks->root); |
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while (node) { |
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entry = rb_entry(node, struct ext4_system_zone, node); |
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printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ", |
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entry->start_blk, entry->start_blk + entry->count - 1); |
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first = 0; |
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node = rb_next(node); |
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} |
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rcu_read_unlock(); |
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printk(KERN_CONT "\n"); |
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} |
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static int ext4_protect_reserved_inode(struct super_block *sb, |
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struct ext4_system_blocks *system_blks, |
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u32 ino) |
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{ |
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struct inode *inode; |
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struct ext4_sb_info *sbi = EXT4_SB(sb); |
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struct ext4_map_blocks map; |
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u32 i = 0, num; |
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int err = 0, n; |
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if ((ino < EXT4_ROOT_INO) || |
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(ino > le32_to_cpu(sbi->s_es->s_inodes_count))) |
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return -EINVAL; |
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inode = ext4_iget(sb, ino, EXT4_IGET_SPECIAL); |
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if (IS_ERR(inode)) |
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return PTR_ERR(inode); |
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num = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits; |
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while (i < num) { |
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cond_resched(); |
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map.m_lblk = i; |
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map.m_len = num - i; |
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n = ext4_map_blocks(NULL, inode, &map, 0); |
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if (n < 0) { |
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err = n; |
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break; |
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} |
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if (n == 0) { |
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i++; |
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} else { |
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err = add_system_zone(system_blks, map.m_pblk, n, ino); |
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if (err < 0) { |
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if (err == -EFSCORRUPTED) { |
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EXT4_ERROR_INODE_ERR(inode, -err, |
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"blocks %llu-%llu from inode overlap system zone", |
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map.m_pblk, |
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map.m_pblk + map.m_len - 1); |
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} |
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break; |
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} |
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i += n; |
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} |
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} |
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iput(inode); |
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return err; |
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} |
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static void ext4_destroy_system_zone(struct rcu_head *rcu) |
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{ |
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struct ext4_system_blocks *system_blks; |
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system_blks = container_of(rcu, struct ext4_system_blocks, rcu); |
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release_system_zone(system_blks); |
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kfree(system_blks); |
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} |
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/* |
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* Build system zone rbtree which is used for block validity checking. |
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* |
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* The update of system_blks pointer in this function is protected by |
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* sb->s_umount semaphore. However we have to be careful as we can be |
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* racing with ext4_inode_block_valid() calls reading system_blks rbtree |
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* protected only by RCU. That's why we first build the rbtree and then |
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* swap it in place. |
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*/ |
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int ext4_setup_system_zone(struct super_block *sb) |
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{ |
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ext4_group_t ngroups = ext4_get_groups_count(sb); |
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struct ext4_sb_info *sbi = EXT4_SB(sb); |
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struct ext4_system_blocks *system_blks; |
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struct ext4_group_desc *gdp; |
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ext4_group_t i; |
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int flex_size = ext4_flex_bg_size(sbi); |
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int ret; |
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system_blks = kzalloc(sizeof(*system_blks), GFP_KERNEL); |
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if (!system_blks) |
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return -ENOMEM; |
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for (i=0; i < ngroups; i++) { |
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cond_resched(); |
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if (ext4_bg_has_super(sb, i) && |
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((i < 5) || ((i % flex_size) == 0))) { |
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ret = add_system_zone(system_blks, |
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ext4_group_first_block_no(sb, i), |
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ext4_bg_num_gdb(sb, i) + 1, 0); |
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if (ret) |
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goto err; |
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} |
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gdp = ext4_get_group_desc(sb, i, NULL); |
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ret = add_system_zone(system_blks, |
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ext4_block_bitmap(sb, gdp), 1, 0); |
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if (ret) |
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goto err; |
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ret = add_system_zone(system_blks, |
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ext4_inode_bitmap(sb, gdp), 1, 0); |
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if (ret) |
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goto err; |
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ret = add_system_zone(system_blks, |
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ext4_inode_table(sb, gdp), |
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sbi->s_itb_per_group, 0); |
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if (ret) |
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goto err; |
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} |
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if (ext4_has_feature_journal(sb) && sbi->s_es->s_journal_inum) { |
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ret = ext4_protect_reserved_inode(sb, system_blks, |
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le32_to_cpu(sbi->s_es->s_journal_inum)); |
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if (ret) |
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goto err; |
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} |
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/* |
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* System blks rbtree complete, announce it once to prevent racing |
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* with ext4_inode_block_valid() accessing the rbtree at the same |
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* time. |
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*/ |
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rcu_assign_pointer(sbi->s_system_blks, system_blks); |
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if (test_opt(sb, DEBUG)) |
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debug_print_tree(sbi); |
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return 0; |
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err: |
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release_system_zone(system_blks); |
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kfree(system_blks); |
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return ret; |
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} |
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/* |
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* Called when the filesystem is unmounted or when remounting it with |
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* noblock_validity specified. |
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* |
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* The update of system_blks pointer in this function is protected by |
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* sb->s_umount semaphore. However we have to be careful as we can be |
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* racing with ext4_inode_block_valid() calls reading system_blks rbtree |
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* protected only by RCU. So we first clear the system_blks pointer and |
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* then free the rbtree only after RCU grace period expires. |
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*/ |
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void ext4_release_system_zone(struct super_block *sb) |
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{ |
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struct ext4_system_blocks *system_blks; |
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system_blks = rcu_dereference_protected(EXT4_SB(sb)->s_system_blks, |
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lockdep_is_held(&sb->s_umount)); |
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rcu_assign_pointer(EXT4_SB(sb)->s_system_blks, NULL); |
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if (system_blks) |
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call_rcu(&system_blks->rcu, ext4_destroy_system_zone); |
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} |
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/* |
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* Returns 1 if the passed-in block region (start_blk, |
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* start_blk+count) is valid; 0 if some part of the block region |
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* overlaps with some other filesystem metadata blocks. |
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*/ |
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int ext4_inode_block_valid(struct inode *inode, ext4_fsblk_t start_blk, |
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unsigned int count) |
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{ |
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struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); |
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struct ext4_system_blocks *system_blks; |
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struct ext4_system_zone *entry; |
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struct rb_node *n; |
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int ret = 1; |
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if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) || |
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(start_blk + count < start_blk) || |
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(start_blk + count > ext4_blocks_count(sbi->s_es))) |
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return 0; |
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/* |
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* Lock the system zone to prevent it being released concurrently |
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* when doing a remount which inverse current "[no]block_validity" |
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* mount option. |
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*/ |
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rcu_read_lock(); |
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system_blks = rcu_dereference(sbi->s_system_blks); |
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if (system_blks == NULL) |
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goto out_rcu; |
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n = system_blks->root.rb_node; |
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while (n) { |
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entry = rb_entry(n, struct ext4_system_zone, node); |
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if (start_blk + count - 1 < entry->start_blk) |
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n = n->rb_left; |
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else if (start_blk >= (entry->start_blk + entry->count)) |
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n = n->rb_right; |
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else { |
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ret = (entry->ino == inode->i_ino); |
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break; |
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} |
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} |
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out_rcu: |
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rcu_read_unlock(); |
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return ret; |
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} |
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int ext4_check_blockref(const char *function, unsigned int line, |
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struct inode *inode, __le32 *p, unsigned int max) |
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{ |
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__le32 *bref = p; |
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unsigned int blk; |
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if (ext4_has_feature_journal(inode->i_sb) && |
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(inode->i_ino == |
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le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum))) |
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return 0; |
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while (bref < p+max) { |
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blk = le32_to_cpu(*bref++); |
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if (blk && |
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unlikely(!ext4_inode_block_valid(inode, blk, 1))) { |
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ext4_error_inode(inode, function, line, blk, |
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"invalid block"); |
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return -EFSCORRUPTED; |
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} |
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} |
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return 0; |
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} |
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