path: root/fs/ext4/orphan.c

/*
 * Ext4 orphan inode handling
 */
#include <linux/fs.h>
#include <linux/quotaops.h>
#include <linux/buffer_head.h>

#include "ext4.h"
#include "ext4_jbd2.h"

static int ext4_orphan_file_add(handle_t *handle, struct inode *inode)
{
	int i, j, start;
	struct ext4_orphan_info *oi = &EXT4_SB(inode->i_sb)->s_orphan_info;
	int ret = 0;
	bool found = false;
	__le32 *bdata;
	int inodes_per_ob = ext4_inodes_per_orphan_block(inode->i_sb);
	int looped = 0;

	/*
	 * Find block with free orphan entry. Use CPU number for a naive hash
	 * for a search start in the orphan file
	 */
	start = raw_smp_processor_id()*13 % oi->of_blocks;
	i = start;
	do {
		if (atomic_dec_if_positive(&oi->of_binfo[i].ob_free_entries)
		    >= 0) {
			found = true;
			break;
		}
		if (++i >= oi->of_blocks)
			i = 0;
	} while (i != start);

	if (!found) {
		/*
		 * For now we don't grow or shrink orphan file. We just use
		 * whatever was allocated at mke2fs time. The additional
		 * credits we would have to reserve for each orphan inode
		 * operation just don't seem worth it.
		 */
		return -ENOSPC;
	}

	ret = ext4_journal_get_write_access(handle, inode->i_sb,
				oi->of_binfo[i].ob_bh, EXT4_JTR_ORPHAN_FILE);
	if (ret) {
		atomic_inc(&oi->of_binfo[i].ob_free_entries);
		return ret;
	}

	bdata = (__le32 *)(oi->of_binfo[i].ob_bh->b_data);
	/* Find empty slot in a block */
	j = 0;
	do {
		if (looped) {
			/*
			 * Did we walk through the block several times without
			 * finding free entry? It is theoretically possible
			 * if entries get constantly allocated and freed or
			 * if the block is corrupted. Avoid indefinite looping
			 * and bail. We'll use orphan list instead.
			 */
			if (looped > 3) {
				atomic_inc(&oi->of_binfo[i].ob_free_entries);
				return -ENOSPC;
			}
			cond_resched();
		}
		while (bdata[j]) {
			if (++j >= inodes_per_ob) {
				j = 0;
				looped++;
			}
		}
	} while (cmpxchg(&bdata[j], (__le32)0, cpu_to_le32(inode->i_ino)) !=
		 (__le32)0);

	EXT4_I(inode)->i_orphan_idx = i * inodes_per_ob + j;
	ext4_set_inode_state(inode, EXT4_STATE_ORPHAN_FILE);

	return ext4_handle_dirty_metadata(handle, NULL, oi->of_binfo[i].ob_bh);
}

/*
 * ext4_orphan_add() links an unlinked or truncated inode into a list of
 * such inodes, starting at the superblock, in case we crash before the
 * file is closed/deleted, or in case the inode truncate spans multiple
 * transactions and the last transaction is not recovered after a crash.
 *
 * At filesystem recovery time, we walk this list deleting unlinked
 * inodes and truncating linked inodes in ext4_orphan_cleanup().
 *
 * Orphan list manipulation functions must be called under i_rwsem unless
 * we are just creating the inode or deleting it.
 */
int ext4_orphan_add(handle_t *handle, struct inode *inode)
{
	struct super_block *sb = inode->i_sb;
	struct ext4_sb_info *sbi = EXT4_SB(sb);
	struct ext4_iloc iloc;
	int err = 0, rc;
	bool dirty = false;

	if (!sbi->s_journal || is_bad_inode(inode))
		return 0;

	WARN_ON_ONCE(!(inode->i_state & (I_NEW | I_FREEING)) &&
		     !inode_is_locked(inode));
	/*
	 * Inode orphaned in orphan file or in orphan list?
	 */
	if (ext4_test_inode_state(inode, EXT4_STATE_ORPHAN_FILE) ||
	    !list_empty(&EXT4_I(inode)->i_orphan))
		return 0;

	/*
	 * Orphan handling is only valid for files with data blocks
	 * being truncated, or files being unlinked. Note that we either
	 * hold i_rwsem, or the inode can not be referenced from outside,
	 * so i_nlink should not be bumped due to race
	 */
	ASSERT((S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
		  S_ISLNK(inode->i_mode)) || inode->i_nlink == 0);

	if (sbi->s_orphan_info.of_blocks) {
		err = ext4_orphan_file_add(handle, inode);
		/*
		 * Fallback to normal orphan list of orphan file is
		 * out of space
		 */
		if (err != -ENOSPC)
			return err;
	}

	BUFFER_TRACE(sbi->s_sbh, "get_write_access");
	err = ext4_journal_get_write_access(handle, sb, sbi->s_sbh,
					    EXT4_JTR_NONE);
	if (err)
		goto out;

	err = ext4_reserve_inode_write(handle, inode, &iloc);
	if (err)
		goto out;

	mutex_lock(&sbi->s_orphan_lock);
	/*
	 * Due to previous errors inode may be already a part of on-disk
	 * orphan list. If so skip on-disk list modification.
	 */
	if (!NEXT_ORPHAN(inode) || NEXT_ORPHAN(inode) >
	    (le32_to_cpu(sbi->s_es->s_inodes_count))) {
		/* Insert this inode at the head of the on-disk orphan list */
		NEXT_ORPHAN(inode) = le32_to_cpu(sbi->s_es->s_last_orphan);
		lock_buffer(sbi->s_sbh);
		sbi->s_es->s_last_orphan = cpu_to_le32(inode->i_ino);
		ext4_superblock_csum_set(sb);
		unlock_buffer(sbi->s_sbh);
		dirty = true;
	}
	list_add(&EXT4_I(inode)->i_orphan, &sbi->s_orphan);
	mutex_unlock(&sbi->s_orphan_lock);

	if (dirty) {
		err = ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
		rc = ext4_mark_iloc_dirty(handle, inode, &iloc);
		if (!err)
			err = rc;
		if (err) {
			/*
			 * We have to remove inode from in-memory list if
			 * addition to on disk orphan list failed. Stray orphan
			 * list entries can cause panics at unmount time.
			 */
			mutex_lock(&sbi->s_orphan_lock);
			list_del_init(&EXT4_I(inode)->i_orphan);
			mutex_unlock(&sbi->s_orphan_lock);
		}
	} else
		brelse(iloc.bh);

	ext4_debug("superblock will point to %lu\n", inode->i_ino);
	ext4_debug("orphan inode %lu will point to %d\n",
			inode->i_ino, NEXT_ORPHAN(inode));
out:
	ext4_std_error(sb, err);
	return err;
}

static int ext4_orphan_file_del(handle_t *handle, struct inode *inode)
{
	struct ext4_orphan_info *oi = &EXT4_SB(inode->i_sb)->s_orphan_info;
	__le32 *bdata;
	int blk, off;
	int inodes_per_ob = ext4_inodes_per_orphan_block(inode->i_sb);
	int ret = 0;

	if (!handle)
		goto out;
	blk = EXT4_I(inode)->i_orphan_idx / inodes_per_ob;
	off = EXT4_I(inode)->i_orphan_idx % inodes_per_ob;
	if (WARN_ON_ONCE(blk >= oi->of_blocks))
		goto out;

	ret = ext4_journal_get_write_access(handle, inode->i_sb,
				oi->of_binfo[blk].ob_bh, EXT4_JTR_ORPHAN_FILE);
	if (ret)
		goto out;

	bdata = (__le32 *)(oi->of_binfo[blk].ob_bh->b_data);
	bdata[off] = 0;
	atomic_inc(&oi->of_binfo[blk].ob_free_entries);
	ret = ext4_handle_dirty_metadata(handle, NULL, oi->of_binfo[blk].ob_bh);
out:
	ext4_clear_inode_state(inode, EXT4_STATE_ORPHAN_FILE);
	INIT_LIST_HEAD(&EXT4_I(inode)->i_orphan);

	return ret;
}

/*
 * ext4_orphan_del() removes an unlinked or truncated inode from the list
 * of such inodes stored on disk, because it is finally being cleaned up.
 */
int ext4_orphan_del(handle_t *handle, struct inode *inode)
{
	struct list_head *prev;
	struct ext4_inode_info *ei = EXT4_I(inode);
	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
	__u32 ino_next;
	struct ext4_iloc iloc;
	int err = 0;

	if (!sbi->s_journal && !(sbi->s_mount_state & EXT4_ORPHAN_FS))
		return 0;

	WARN_ON_ONCE(!(inode->i_state & (I_NEW | I_FREEING)) &&
		     !inode_is_locked(inode));
	if (ext4_test_inode_state(inode, EXT4_STATE_ORPHAN_FILE))
		return ext4_orphan_file_del(handle, inode);

	/* Do this quick check before taking global s_orphan_lock. */
	if (list_empty(&ei->i_orphan))
		return 0;

	if (handle) {
		/* Grab inode buffer early before taking global s_orphan_lock */
		err = ext4_reserve_inode_write(handle, inode, &iloc);
	}

	mutex_lock(&sbi->s_orphan_lock);
	ext4_debug("remove inode %lu from orphan list\n", inode->i_ino);

	prev = ei->i_orphan.prev;
	list_del_init(&ei->i_orphan);

	/* If we're on an error path, we ma