migrate.c

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/*
 * Copyright IBM Corporation, 2007
 * Author Aneesh Kumar K.V <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 */

#include <linux/slab.h>
#include "ext4_jbd2.h"

/*
 * The contiguous blocks details which can be
 * represented by a single extent
 */
struct migrate_struct {
    ext4_lblk_t first_block, last_block, curr_block;
    ext4_fsblk_t first_pblock, last_pblock;
};

static int finish_range(handle_t *handle, struct inode *inode,
                struct migrate_struct *lb)

{
    int retval = 0, needed;
    struct ext4_extent newext;
    struct ext4_ext_path *path;
    if (lb->first_pblock == 0)
        return 0;

    /* Add the extent to temp inode*/
    newext.ee_block = cpu_to_le32(lb->first_block);
    newext.ee_len   = cpu_to_le16(lb->last_block - lb->first_block + 1);
    ext4_ext_store_pblock(&newext, lb->first_pblock);
    path = ext4_ext_find_extent(inode, lb->first_block, NULL);

    if (IS_ERR(path)) {
        retval = PTR_ERR(path);
        path = NULL;
        goto err_out;
    }

    /*
     * Calculate the credit needed to inserting this extent
     * Since we are doing this in loop we may accumalate extra
     * credit. But below we try to not accumalate too much
     * of them by restarting the journal.
     */
    needed = ext4_ext_calc_credits_for_single_extent(inode,
            lb->last_block - lb->first_block + 1, path);

    /*
     * Make sure the credit we accumalated is not really high
     */
    if (needed && ext4_handle_has_enough_credits(handle,
                        EXT4_RESERVE_TRANS_BLOCKS)) {
        retval = ext4_journal_restart(handle, needed);
        if (retval)
            goto err_out;
    } else if (needed) {
        retval = ext4_journal_extend(handle, needed);
        if (retval) {
            /*
             * IF not able to extend the journal restart the journal
             */
            retval = ext4_journal_restart(handle, needed);
            if (retval)
                goto err_out;
        }
    }
    retval = ext4_ext_insert_extent(handle, inode, path, &newext, 0);
err_out:
    if (path) {
        ext4_ext_drop_refs(path);
        kfree(path);
    }
    lb->first_pblock = 0;
    return retval;
}

static int update_extent_range(handle_t *handle, struct inode *inode,
                   ext4_fsblk_t pblock, struct migrate_struct *lb)
{
    int retval;
    /*
     * See if we can add on to the existing range (if it exists)
     */
    if (lb->first_pblock &&
        (lb->last_pblock+1 == pblock) &&
        (lb->last_block+1 == lb->curr_block)) {
        lb->last_pblock = pblock;
        lb->last_block = lb->curr_block;
        lb->curr_block++;
        return 0;
    }
    /*
     * Start a new range.
     */
    retval = finish_range(handle, inode, lb);
    lb->first_pblock = lb->last_pblock = pblock;
    lb->first_block = lb->last_block = lb->curr_block;
    lb->curr_block++;
    return retval;
}

static int update_ind_extent_range(handle_t *handle, struct inode *inode,
                   ext4_fsblk_t pblock,
                   struct migrate_struct *lb)
{
    struct buffer_head *bh;
    __le32 *i_data;
    int i, retval = 0;
    unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

    bh = sb_bread(inode->i_sb, pblock);
    if (!bh)
        return -EIO;

    i_data = (__le32 *)bh->b_data;
    for (i = 0; i < max_entries; i++) {
        if (i_data[i]) {
            retval = update_extent_range(handle, inode,
                        le32_to_cpu(i_data[i]), lb);
            if (retval)
                break;
        } else {
            lb->curr_block++;
        }
    }
    put_bh(bh);
    return retval;

}

static int update_dind_extent_range(handle_t *handle, struct inode *inode,
                    ext4_fsblk_t pblock,
                    struct migrate_struct *lb)
{
    struct buffer_head *bh;
    __le32 *i_data;
    int i, retval = 0;
    unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

    bh = sb_bread(inode->i_sb, pblock);
    if (!bh)
        return -EIO;

    i_data = (__le32 *)bh->b_data;
    for (i = 0; i < max_entries; i++) {
        if (i_data[i]) {
            retval = update_ind_extent_range(handle, inode,
                        le32_to_cpu(i_data[i]), lb);
            if (retval)
                break;
        } else {
            /* Only update the file block number */
            lb->curr_block += max_entries;
        }
    }
    put_bh(bh);
    return retval;

}

static int update_tind_extent_range(handle_t *handle, struct inode *inode,
                    ext4_fsblk_t pblock,
                    struct migrate_struct *lb)
{
    struct buffer_head *bh;
    __le32 *i_data;
    int i, retval = 0;
    unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

    bh = sb_bread(inode->i_sb, pblock);
    if (!bh)
        return -EIO;

    i_data = (__le32 *)bh->b_data;
    for (i = 0; i < max_entries; i++) {
        if (i_data[i]) {
            retval = update_dind_extent_range(handle, inode,
                        le32_to_cpu(i_data[i]), lb);
            if (retval)
                break;
        } else {
            /* Only update the file block number */
            lb->curr_block += max_entries * max_entries;
        }
    }
    put_bh(bh);
    return retval;

}

static int extend_credit_for_blkdel(handle_t *handle, struct inode *inode)
{
    int retval = 0, needed;

    if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
        return 0;
    /*
     * We are freeing a blocks. During this we touch
     * superblock, group descriptor and block bitmap.
     * So allocate a credit of 3. We may update
     * quota (user and group).
     */
    needed = 3 + EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb);

    if (ext4_journal_extend(handle, needed) != 0)
        retval = ext4_journal_restart(handle, needed);

    return retval;
}

static int free_dind_blocks(handle_t *handle,
                struct inode *inode, __le32 i_data)
{
    int i;
    __le32 *tmp_idata;
    struct buffer_head *bh;
    unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

    bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
    if (!bh)
        return -EIO;

    tmp_idata = (__le32 *)bh->b_data;
    for (i = 0; i < max_entries; i++) {
        if (tmp_idata[i]) {
            extend_credit_for_blkdel(handle, inode);
            ext4_free_blocks(handle, inode, NULL,
                     le32_to_cpu(tmp_idata[i]), 1,
                     EXT4_FREE_BLOCKS_METADATA |
                     EXT4_FREE_BLOCKS_FORGET);
        }
    }
    put_bh(bh);
    extend_credit_for_blkdel(handle, inode);
    ext4_free_blocks(handle, inode, NULL, le32_to_cpu(i_data), 1,
             EXT4_FREE_BLOCKS_METADATA |
             EXT4_FREE_BLOCKS_FORGET);
    return 0;
}

static int free_tind_blocks(handle_t *handle,
                struct inode *inode, __le32 i_data)
{
    int i, retval = 0;
    __le32 *tmp_idata;
    struct buffer_head *bh;
    unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

    bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
    if (!bh)
        return -EIO;

    tmp_idata = (__le32 *)bh->b_data;
    for (i = 0; i < max_entries; i++) {
        if (tmp_idata[i]) {
            retval = free_dind_blocks(handle,
                    inode, tmp_idata[i]);
            if (retval) {
                put_bh(bh);
                return retval;
            }
        }
    }
    put_bh(bh);
    extend_credit_for_blkdel(handle, inode);
    ext4_free_blocks(handle, inode, NULL, le32_to_cpu(i_data), 1,
             EXT4_FREE_BLOCKS_METADATA |
             EXT4_FREE_BLOCKS_FORGET);
    return 0;
}

static int free_ind_block(handle_t *handle, struct inode *inode, __le32 *i_data)
{
    int retval;

    /* ei->i_data[EXT4_IND_BLOCK] */
    if (i_data[0]) {
        extend_credit_for_blkdel(handle, inode);
        ext4_free_blocks(handle, inode, NULL,
                le32_to_cpu(i_data[0]), 1,
                 EXT4_FREE_BLOCKS_METADATA |
                 EXT4_FREE_BLOCKS_FORGET);
    }

    /* ei->i_data[EXT4_DIND_BLOCK] */
    if (i_data[1]) {
        retval = free_dind_blocks(handle, inode, i_data[1]);
        if (retval)
            return retval;
    }

    /* ei->i_data[EXT4_TIND_BLOCK] */
    if (i_data[2]) {
        retval = free_tind_blocks(handle, inode, i_data[2]);
        if (retval)
            return retval;
    }
    return 0;
}

static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
                        struct inode *tmp_inode)
{
    int retval;
    __le32  i_data[3];
    struct ext4_inode_info *ei = EXT4_I(inode);
    struct ext4_inode_info *tmp_ei = EXT4_I(tmp_inode);

    /*
     * One credit accounted for writing the
     * i_data field of the original inode
     */
    retval = ext4_journal_extend(handle, 1);
    if (retval) {
        retval = ext4_journal_restart(handle, 1);
        if (retval)
            goto err_out;
    }

    i_data[0] = ei->i_data[EXT4_IND_BLOCK];
    i_data[1] = ei->i_data[EXT4_DIND_BLOCK];
    i_data[2] = ei->i_data[EXT4_TIND_BLOCK];

    down_write(&EXT4_I(inode)->i_data_sem);
    /*
     * if EXT4_STATE_EXT_MIGRATE is cleared a block allocation
     * happened after we started the migrate. We need to
     * fail the migrate
     */
    if (!ext4_test_inode_state(inode, EXT4_STATE_EXT_MIGRATE)) {
        retval = -EAGAIN;
        up_write(&EXT4_I(inode)->i_data_sem);
        goto err_out;
    } else
        ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
    /*
     * We have the extent map build with the tmp inode.
     * Now copy the i_data across
     */
    ext4_set_inode_flag(inode, EXT4_INODE_EXTENTS);
    memcpy(ei->i_data, tmp_ei->i_data, sizeof(ei->i_data));

    /*
     * Update i_blocks with the new blocks that got
     * allocated while adding extents for extent index
     * blocks.
     *
     * While converting to extents we need not
     * update the orignal inode i_blocks for extent blocks
     * via quota APIs. The quota update happened via tmp_inode already.
     */
    spin_lock(&inode->i_lock);
    inode->i_blocks += tmp_inode->i_blocks;
    spin_unlock(&inode->i_lock);
    up_write(&EXT4_I(inode)->i_data_sem);

    /*
     * We mark the inode dirty after, because we decrement the
     * i_blocks when freeing the indirect meta-data blocks
     */
    retval = free_ind_block(handle, inode, i_data);
    ext4_mark_inode_dirty(handle, inode);

err_out:
    return retval;
}

static int free_ext_idx(handle_t *handle, struct inode *inode,
                    struct ext4_extent_idx *ix)
{
    int i, retval = 0;
    ext4_fsblk_t block;
    struct buffer_head *bh;
    struct ext4_extent_header *eh;

    block = ext4_idx_pblock(ix);
    bh = sb_bread(inode->i_sb, block);
    if (!bh)
        return -EIO;

    eh = (struct ext4_extent_header *)bh->b_data;
    if (eh->eh_depth != 0) {
        ix = EXT_FIRST_INDEX(eh);
        for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
            retval = free_ext_idx(handle, inode, ix);
            if (retval)
                break;
        }
    }
    put_bh(bh);
    extend_credit_for_blkdel(handle, inode);
    ext4_free_blocks(handle, inode, NULL, block, 1,
             EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
    return retval;
}

/*
 * Free the extent meta data blocks only
 */
static int free_ext_block(handle_t *handle, struct inode *inode)
{
    int i, retval = 0;
    struct ext4_inode_info *ei = EXT4_I(inode);
    struct ext4_extent_header *eh = (struct ext4_extent_header *)ei->i_data;
    struct ext4_extent_idx *ix;
    if (eh->eh_depth == 0)
        /*
         * No extra blocks allocated for extent meta data
         */
        return 0;
    ix = EXT_FIRST_INDEX(eh);
    for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
        retval = free_ext_idx(handle, inode, ix);
        if (retval)
            return retval;
    }
    return retval;

}

int ext4_ext_migrate(struct inode *inode)
{
    handle_t *handle;
    int retval = 0, i;
    __le32 *i_data;
    struct ext4_inode_info *ei;
    struct inode *tmp_inode = NULL;
    struct migrate_struct lb;
    unsigned long max_entries;
    __u32 goal;
    uid_t owner[2];

    /*
     * If the filesystem does not support extents, or the inode
     * already is extent-based, error out.
     */
    if (!EXT4_HAS_INCOMPAT_FEATURE(inode->i_sb,
                       EXT4_FEATURE_INCOMPAT_EXTENTS) ||
        (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
        return -EINVAL;

    if (S_ISLNK(inode->i_mode) && inode->i_blocks == 0)
        /*
         * don't migrate fast symlink
         */
        return retval;

    handle = ext4_journal_start(inode,
                    EXT4_DATA_TRANS_BLOCKS(inode->i_sb) +
                    EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +
                    EXT4_MAXQUOTAS_INIT_BLOCKS(inode->i_sb)
                    + 1);
    if (IS_ERR(handle)) {
        retval = PTR_ERR(handle);
        return retval;
    }
    goal = (((inode->i_ino - 1) / EXT4_INODES_PER_GROUP(inode->i_sb)) *
        EXT4_INODES_PER_GROUP(inode->i_sb)) + 1;
    owner[0] = i_uid_read(inode);
    owner[1] = i_gid_read(inode);
    tmp_inode = ext4_new_inode(handle, inode->i_sb->s_root->d_inode,
                   S_IFREG, NULL, goal, owner);
    if (IS_ERR(tmp_inode)) {
        retval = PTR_ERR(tmp_inode);
        ext4_journal_stop(handle);
        return retval;
    }
    i_size_write(tmp_inode, i_size_read(inode));
    /*
     * Set the i_nlink to zero so it will be deleted later
     * when we drop inode reference.
     */
    clear_nlink(tmp_inode);

    ext4_ext_tree_init(handle, tmp_inode);
    ext4_orphan_add(handle, tmp_inode);
    ext4_journal_stop(handle);

    /*
     * start with one credit accounted for
     * superblock modification.
     *
     * For the tmp_inode we already have committed the
     * trascation that created the inode. Later as and
     * when we add extents we extent the journal
     */
    /*
     * Even though we take i_mutex we can still cause block
     * allocation via mmap write to holes. If we have allocated
     * new blocks we fail migrate.  New block allocation will
     * clear EXT4_STATE_EXT_MIGRATE flag.  The flag is updated
     * with i_data_sem held to prevent racing with block
     * allocation.
     */
    down_read((&EXT4_I(inode)->i_data_sem));
    ext4_set_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
    up_read((&EXT4_I(inode)->i_data_sem));

    handle = ext4_journal_start(inode, 1);
    if (IS_ERR(handle)) {
        /*
         * It is impossible to update on-disk structures without
         * a handle, so just rollback in-core changes and live other
         * work to orphan_list_cleanup()
         */
        ext4_orphan_del(NULL, tmp_inode);
        retval = PTR_ERR(handle);
        goto out;
    }

    ei = EXT4_I(inode);
    i_data = ei->i_data;
    memset(&lb, 0, sizeof(lb));

    /* 32 bit block address 4 bytes */
    max_entries = inode->i_sb->s_blocksize >> 2;
    for (i = 0; i < EXT4_NDIR_BLOCKS; i++) {
        if (i_data[i]) {
            retval = update_extent_range(handle, tmp_inode,
                        le32_to_cpu(i_data[i]), &lb);
            if (retval)
                goto err_out;
        } else
            lb.curr_block++;
    }
    if (i_data[EXT4_IND_BLOCK]) {
        retval = update_ind_extent_range(handle, tmp_inode,
                le32_to_cpu(i_data[EXT4_IND_BLOCK]), &lb);
            if (retval)
                goto err_out;
    } else
        lb.curr_block += max_entries;
    if (i_data[EXT4_DIND_BLOCK]) {
        retval = update_dind_extent_range(handle, tmp_inode,
                le32_to_cpu(i_data[EXT4_DIND_BLOCK]), &lb);
            if (retval)
                goto err_out;
    } else
        lb.curr_block += max_entries * max_entries;
    if (i_data[EXT4_TIND_BLOCK]) {
        retval = update_tind_extent_range(handle, tmp_inode,
                le32_to_cpu(i_data[EXT4_TIND_BLOCK]), &lb);
            if (retval)
                goto err_out;
    }
    /*
     * Build the last extent
     */
    retval = finish_range(handle, tmp_inode, &lb);
err_out:
    if (retval)
        /*
         * Failure case delete the extent information with the
         * tmp_inode
         */
        free_ext_block(handle, tmp_inode);
    else {
        retval = ext4_ext_swap_inode_data(handle, inode, tmp_inode);
        if (retval)
            /*
             * if we fail to swap inode data free the extent
             * details of the tmp inode
             */
            free_ext_block(handle, tmp_inode);
    }

    /* We mark the tmp_inode dirty via ext4_ext_tree_init. */
    if (ext4_journal_extend(handle, 1) != 0)
        ext4_journal_restart(handle, 1);

    /*
     * Mark the tmp_inode as of size zero
     */
    i_size_write(tmp_inode, 0);

    /*
     * set the  i_blocks count to zero
     * so that the ext4_delete_inode does the
     * right job
     *
     * We don't need to take the i_lock because
     * the inode is not visible to user space.
     */
    tmp_inode->i_blocks = 0;

    /* Reset the extent details */
    ext4_ext_tree_init(handle, tmp_inode);
    ext4_journal_stop(handle);
out:
    unlock_new_inode(tmp_inode);
    iput(tmp_inode);

    return retval;
}