ext4: Add EXT4_IOC_MIGRATE ioctl

The below patch add ioctl for migrating ext3 indirect block mapped inode
to ext4 extent mapped inode.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

4 files changed, 566 insertions, 3 deletions

diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile
index ae6e7e502ac..d5fd80bc0d0 100644
--- a/fs/ext4/Makefile
+++ b/fs/ext4/Makefile
@@ -6,7 +6,7 @@ obj-$(CONFIG_EXT4DEV_FS) += ext4dev.o
 
 ext4dev-y       := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o \
                    ioctl.o namei.o super.o symlink.o hash.o resize.o extents.o \
-                   ext4_jbd2.o
+                   ext4_jbd2.o migrate.o
 
 ext4dev-$(CONFIG_EXT4DEV_FS_XATTR)      += xattr.o xattr_user.o xattr_trusted.o
 ext4dev-$(CONFIG_EXT4DEV_FS_POSIX_ACL)  += acl.o
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 03d1bbb78a2..01eda5c5281 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -61,7 +61,7 @@ static ext4_fsblk_t ext_pblock(struct ext4_extent *ex)
  * idx_pblock:
  * combine low and high parts of a leaf physical block number into ext4_fsblk_t
  */
-static ext4_fsblk_t idx_pblock(struct ext4_extent_idx *ix)
+ext4_fsblk_t idx_pblock(struct ext4_extent_idx *ix)
 {
         ext4_fsblk_t block;
 
@@ -75,7 +75,7 @@ static ext4_fsblk_t idx_pblock(struct ext4_extent_idx *ix)
  * stores a large physical block number into an extent struct,
  * breaking it into parts
  */
-static void ext4_ext_store_pblock(struct ext4_extent *ex, ext4_fsblk_t pb)
+void ext4_ext_store_pblock(struct ext4_extent *ex, ext4_fsblk_t pb)
 {
         ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
         ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 0xffff);
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index c0e5b8cf635..2ed7c37f897 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -254,6 +254,9 @@ flags_err:
                 return err;
         }
 
+        case EXT4_IOC_MIGRATE:
+                return ext4_ext_migrate(inode, filp, cmd, arg);
+
         default:
                 return -ENOTTY;
         }
diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
new file mode 100644
index 00000000000..ec7cb567a7d
--- /dev/null
+++ b/fs/ext4/migrate.c
@@ -0,0 +1,560 @@
+/*
+ * Copyright IBM Corporation, 2007
+ * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
+ *
+ * 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/module.h>
+#include <linux/ext4_jbd2.h>
+#include <linux/ext4_fs_extents.h>
+
+/*
+ * The contiguous blocks details which can be
+ * represented by a single extent
+ */
+struct list_blocks_struct {
+        ext4_lblk_t first_block, last_block;
+        ext4_fsblk_t first_pblock, last_pblock;
+};
+
+static int finish_range(handle_t *handle, struct inode *inode,
+                                struct list_blocks_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);
+                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_insert(inode, path);
+
+        /*
+         * Make sure the credit we accumalated is not really high
+         */
+        if (needed && handle->h_buffer_credits >= EXT4_RESERVE_TRANS_BLOCKS) {
+                retval = ext4_journal_restart(handle, needed);
+                if (retval)
+                        goto err_out;
+        }
+        if (needed) {
+                retval = ext4_journal_extend(handle, needed);
+                if (retval != 0) {
+                        /*
+                         * 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);
+err_out:
+        lb->first_pblock = 0;
+        return retval;
+}
+
+static int update_extent_range(handle_t *handle, struct inode *inode,
+                                ext4_fsblk_t pblock, ext4_lblk_t blk_num,
+                                struct list_blocks_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 == blk_num)) {
+                lb->last_pblock = pblock;
+                lb->last_block = blk_num;
+                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 = blk_num;
+
+        return retval;
+}
+
+static int update_ind_extent_range(handle_t *handle, struct inode *inode,
+                                   ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
+                                   struct list_blocks_struct *lb)
+{
+        struct buffer_head *bh;
+        __le32 *i_data;
+        int i, retval = 0;
+        ext4_lblk_t blk_count = *blk_nump;
+        unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
+
+        if (!pblock) {
+                /* Only update the file block number */
+                *blk_nump += max_entries;
+                return 0;
+        }
+
+        bh = sb_bread(inode->i_sb, pblock);
+        if (!bh)
+                return -EIO;
+
+        i_data = (__le32 *)bh->b_data;
+        for (i = 0; i < max_entries; i++, blk_count++) {
+                if (i_data[i]) {
+                        retval = update_extent_range(handle, inode,
+                                                le32_to_cpu(i_data[i]),
+                                                blk_count, lb);
+                        if (retval)
+                                break;
+                }
+        }
+
+        /* Update the file block number */
+        *blk_nump = blk_count;
+        put_bh(bh);
+        return retval;
+
+}
+
+static int update_dind_extent_range(handle_t *handle, struct inode *inode,
+                                    ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
+                                    struct list_blocks_struct *lb)
+{
+        struct buffer_head *bh;
+        __le32 *i_data;
+        int i, retval = 0;
+        ext4_lblk_t blk_count = *blk_nump;
+        unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
+
+        if (!pblock) {
+                /* Only update the file block number */
+                *blk_nump += max_entries * max_entries;
+                return 0;
+        }
+        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]),
+                                                &blk_count, lb);
+                        if (retval)
+                                break;
+                } else {
+                        /* Only update the file block number */
+                        blk_count += max_entries;
+                }
+        }
+
+        /* Update the file block number */
+        *blk_nump = blk_count;
+        put_bh(bh);
+        return retval;
+
+}
+
+static int update_tind_extent_range(handle_t *handle, struct inode *inode,
+                                     ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
+                                     struct list_blocks_struct *lb)
+{
+        struct buffer_head *bh;
+        __le32 *i_data;
+        int i, retval = 0;
+        ext4_lblk_t blk_count = *blk_nump;
+        unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
+
+        if (!pblock) {
+                /* Only update the file block number */
+                *blk_nump += max_entries * max_entries * max_entries;
+                return 0;
+        }
+        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]),
+                                                &blk_count, lb);
+                        if (retval)
+                                break;
+                } else
+                        /* Only update the file block number */
+                        blk_count += max_entries * max_entries;
+        }
+        /* Update the file block number */
+        *blk_nump = blk_count;
+        put_bh(bh);
+        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])
+                        ext4_free_blocks(handle, inode,
+                                        le32_to_cpu(tmp_idata[i]), 1);
+        }
+        put_bh(bh);
+        ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1);
+        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);
+        ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1);
+        return 0;
+}
+
+static int free_ind_block(handle_t *handle, struct inode *inode)
+{
+        int retval;
+        struct ext4_inode_info *ei = EXT4_I(inode);
+
+        if (ei->i_data[EXT4_IND_BLOCK])
+                ext4_free_blocks(handle, inode,
+                                le32_to_cpu(ei->i_data[EXT4_IND_BLOCK]), 1);
+
+        if (ei->i_data[EXT4_DIND_BLOCK]) {
+                retval = free_dind_blocks(handle, inode,
+                                                ei->i_data[EXT4_DIND_BLOCK]);
+                if (retval)
+                        return retval;
+        }
+
+        if (ei->i_data[EXT4_TIND_BLOCK]) {
+                retval = free_tind_blocks(handle, inode,
+                                                ei->i_data[EXT4_TIND_BLOCK]);
+                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)
+{
+        struct ext4_inode_info *ei = EXT4_I(inode);
+        struct ext4_inode_info *tmp_ei = EXT4_I(tmp_inode);
+
+        retval = free_ind_block(handle, inode);
+        if (retval)
+                goto err_out;
+
+        /*
+         * One credit accounted for writing the
+         * i_data field of the original inode
+         */
+        retval = ext4_journal_extend(handle, 1);
+        if (retval != 0) {
+                retval = ext4_journal_restart(handle, 1);
+                if (retval)
+                        goto err_out;
+        }
+
+        /*
+         * We have the extent map build with the tmp inode.
+         * Now copy the i_data across
+         */
+        ei->i_flags |= EXT4_EXTENTS_FL;
+        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);
+
+        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 = 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);
+        ext4_free_blocks(handle, inode, block, 1);
+        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, struct file *filp,
+                                unsigned int cmd, unsigned long arg)
+{
+        handle_t *handle;
+        int retval = 0, i;
+        __le32 *i_data;
+        ext4_lblk_t blk_count = 0;
+        struct ext4_inode_info *ei;
+        struct inode *tmp_inode = NULL;
+        struct list_blocks_struct lb;
+        unsigned long max_entries;
+
+        if (!test_opt(inode->i_sb, EXTENTS))
+                /*
+                 * if mounted with noextents we don't allow the migrate
+                 */
+                return -EINVAL;
+
+        if ((EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
+                return -EINVAL;
+
+        down_write(&EXT4_I(inode)->i_data_sem);
+        handle = ext4_journal_start(inode,
+                                        EXT4_DATA_TRANS_BLOCKS(inode->i_sb) +
+                                        EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +
+                                        2 * EXT4_QUOTA_INIT_BLOCKS(inode->i_sb)
+                                        + 1);
+        if (IS_ERR(handle)) {
+                retval = PTR_ERR(handle);
+                goto err_out;
+        }
+        tmp_inode = ext4_new_inode(handle,
+                                inode->i_sb->s_root->d_inode,
+                                S_IFREG);
+        if (IS_ERR(tmp_inode)) {
+                retval = -ENOMEM;
+                ext4_journal_stop(handle);
+                tmp_inode = NULL;
+                goto err_out;
+        }
+        i_size_write(tmp_inode, i_size_read(inode));
+        /*
+         * We don't want the inode to be reclaimed
+         * if we got interrupted in between. We have
+         * this tmp inode carrying reference to the
+         * data blocks of the original file. We set
+         * the i_nlink to zero at the last stage after
+         * switching the original file to extent format
+         */
+        tmp_inode->i_nlink = 1;
+
+        ext4_ext_tree_init(handle, tmp_inode);
+        ext4_orphan_add(handle, tmp_inode);
+        ext4_journal_stop(handle);
+
+        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;
+
+        /*
+         * start with one credit accounted for
+         * superblock modification.
+         *
+         * For the tmp_inode we already have commited the
+         * trascation that created the inode. Later as and
+         * when we add extents we extent the journal
+         */
+        handle = ext4_journal_start(inode, 1);
+        for (i = 0; i < EXT4_NDIR_BLOCKS; i++, blk_count++) {
+                if (i_data[i]) {
+                        retval = update_extent_range(handle, tmp_inode,
+                                                le32_to_cpu(i_data[i]),
+                                                blk_count, &lb);
+                        if (retval)
+                                goto err_out;
+                }
+        }
+        if (i_data[EXT4_IND_BLOCK]) {
+                retval = update_ind_extent_range(handle, tmp_inode,
+                                        le32_to_cpu(i_data[EXT4_IND_BLOCK]),
+                                        &blk_count, &lb);
+                        if (retval)
+                                goto err_out;
+        } else
+                blk_count +=  max_entries;
+        if (i_data[EXT4_DIND_BLOCK]) {
+                retval = update_dind_extent_range(handle, tmp_inode,
+                                        le32_to_cpu(i_data[EXT4_DIND_BLOCK]),
+                                        &blk_count, &lb);
+                        if (retval)
+                                goto err_out;
+        } else
+                blk_count += 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]),
+                                        &blk_count, &lb);
+                        if (retval)
+                                goto err_out;
+        }
+        /*
+         * Build the last extent
+         */
+        retval = finish_range(handle, tmp_inode, &lb);
+err_out:
+        /*
+         * We are either freeing extent information or indirect
+         * blocks. During this we touch superblock, group descriptor
+         * and block bitmap. Later we mark the tmp_inode dirty
+         * via ext4_ext_tree_init. So allocate a credit of 4
+         * We may update quota (user and group).
+         *
+         * FIXME!! we may be touching bitmaps in different block groups.
+         */
+        if (ext4_journal_extend(handle,
+                        4 + 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb)) != 0)
+                ext4_journal_restart(handle,
+                                4 + 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb));
+        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, retval);
+
+        /*
+         * 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);
+
+        /*
+         * Set the i_nlink to zero so that
+         * generic_drop_inode really deletes the
+         * inode
+         */
+        tmp_inode->i_nlink = 0;
+
+        ext4_journal_stop(handle);
+
+        up_write(&EXT4_I(inode)->i_data_sem);
+
+        if (tmp_inode)
+                iput(tmp_inode);
+
+        return retval;
+}