Merge ../scsi-rc-fixes-2.6

1 files changed, 1050 insertions, 0 deletions

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
new file mode 100644
index 000000000000..4fe49c3661b2
--- /dev/null
+++ b/fs/ext4/resize.c
@@ -0,0 +1,1050 @@
+/*
+ *  linux/fs/ext4/resize.c
+ *
+ * Support for resizing an ext4 filesystem while it is mounted.
+ *
+ * Copyright (C) 2001, 2002 Andreas Dilger <adilger@clusterfs.com>
+ *
+ * This could probably be made into a module, because it is not often in use.
+ */
+
+
+#define EXT4FS_DEBUG
+
+#include <linux/sched.h>
+#include <linux/smp_lock.h>
+#include <linux/ext4_jbd2.h>
+
+#include <linux/errno.h>
+#include <linux/slab.h>
+
+
+#define outside(b, first, last) ((b) < (first) || (b) >= (last))
+#define inside(b, first, last)  ((b) >= (first) && (b) < (last))
+
+static int verify_group_input(struct super_block *sb,
+                              struct ext4_new_group_data *input)
+{
+        struct ext4_sb_info *sbi = EXT4_SB(sb);
+        struct ext4_super_block *es = sbi->s_es;
+        ext4_fsblk_t start = ext4_blocks_count(es);
+        ext4_fsblk_t end = start + input->blocks_count;
+        unsigned group = input->group;
+        ext4_fsblk_t itend = input->inode_table + sbi->s_itb_per_group;
+        unsigned overhead = ext4_bg_has_super(sb, group) ?
+                (1 + ext4_bg_num_gdb(sb, group) +
+                 le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
+        ext4_fsblk_t metaend = start + overhead;
+        struct buffer_head *bh = NULL;
+        ext4_grpblk_t free_blocks_count, offset;
+        int err = -EINVAL;
+
+        input->free_blocks_count = free_blocks_count =
+                input->blocks_count - 2 - overhead - sbi->s_itb_per_group;
+
+        if (test_opt(sb, DEBUG))
+                printk(KERN_DEBUG "EXT4-fs: adding %s group %u: %u blocks "
+                       "(%d free, %u reserved)\n",
+                       ext4_bg_has_super(sb, input->group) ? "normal" :
+                       "no-super", input->group, input->blocks_count,
+                       free_blocks_count, input->reserved_blocks);
+
+        ext4_get_group_no_and_offset(sb, start, NULL, &offset);
+        if (group != sbi->s_groups_count)
+                ext4_warning(sb, __FUNCTION__,
+                             "Cannot add at group %u (only %lu groups)",
+                             input->group, sbi->s_groups_count);
+        else if (offset != 0)
+                        ext4_warning(sb, __FUNCTION__, "Last group not full");
+        else if (input->reserved_blocks > input->blocks_count / 5)
+                ext4_warning(sb, __FUNCTION__, "Reserved blocks too high (%u)",
+                             input->reserved_blocks);
+        else if (free_blocks_count < 0)
+                ext4_warning(sb, __FUNCTION__, "Bad blocks count %u",
+                             input->blocks_count);
+        else if (!(bh = sb_bread(sb, end - 1)))
+                ext4_warning(sb, __FUNCTION__,
+                             "Cannot read last block (%llu)",
+                             end - 1);
+        else if (outside(input->block_bitmap, start, end))
+                ext4_warning(sb, __FUNCTION__,
+                             "Block bitmap not in group (block %llu)",
+                             (unsigned long long)input->block_bitmap);
+        else if (outside(input->inode_bitmap, start, end))
+                ext4_warning(sb, __FUNCTION__,
+                             "Inode bitmap not in group (block %llu)",
+                             (unsigned long long)input->inode_bitmap);
+        else if (outside(input->inode_table, start, end) ||
+                 outside(itend - 1, start, end))
+                ext4_warning(sb, __FUNCTION__,
+                             "Inode table not in group (blocks %llu-%llu)",
+                             (unsigned long long)input->inode_table, itend - 1);
+        else if (input->inode_bitmap == input->block_bitmap)
+                ext4_warning(sb, __FUNCTION__,
+                             "Block bitmap same as inode bitmap (%llu)",
+                             (unsigned long long)input->block_bitmap);
+        else if (inside(input->block_bitmap, input->inode_table, itend))
+                ext4_warning(sb, __FUNCTION__,
+                             "Block bitmap (%llu) in inode table (%llu-%llu)",
+                             (unsigned long long)input->block_bitmap,
+                             (unsigned long long)input->inode_table, itend - 1);
+        else if (inside(input->inode_bitmap, input->inode_table, itend))
+                ext4_warning(sb, __FUNCTION__,
+                             "Inode bitmap (%llu) in inode table (%llu-%llu)",
+                             (unsigned long long)input->inode_bitmap,
+                             (unsigned long long)input->inode_table, itend - 1);
+        else if (inside(input->block_bitmap, start, metaend))
+                ext4_warning(sb, __FUNCTION__,
+                             "Block bitmap (%llu) in GDT table"
+                             " (%llu-%llu)",
+                             (unsigned long long)input->block_bitmap,
+                             start, metaend - 1);
+        else if (inside(input->inode_bitmap, start, metaend))
+                ext4_warning(sb, __FUNCTION__,
+                             "Inode bitmap (%llu) in GDT table"
+                             " (%llu-%llu)",
+                             (unsigned long long)input->inode_bitmap,
+                             start, metaend - 1);
+        else if (inside(input->inode_table, start, metaend) ||
+                 inside(itend - 1, start, metaend))
+                ext4_warning(sb, __FUNCTION__,
+                             "Inode table (%llu-%llu) overlaps"
+                             "GDT table (%llu-%llu)",
+                             (unsigned long long)input->inode_table,
+                             itend - 1, start, metaend - 1);
+        else
+                err = 0;
+        brelse(bh);
+
+        return err;
+}
+
+static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
+                                  ext4_fsblk_t blk)
+{
+        struct buffer_head *bh;
+        int err;
+
+        bh = sb_getblk(sb, blk);
+        if (!bh)
+                return ERR_PTR(-EIO);
+        if ((err = ext4_journal_get_write_access(handle, bh))) {
+                brelse(bh);
+                bh = ERR_PTR(err);
+        } else {
+                lock_buffer(bh);
+                memset(bh->b_data, 0, sb->s_blocksize);
+                set_buffer_uptodate(bh);
+                unlock_buffer(bh);
+        }
+
+        return bh;
+}
+
+/*
+ * To avoid calling the atomic setbit hundreds or thousands of times, we only
+ * need to use it within a single byte (to ensure we get endianness right).
+ * We can use memset for the rest of the bitmap as there are no other users.
+ */
+static void mark_bitmap_end(int start_bit, int end_bit, char *bitmap)
+{
+        int i;
+
+        if (start_bit >= end_bit)
+                return;
+
+        ext4_debug("mark end bits +%d through +%d used\n", start_bit, end_bit);
+        for (i = start_bit; i < ((start_bit + 7) & ~7UL); i++)
+                ext4_set_bit(i, bitmap);
+        if (i < end_bit)
+                memset(bitmap + (i >> 3), 0xff, (end_bit - i) >> 3);
+}
+
+/*
+ * Set up the block and inode bitmaps, and the inode table for the new group.
+ * This doesn't need to be part of the main transaction, since we are only
+ * changing blocks outside the actual filesystem.  We still do journaling to
+ * ensure the recovery is correct in case of a failure just after resize.
+ * If any part of this fails, we simply abort the resize.
+ */
+static int setup_new_group_blocks(struct super_block *sb,
+                                  struct ext4_new_group_data *input)
+{
+        struct ext4_sb_info *sbi = EXT4_SB(sb);
+        ext4_fsblk_t start = ext4_group_first_block_no(sb, input->group);
+        int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
+                le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) : 0;
+        unsigned long gdblocks = ext4_bg_num_gdb(sb, input->group);
+        struct buffer_head *bh;
+        handle_t *handle;
+        ext4_fsblk_t block;
+        ext4_grpblk_t bit;
+        int i;
+        int err = 0, err2;
+
+        handle = ext4_journal_start_sb(sb, reserved_gdb + gdblocks +
+                                       2 + sbi->s_itb_per_group);
+        if (IS_ERR(handle))
+                return PTR_ERR(handle);
+
+        lock_super(sb);
+        if (input->group != sbi->s_groups_count) {
+                err = -EBUSY;
+                goto exit_journal;
+        }
+
+        if (IS_ERR(bh = bclean(handle, sb, input->block_bitmap))) {
+                err = PTR_ERR(bh);
+                goto exit_journal;
+        }
+
+        if (ext4_bg_has_super(sb, input->group)) {
+                ext4_debug("mark backup superblock %#04lx (+0)\n", start);
+                ext4_set_bit(0, bh->b_data);
+        }
+
+        /* Copy all of the GDT blocks into the backup in this group */
+        for (i = 0, bit = 1, block = start + 1;
+             i < gdblocks; i++, block++, bit++) {
+                struct buffer_head *gdb;
+
+                ext4_debug("update backup group %#04lx (+%d)\n", block, bit);
+
+                gdb = sb_getblk(sb, block);
+                if (!gdb) {
+                        err = -EIO;
+                        goto exit_bh;
+                }
+                if ((err = ext4_journal_get_write_access(handle, gdb))) {
+                        brelse(gdb);
+                        goto exit_bh;
+                }
+                lock_buffer(bh);
+                memcpy(gdb->b_data, sbi->s_group_desc[i]->b_data, bh->b_size);
+                set_buffer_uptodate(gdb);
+                unlock_buffer(bh);
+                ext4_journal_dirty_metadata(handle, gdb);
+                ext4_set_bit(bit, bh->b_data);
+                brelse(gdb);
+        }
+
+        /* Zero out all of the reserved backup group descriptor table blocks */
+        for (i = 0, bit = gdblocks + 1, block = start + bit;
+             i < reserved_gdb; i++, block++, bit++) {
+                struct buffer_head *gdb;
+
+                ext4_debug("clear reserved block %#04lx (+%d)\n", block, bit);
+
+                if (IS_ERR(gdb = bclean(handle, sb, block))) {
+                        err = PTR_ERR(bh);
+                        goto exit_bh;
+                }
+                ext4_journal_dirty_metadata(handle, gdb);
+                ext4_set_bit(bit, bh->b_data);
+                brelse(gdb);
+        }
+        ext4_debug("mark block bitmap %#04x (+%ld)\n", input->block_bitmap,
+                   input->block_bitmap - start);
+        ext4_set_bit(input->block_bitmap - start, bh->b_data);
+        ext4_debug("mark inode bitmap %#04x (+%ld)\n", input->inode_bitmap,
+                   input->inode_bitmap - start);
+        ext4_set_bit(input->inode_bitmap - start, bh->b_data);
+
+        /* Zero out all of the inode table blocks */
+        for (i = 0, block = input->inode_table, bit = block - start;
+             i < sbi->s_itb_per_group; i++, bit++, block++) {
+                struct buffer_head *it;
+
+                ext4_debug("clear inode block %#04lx (+%d)\n", block, bit);
+                if (IS_ERR(it = bclean(handle, sb, block))) {
+                        err = PTR_ERR(it);
+                        goto exit_bh;
+                }
+                ext4_journal_dirty_metadata(handle, it);
+                brelse(it);
+                ext4_set_bit(bit, bh->b_data);
+        }
+        mark_bitmap_end(input->blocks_count, EXT4_BLOCKS_PER_GROUP(sb),
+                        bh->b_data);
+        ext4_journal_dirty_metadata(handle, bh);
+        brelse(bh);
+
+        /* Mark unused entries in inode bitmap used */
+        ext4_debug("clear inode bitmap %#04x (+%ld)\n",
+                   input->inode_bitmap, input->inode_bitmap - start);
+        if (IS_ERR(bh = bclean(handle, sb, input->inode_bitmap))) {
+                err = PTR_ERR(bh);
+                goto exit_journal;
+        }
+
+        mark_bitmap_end(EXT4_INODES_PER_GROUP(sb), EXT4_BLOCKS_PER_GROUP(sb),
+                        bh->b_data);
+        ext4_journal_dirty_metadata(handle, bh);
+exit_bh:
+        brelse(bh);
+
+exit_journal:
+        unlock_super(sb);
+        if ((err2 = ext4_journal_stop(handle)) && !err)
+                err = err2;
+
+        return err;
+}
+
+
+/*
+ * Iterate through the groups which hold BACKUP superblock/GDT copies in an
+ * ext4 filesystem.  The counters should be initialized to 1, 5, and 7 before
+ * calling this for the first time.  In a sparse filesystem it will be the
+ * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
+ * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
+ */
+static unsigned ext4_list_backups(struct super_block *sb, unsigned *three,
+                                  unsigned *five, unsigned *seven)
+{
+        unsigned *min = three;
+        int mult = 3;
+        unsigned ret;
+
+        if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
+                                        EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
+                ret = *min;
+                *min += 1;
+                return ret;
+        }
+
+        if (*five < *min) {
+                min = five;
+                mult = 5;
+        }
+        if (*seven < *min) {
+                min = seven;
+                mult = 7;
+        }
+
+        ret = *min;
+        *min *= mult;
+
+        return ret;
+}
+
+/*
+ * Check that all of the backup GDT blocks are held in the primary GDT block.
+ * It is assumed that they are stored in group order.  Returns the number of
+ * groups in current filesystem that have BACKUPS, or -ve error code.
+ */
+static int verify_reserved_gdb(struct super_block *sb,
+                               struct buffer_head *primary)
+{
+        const ext4_fsblk_t blk = primary->b_blocknr;
+        const unsigned long end = EXT4_SB(sb)->s_groups_count;
+        unsigned three = 1;
+        unsigned five = 5;
+        unsigned seven = 7;
+        unsigned grp;
+        __le32 *p = (__le32 *)primary->b_data;
+        int gdbackups = 0;
+
+        while ((grp = ext4_list_backups(sb, &three, &five, &seven)) < end) {
+                if (le32_to_cpu(*p++) !=
+                    grp * EXT4_BLOCKS_PER_GROUP(sb) + blk){
+                        ext4_warning(sb, __FUNCTION__,
+                                     "reserved GDT %llu"
+                                     " missing grp %d (%llu)",
+                                     blk, grp,
+                                     grp *
+                                     (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
+                                     blk);
+                        return -EINVAL;
+                }
+                if (++gdbackups > EXT4_ADDR_PER_BLOCK(sb))
+                        return -EFBIG;
+        }
+
+        return gdbackups;
+}
+
+/*
+ * Called when we need to bring a reserved group descriptor table block into
+ * use from the resize inode.  The primary copy of the new GDT block currently
+ * is an indirect block (under the double indirect block in the resize inode).
+ * The new backup GDT blocks will be stored as leaf blocks in this indirect
+ * block, in group order.  Even though we know all the block numbers we need,
+ * we check to ensure that the resize inode has actually reserved these blocks.
+ *
+ * Don't need to update the block bitmaps because the blocks are still in use.
+ *
+ * We get all of the error cases out of the way, so that we are sure to not
+ * fail once we start modifying the data on disk, because JBD has no rollback.
+ */
+static int add_new_gdb(handle_t *handle, struct inode *inode,
+                       struct ext4_new_group_data *input,
+                       struct buffer_head **primary)
+{
+        struct super_block *sb = inode->i_sb;
+        struct ext4_super_block *es = EXT4_SB(sb)->s_es;
+        unsigned long gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
+        ext4_fsblk_t gdblock = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
+        struct buffer_head **o_group_desc, **n_group_desc;
+        struct buffer_head *dind;
+        int gdbackups;
+        struct ext4_iloc iloc;
+        __le32 *data;
+        int err;
+
+        if (test_opt(sb, DEBUG))
+                printk(KERN_DEBUG
+                       "EXT4-fs: ext4_add_new_gdb: adding group block %lu\n",
+                       gdb_num);
+
+        /*
+         * If we are not using the primary superblock/GDT copy don't resize,
+         * because the user tools have no way of handling this.  Probably a
+         * bad time to do it anyways.
+         */
+        if (EXT4_SB(sb)->s_sbh->b_blocknr !=
+            le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) {
+                ext4_warning(sb, __FUNCTION__,
+                        "won't resize using backup superblock at %llu",
+                        (unsigned long long)EXT4_SB(sb)->s_sbh->b_blocknr);
+                return -EPERM;
+        }
+
+        *primary = sb_bread(sb, gdblock);
+        if (!*primary)
+                return -EIO;
+
+        if ((gdbackups = verify_reserved_gdb(sb, *primary)) < 0) {
+                err = gdbackups;
+                goto exit_bh;
+        }
+
+        data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
+        dind = sb_bread(sb, le32_to_cpu(*data));
+        if (!dind) {
+                err = -EIO;
+                goto exit_bh;
+        }
+
+        data = (__le32 *)dind->b_data;
+        if (le32_to_cpu(data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)]) != gdblock) {
+                ext4_warning(sb, __FUNCTION__,
+                             "new group %u GDT block %llu not reserved",
+                             input->group, gdblock);
+                err = -EINVAL;
+                goto exit_dind;
+        }
+
+        if ((err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh)))
+                goto exit_dind;
+
+        if ((err = ext4_journal_get_write_access(handle, *primary)))
+                goto exit_sbh;
+
+        if ((err = ext4_journal_get_write_access(handle, dind)))
+                goto exit_primary;
+
+        /* ext4_reserve_inode_write() gets a reference on the iloc */
+        if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
+                goto exit_dindj;
+
+        n_group_desc = kmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
+                        GFP_KERNEL);
+        if (!n_group_desc) {
+                err = -ENOMEM;
+                ext4_warning (sb, __FUNCTION__,
+                              "not enough memory for %lu groups", gdb_num + 1);
+                goto exit_inode;
+        }
+
+        /*
+         * Finally, we have all of the possible failures behind us...
+         *
+         * Remove new GDT block from inode double-indirect block and clear out
+         * the new GDT block for use (which also "frees" the backup GDT blocks
+         * from the reserved inode).  We don't need to change the bitmaps for
+         * these blocks, because they are marked as in-use from being in the
+         * reserved inode, and will become GDT blocks (primary and backup).
+         */
+        data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)] = 0;
+        ext4_journal_dirty_metadata(handle, dind);
+        brelse(dind);
+        inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >> 9;
+        ext4_mark_iloc_dirty(handle, inode, &iloc);
+        memset((*primary)->b_data, 0, sb->s_blocksize);
+        ext4_journal_dirty_metadata(handle, *primary);
+
+        o_group_desc = EXT4_SB(sb)->s_group_desc;
+        memcpy(n_group_desc, o_group_desc,
+               EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
+        n_group_desc[gdb_num] = *primary;
+        EXT4_SB(sb)->s_group_desc = n_group_desc;
+        EXT4_SB(sb)->s_gdb_count++;
+        kfree(o_group_desc);
+
+        es->s_reserved_gdt_blocks =
+                cpu_to_le16(le16_to_cpu(es->s_reserved_gdt_blocks) - 1);
+        ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh);
+
+        return 0;
+
+exit_inode:
+        //ext4_journal_release_buffer(handle, iloc.bh);
+        brelse(iloc.bh);
+exit_dindj:
+        //ext4_journal_release_buffer(handle, dind);
+exit_primary:
+        //ext4_journal_release_buffer(handle, *primary);
+exit_sbh:
+        //ext4_journal_release_buffer(handle, *primary);
+exit_dind:
+        brelse(dind);
+exit_bh:
+        brelse(*primary);
+
+        ext4_debug("leaving with error %d\n", err);
+        return err;
+}
+
+/*
+ * Called when we are adding a new group which has a backup copy of each of
+ * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
+ * We need to add these reserved backup GDT blocks to the resize inode, so
+ * that they are kept for future resizing and not allocated to files.
+ *
+ * Each reserved backup GDT block will go into a different indirect block.
+ * The indirect blocks are actually the primary reserved GDT blocks,
+ * so we know in advance what their block numbers are.  We only get the
+ * double-indirect block to verify it is pointing to the primary reserved
+ * GDT blocks so we don't overwrite a data block by accident.  The reserved
+ * backup GDT blocks are stored in their reserved primary GDT block.
+ */
+static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
+                              struct ext4_new_group_data *input)
+{
+        struct super_block *sb = inode->i_sb;
+        int reserved_gdb =le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
+        struct buffer_head **primary;
+        struct buffer_head *dind;
+        struct ext4_iloc iloc;
+        ext4_fsblk_t blk;
+        __le32 *data, *end;
+        int gdbackups = 0;
+        int res, i;
+        int err;
+
+        primary = kmalloc(reserved_gdb * sizeof(*primary), GFP_KERNEL);
+        if (!primary)
+                return -ENOMEM;
+
+        data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
+        dind = sb_bread(sb, le32_to_cpu(*data));
+        if (!dind) {
+                err = -EIO;
+                goto exit_free;
+        }
+
+        blk = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + EXT4_SB(sb)->s_gdb_count;
+        data = (__le32 *)dind->b_data + EXT4_SB(sb)->s_gdb_count;
+        end = (__le32 *)dind->b_data + EXT4_ADDR_PER_BLOCK(sb);
+
+        /* Get each reserved primary GDT block and verify it holds backups */
+        for (res = 0; res < reserved_gdb; res++, blk++) {
+                if (le32_to_cpu(*data) != blk) {
+                        ext4_warning(sb, __FUNCTION__,
+                                     "reserved block %llu"
+                                     " not at offset %ld",
+                                     blk,
+                                     (long)(data - (__le32 *)dind->b_data));
+                        err = -EINVAL;
+                        goto exit_bh;
+                }
+                primary[res] = sb_bread(sb, blk);
+                if (!primary[res]) {
+                        err = -EIO;
+                        goto exit_bh;
+                }
+                if ((gdbackups = verify_reserved_gdb(sb, primary[res])) < 0) {
+                        brelse(primary[res]);
+                        err = gdbackups;
+                        goto exit_bh;
+                }
+                if (++data >= end)
+                        data = (__le32 *)dind->b_data;
+        }
+
+        for (i = 0; i < reserved_gdb; i++) {
+                if ((err = ext4_journal_get_write_access(handle, primary[i]))) {
+                        /*
+                        int j;
+                        for (j = 0; j < i; j++)
+                                ext4_journal_release_buffer(handle, primary[j]);
+                         */
+                        goto exit_bh;
+                }
+        }
+
+        if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
+                goto exit_bh;
+
+        /*
+         * Finally we can add each of the reserved backup GDT blocks from
+         * the new group to its reserved primary GDT block.
+         */
+        blk = input->group * EXT4_BLOCKS_PER_GROUP(sb);
+        for (i = 0; i < reserved_gdb; i++) {
+                int err2;
+                data = (__le32 *)primary[i]->b_data;
+                /* printk("reserving backup %lu[%u] = %lu\n",
+                       primary[i]->b_blocknr, gdbackups,
+                       blk + primary[i]->b_blocknr); */
+                data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
+                err2 = ext4_journal_dirty_metadata(handle, primary[i]);
+                if (!err)
+                        err = err2;
+        }
+        inode->i_blocks += reserved_gdb * sb->s_blocksize >> 9;
+        ext4_mark_iloc_dirty(handle, inode, &iloc);
+
+exit_bh:
+        while (--res >= 0)
+                brelse(primary[res]);
+        brelse(dind);
+
+exit_free:
+        kfree(primary);
+
+        return err;
+}
+
+/*
+ * Update the backup copies of the ext4 metadata.  These don't need to be part
+ * of the main resize transaction, because e2fsck will re-write them if there
+ * is a problem (basically only OOM will cause a problem).  However, we
+ * _should_ update the backups if possible, in case the primary gets trashed
+ * for some reason and we need to run e2fsck from a backup superblock.  The
+ * important part is that the new block and inode counts are in the backup
+ * superblocks, and the location of the new group metadata in the GDT backups.
+ *
+ * We do not need lock_super() for this, because these blocks are not
+ * otherwise touched by the filesystem code when it is mounted.  We don't
+ * need to worry about last changing from sbi->s_groups_count, because the
+ * worst that can happen is that we do not copy the full number of backups
+ * at this time.  The resize which changed s_groups_count will backup again.
+ */
+static void update_backups(struct super_block *sb,
+                           int blk_off, char *data, int size)
+{
+        struct ext4_sb_info *sbi = EXT4_SB(sb);
+        const unsigned long last = sbi->s_groups_count;
+        const int bpg = EXT4_BLOCKS_PER_GROUP(sb);
+        unsigned three = 1;
+        unsigned five = 5;
+        unsigned seven = 7;
+        unsigned group;
+        int rest = sb->s_blocksize - size;
+        handle_t *handle;
+        int err = 0, err2;
+
+        handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
+        if (IS_ERR(handle)) {
+                group = 1;
+                err = PTR_ERR(handle);
+                goto exit_err;
+        }
+
+        while ((group = ext4_list_backups(sb, &three, &five, &seven)) < last) {
+                struct buffer_head *bh;
+
+                /* Out of journal space, and can't get more - abort - so sad */
+                if (handle->h_buffer_credits == 0 &&
+                    ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA) &&
+                    (err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
+                        break;
+
+                bh = sb_getblk(sb, group * bpg + blk_off);
+                if (!bh) {
+                        err = -EIO;
+                        break;
+                }
+                ext4_debug("update metadata backup %#04lx\n",
+                          (unsigned long)bh->b_blocknr);
+                if ((err = ext4_journal_get_write_access(handle, bh)))
+                        break;
+                lock_buffer(bh);
+                memcpy(bh->b_data, data, size);
+                if (rest)
+                        memset(bh->b_data + size, 0, rest);
+                set_buffer_uptodate(bh);
+                unlock_buffer(bh);
+                ext4_journal_dirty_metadata(handle, bh);
+                brelse(bh);
+        }
+        if ((err2 = ext4_journal_stop(handle)) && !err)
+                err = err2;
+
+        /*
+         * Ugh! Need to have e2fsck write the backup copies.  It is too
+         * late to revert the resize, we shouldn't fail just because of
+         * the backup copies (they are only needed in case of corruption).
+         *
+         * However, if we got here we have a journal problem too, so we
+         * can't really start a transaction to mark the superblock.
+         * Chicken out and just set the flag on the hope it will be written
+         * to disk, and if not - we will simply wait until next fsck.
+         */
+exit_err:
+        if (err) {
+                ext4_warning(sb, __FUNCTION__,
+                             "can't update backup for group %d (err %d), "
+                             "forcing fsck on next reboot", group, err);
+                sbi->s_mount_state &= ~EXT4_VALID_FS;
+                sbi->s_es->s_state &= cpu_to_le16(~EXT4_VALID_FS);
+                mark_buffer_dirty(sbi->s_sbh);
+        }
+}
+
+/* Add group descriptor data to an existing or new group descriptor block.
+ * Ensure we handle all possible error conditions _before_ we start modifying
+ * the filesystem, because we cannot abort the transaction and not have it
+ * write the data to disk.
+ *
+ * If we are on a GDT block boundary, we need to get the reserved GDT block.
+ * Otherwise, we may need to add backup GDT blocks for a sparse group.
+ *
+ * We only need to hold the superblock lock while we are actually adding
+ * in the new group's counts to the superblock.  Prior to that we have
+ * not really "added" the group at all.  We re-check that we are still
+ * adding in the last group in case things have changed since verifying.
+ */
+int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
+{
+        struct ext4_sb_info *sbi = EXT4_SB(sb);
+        struct ext4_super_block *es = sbi->s_es;
+        int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
+                le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
+        struct buffer_head *primary = NULL;
+        struct ext4_group_desc *gdp;
+        struct inode *inode = NULL;
+        handle_t *handle;
+        int gdb_off, gdb_num;
+        int err, err2;
+
+        gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
+        gdb_off = input->group % EXT4_DESC_PER_BLOCK(sb);
+
+        if (gdb_off == 0 && !EXT4_HAS_RO_COMPAT_FEATURE(sb,
+                                        EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
+                ext4_warning(sb, __FUNCTION__,
+                             "Can't resize non-sparse filesystem further");
+                return -EPERM;
+        }
+
+        if (ext4_blocks_count(es) + input->blocks_count <
+            ext4_blocks_count(es)) {
+                ext4_warning(sb, __FUNCTION__, "blocks_count overflow\n");
+                return -EINVAL;
+        }
+
+        if (le32_to_cpu(es->s_inodes_count) + EXT4_INODES_PER_GROUP(sb) <
+            le32_to_cpu(es->s_inodes_count)) {
+                ext4_warning(sb, __FUNCTION__, "inodes_count overflow\n");
+                return -EINVAL;
+        }
+
+        if (reserved_gdb || gdb_off == 0) {
+                if (!EXT4_HAS_COMPAT_FEATURE(sb,
+                                             EXT4_FEATURE_COMPAT_RESIZE_INODE)){
+                        ext4_warning(sb, __FUNCTION__,
+                                     "No reserved GDT blocks, can't resize");
+                        return -EPERM;
+                }
+                inode = iget(sb, EXT4_RESIZE_INO);
+                if (!inode || is_bad_inode(inode)) {
+                        ext4_warning(sb, __FUNCTION__,
+                                     "Error opening resize inode");
+                        iput(inode);
+                        return -ENOENT;
+                }
+        }
+
+        if ((err = verify_group_input(sb, input)))
+                goto exit_put;
+
+        if ((err = setup_new_group_blocks(sb, input)))
+                goto exit_put;
+
+        /*
+         * We will always be modifying at least the superblock and a GDT
+         * block.  If we are adding a group past the last current GDT block,
+         * we will also modify the inode and the dindirect block.  If we
+         * are adding a group with superblock/GDT backups  we will also
+         * modify each of the reserved GDT dindirect blocks.
+         */
+        handle = ext4_journal_start_sb(sb,
+                                       ext4_bg_has_super(sb, input->group) ?
+                                       3 + reserved_gdb : 4);
+        if (IS_ERR(handle)) {
+                err = PTR_ERR(handle);
+                goto exit_put;
+        }
+
+        lock_super(sb);
+        if (input->group != sbi->s_groups_count) {
+                ext4_warning(sb, __FUNCTION__,
+                             "multiple resizers run on filesystem!");
+                err = -EBUSY;
+                goto exit_journal;
+        }
+
+        if ((err = ext4_journal_get_write_access(handle, sbi->s_sbh)))
+                goto exit_journal;
+
+        /*
+         * We will only either add reserved group blocks to a backup group
+         * or remove reserved blocks for the first group in a new group block.
+         * Doing both would be mean more complex code, and sane people don't
+         * use non-sparse filesystems anymore.  This is already checked above.
+         */
+        if (gdb_off) {
+                primary = sbi->s_group_desc[gdb_num];
+                if ((err = ext4_journal_get_write_access(handle, primary)))
+                        goto exit_journal;
+
+                if (reserved_gdb && ext4_bg_num_gdb(sb, input->group) &&
+                    (err = reserve_backup_gdb(handle, inode, input)))
+                        goto exit_journal;
+        } else if ((err = add_new_gdb(handle, inode, input, &primary)))
+                goto exit_journal;
+
+        /*
+         * OK, now we've set up the new group.  Time to make it active.
+         *
+         * Current kernels don't lock all allocations via lock_super(),
+         * so we have to be safe wrt. concurrent accesses the group
+         * data.  So we need to be careful to set all of the relevant
+         * group descriptor data etc. *before* we enable the group.
+         *
+         * The key field here is sbi->s_groups_count: as long as
+         * that retains its old value, nobody is going to access the new
+         * group.
+         *
+         * So first we update all the descriptor metadata for the new
+         * group; then we update the total disk blocks count; then we
+         * update the groups count to enable the group; then finally we
+         * update the free space counts so that the system can start
+         * using the new disk blocks.
+         */
+
+        /* Update group descriptor block for new group */
+        gdp = (struct ext4_group_desc *)primary->b_data + gdb_off;
+
+        ext4_block_bitmap_set(sb, gdp, input->block_bitmap); /* LV FIXME */
+        ext4_inode_bitmap_set(sb, gdp, input->inode_bitmap); /* LV FIXME */
+        ext4_inode_table_set(sb, gdp, input->inode_table); /* LV FIXME */
+        gdp->bg_free_blocks_count = cpu_to_le16(input->free_blocks_count);
+        gdp->bg_free_inodes_count = cpu_to_le16(EXT4_INODES_PER_GROUP(sb));
+
+        /*
+         * Make the new blocks and inodes valid next.  We do this before
+         * increasing the group count so that once the group is enabled,
+         * all of its blocks and inodes are already valid.
+         *
+         * We always allocate group-by-group, then block-by-block or
+         * inode-by-inode within a group, so enabling these
+         * blocks/inodes before the group is live won't actually let us
+         * allocate the new space yet.
+         */
+        ext4_blocks_count_set(es, ext4_blocks_count(es) +
+                input->blocks_count);
+        es->s_inodes_count = cpu_to_le32(le32_to_cpu(es->s_inodes_count) +
+                EXT4_INODES_PER_GROUP(sb));
+
+        /*
+         * We need to protect s_groups_count against other CPUs seeing
+         * inconsistent state in the superblock.
+         *
+         * The precise rules we use are:
+         *
+         * * Writers of s_groups_count *must* hold lock_super
+         * AND
+         * * Writers must perform a smp_wmb() after updating all dependent
+         *   data and before modifying the groups count
+         *
+         * * Readers must hold lock_super() over the access
+         * OR
+         * * Readers must perform an smp_rmb() after reading the groups count
+         *   and before reading any dependent data.
+         *
+         * NB. These rules can be relaxed when checking the group count
+         * while freeing data, as we can only allocate from a block
+         * group after serialising against the group count, and we can
+         * only then free after serialising in turn against that
+         * allocation.
+         */
+        smp_wmb();
+
+        /* Update the global fs size fields */
+        sbi->s_groups_count++;
+
+        ext4_journal_dirty_metadata(handle, primary);
+
+        /* Update the reserved block counts only once the new group is
+         * active. */
+        ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) +
+                input->reserved_blocks);
+
+        /* Update the free space counts */
+        percpu_counter_mod(&sbi->s_freeblocks_counter,
+                           input->free_blocks_count);
+        percpu_counter_mod(&sbi->s_freeinodes_counter,
+                           EXT4_INODES_PER_GROUP(sb));
+
+        ext4_journal_dirty_metadata(handle, sbi->s_sbh);
+        sb->s_dirt = 1;
+
+exit_journal:
+        unlock_super(sb);
+        if ((err2 = ext4_journal_stop(handle)) && !err)
+                err = err2;
+        if (!err) {
+                update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
+                               sizeof(struct ext4_super_block));
+                update_backups(sb, primary->b_blocknr, primary->b_data,
+                               primary->b_size);
+        }
+exit_put:
+        iput(inode);
+        return err;
+} /* ext4_group_add */
+
+/* Extend the filesystem to the new number of blocks specified.  This entry
+ * point is only used to extend the current filesystem to the end of the last
+ * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
+ * for emergencies (because it has no dependencies on reserved blocks).
+ *
+ * If we _really_ wanted, we could use default values to call ext4_group_add()
+ * allow the "remount" trick to work for arbitrary resizing, assuming enough
+ * GDT blocks are reserved to grow to the desired size.
+ */
+int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
+                      ext4_fsblk_t n_blocks_count)
+{
+        ext4_fsblk_t o_blocks_count;
+        unsigned long o_groups_count;
+        ext4_grpblk_t last;
+        ext4_grpblk_t add;
+        struct buffer_head * bh;
+        handle_t *handle;
+        int err;
+        unsigned long freed_blocks;
+
+        /* We don't need to worry about locking wrt other resizers just
+         * yet: we're going to revalidate es->s_blocks_count after
+         * taking lock_super() below. */
+        o_blocks_count = ext4_blocks_count(es);
+        o_groups_count = EXT4_SB(sb)->s_groups_count;
+
+        if (test_opt(sb, DEBUG))
+                printk(KERN_DEBUG "EXT4-fs: extending last group from %llu uto %llu blocks\n",
+                       o_blocks_count, n_blocks_count);
+
+        if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
+                return 0;
+
+        if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
+                printk(KERN_ERR "EXT4-fs: filesystem on %s:"
+                        " too large to resize to %llu blocks safely\n",
+                        sb->s_id, n_blocks_count);
+                if (sizeof(sector_t) < 8)
+                        ext4_warning(sb, __FUNCTION__,
+                        "CONFIG_LBD not enabled\n");
+                return -EINVAL;
+        }
+
+        if (n_blocks_count < o_blocks_count) {
+                ext4_warning(sb, __FUNCTION__,
+                             "can't shrink FS - resize aborted");
+                return -EBUSY;
+        }
+
+        /* Handle the remaining blocks in the last group only. */
+        ext4_get_group_no_and_offset(sb, o_blocks_count, NULL, &last);
+
+        if (last == 0) {
+                ext4_warning(sb, __FUNCTION__,
+                             "need to use ext2online to resize further");
+                return -EPERM;
+        }
+
+        add = EXT4_BLOCKS_PER_GROUP(sb) - last;
+
+        if (o_blocks_count + add < o_blocks_count) {
+                ext4_warning(sb, __FUNCTION__, "blocks_count overflow");
+                return -EINVAL;
+        }
+
+        if (o_blocks_count + add > n_blocks_count)
+                add = n_blocks_count - o_blocks_count;
+
+        if (o_blocks_count + add < n_blocks_count)
+                ext4_warning(sb, __FUNCTION__,
+                             "will only finish group (%llu"
+                             " blocks, %u new)",
+                             o_blocks_count + add, add);
+
+        /* See if the device is actually as big as what was requested */
+        bh = sb_bread(sb, o_blocks_count + add -1);
+        if (!bh) {
+                ext4_warning(sb, __FUNCTION__,
+                             "can't read last block, resize aborted");
+                return -ENOSPC;
+        }
+        brelse(bh);
+
+        /* We will update the superblock, one block bitmap, and
+         * one group descriptor via ext4_free_blocks().
+         */
+        handle = ext4_journal_start_sb(sb, 3);
+        if (IS_ERR(handle)) {
+                err = PTR_ERR(handle);
+                ext4_warning(sb, __FUNCTION__, "error %d on journal start",err);
+                goto exit_put;
+        }
+
+        lock_super(sb);
+        if (o_blocks_count != ext4_blocks_count(es)) {
+                ext4_warning(sb, __FUNCTION__,
+                             "multiple resizers run on filesystem!");
+                unlock_super(sb);
+                err = -EBUSY;
+                goto exit_put;
+        }
+
+        if ((err = ext4_journal_get_write_access(handle,
+                                                 EXT4_SB(sb)->s_sbh))) {
+                ext4_warning(sb, __FUNCTION__,
+                             "error %d on journal write access", err);
+                unlock_super(sb);
+                ext4_journal_stop(handle);
+                goto exit_put;
+        }
+        ext4_blocks_count_set(es, o_blocks_count + add);
+        ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh);
+        sb->s_dirt = 1;
+        unlock_super(sb);
+        ext4_debug("freeing blocks %lu through %llu\n", o_blocks_count,
+                   o_blocks_count + add);
+        ext4_free_blocks_sb(handle, sb, o_blocks_count, add, &freed_blocks);
+        ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
+                   o_blocks_count + add);
+        if ((err = ext4_journal_stop(handle)))
+                goto exit_put;
+        if (test_opt(sb, DEBUG))
+                printk(KERN_DEBUG "EXT4-fs: extended group to %llu blocks\n",
+                       ext4_blocks_count(es));
+        update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr, (char *)es,
+                       sizeof(struct ext4_super_block));
+exit_put:
+        return err;
+} /* ext4_group_extend */