diff options
Diffstat (limited to 'fs/ext4/resize.c')
| -rw-r--r-- | fs/ext4/resize.c | 1045 |
1 files changed, 1045 insertions, 0 deletions
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c new file mode 100644 index 000000000000..1e9578052cd3 --- /dev/null +++ b/fs/ext4/resize.c @@ -0,0 +1,1045 @@ +/* + * 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)", + input->block_bitmap); + else if (outside(input->inode_bitmap, start, end)) + ext4_warning(sb, __FUNCTION__, + "Inode bitmap not in group (block %llu)", + 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)", + input->inode_table, itend - 1); + else if (input->inode_bitmap == input->block_bitmap) + ext4_warning(sb, __FUNCTION__, + "Block bitmap same as inode bitmap (%llu)", + 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)", + input->block_bitmap, 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)", + input->inode_bitmap, 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)", + 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)", + 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)", + 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 */ |
