/*
* 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/errno.h>
#include <linux/slab.h>
#include "ext4_jbd2.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;
ext4_group_t 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, "Cannot add at group %u (only %u groups)",
input->group, sbi->s_groups_count);
else if (offset != 0)
ext4_warning(sb, "Last group not full");
else if (input->reserved_blocks > input->blocks_count / 5)
ext4_warning(sb, "Reserved blocks too high (%u)",
input->reserved_blocks);
else if (free_blocks_count < 0)
ext4_warning(sb, "Bad blocks count %u",
input->blocks_count);
else if (!(bh = sb_bread(sb, end - 1)))
ext4_warning(sb, "Cannot read last block (%llu)",
end - 1);
else if (outside(input->block_bitmap, start, end))
ext4_warning(sb, "Block bitmap not in group (block %llu)",
(unsigned long long)input->block_bitmap);
else if (outside(input->inode_bitmap, start, end))
ext4_warning(sb, "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, "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, "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, "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, "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, "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, "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, "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;
}
/*
* If we have fewer than thresh credits, extend by EXT4_MAX_TRANS_DATA.
* If that fails, restart the transaction & regain write access for the
* buffer head which is used for block_bitmap modifications.
*/
static int extend_or_restart_transaction(handle_t *handle, int thresh,
struct buffer_head *bh)
{
int err;
if (ext4_handle_has_enough_credits(handle, thresh))
return 0;
err = ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA);
if (err < 0)
return err;
if (err) {
if ((err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
return err;
if ((err = ext4_journal_get_write_access(handle, bh)))
return err;
}
return 0;
}
/*
* 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;
/* This transaction may be extended/restarted along the way */
handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
if (IS_ERR(handle))
return PTR_ERR(handle);
mutex_lock(&sbi->s_resize_lock);
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 %#04llx (+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 %#04llx (+%d)\n", block, bit);
if ((err = extend_or_restart_transaction(handle, 1, bh)))
goto exit_bh;
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(gdb);
memcpy(gdb->b_data, sbi->s_group_desc[i]->b_data, gdb->b_size);
set_buffer_uptodate(gdb);
unlock_buffer(gdb);
ext4_handle_dirty_metadata(handle, NULL, gdb);
ext4_set_bit(bit, bh->b_data);
brelse(gdb);
}
/* Zero out all of the reserved backup group descriptor table blocks */
ext4_debug("clear inode table blocks %#04llx -> %#04llx\n",
block, sbi->s_itb_per_group);
err = sb_issue_zeroout(sb, gdblocks + start + 1, reserved_gdb,
GFP_NOFS);
if (err)
goto exit_bh;
ext4_debug("mark block bitmap %#04llx (+%llu)\n", input->block_bitmap,
input->block_bitmap - start);
ext4_set_bit(input->block_bitmap - start, bh->b_data);
ext4_debug("mark inode bitmap %#04llx (+%llu)\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 */
block = input->inode_table;
ext4_debug("clear inode table blocks %#04llx -> %#04llx\n",
block, sbi->s_itb_per_group);
err = sb_issue_zeroout(sb, block, sbi->s_itb_per_group, GFP_NOFS);
if (err)
goto exit_bh;
if ((err = extend_or_restart_transaction(handle, 2, bh)))
goto exit_bh;
ext4_mark_bitmap_end(input->blocks_count, sb->s_blocksize * 8,
bh->b_data);
ext4_handle_dirty_metadata(handle, NULL, bh);
brelse(bh);
/* Mark unused entries in inode bitmap used */
ext4_debug("clear inode bitmap %#04llx (+%llu)\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;
}
ext4_mark_bitmap_end(EXT4_INODES_PER_GROUP(sb), sb->s_blocksize * 8,
bh->b_data);
ext4_handle_dirty_metadata(handle, NULL, bh);
exit_bh:
brelse(bh);
exit_journal:
mutex_unlock(&sbi->s_resize_lock);
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 ext4_group_t 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, "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, "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, "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_NOFS);
if (!n_group_desc) {
err = -ENOMEM;
ext4_warning(sb,
"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_handle_dirty_metadata(handle, NULL, 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_handle_dirty_metadata(handle, NULL, *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);
le16_add_cpu(&es->s_reserved_gdt_blocks, -1);
ext4_handle_dirty_metadata(handle, NULL, 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_NOFS);
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 %
EXT4_ADDR_PER_BLOCK(sb));
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, "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_handle_dirty_metadata(handle, NULL, 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 take the s_resize_lock 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 ext4_group_t last = sbi->s_groups_count;
const int bpg = EXT4_BLOCKS_PER_GROUP(sb);
unsigned three = 1;
unsigned five = 5;
unsigned seven = 7;
ext4_group_t 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 (ext4_handle_valid(handle) &&
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_handle_dirty_metadata(handle, NULL, 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, "can't update backup for group %u (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, "Can't resize non-sparse filesystem further");
return -EPERM;
}
if (ext4_blocks_count(es) + input->blocks_count <
ext4_blocks_count(es)) {
ext4_warning(sb, "blocks_count overflow");
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, "inodes_count overflow");
return -EINVAL;
}
if (reserved_gdb || gdb_off == 0) {
if (!EXT4_HAS_COMPAT_FEATURE(sb,
EXT4_FEATURE_COMPAT_RESIZE_INODE)
|| !le16_to_cpu(es->s_reserved_gdt_blocks)) {
ext4_warning(sb,
"No reserved GDT blocks, can't resize");
return -EPERM;
}
inode = ext4_iget(sb, EXT4_RESIZE_INO);
if (IS_ERR(inode)) {
ext4_warning(sb, "Error opening resize inode");
return PTR_ERR(inode);
}
}
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;
}
mutex_lock(&sbi->s_resize_lock);
if (input->group != sbi->s_groups_count) {
ext4_warning(sb, "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.
*
* We do not lock all allocations via s_resize_lock
* 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 *)((char *)primary->b_data +
gdb_off * EXT4_DESC_SIZE(sb));
memset(gdp, 0, EXT4_DESC_SIZE(sb));
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 */
ext4_free_blks_set(sb, gdp, input->free_blocks_count);
ext4_free_inodes_set(sb, gdp, EXT4_INODES_PER_GROUP(sb));
gdp->bg_flags = cpu_to_le16(EXT4_BG_INODE_ZEROED);
gdp->bg_checksum = ext4_group_desc_csum(sbi, input->group, gdp);
/*
* We can allocate memory for mb_alloc based on the new group
* descriptor
*/
err = ext4_mb_add_groupinfo(sb, input->group, gdp);
if (err)
goto exit_journal;
/*
* 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);
le32_add_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 s_resize_lock
* AND
* * Writers must perform a smp_wmb() after updating all dependent
* data and before modifying the groups count
*
* * Readers must hold s_resize_lock 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_handle_dirty_metadata(handle, NULL, 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_add(&sbi->s_freeblocks_counter,
input->free_blocks_count);
percpu_counter_add(&sbi->s_freeinodes_counter,
EXT4_INODES_PER_GROUP(sb));
if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG) &&
sbi->s_log_groups_per_flex) {
ext4_group_t flex_group;
flex_group = ext4_flex_group(sbi, input->group);
atomic_add(input->free_blocks_count,
&sbi->s_flex_groups[flex_group].free_blocks);
atomic_add(EXT4_INODES_PER_GROUP(sb),
&sbi->s_flex_groups[flex_group].free_inodes);
}
ext4_handle_dirty_super(handle, sb);
exit_journal:
mutex_unlock(&sbi->s_resize_lock);
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;
ext4_grpblk_t last;
ext4_grpblk_t add;
struct buffer_head *bh;
handle_t *handle;
int err;
ext4_group_t group;
/* We don't need to worry about locking wrt other resizers just
* yet: we're going to revalidate es->s_blocks_count after
* taking the s_resize_lock below. */
o_blocks_count = ext4_blocks_count(es);
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, "CONFIG_LBDAF not enabled");
return -EINVAL;
}
if (n_blocks_count < o_blocks_count) {
ext4_warning(sb, "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, &group, &last);
if (last == 0) {
ext4_warning(sb, "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, "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, "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, "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, "error %d on journal start", err);
goto exit_put;
}
mutex_lock(&EXT4_SB(sb)->s_resize_lock);
if (o_blocks_count != ext4_blocks_count(es)) {
ext4_warning(sb, "multiple resizers run on filesystem!");
mutex_unlock(&EXT4_SB(sb)->s_resize_lock);
ext4_journal_stop(handle);
err = -EBUSY;
goto exit_put;
}
if ((err = ext4_journal_get_write_access(handle,
EXT4_SB(sb)->s_sbh))) {
ext4_warning(sb, "error %d on journal write access", err);
mutex_unlock(&EXT4_SB(sb)->s_resize_lock);
ext4_journal_stop(handle);
goto exit_put;
}
ext4_blocks_count_set(es, o_blocks_count + add);
mutex_unlock(&EXT4_SB(sb)->s_resize_lock);
ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
o_blocks_count + add);
/* We add the blocks to the bitmap and set the group need init bit */
ext4_add_groupblocks(handle, sb, o_blocks_count, add);
ext4_handle_dirty_super(handle, sb);
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 */
