linux/fs/ext4/resize.c

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/*
* 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"
Ext4: Uninitialized Block Groups In pass1 of e2fsck, every inode table in the fileystem is scanned and checked, regardless of whether it is in use. This is this the most time consuming part of the filesystem check. The unintialized block group feature can greatly reduce e2fsck time by eliminating checking of uninitialized inodes. With this feature, there is a a high water mark of used inodes for each block group. Block and inode bitmaps can be uninitialized on disk via a flag in the group descriptor to avoid reading or scanning them at e2fsck time. A checksum of each group descriptor is used to ensure that corruption in the group descriptor's bit flags does not cause incorrect operation. The feature is enabled through a mkfs option mke2fs /dev/ -O uninit_groups A patch adding support for uninitialized block groups to e2fsprogs tools has been posted to the linux-ext4 mailing list. The patches have been stress tested with fsstress and fsx. In performance tests testing e2fsck time, we have seen that e2fsck time on ext3 grows linearly with the total number of inodes in the filesytem. In ext4 with the uninitialized block groups feature, the e2fsck time is constant, based solely on the number of used inodes rather than the total inode count. Since typical ext4 filesystems only use 1-10% of their inodes, this feature can greatly reduce e2fsck time for users. With performance improvement of 2-20 times, depending on how full the filesystem is. The attached graph shows the major improvements in e2fsck times in filesystems with a large total inode count, but few inodes in use. In each group descriptor if we have EXT4_BG_INODE_UNINIT set in bg_flags: Inode table is not initialized/used in this group. So we can skip the consistency check during fsck. EXT4_BG_BLOCK_UNINIT set in bg_flags: No block in the group is used. So we can skip the block bitmap verification for this group. We also add two new fields to group descriptor as a part of uninitialized group patch. __le16 bg_itable_unused; /* Unused inodes count */ __le16 bg_checksum; /* crc16(sb_uuid+group+desc) */ bg_itable_unused: If we have EXT4_BG_INODE_UNINIT not set in bg_flags then bg_itable_unused will give the offset within the inode table till the inodes are used. This can be used by fsck to skip list of inodes that are marked unused. bg_checksum: Now that we depend on bg_flags and bg_itable_unused to determine the block and inode usage, we need to make sure group descriptor is not corrupt. We add checksum to group descriptor to detect corruption. If the descriptor is found to be corrupt, we mark all the blocks and inodes in the group used. Signed-off-by: Avantika Mathur <mathur@us.ibm.com> Signed-off-by: Andreas Dilger <adilger@clusterfs.com> Signed-off-by: Mingming Cao <cmm@us.ibm.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
2007-10-16 22:38:25 +00:00
#include "group.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, __func__,
"Cannot add at group %u (only %u groups)",
input->group, sbi->s_groups_count);
else if (offset != 0)
ext4_warning(sb, __func__, "Last group not full");
else if (input->reserved_blocks > input->blocks_count / 5)
ext4_warning(sb, __func__, "Reserved blocks too high (%u)",
input->reserved_blocks);
else if (free_blocks_count < 0)
ext4_warning(sb, __func__, "Bad blocks count %u",
input->blocks_count);
else if (!(bh = sb_bread(sb, end - 1)))
ext4_warning(sb, __func__,
"Cannot read last block (%llu)",
end - 1);
else if (outside(input->block_bitmap, start, end))
ext4_warning(sb, __func__,
"Block bitmap not in group (block %llu)",
(unsigned long long)input->block_bitmap);
else if (outside(input->inode_bitmap, start, end))
ext4_warning(sb, __func__,
"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, __func__,
"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, __func__,
"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, __func__,
"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, __func__,
"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, __func__,
"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, __func__,
"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, __func__,
"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);
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 %#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 */
for (i = 0, bit = gdblocks + 1, block = start + bit;
i < reserved_gdb; i++, block++, bit++) {
struct buffer_head *gdb;
ext4_debug("clear reserved block %#04llx (+%d)\n", block, bit);
if ((err = extend_or_restart_transaction(handle, 1, bh)))
goto exit_bh;
if (IS_ERR(gdb = bclean(handle, sb, block))) {
err = PTR_ERR(bh);
goto exit_bh;
}
ext4_handle_dirty_metadata(handle, NULL, gdb);
ext4_set_bit(bit, bh->b_data);
brelse(gdb);
}
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 */
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 %#04llx (+%d)\n", block, bit);
if ((err = extend_or_restart_transaction(handle, 1, bh)))
goto exit_bh;
if (IS_ERR(it = bclean(handle, sb, block))) {
err = PTR_ERR(it);
goto exit_bh;
}
ext4_handle_dirty_metadata(handle, NULL, it);
brelse(it);
ext4_set_bit(bit, bh->b_data);
}
if ((err = extend_or_restart_transaction(handle, 2, bh)))
goto exit_bh;
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;
}
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:
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 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, __func__,
"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, __func__,
"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, __func__,
"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, __func__,
"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, __func__,
"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 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 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, __func__,
"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 num_grp_locked = 0;
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, __func__,
"Can't resize non-sparse filesystem further");
return -EPERM;
}
if (ext4_blocks_count(es) + input->blocks_count <
ext4_blocks_count(es)) {
ext4_warning(sb, __func__, "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, __func__, "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, __func__,
"No reserved GDT blocks, can't resize");
return -EPERM;
}
inode = ext4_iget(sb, EXT4_RESIZE_INO);
if (IS_ERR(inode)) {
ext4_warning(sb, __func__,
"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;
}
lock_super(sb);
if (input->group != sbi->s_groups_count) {
ext4_warning(sb, __func__,
"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.
*/
num_grp_locked = ext4_mb_get_buddy_cache_lock(sb, input->group);
/* 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);
Ext4: Uninitialized Block Groups In pass1 of e2fsck, every inode table in the fileystem is scanned and checked, regardless of whether it is in use. This is this the most time consuming part of the filesystem check. The unintialized block group feature can greatly reduce e2fsck time by eliminating checking of uninitialized inodes. With this feature, there is a a high water mark of used inodes for each block group. Block and inode bitmaps can be uninitialized on disk via a flag in the group descriptor to avoid reading or scanning them at e2fsck time. A checksum of each group descriptor is used to ensure that corruption in the group descriptor's bit flags does not cause incorrect operation. The feature is enabled through a mkfs option mke2fs /dev/ -O uninit_groups A patch adding support for uninitialized block groups to e2fsprogs tools has been posted to the linux-ext4 mailing list. The patches have been stress tested with fsstress and fsx. In performance tests testing e2fsck time, we have seen that e2fsck time on ext3 grows linearly with the total number of inodes in the filesytem. In ext4 with the uninitialized block groups feature, the e2fsck time is constant, based solely on the number of used inodes rather than the total inode count. Since typical ext4 filesystems only use 1-10% of their inodes, this feature can greatly reduce e2fsck time for users. With performance improvement of 2-20 times, depending on how full the filesystem is. The attached graph shows the major improvements in e2fsck times in filesystems with a large total inode count, but few inodes in use. In each group descriptor if we have EXT4_BG_INODE_UNINIT set in bg_flags: Inode table is not initialized/used in this group. So we can skip the consistency check during fsck. EXT4_BG_BLOCK_UNINIT set in bg_flags: No block in the group is used. So we can skip the block bitmap verification for this group. We also add two new fields to group descriptor as a part of uninitialized group patch. __le16 bg_itable_unused; /* Unused inodes count */ __le16 bg_checksum; /* crc16(sb_uuid+group+desc) */ bg_itable_unused: If we have EXT4_BG_INODE_UNINIT not set in bg_flags then bg_itable_unused will give the offset within the inode table till the inodes are used. This can be used by fsck to skip list of inodes that are marked unused. bg_checksum: Now that we depend on bg_flags and bg_itable_unused to determine the block and inode usage, we need to make sure group descriptor is not corrupt. We add checksum to group descriptor to detect corruption. If the descriptor is found to be corrupt, we mark all the blocks and inodes in the group used. Signed-off-by: Avantika Mathur <mathur@us.ibm.com> Signed-off-by: Andreas Dilger <adilger@clusterfs.com> Signed-off-by: Mingming Cao <cmm@us.ibm.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
2007-10-16 22:38:25 +00:00
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) {
ext4_mb_put_buddy_cache_lock(sb, input->group, num_grp_locked);
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 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_mb_put_buddy_cache_lock(sb, input->group, num_grp_locked);
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)) {
ext4_group_t flex_group;
flex_group = ext4_flex_group(sbi, input->group);
sbi->s_flex_groups[flex_group].free_blocks +=
input->free_blocks_count;
sbi->s_flex_groups[flex_group].free_inodes +=
EXT4_INODES_PER_GROUP(sb);
}
ext4_handle_dirty_metadata(handle, NULL, 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;
ext4_group_t o_groups_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 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, __func__, "CONFIG_LBD not enabled");
return -EINVAL;
}
if (n_blocks_count < o_blocks_count) {
ext4_warning(sb, __func__,
"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, __func__,
"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, __func__, "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, __func__,
"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, __func__,
"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, __func__, "error %d on journal start", err);
goto exit_put;
}
lock_super(sb);
if (o_blocks_count != ext4_blocks_count(es)) {
ext4_warning(sb, __func__,
"multiple resizers run on filesystem!");
unlock_super(sb);
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, __func__,
"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_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
sb->s_dirt = 1;
unlock_super(sb);
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_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 */