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ext4: Add blocks added during resize to bitmap
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With this change new blocks added during resize
are marked as free in the block bitmap and the
group is flagged with EXT4_GROUP_INFO_NEED_INIT_BIT
flag.  This makes sure when mballoc tries to allocate
blocks from the new group we would reload the
buddy information using the bitmap present in the disk.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
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Aneesh Kumar K.V authored and Theodore Ts'o committed Jan 6, 2009
1 parent 3a06d77 commit e21675d
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Showing 3 changed files with 34 additions and 118 deletions.
136 changes: 30 additions & 106 deletions fs/ext4/balloc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@
#include "ext4.h"
#include "ext4_jbd2.h"
#include "group.h"
#include "mballoc.h"

/*
* balloc.c contains the blocks allocation and deallocation routines
Expand Down Expand Up @@ -350,62 +351,43 @@ ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
}

/**
* ext4_free_blocks_sb() -- Free given blocks and update quota
* ext4_add_groupblocks() -- Add given blocks to an existing group
* @handle: handle to this transaction
* @sb: super block
* @block: start physcial block to free
* @block: start physcial block to add to the block group
* @count: number of blocks to free
* @pdquot_freed_blocks: pointer to quota
*
* XXX This function is only used by the on-line resizing code, which
* should probably be fixed up to call the mballoc variant. There
* this needs to be cleaned up later; in fact, I'm not convinced this
* is 100% correct in the face of the mballoc code. The online resizing
* code needs to be fixed up to more tightly (and correctly) interlock
* with the mballoc code.
* This marks the blocks as free in the bitmap. We ask the
* mballoc to reload the buddy after this by setting group
* EXT4_GROUP_INFO_NEED_INIT_BIT flag
*/
void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
ext4_fsblk_t block, unsigned long count,
unsigned long *pdquot_freed_blocks)
void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
ext4_fsblk_t block, unsigned long count)
{
struct buffer_head *bitmap_bh = NULL;
struct buffer_head *gd_bh;
ext4_group_t block_group;
ext4_grpblk_t bit;
unsigned int i;
unsigned int overflow;
struct ext4_group_desc *desc;
struct ext4_super_block *es;
struct ext4_sb_info *sbi;
int err = 0, ret;
ext4_grpblk_t group_freed;
ext4_grpblk_t blocks_freed;
struct ext4_group_info *grp;

*pdquot_freed_blocks = 0;
sbi = EXT4_SB(sb);
es = sbi->s_es;
if (block < le32_to_cpu(es->s_first_data_block) ||
block + count < block ||
block + count > ext4_blocks_count(es)) {
ext4_error(sb, "ext4_free_blocks",
"Freeing blocks not in datazone - "
"block = %llu, count = %lu", block, count);
goto error_return;
}

ext4_debug("freeing block(s) %llu-%llu\n", block, block + count - 1);
ext4_debug("Adding block(s) %llu-%llu\n", block, block + count - 1);

do_more:
overflow = 0;
ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
/*
* Check to see if we are freeing blocks across a group
* boundary.
*/
if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
overflow = bit + count - EXT4_BLOCKS_PER_GROUP(sb);
count -= overflow;
goto error_return;
}
brelse(bitmap_bh);
bitmap_bh = ext4_read_block_bitmap(sb, block_group);
if (!bitmap_bh)
goto error_return;
Expand All @@ -418,18 +400,17 @@ void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
in_range(block + count - 1, ext4_inode_table(sb, desc),
sbi->s_itb_per_group)) {
ext4_error(sb, "ext4_free_blocks",
"Freeing blocks in system zones - "
ext4_error(sb, __func__,
"Adding blocks in system zones - "
"Block = %llu, count = %lu",
block, count);
goto error_return;
}

/*
* We are about to start releasing blocks in the bitmap,
* We are about to add blocks to the bitmap,
* so we need undo access.
*/
/* @@@ check errors */
BUFFER_TRACE(bitmap_bh, "getting undo access");
err = ext4_journal_get_undo_access(handle, bitmap_bh);
if (err)
Expand All @@ -445,87 +426,28 @@ void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
if (err)
goto error_return;

jbd_lock_bh_state(bitmap_bh);

for (i = 0, group_freed = 0; i < count; i++) {
/*
* An HJ special. This is expensive...
*/
#ifdef CONFIG_JBD2_DEBUG
jbd_unlock_bh_state(bitmap_bh);
{
struct buffer_head *debug_bh;
debug_bh = sb_find_get_block(sb, block + i);
if (debug_bh) {
BUFFER_TRACE(debug_bh, "Deleted!");
if (!bh2jh(bitmap_bh)->b_committed_data)
BUFFER_TRACE(debug_bh,
"No commited data in bitmap");
BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
__brelse(debug_bh);
}
}
jbd_lock_bh_state(bitmap_bh);
#endif
if (need_resched()) {
jbd_unlock_bh_state(bitmap_bh);
cond_resched();
jbd_lock_bh_state(bitmap_bh);
}
/* @@@ This prevents newly-allocated data from being
* freed and then reallocated within the same
* transaction.
*
* Ideally we would want to allow that to happen, but to
* do so requires making jbd2_journal_forget() capable of
* revoking the queued write of a data block, which
* implies blocking on the journal lock. *forget()
* cannot block due to truncate races.
*
* Eventually we can fix this by making jbd2_journal_forget()
* return a status indicating whether or not it was able
* to revoke the buffer. On successful revoke, it is
* safe not to set the allocation bit in the committed
* bitmap, because we know that there is no outstanding
* activity on the buffer any more and so it is safe to
* reallocate it.
*/
BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
J_ASSERT_BH(bitmap_bh,
bh2jh(bitmap_bh)->b_committed_data != NULL);
ext4_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
bh2jh(bitmap_bh)->b_committed_data);

/*
* We clear the bit in the bitmap after setting the committed
* data bit, because this is the reverse order to that which
* the allocator uses.
*/
for (i = 0, blocks_freed = 0; i < count; i++) {
BUFFER_TRACE(bitmap_bh, "clear bit");
if (!ext4_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
bit + i, bitmap_bh->b_data)) {
jbd_unlock_bh_state(bitmap_bh);
ext4_error(sb, __func__,
"bit already cleared for block %llu",
(ext4_fsblk_t)(block + i));
jbd_lock_bh_state(bitmap_bh);
BUFFER_TRACE(bitmap_bh, "bit already cleared");
} else {
group_freed++;
blocks_freed++;
}
}
jbd_unlock_bh_state(bitmap_bh);

spin_lock(sb_bgl_lock(sbi, block_group));
le16_add_cpu(&desc->bg_free_blocks_count, group_freed);
le16_add_cpu(&desc->bg_free_blocks_count, blocks_freed);
desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc);
spin_unlock(sb_bgl_lock(sbi, block_group));
percpu_counter_add(&sbi->s_freeblocks_counter, count);
percpu_counter_add(&sbi->s_freeblocks_counter, blocks_freed);

if (sbi->s_log_groups_per_flex) {
ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
spin_lock(sb_bgl_lock(sbi, flex_group));
sbi->s_flex_groups[flex_group].free_blocks += count;
sbi->s_flex_groups[flex_group].free_blocks += blocks_freed;
spin_unlock(sb_bgl_lock(sbi, flex_group));
}

Expand All @@ -536,15 +458,17 @@ void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
/* And the group descriptor block */
BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
ret = ext4_handle_dirty_metadata(handle, NULL, gd_bh);
if (!err) err = ret;
*pdquot_freed_blocks += group_freed;

if (overflow && !err) {
block += count;
count = overflow;
goto do_more;
}
if (!err)
err = ret;
sb->s_dirt = 1;
/*
* request to reload the buddy with the
* new bitmap information
*/
grp = ext4_get_group_info(sb, block_group);
set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
ext4_mb_update_group_info(grp, blocks_freed);

error_return:
brelse(bitmap_bh);
ext4_std_error(sb, err);
Expand Down
5 changes: 2 additions & 3 deletions fs/ext4/ext4.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1014,9 +1014,8 @@ extern int ext4_claim_free_blocks(struct ext4_sb_info *sbi, s64 nblocks);
extern int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks);
extern void ext4_free_blocks(handle_t *handle, struct inode *inode,
ext4_fsblk_t block, unsigned long count, int metadata);
extern void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
ext4_fsblk_t block, unsigned long count,
unsigned long *pdquot_freed_blocks);
extern void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
ext4_fsblk_t block, unsigned long count);
extern ext4_fsblk_t ext4_count_free_blocks(struct super_block *);
extern void ext4_check_blocks_bitmap(struct super_block *);
extern struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb,
Expand Down
11 changes: 2 additions & 9 deletions fs/ext4/resize.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -977,9 +977,7 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
struct buffer_head *bh;
handle_t *handle;
int err;
unsigned long freed_blocks;
ext4_group_t group;
struct ext4_group_info *grp;

/* We don't need to worry about locking wrt other resizers just
* yet: we're going to revalidate es->s_blocks_count after
Expand Down Expand Up @@ -1077,7 +1075,8 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
unlock_super(sb);
ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
o_blocks_count + add);
ext4_free_blocks_sb(handle, sb, o_blocks_count, add, &freed_blocks);
/* 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)))
Expand Down Expand Up @@ -1120,12 +1119,6 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
ClearPageUptodate(page);
page_cache_release(page);
}

/* Get the info on the last group */
grp = ext4_get_group_info(sb, group);

/* Update free blocks in group info */
ext4_mb_update_group_info(grp, add);
}

if (test_opt(sb, DEBUG))
Expand Down

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