Skip to content

Commit

Permalink
ext4: bigalloc changes to block bitmap initialization functions
Browse files Browse the repository at this point in the history 
Add bigalloc support to ext4_init_block_bitmap() and
ext4_free_blocks_after_init().

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  • Loading branch information
Theodore Ts'o committed Sep 9, 2011
1 parent fd034a8 commit d5b8f31
Show file tree
Hide file tree
Showing 2 changed files with 103 additions and 41 deletions.
131 changes: 90 additions & 41 deletions fs/ext4/balloc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -23,9 +23,6 @@

#include <trace/events/ext4.h>

static unsigned int num_base_meta_blocks(struct super_block *sb,
ext4_group_t block_group);

/*
* balloc.c contains the blocks allocation and deallocation routines
*/
Expand Down Expand Up @@ -58,56 +55,107 @@ static int ext4_block_in_group(struct super_block *sb, ext4_fsblk_t block,
return 0;
}

static int ext4_group_used_meta_blocks(struct super_block *sb,
ext4_group_t block_group,
struct ext4_group_desc *gdp)
/* Return the number of clusters used for file system metadata; this
* represents the overhead needed by the file system.
*/
unsigned ext4_num_overhead_clusters(struct super_block *sb,
ext4_group_t block_group,
struct ext4_group_desc *gdp)
{
ext4_fsblk_t tmp;
unsigned num_clusters;
int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c;
ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
ext4_fsblk_t itbl_blk;
struct ext4_sb_info *sbi = EXT4_SB(sb);
/* block bitmap, inode bitmap, and inode table blocks */
int used_blocks = sbi->s_itb_per_group + 2;

if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
if (!ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp),
block_group))
used_blocks--;

if (!ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp),
block_group))
used_blocks--;

tmp = ext4_inode_table(sb, gdp);
for (; tmp < ext4_inode_table(sb, gdp) +
sbi->s_itb_per_group; tmp++) {
if (!ext4_block_in_group(sb, tmp, block_group))
used_blocks -= 1;
/* This is the number of clusters used by the superblock,
* block group descriptors, and reserved block group
* descriptor blocks */
num_clusters = ext4_num_base_meta_clusters(sb, block_group);

/*
* For the allocation bitmaps and inode table, we first need
* to check to see if the block is in the block group. If it
* is, then check to see if the cluster is already accounted
* for in the clusters used for the base metadata cluster, or
* if we can increment the base metadata cluster to include
* that block. Otherwise, we will have to track the cluster
* used for the allocation bitmap or inode table explicitly.
* Normally all of these blocks are contiguous, so the special
* case handling shouldn't be necessary except for *very*
* unusual file system layouts.
*/
if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
block_cluster = EXT4_B2C(sbi, (start -
ext4_block_bitmap(sb, gdp)));
if (block_cluster < num_clusters)
block_cluster = -1;
else if (block_cluster == num_clusters) {
num_clusters++;
block_cluster = -1;
}
}

if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
inode_cluster = EXT4_B2C(sbi,
start - ext4_inode_bitmap(sb, gdp));
if (inode_cluster < num_clusters)
inode_cluster = -1;
else if (inode_cluster == num_clusters) {
num_clusters++;
inode_cluster = -1;
}
}

itbl_blk = ext4_inode_table(sb, gdp);
for (i = 0; i < sbi->s_itb_per_group; i++) {
if (ext4_block_in_group(sb, itbl_blk + i, block_group)) {
c = EXT4_B2C(sbi, start - itbl_blk + i);
if ((c < num_clusters) || (c == inode_cluster) ||
(c == block_cluster) || (c == itbl_cluster))
continue;
if (c == num_clusters) {
num_clusters++;
continue;
}
num_clusters++;
itbl_cluster = c;
}
}
return used_blocks;

if (block_cluster != -1)
num_clusters++;
if (inode_cluster != -1)
num_clusters++;

return num_clusters;
}

static unsigned int num_blocks_in_group(struct super_block *sb,
ext4_group_t block_group)
static unsigned int num_clusters_in_group(struct super_block *sb,
ext4_group_t block_group)
{
unsigned int blocks;

if (block_group == ext4_get_groups_count(sb) - 1) {
/*
* Even though mke2fs always initializes the first and
* last group, just in case some other tool was used,
* we need to make sure we calculate the right free
* blocks.
*/
return ext4_blocks_count(EXT4_SB(sb)->s_es) -
blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) -
ext4_group_first_block_no(sb, block_group);
} else
return EXT4_BLOCKS_PER_GROUP(sb);
blocks = EXT4_BLOCKS_PER_GROUP(sb);
return EXT4_NUM_B2C(EXT4_SB(sb), blocks);
}

/* Initializes an uninitialized block bitmap */
void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
ext4_group_t block_group,
struct ext4_group_desc *gdp)
{
unsigned int bit, bit_max = num_base_meta_blocks(sb, block_group);
unsigned int bit, bit_max;
struct ext4_sb_info *sbi = EXT4_SB(sb);
ext4_fsblk_t start, tmp;
int flex_bg = 0;
Expand All @@ -126,6 +174,7 @@ void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
}
memset(bh->b_data, 0, sb->s_blocksize);

bit_max = ext4_num_base_meta_clusters(sb, block_group);
for (bit = 0; bit < bit_max; bit++)
ext4_set_bit(bit, bh->b_data);

Expand All @@ -137,24 +186,25 @@ void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
/* Set bits for block and inode bitmaps, and inode table */
tmp = ext4_block_bitmap(sb, gdp);
if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
ext4_set_bit(tmp - start, bh->b_data);
ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);

tmp = ext4_inode_bitmap(sb, gdp);
if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
ext4_set_bit(tmp - start, bh->b_data);
ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);

tmp = ext4_inode_table(sb, gdp);
for (; tmp < ext4_inode_table(sb, gdp) +
sbi->s_itb_per_group; tmp++) {
if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
ext4_set_bit(tmp - start, bh->b_data);
ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
}

/*
* Also if the number of blocks within the group is less than
* the blocksize * 8 ( which is the size of bitmap ), set rest
* of the block bitmap to 1
*/
ext4_mark_bitmap_end(num_blocks_in_group(sb, block_group),
ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
sb->s_blocksize * 8, bh->b_data);
}

Expand All @@ -165,9 +215,8 @@ unsigned ext4_free_blocks_after_init(struct super_block *sb,
ext4_group_t block_group,
struct ext4_group_desc *gdp)
{
return num_blocks_in_group(sb, block_group) -
num_base_meta_blocks(sb, block_group) -
ext4_group_used_meta_blocks(sb, block_group, gdp);
return num_clusters_in_group(sb, block_group) -
ext4_num_overhead_clusters(sb, block_group, gdp);
}

/*
Expand Down Expand Up @@ -611,14 +660,14 @@ unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
}

/*
* This function returns the number of file system metadata blocks at
* This function returns the number of file system metadata clusters at
* the beginning of a block group, including the reserved gdt blocks.
*/
static unsigned int num_base_meta_blocks(struct super_block *sb,
ext4_group_t block_group)
unsigned ext4_num_base_meta_clusters(struct super_block *sb,
ext4_group_t block_group)
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
int num;
unsigned num;

/* Check for superblock and gdt backups in this group */
num = ext4_bg_has_super(sb, block_group);
Expand All @@ -633,7 +682,7 @@ static unsigned int num_base_meta_blocks(struct super_block *sb,
} else { /* For META_BG_BLOCK_GROUPS */
num += ext4_bg_num_gdb(sb, block_group);
}
return num;
return EXT4_NUM_B2C(sbi, num);
}
/**
* ext4_inode_to_goal_block - return a hint for block allocation
Expand Down
13 changes: 13 additions & 0 deletions fs/ext4/ext4.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -261,6 +261,14 @@ struct ext4_io_submit {
#endif
#define EXT4_BLOCK_ALIGN(size, blkbits) ALIGN((size), (1 << (blkbits)))

/* Translate a block number to a cluster number */
#define EXT4_B2C(sbi, blk) ((blk) >> (sbi)->s_cluster_bits)
/* Translate a cluster number to a block number */
#define EXT4_C2B(sbi, cluster) ((cluster) << (sbi)->s_cluster_bits)
/* Translate # of blks to # of clusters */
#define EXT4_NUM_B2C(sbi, blks) (((blks) + (sbi)->s_cluster_ratio - 1) >> \
(sbi)->s_cluster_bits)

/*
* Structure of a blocks group descriptor
*/
Expand Down Expand Up @@ -1770,6 +1778,11 @@ extern void ext4_init_block_bitmap(struct super_block *sb,
extern unsigned ext4_free_blocks_after_init(struct super_block *sb,
ext4_group_t block_group,
struct ext4_group_desc *gdp);
extern unsigned ext4_num_base_meta_clusters(struct super_block *sb,
ext4_group_t block_group);
extern unsigned ext4_num_overhead_clusters(struct super_block *sb,
ext4_group_t block_group,
struct ext4_group_desc *gdp);
ext4_fsblk_t ext4_inode_to_goal_block(struct inode *);

/* dir.c */
Expand Down

0 comments on commit d5b8f31

Please sign in to comment.