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Date: Tue, 3 May 2011 18:24:36 -0400
From: Theodore Ts'o <tytso@....edu>
To: Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc: Theodore Ts'o <tytso@....edu>
Subject: [PATCH 06/19] ext4: bigalloc changes to block bitmap initialization functions
Add bigalloc support to ext4_init_block_bitmap() and
ext4_free_blocks_after_init().
Signed-off-by: "Theodore Ts'o" <tytso@....edu>
---
fs/ext4/balloc.c | 131 +++++++++++++++++++++++++++++++++++++-----------------
fs/ext4/ext4.h | 13 +++++
2 files changed, 103 insertions(+), 41 deletions(-)
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 99ea977..332854c 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -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
*/
@@ -58,37 +55,87 @@ 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
@@ -96,10 +143,11 @@ static unsigned int num_blocks_in_group(struct super_block *sb,
* 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 */
@@ -107,7 +155,7 @@ 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;
@@ -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);
@@ -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);
}
@@ -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);
}
/*
@@ -730,14 +779,14 @@ 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);
@@ -752,5 +801,5 @@ 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);
}
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index f66a566..9fe03c0 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -258,6 +258,14 @@ 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
*/
@@ -1684,6 +1692,11 @@ 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);
/* dir.c */
extern int __ext4_check_dir_entry(const char *, unsigned int, struct inode *,
--
1.7.3.1
--
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