Le jeu 30/03/2006 à 03:54, Andrew Morton a écrit :
> Mingming Cao <cmm@xxxxxxxxxx> wrote:
> >
> > The things need to be done to complete this work is the issue with
> > current percpu counter, which could not handle u32 type count well.
>
> I'm surprised there's much of a problem here. It is a 32-bit value, so it
> should mainly be a matter of treating the return value from
> percpu_counter_read() as unsigned long.
>
> However a stickier problem is when dealing with a filesystem which has,
> say, 0xffff_ff00 blocks. Because percpu counters are approximate, and a
> counter which really has a value of 0xffff_feee might return 0x00000123.
> What do we do then?
>
> Of course the simple option is to nuke the percpu counters in ext3 and use
> atomic_long_t (which is signed, so appropriate treat-it-as-unsigned code
> would be needed). I doubt if the percpu counters in ext3 are gaining us
> much.
I tried to make something in this way.
Does the attached patch look like the thing you though about ?
Regards,
Laurent
--
Laurent Vivier
Bull, Architect of an Open World (TM)
http://www.bullopensource.org/ext4
Index: linux-2.6.16-lv/fs/ext3/balloc.c
===================================================================
--- linux-2.6.16-lv.orig/fs/ext3/balloc.c 2006-04-07 16:27:11.000000000 +0200
+++ linux-2.6.16-lv/fs/ext3/balloc.c 2006-04-07 17:05:28.000000000 +0200
@@ -471,7 +471,7 @@ do_more:
cpu_to_le16(le16_to_cpu(desc->bg_free_blocks_count) +
group_freed);
spin_unlock(sb_bgl_lock(sbi, block_group));
- percpu_counter_mod(&sbi->s_freeblocks_counter, count);
+ atomic_long_set(&sbi->s_freeblocks_counter, count);
/* We dirtied the bitmap block */
BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
@@ -1129,7 +1129,7 @@ static int ext3_has_free_blocks(struct e
{
sector_t free_blocks, root_blocks;
- free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
+ free_blocks = (sector_t)atomic_long_read(&sbi->s_freeblocks_counter);
root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
sbi->s_resuid != current->fsuid &&
@@ -1381,7 +1381,7 @@ allocated:
gdp->bg_free_blocks_count =
cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) - 1);
spin_unlock(sb_bgl_lock(sbi, group_no));
- percpu_counter_mod(&sbi->s_freeblocks_counter, -1);
+ atomic_long_dec(&sbi->s_freeblocks_counter);
BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
err = ext3_journal_dirty_metadata(handle, gdp_bh);
Index: linux-2.6.16-lv/include/linux/ext3_fs_sb.h
===================================================================
--- linux-2.6.16-lv.orig/include/linux/ext3_fs_sb.h 2006-04-07 16:27:11.000000000 +0200
+++ linux-2.6.16-lv/include/linux/ext3_fs_sb.h 2006-04-07 17:01:23.000000000 +0200
@@ -20,7 +20,6 @@
#include <linux/timer.h>
#include <linux/wait.h>
#include <linux/blockgroup_lock.h>
-#include <linux/percpu_counter.h>
#endif
#include <linux/rbtree.h>
@@ -54,9 +53,9 @@ struct ext3_sb_info {
u32 s_next_generation;
u32 s_hash_seed[4];
int s_def_hash_version;
- struct percpu_counter s_freeblocks_counter;
- struct percpu_counter s_freeinodes_counter;
- struct percpu_counter s_dirs_counter;
+ atomic_long_t s_freeblocks_counter;
+ atomic_long_t s_freeinodes_counter;
+ atomic_long_t s_dirs_counter;
struct blockgroup_lock s_blockgroup_lock;
/* root of the per fs reservation window tree */
Index: linux-2.6.16-lv/fs/ext3/super.c
===================================================================
--- linux-2.6.16-lv.orig/fs/ext3/super.c 2006-04-07 16:27:11.000000000 +0200
+++ linux-2.6.16-lv/fs/ext3/super.c 2006-04-07 17:14:22.000000000 +0200
@@ -404,9 +404,6 @@ static void ext3_put_super (struct super
for (i = 0; i < sbi->s_gdb_count; i++)
brelse(sbi->s_group_desc[i]);
kfree(sbi->s_group_desc);
- percpu_counter_destroy(&sbi->s_freeblocks_counter);
- percpu_counter_destroy(&sbi->s_freeinodes_counter);
- percpu_counter_destroy(&sbi->s_dirs_counter);
brelse(sbi->s_sbh);
#ifdef CONFIG_QUOTA
for (i = 0; i < MAXQUOTAS; i++)
@@ -1580,9 +1577,9 @@ static int ext3_fill_super (struct super
goto failed_mount;
}
- percpu_counter_init(&sbi->s_freeblocks_counter);
- percpu_counter_init(&sbi->s_freeinodes_counter);
- percpu_counter_init(&sbi->s_dirs_counter);
+ atomic_long_set(&sbi->s_freeblocks_counter, 0);
+ atomic_long_set(&sbi->s_freeinodes_counter, 0);
+ atomic_long_set(&sbi->s_dirs_counter, 0);
bgl_lock_init(&sbi->s_blockgroup_lock);
for (i = 0; i < db_count; i++) {
@@ -1730,11 +1727,11 @@ static int ext3_fill_super (struct super
test_opt(sb,DATA_FLAGS) == EXT3_MOUNT_ORDERED_DATA ? "ordered":
"writeback");
- percpu_counter_mod(&sbi->s_freeblocks_counter,
+ atomic_long_set(&sbi->s_freeblocks_counter,
ext3_count_free_blocks(sb));
- percpu_counter_mod(&sbi->s_freeinodes_counter,
+ atomic_long_set(&sbi->s_freeinodes_counter,
ext3_count_free_inodes(sb));
- percpu_counter_mod(&sbi->s_dirs_counter,
+ atomic_long_set(&sbi->s_dirs_counter,
ext3_count_dirs(sb));
lock_kernel();
Index: linux-2.6.16-lv/fs/ext3/resize.c
===================================================================
--- linux-2.6.16-lv.orig/fs/ext3/resize.c 2006-04-07 16:27:11.000000000 +0200
+++ linux-2.6.16-lv/fs/ext3/resize.c 2006-04-07 17:12:13.000000000 +0200
@@ -871,9 +871,9 @@ int ext3_group_add(struct super_block *s
input->reserved_blocks);
/* Update the free space counts */
- percpu_counter_mod(&sbi->s_freeblocks_counter,
+ atomic_long_set(&sbi->s_freeblocks_counter,
input->free_blocks_count);
- percpu_counter_mod(&sbi->s_freeinodes_counter,
+ atomic_long_set(&sbi->s_freeinodes_counter,
EXT3_INODES_PER_GROUP(sb));
ext3_journal_dirty_metadata(handle, sbi->s_sbh);
Index: linux-2.6.16-lv/fs/ext3/ialloc.c
===================================================================
--- linux-2.6.16-lv.orig/fs/ext3/ialloc.c 2006-04-07 16:27:11.000000000 +0200
+++ linux-2.6.16-lv/fs/ext3/ialloc.c 2006-04-07 17:09:54.000000000 +0200
@@ -170,9 +170,9 @@ void ext3_free_inode (handle_t *handle,
gdp->bg_used_dirs_count = cpu_to_le16(
le16_to_cpu(gdp->bg_used_dirs_count) - 1);
spin_unlock(sb_bgl_lock(sbi, block_group));
- percpu_counter_inc(&sbi->s_freeinodes_counter);
+ atomic_long_inc(&sbi->s_freeinodes_counter);
if (is_directory)
- percpu_counter_dec(&sbi->s_dirs_counter);
+ atomic_long_dec(&sbi->s_dirs_counter);
}
BUFFER_TRACE(bh2, "call ext3_journal_dirty_metadata");
@@ -207,7 +207,7 @@ static int find_group_dir(struct super_b
struct buffer_head *bh;
int group, best_group = -1;
- freei = percpu_counter_read_positive(&EXT3_SB(sb)->s_freeinodes_counter);
+ freei = (sector_t)atomic_long_read(&EXT3_SB(sb)->s_freeinodes_counter);
avefreei = freei / ngroups;
for (group = 0; group < ngroups; group++) {
@@ -269,11 +269,11 @@ static int find_group_orlov(struct super
struct ext3_group_desc *desc;
struct buffer_head *bh;
- freei = percpu_counter_read_positive(&sbi->s_freeinodes_counter);
+ freei = (sector_t)atomic_long_read(&sbi->s_freeinodes_counter);
avefreei = freei / ngroups;
- freeb = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
+ freeb = (sector_t)atomic_long_read(&sbi->s_freeblocks_counter);
avefreeb = freeb / ngroups;
- ndirs = percpu_counter_read_positive(&sbi->s_dirs_counter);
+ ndirs = (sector_t)atomic_long_read(&sbi->s_dirs_counter);
if ((parent == sb->s_root->d_inode) ||
(EXT3_I(parent)->i_flags & EXT3_TOPDIR_FL)) {
@@ -539,9 +539,9 @@ got:
err = ext3_journal_dirty_metadata(handle, bh2);
if (err) goto fail;
- percpu_counter_dec(&sbi->s_freeinodes_counter);
+ atomic_long_dec(&sbi->s_freeinodes_counter);
if (S_ISDIR(mode))
- percpu_counter_inc(&sbi->s_dirs_counter);
+ atomic_long_inc(&sbi->s_dirs_counter);
sb->s_dirt = 1;
inode->i_uid = current->fsuid;
