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Date: Thu, 2 Jun 2011 11:50:49 +0300
From: Amir Goldstein <amir73il@...il.com>
To: Andreas Dilger <adilger.kernel@...ger.ca>
Cc: Akinobu Mita <akinobu.mita@...il.com>,
linux-kernel@...r.kernel.org, "Theodore Ts'o" <tytso@....edu>,
linux-ext4@...r.kernel.org, Yongqiang Yang <xiaoqiangnk@...il.com>
Subject: Re: [PATCH v2 1/2] ext4: arrange ext4_*_bit() macros
On Wed, Jun 1, 2011 at 11:49 PM, Andreas Dilger
<adilger.kernel@...ger.ca> wrote:
> On 2011-06-01, at 8:36 AM, Akinobu Mita wrote:
>> - remove unused ext4_{set,clear}_bit_atomic and ext4_find_first_zero_bit
FYI, one of the snapshot patches (snapshot_exclude_bitmap.patch)
uses ext4_set_bit_atomic() to set bits in the exclude bitmap when
moving blocks to snapshot file.
Since moving blocks is not done in allocation context, there is no
buddy/group lock held while manipulating the exclude bitmap.
So I would appreciate if this specific macro will not be removed.
Thanks, Yongqiang , for pointing that out.
>> - rename ext4_{set,clear}_bit to ext4_test_and_{set,clear}_bit
>> - reintroduce ext4_{set,clear}_bit for __{set,clear}_bit_le
>>
>> This changes ext4_{set,clear}_bit safely, because if someone uses
>> these macros without noticing the change, new ext4_{set,clear}_bit
>> don't have return value and causes compiler errors where the return
>> value is used.
>
> I don't think it makes sense to change all of the ext4_set_bit() calls that
> don't check the return code to use ext4_test_and_set_bit(), just to return
> them back to ext4_set_bit() in the next patch.
>
> If you want to do this in separate steps, and maintain git bisect working,
> then it would be more clear to have two patches:
>
> Patch #1: Add new ext4_test_and_set_bit() macro
> #define ext4_test_and_set_bit __test_and_set_bit_le
> {change ext4_set_bit() calls that check return to ext4_test_and_set_bit()}
>
> Patch #2: Change ext4_set_bit() to not return old bit
> #define ext4_set_bit __set_bit_le
> {nothing else changes}
>
> Alternately, you could just leave the calls that do not check the return
> value as ext4_set_bit() and have only a single patch.
>
>
>> Signed-off-by: Akinobu Mita <akinobu.mita@...il.com>
>> Cc: "Theodore Ts'o" <tytso@....edu>
>> Cc: Andreas Dilger <adilger.kernel@...ger.ca>
>> Cc: linux-ext4@...r.kernel.org
>> ---
>> v2: rewritten to keep ext4_*_bit() macros
>>
>> fs/ext4/balloc.c | 8 ++++----
>> fs/ext4/ext4.h | 9 ++++-----
>> fs/ext4/ialloc.c | 9 ++++-----
>> fs/ext4/mballoc.c | 4 ++--
>> fs/ext4/resize.c | 12 ++++++------
>> 5 files changed, 20 insertions(+), 22 deletions(-)
>>
>> diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
>> index 264f694..b6747e4 100644
>> --- a/fs/ext4/balloc.c
>> +++ b/fs/ext4/balloc.c
>> @@ -144,7 +144,7 @@ unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
>> int flex_bg = 0;
>>
>> for (bit = 0; bit < bit_max; bit++)
>> - ext4_set_bit(bit, bh->b_data);
>> + ext4_test_and_set_bit(bit, bh->b_data);
>>
>> start = ext4_group_first_block_no(sb, block_group);
>>
>> @@ -155,18 +155,18 @@ unsigned 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_test_and_set_bit(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_test_and_set_bit(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_test_and_set_bit(tmp - start, bh->b_data);
>> }
>> /*
>> * Also if the number of blocks within the group is
>> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
>> index 1921392..04db84f 100644
>> --- a/fs/ext4/ext4.h
>> +++ b/fs/ext4/ext4.h
>> @@ -930,12 +930,11 @@ struct ext4_inode_info {
>> #define test_opt2(sb, opt) (EXT4_SB(sb)->s_mount_opt2 & \
>> EXT4_MOUNT2_##opt)
>>
>> -#define ext4_set_bit __test_and_set_bit_le
>> -#define ext4_set_bit_atomic ext2_set_bit_atomic
>> -#define ext4_clear_bit __test_and_clear_bit_le
>> -#define ext4_clear_bit_atomic ext2_clear_bit_atomic
>> +#define ext4_test_and_set_bit __test_and_set_bit_le
>> +#define ext4_set_bit __set_bit_le
>> +#define ext4_test_and_clear_bit __test_and_clear_bit_le
>> +#define ext4_clear_bit __clear_bit_le
>> #define ext4_test_bit test_bit_le
>> -#define ext4_find_first_zero_bit find_first_zero_bit_le
>> #define ext4_find_next_zero_bit find_next_zero_bit_le
>> #define ext4_find_next_bit find_next_bit_le
>>
>> diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
>> index 21bb2f6..90bef6b 100644
>> --- a/fs/ext4/ialloc.c
>> +++ b/fs/ext4/ialloc.c
>> @@ -59,7 +59,7 @@ void ext4_mark_bitmap_end(int start_bit, int end_bit, char *bitmap)
>>
>> ext4_debug("mark end bits +%d through +%d used\n", start_bit, end_bit);
>> for (i = start_bit; i < ((start_bit + 7) & ~7UL); i++)
>> - ext4_set_bit(i, bitmap);
>> + ext4_test_and_set_bit(i, bitmap);
>> if (i < end_bit)
>> memset(bitmap + (i >> 3), 0xff, (end_bit - i) >> 3);
>> }
>> @@ -252,7 +252,7 @@ void ext4_free_inode(handle_t *handle, struct inode *inode)
>> fatal = ext4_journal_get_write_access(handle, bh2);
>> }
>> ext4_lock_group(sb, block_group);
>> - cleared = ext4_clear_bit(bit, bitmap_bh->b_data);
>> + cleared = ext4_test_and_clear_bit(bit, bitmap_bh->b_data);
>> if (fatal || !cleared) {
>> ext4_unlock_group(sb, block_group);
>> goto out;
>> @@ -729,7 +729,7 @@ static int ext4_claim_inode(struct super_block *sb,
>> */
>> down_read(&grp->alloc_sem);
>> ext4_lock_group(sb, group);
>> - if (ext4_set_bit(ino, inode_bitmap_bh->b_data)) {
>> + if (ext4_test_and_set_bit(ino, inode_bitmap_bh->b_data)) {
>> /* not a free inode */
>> retval = 1;
>> goto err_ret;
>> @@ -884,8 +884,7 @@ got_group:
>> goto fail;
>>
>> repeat_in_this_group:
>> - ino = ext4_find_next_zero_bit((unsigned long *)
>> - inode_bitmap_bh->b_data,
>> + ino = ext4_find_next_zero_bit(inode_bitmap_bh->b_data,
>> EXT4_INODES_PER_GROUP(sb), ino);
>>
>> if (ino < EXT4_INODES_PER_GROUP(sb)) {
>> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
>> index 859f2ae..b423adf 100644
>> --- a/fs/ext4/mballoc.c
>> +++ b/fs/ext4/mballoc.c
>> @@ -384,13 +384,13 @@ static inline int mb_test_bit(int bit, void *addr)
>> static inline void mb_set_bit(int bit, void *addr)
>> {
>> addr = mb_correct_addr_and_bit(&bit, addr);
>> - ext4_set_bit(bit, addr);
>> + ext4_test_and_set_bit(bit, addr);
>> }
>>
>> static inline void mb_clear_bit(int bit, void *addr)
>> {
>> addr = mb_correct_addr_and_bit(&bit, addr);
>> - ext4_clear_bit(bit, addr);
>> + ext4_test_and_clear_bit(bit, addr);
>> }
>>
>> static inline int mb_find_next_zero_bit(void *addr, int max, int start)
>> diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
>> index 80bbc9c..cc40963 100644
>> --- a/fs/ext4/resize.c
>> +++ b/fs/ext4/resize.c
>> @@ -194,7 +194,7 @@ static int setup_new_group_blocks(struct super_block *sb,
>>
>> if (ext4_bg_has_super(sb, input->group)) {
>> ext4_debug("mark backup superblock %#04llx (+0)\n", start);
>> - ext4_set_bit(0, bh->b_data);
>> + ext4_test_and_set_bit(0, bh->b_data);
>> }
>>
>> /* Copy all of the GDT blocks into the backup in this group */
>> @@ -225,7 +225,7 @@ static int setup_new_group_blocks(struct super_block *sb,
>> brelse(gdb);
>> goto exit_bh;
>> }
>> - ext4_set_bit(bit, bh->b_data);
>> + ext4_test_and_set_bit(bit, bh->b_data);
>> brelse(gdb);
>> }
>>
>> @@ -237,14 +237,14 @@ static int setup_new_group_blocks(struct super_block *sb,
>> if (err)
>> goto exit_bh;
>> for (i = 0, bit = gdblocks + 1; i < reserved_gdb; i++, bit++)
>> - ext4_set_bit(bit, bh->b_data);
>> + ext4_test_and_set_bit(bit, bh->b_data);
>>
>> 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_test_and_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);
>> + ext4_test_and_set_bit(input->inode_bitmap - start, bh->b_data);
>>
>> /* Zero out all of the inode table blocks */
>> block = input->inode_table;
>> @@ -255,7 +255,7 @@ static int setup_new_group_blocks(struct super_block *sb,
>> goto exit_bh;
>> for (i = 0, bit = input->inode_table - start;
>> i < sbi->s_itb_per_group; i++, bit++)
>> - ext4_set_bit(bit, bh->b_data);
>> + ext4_test_and_set_bit(bit, bh->b_data);
>>
>> if ((err = extend_or_restart_transaction(handle, 2, bh)))
>> goto exit_bh;
>> --
>> 1.7.4.4
>>
>
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