linux-ext4 - Re: [PATCH RFC 05/30] ext4: snapshot hooks

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Date:	Tue, 7 Jun 2011 16:24:44 +0300
From:	"Amir G." <amir73il@...rs.sourceforge.net>
To:	Lukas Czerner <lczerner@...hat.com>
Cc:	linux-ext4@...r.kernel.org, tytso@....edu,
	Amir Goldstein <amir73il@...rs.sf.net>,
	Yongqiang Yang <xiaoqiangnk@...il.com>
Subject: Re: [PATCH RFC 05/30] ext4: snapshot hooks - delete blocks

On Tue, Jun 7, 2011 at 2:24 PM, Lukas Czerner <lczerner@...hat.com> wrote:
> On Mon, 9 May 2011, amir73il@...rs.sourceforge.net wrote:
>
>> From: Amir Goldstein <amir73il@...rs.sf.net>
>>
>> Before deleting file blocks in ext4_free_blocks(),
>> we call the snapshot API ext4_snapshot_get_delete_access(),
>> to optionally move the block to the snapshot file instead of
>> freeing them.
>>
>> Signed-off-by: Amir Goldstein <amir73il@...rs.sf.net>
>> Signed-off-by: Yongqiang Yang <xiaoqiangnk@...il.com>
>> ---
>>  fs/ext4/ext4.h    |   10 +++++++---
>>  fs/ext4/mballoc.c |   30 +++++++++++++++++++++++++++---
>>  2 files changed, 34 insertions(+), 6 deletions(-)
>>
>> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
>> index ca25e67..4e9e46a 100644
>> --- a/fs/ext4/ext4.h
>> +++ b/fs/ext4/ext4.h
>> @@ -1729,9 +1729,13 @@ extern int ext4_mb_reserve_blocks(struct super_block *, int);
>>  extern void ext4_discard_preallocations(struct inode *);
>>  extern int __init ext4_init_mballoc(void);
>>  extern void ext4_exit_mballoc(void);
>> -extern void ext4_free_blocks(handle_t *handle, struct inode *inode,
>> -                          struct buffer_head *bh, ext4_fsblk_t block,
>> -                          unsigned long count, int flags);
>> +extern void __ext4_free_blocks(const char *where, unsigned int line,
>> +                            handle_t *handle,  struct inode *inode,
>> +                            struct buffer_head *bh, ext4_fsblk_t block,
>> +                            unsigned long count, int flags);
>> +#define ext4_free_blocks(handle, inode, bh, block, count, flags) \
>> +     __ext4_free_blocks(__func__, __LINE__ , (handle), (inode), (bh), \
>> +                        (block), (count), (flags))
>>  extern int ext4_mb_add_groupinfo(struct super_block *sb,
>>               ext4_group_t i, struct ext4_group_desc *desc);
>>  extern int ext4_trim_fs(struct super_block *, struct fstrim_range *);
>> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
>> index e8bfd8d..3b1c6d1 100644
>> --- a/fs/ext4/mballoc.c
>> +++ b/fs/ext4/mballoc.c
>> @@ -4445,9 +4445,9 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
>>   * @count:           number of blocks to count
>>   * @metadata:                Are these metadata blocks
>>   */
>> -void ext4_free_blocks(handle_t *handle, struct inode *inode,
>> -                   struct buffer_head *bh, ext4_fsblk_t block,
>> -                   unsigned long count, int flags)
>> +void __ext4_free_blocks(const char *where, unsigned int line, handle_t *handle,
>> +                     struct inode *inode, struct buffer_head *bh,
>> +                     ext4_fsblk_t block, unsigned long count, int flags)
>>  {
>>       struct buffer_head *bitmap_bh = NULL;
>>       struct super_block *sb = inode->i_sb;
>> @@ -4461,6 +4461,7 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode,
>>       struct ext4_buddy e4b;
>>       int err = 0;
>>       int ret;
>> +     int maxblocks;
>>
>>       if (bh) {
>>               if (block)
>> @@ -4543,6 +4544,29 @@ do_more:
>>               goto error_return;
>>       }
>>
>> +     maxblocks = count;
>> +     ret = ext4_snapshot_get_delete_access(handle, inode,
>> +                                           block, &maxblocks);
>
> It would be nice to have this defined in the same commit, so I know what
> is it doing.

Sorry, full patches again :-/
I will post them soon without any fixes, so you can have a look.

>
>> +     if (ret < 0) {
>> +             ext4_journal_abort_handle(where, line, __func__,
>> +                                       NULL, handle, ret);
>> +             err = ret;
>> +             goto error_return;
>> +     }
>> +     if (ret > 0) {
>> +             /* 'ret' blocks were moved to snapshot - skip them */
>> +             block += maxblocks;
>> +             count -= maxblocks;
>> +             count += overflow;
>> +             cond_resched();
>> +             if (count > 0)
>> +                     goto do_more;
>> +             /* no more blocks to free/move to snapshot */
>> +             ext4_mark_super_dirty(sb);
>> +             goto error_return;
>> +     }
>> +     overflow += count - maxblocks;
>> +     count = maxblocks;
>>       BUFFER_TRACE(bitmap_bh, "getting write access");
>>       err = ext4_handle_get_bitmap_access(handle, sb, block_group, bitmap_bh);
>>       if (err)
>>
>
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