On 02/09/2012 11:50 PM, Lutz Euler wrote:
> Hi Liu,
> 
> thanks for looking into this!
> 
> You wrote:
> 
>> Would you please test the following patch on your box?
>>
>> thanks,
>> liubo
>>
>> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
>> index 77ea23c..b6e2c92 100644
>> --- a/fs/btrfs/extent-tree.c
>> +++ b/fs/btrfs/extent-tree.c
>> @@ -7653,9 +7653,16 @@ int btrfs_trim_fs(struct btrfs_root *root, struct 
>> fstrim_range *range)
>>      u64 start;
>>      u64 end;
>>      u64 trimmed = 0;
>> +    u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
>>      int ret = 0;
>>  
>> -    cache = btrfs_lookup_block_group(fs_info, range->start);
>> +    /*
>> +     * try to trim all FS space, our block group may start from non-zero.
>> +     */
>> +    if (range->len == total_bytes)
>> +            cache = btrfs_lookup_first_block_group(fs_info, range->start);
>> +    else
>> +            cache = btrfs_lookup_block_group(fs_info, range->start);
>>  
>>      while (cache) {
>>              if (cache->key.objectid >= (range->start + range->len)) {
>> -- 
>> 1.6.5.2
> 
> I'm sorry but that didn't help.
> I applied the patch on top of v3.3-rc2-172-g23783f8 and still fstrim
> says: "0 bytes were trimmed".
> 
> I left the printk's I mentioned in place. They show that now "cache"
> is not 0 so the "while (cache)" loop is entered but nevertheless
> "btrfs_trim_block_group" is never called. So I put in more printk's
> and found that the objectid is so large that the loop is immediately
> terminated (output of printk's in "//" comments below):
> 
> int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
> {
>       struct btrfs_fs_info *fs_info = root->fs_info;
>       struct btrfs_block_group_cache *cache = NULL;
>       u64 group_trimmed;
>       u64 start;
>       u64 end;
>       u64 trimmed = 0;
>       u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
>       int ret = 0;
> 
> // range.start = 0, .len = 160815300608, .minlen = 512
> 
>       /*
>        * try to trim all FS space, our block group may start from non-zero.
>        */
>       if (range->len == total_bytes)
>               cache = btrfs_lookup_first_block_group(fs_info, range->start);
>       else
>               cache = btrfs_lookup_block_group(fs_info, range->start);
> 
> // cache != 0
> 
>       while (cache) {
> 
> // cache->key.objectid = 213702934528
> 
>               if (cache->key.objectid >= (range->start + range->len)) {
>                       btrfs_put_block_group(cache);
>                       break;
>               }
> 
> // This line is not reached.
> 
> Here's the output of "btrfs fi show /dev/sda3" again:
> 
> failed to read /dev/sr0
> Label: none  uuid: 88af7576-3027-4a3b-a5ae-34bfd167982f
>       Total devices 2 FS bytes used 29.05GB
>       devid    4 size 74.53GB used 40.06GB path /dev/sdb1
>       devid    3 size 75.24GB used 40.06GB path /dev/sda3
> 

Hi Lutz,

Great thanks for your details, now this should be a worked one.

liubo,
thanks,

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 77ea23c..693241a 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -7653,12 +7653,22 @@ int btrfs_trim_fs(struct btrfs_root *root, struct 
fstrim_range *range)
        u64 start;
        u64 end;
        u64 trimmed = 0;
+       u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
+       bool all = false;
        int ret = 0;
 
-       cache = btrfs_lookup_block_group(fs_info, range->start);
+       /* try to trim all FS space */
+       if (range->len == total_bytes)
+               all = true;
+
+       if (all)
+               /* our block group may start from non-zero */
+               cache = btrfs_lookup_first_block_group(fs_info, range->start);
+       else
+               cache = btrfs_lookup_block_group(fs_info, range->start);
 
        while (cache) {
-               if (cache->key.objectid >= (range->start + range->len)) {
+               if (!all && cache->key.objectid >= (range->start + range->len)) 
{
                        btrfs_put_block_group(cache);
                        break;
                }
-- 
1.6.5.2



> Kind regards,
> 
> Lutz
> 

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