linux-kernel - Re: [PATCH v4 3/3] btrfs: Don't block system suspend during fstrim

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Message-ID: <9d81c1b9-60d2-419d-ae9b-96dbb92442b9@gmail.com>
Date: Mon, 16 Sep 2024 12:53:44 +0200
From: Luca Stefani <luca.stefani.ge1@...il.com>
To: Qu Wenruo <wqu@...e.com>
Cc: Chris Mason <clm@...com>, Josef Bacik <josef@...icpanda.com>,
 David Sterba <dsterba@...e.com>, linux-btrfs@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/3] btrfs: Don't block system suspend during fstrim



On 16/09/24 12:41, Qu Wenruo wrote:
> 
> 
> 在 2024/9/16 19:46, Luca Stefani 写道:
>> Sometimes the system isn't able to suspend because the task
>> responsible for trimming the device isn't able to finish in
>> time, especially since we have a free extent discarding phase,
>> which can trim a lot of unallocated space, and there is no
>> limits on the trim size (unlike the block group part).
>>
>> Since discard isn't a critical call it can be interrupted
>> at any time, in such cases we stop the trim, report the amount
>> of discarded bytes and return failure.
>>
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=219180
>> Link: https://bugzilla.suse.com/show_bug.cgi?id=1229737
>> Signed-off-by: Luca Stefani <luca.stefani.ge1@...il.com>
>> ---
>>   fs/btrfs/extent-tree.c | 19 ++++++++++++++++++-
>>   1 file changed, 18 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
>> index cbe66d0acff8..ab2e5d366a3a 100644
>> --- a/fs/btrfs/extent-tree.c
>> +++ b/fs/btrfs/extent-tree.c
>> @@ -16,6 +16,7 @@
>>   #include <linux/percpu_counter.h>
>>   #include <linux/lockdep.h>
>>   #include <linux/crc32c.h>
>> +#include <linux/freezer.h>
>>   #include "ctree.h"
>>   #include "extent-tree.h"
>>   #include "transaction.h"
>> @@ -1235,6 +1236,11 @@ static int remove_extent_backref(struct 
>> btrfs_trans_handle *trans,
>>       return ret;
>>   }
>> +static bool btrfs_trim_interrupted(void)
>> +{
>> +    return fatal_signal_pending(current) || freezing(current);
>> +}
>> +
>>   static int btrfs_issue_discard(struct block_device *bdev, u64 start, 
>> u64 len,
>>                      u64 *discarded_bytes)
>>   {
>> @@ -1319,6 +1325,11 @@ static int btrfs_issue_discard(struct 
>> block_device *bdev, u64 start, u64 len,
>>           start += bytes_to_discard;
>>           bytes_left -= bytes_to_discard;
>>           *discarded_bytes += bytes_to_discard;
>> +
>> +        if (btrfs_trim_interrupted()) {
>> +            ret = -ERESTARTSYS;
>> +            break;
>> +        }
>>       }
>>       return ret;
>> @@ -6473,7 +6484,7 @@ static int btrfs_trim_free_extents(struct 
>> btrfs_device *device, u64 *trimmed)
>>           start += len;
>>           *trimmed += bytes;
>> -        if (fatal_signal_pending(current)) {
>> +        if (btrfs_trim_interrupted()) {
>>               ret = -ERESTARTSYS;
>>               break;
>>           }
>> @@ -6522,6 +6533,9 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, 
>> struct fstrim_range *range)
>>       cache = btrfs_lookup_first_block_group(fs_info, range->start);
>>       for (; cache; cache = btrfs_next_block_group(cache)) {
>> +        if (btrfs_trim_interrupted())
>> +            break;
>> +
> 
> Please update @bg_ret return value.
Done in v5.
> 
>>           if (cache->start >= range_end) {
>>               btrfs_put_block_group(cache);
>>               break;
>> @@ -6561,6 +6575,9 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, 
>> struct fstrim_range *range)
>>       mutex_lock(&fs_devices->device_list_mutex);
>>       list_for_each_entry(device, &fs_devices->devices, dev_list) {
>> +        if (btrfs_trim_interrupted())
>> +            break;
>> +
> 
> The same here, please update @dev_ret.
ditto.
> 
> Thanks,
> Qu
>>           if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))
>>               continue;