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From: David Sterba <dsterba@suse.cz>
To: Nikolay Borisov <nborisov@suse.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 3/7] btrfs: Use ihold instead of igrab in cow_file_range_async
Date: Fri, 4 Jan 2019 16:29:18 +0100	[thread overview]
Message-ID: <20190104152918.GP23615@twin.jikos.cz> (raw)
In-Reply-To: <20190103085005.32053-4-nborisov@suse.com>

On Thu, Jan 03, 2019 at 10:50:01AM +0200, Nikolay Borisov wrote:
> ihold is supposed to be used when the caller already has a reference to
> the inode. In the case of cow_file_range_async this invariants holds,
> since the 3 call chains leading to this function all take a reference:
> 
> btrfs_writepage  <--- does igrab
>  extent_write_full_page
>   __extent_writepage
>    writepage_delalloc
>      btrfs_run_delalloc_range
>       cow_file_range_async
> 
> extent_write_cache_pages <--- does igrab
>  __extent_writepage (same callchain as above)
> 
> and
> 
> submit_compressed_extents <-- already called from async CoW submit path,
> 			      which would have done ihold.
>  extent_write_locked_range
>   __extent_writepage

So by the logic the inode reference needs to be taken early, eg. in
btrfs_writepage and all low-level callbacks or helpers are fine with
ihold.

Reviewed-by: David Sterba <dsterba@suse.com>

  reply	other threads:[~2019-01-04 15:29 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-03  8:49 [PATCH 0/7] More misc fixes Nikolay Borisov
2019-01-03  8:49 ` [PATCH 1/7] btrfs: Remove inode argument from async_cow_submit Nikolay Borisov
2019-01-05  6:02   ` Anand Jain
2019-01-07 10:12   ` Johannes Thumshirn
2019-01-03  8:50 ` [PATCH 2/7] btrfs: Remove isize local variable in compress_file_range Nikolay Borisov
2019-01-05  6:17   ` Anand Jain
2019-01-07 10:17   ` Johannes Thumshirn
2019-01-07 17:41   ` David Sterba
2019-01-03  8:50 ` [PATCH 3/7] btrfs: Use ihold instead of igrab in cow_file_range_async Nikolay Borisov
2019-01-04 15:29   ` David Sterba [this message]
2019-01-03  8:50 ` [PATCH 4/7] btrfs: Remove WARN_ON in btrfs_alloc_delalloc_work Nikolay Borisov
2019-01-04 15:30   ` David Sterba
2019-01-07 10:19   ` Johannes Thumshirn
2019-01-03  8:50 ` [PATCH 5/7] btrfs: Document logic in async_cow_submit Nikolay Borisov
2019-01-03  8:50 ` [PATCH 6/7] btrfs: Replace open-coded maths with DIV_ROUND_UP Nikolay Borisov
2019-01-03 14:44   ` David Sterba
2019-01-03 15:33     ` Nikolay Borisov
2019-01-07 15:29       ` David Sterba
2019-01-03  8:50 ` [PATCH 7/7] btrfs: Refactor shrink_delalloc Nikolay Borisov
2019-01-04 15:35   ` David Sterba
2019-01-07 17:58     ` David Sterba
2019-01-07 17:59 ` [PATCH 0/7] More misc fixes David Sterba

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