From: Christoph Hellwig <hch@infradead.org> To: Qu Wenruo <quwenruo.btrfs@gmx.com> Cc: Linux FS Devel <linux-fsdevel@vger.kernel.org>, dm-devel@redhat.com, "linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org> Subject: Re: Any bio_clone_slow() implementation which doesn't share bi_io_vec? Date: Mon, 22 Nov 2021 23:43:58 -0800 [thread overview] Message-ID: <YZybvlheyLGAadFF@infradead.org> (raw) In-Reply-To: <5d8351f1-1b09-bff0-02f2-a417c1669607@gmx.com> On Tue, Nov 23, 2021 at 02:44:32PM +0800, Qu Wenruo wrote: > Hi, > > Although there are some out-of-date comments mentions other > bio_clone_*() variants, but there isn't really any other bio clone > variants other than __bio_clone_fast(), which shares bi_io_vec with the > source bio. > > This limits means we can't free the source bio before the cloned one. > > Is there any bio_clone variant which do a deep clone, including bi_io_vec? There is no use case for that, unless the actual data changes like in the bounce buffering code. > That's why the bio_clone thing is involved, there is still some corner > cases that we don't want to fail the whole large bio if there is only > one stripe failed (mostly for read bio, that we want to salvage as much > data as possible) > > Thus regular bio_split() + bio_chain() solution is not that good here. > > Any idea why no such bio_clone_slow() or bio_split_slow() provided in > block layer? > > Or really bio_split() + bio_chain() is the only recommended solution? You can use bio_split witout bio_chain. You just need your own bi_end_io handler that first performs the action you want and then contains code equivalent to __bio_chain_endio. As a bonus you can pint bi_private to whatever you want, it does not have to be the parent bio, just something that allows you to find it.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org> To: Qu Wenruo <quwenruo.btrfs@gmx.com> Cc: Linux FS Devel <linux-fsdevel@vger.kernel.org>, dm-devel@redhat.com, "linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org> Subject: Re: [dm-devel] Any bio_clone_slow() implementation which doesn't share bi_io_vec? Date: Mon, 22 Nov 2021 23:43:58 -0800 [thread overview] Message-ID: <YZybvlheyLGAadFF@infradead.org> (raw) In-Reply-To: <5d8351f1-1b09-bff0-02f2-a417c1669607@gmx.com> On Tue, Nov 23, 2021 at 02:44:32PM +0800, Qu Wenruo wrote: > Hi, > > Although there are some out-of-date comments mentions other > bio_clone_*() variants, but there isn't really any other bio clone > variants other than __bio_clone_fast(), which shares bi_io_vec with the > source bio. > > This limits means we can't free the source bio before the cloned one. > > Is there any bio_clone variant which do a deep clone, including bi_io_vec? There is no use case for that, unless the actual data changes like in the bounce buffering code. > That's why the bio_clone thing is involved, there is still some corner > cases that we don't want to fail the whole large bio if there is only > one stripe failed (mostly for read bio, that we want to salvage as much > data as possible) > > Thus regular bio_split() + bio_chain() solution is not that good here. > > Any idea why no such bio_clone_slow() or bio_split_slow() provided in > block layer? > > Or really bio_split() + bio_chain() is the only recommended solution? You can use bio_split witout bio_chain. You just need your own bi_end_io handler that first performs the action you want and then contains code equivalent to __bio_chain_endio. As a bonus you can pint bi_private to whatever you want, it does not have to be the parent bio, just something that allows you to find it. -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel
next prev parent reply other threads:[~2021-11-23 7:44 UTC|newest] Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-11-23 6:44 Any bio_clone_slow() implementation which doesn't share bi_io_vec? Qu Wenruo 2021-11-23 6:44 ` [dm-devel] " Qu Wenruo 2021-11-23 7:43 ` Christoph Hellwig [this message] 2021-11-23 7:43 ` Christoph Hellwig 2021-11-23 8:10 ` Qu Wenruo 2021-11-23 8:10 ` [dm-devel] " Qu Wenruo 2021-11-23 8:13 ` Christoph Hellwig 2021-11-23 8:13 ` [dm-devel] " Christoph Hellwig 2021-11-23 11:09 ` Qu Wenruo 2021-11-23 11:09 ` [dm-devel] " Qu Wenruo 2021-11-23 11:39 ` Johannes Thumshirn 2021-11-23 11:39 ` [dm-devel] " Johannes Thumshirn 2021-11-23 14:28 ` hch 2021-11-23 14:28 ` [dm-devel] " hch 2021-11-23 23:07 ` Qu Wenruo 2021-11-23 23:07 ` [dm-devel] " Qu Wenruo 2021-11-24 6:09 ` hch 2021-11-24 6:09 ` [dm-devel] " hch 2021-11-24 6:18 ` Qu Wenruo 2021-11-24 6:18 ` [dm-devel] " Qu Wenruo 2021-11-24 7:02 ` hch 2021-11-24 7:02 ` [dm-devel] " hch 2021-11-24 7:22 ` hch 2021-11-24 7:22 ` [dm-devel] " hch 2021-11-24 7:25 ` Naohiro Aota 2021-11-24 7:25 ` [dm-devel] " Naohiro Aota 2021-11-24 7:39 ` Qu Wenruo 2021-11-24 7:39 ` [dm-devel] " Qu Wenruo 2021-11-26 12:33 ` Qu Wenruo 2021-11-26 12:33 ` Qu Wenruo
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