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Mon, 25 Mar 2019 16:43:51 +0000 (UTC) Subject: Re: [PATCH v3 07/12] btrfs: replace pending/pinned chunks lists with io tree To: dsterba@suse.cz, linux-btrfs@vger.kernel.org, Jeff Mahoney References: <20190325123132.27835-1-nborisov@suse.com> <20190325123132.27835-8-nborisov@suse.com> <20190325162651.GI10640@twin.jikos.cz> From: Nikolay Borisov Openpgp: preference=signencrypt Autocrypt: addr=nborisov@suse.com; prefer-encrypt=mutual; keydata= mQINBFiKBz4BEADNHZmqwhuN6EAzXj9SpPpH/nSSP8YgfwoOqwrP+JR4pIqRK0AWWeWCSwmZ T7g+RbfPFlmQp+EwFWOtABXlKC54zgSf+uulGwx5JAUFVUIRBmnHOYi/lUiE0yhpnb1KCA7f u/W+DkwGerXqhhe9TvQoGwgCKNfzFPZoM+gZrm+kWv03QLUCr210n4cwaCPJ0Nr9Z3c582xc bCUVbsjt7BN0CFa2BByulrx5xD9sDAYIqfLCcZetAqsTRGxM7LD0kh5WlKzOeAXj5r8DOrU2 GdZS33uKZI/kZJZVytSmZpswDsKhnGzRN1BANGP8sC+WD4eRXajOmNh2HL4P+meO1TlM3GLl EQd2shHFY0qjEo7wxKZI1RyZZ5AgJnSmehrPCyuIyVY210CbMaIKHUIsTqRgY5GaNME24w7h TyyVCy2qAM8fLJ4Vw5bycM/u5xfWm7gyTb9V1TkZ3o1MTrEsrcqFiRrBY94Rs0oQkZvunqia c+NprYSaOG1Cta14o94eMH271Kka/reEwSZkC7T+o9hZ4zi2CcLcY0DXj0qdId7vUKSJjEep c++s8ncFekh1MPhkOgNj8pk17OAESanmDwksmzh1j12lgA5lTFPrJeRNu6/isC2zyZhTwMWs k3LkcTa8ZXxh0RfWAqgx/ogKPk4ZxOXQEZetkEyTFghbRH2BIwARAQABtCNOaWtvbGF5IEJv cmlzb3YgPG5ib3Jpc292QHN1c2UuY29tPokCOAQTAQIAIgUCWIo48QIbAwYLCQgHAwIGFQgC CQoLBBYCAwECHgECF4AACgkQcb6CRuU/KFc0eg/9GLD3wTQz9iZHMFbjiqTCitD7B6dTLV1C ddZVlC8Hm/TophPts1bWZORAmYIihHHI1EIF19+bfIr46pvfTu0yFrJDLOADMDH+Ufzsfy2v HSqqWV/nOSWGXzh8bgg/ncLwrIdEwBQBN9SDS6aqsglagvwFD91UCg/TshLlRxD5BOnuzfzI Leyx2c6YmH7Oa1R4MX9Jo79SaKwdHt2yRN3SochVtxCyafDlZsE/efp21pMiaK1HoCOZTBp5 VzrIP85GATh18pN7YR9CuPxxN0V6IzT7IlhS4Jgj0NXh6vi1DlmKspr+FOevu4RVXqqcNTSS E2rycB2v6cttH21UUdu/0FtMBKh+rv8+yD49FxMYnTi1jwVzr208vDdRU2v7Ij/TxYt/v4O8 V+jNRKy5Fevca/1xroQBICXsNoFLr10X5IjmhAhqIH8Atpz/89ItS3+HWuE4BHB6RRLM0gy8 T7rN6ja+KegOGikp/VTwBlszhvfLhyoyjXI44Tf3oLSFM+8+qG3B7MNBHOt60CQlMkq0fGXd mm4xENl/SSeHsiomdveeq7cNGpHi6i6ntZK33XJLwvyf00PD7tip/GUj0Dic/ZUsoPSTF/mG EpuQiUZs8X2xjK/AS/l3wa4Kz2tlcOKSKpIpna7V1+CMNkNzaCOlbv7QwprAerKYywPCoOSC 7P25Ag0EWIoHPgEQAMiUqvRBZNvPvki34O/dcTodvLSyOmK/MMBDrzN8Cnk302XfnGlW/YAQ csMWISKKSpStc6tmD+2Y0z9WjyRqFr3EGfH1RXSv9Z1vmfPzU42jsdZn667UxrRcVQXUgoKg QYx055Q2FdUeaZSaivoIBD9WtJq/66UPXRRr4H/+Y5FaUZx+gWNGmBT6a0S/GQnHb9g3nonD jmDKGw+YO4P6aEMxyy3k9PstaoiyBXnzQASzdOi39BgWQuZfIQjN0aW+Dm8kOAfT5i/yk59h VV6v3NLHBjHVw9kHli3jwvsizIX9X2W8tb1SefaVxqvqO1132AO8V9CbE1DcVT8fzICvGi42 FoV/k0QOGwq+LmLf0t04Q0csEl+h69ZcqeBSQcIMm/Ir+NorfCr6HjrB6lW7giBkQl6hhomn l1mtDP6MTdbyYzEiBFcwQD4terc7S/8ELRRybWQHQp7sxQM/Lnuhs77MgY/e6c5AVWnMKd/z MKm4ru7A8+8gdHeydrRQSWDaVbfy3Hup0Ia76J9FaolnjB8YLUOJPdhI2vbvNCQ2ipxw3Y3c KhVIpGYqwdvFIiz0Fej7wnJICIrpJs/+XLQHyqcmERn3s/iWwBpeogrx2Lf8AGezqnv9woq7 OSoWlwXDJiUdaqPEB/HmGfqoRRN20jx+OOvuaBMPAPb+aKJyle8zABEBAAGJAh8EGAECAAkF AliKBz4CGwwACgkQcb6CRuU/KFdacg/+M3V3Ti9JYZEiIyVhqs+yHb6NMI1R0kkAmzsGQ1jU zSQUz9AVMR6T7v2fIETTT/f5Oout0+Hi9cY8uLpk8CWno9V9eR/B7Ifs2pAA8lh2nW43FFwp IDiSuDbH6oTLmiGCB206IvSuaQCp1fed8U6yuqGFcnf0ZpJm/sILG2ECdFK9RYnMIaeqlNQm iZicBY2lmlYFBEaMXHoy+K7nbOuizPWdUKoKHq+tmZ3iA+qL5s6Qlm4trH28/fPpFuOmgP8P K+7LpYLNSl1oQUr+WlqilPAuLcCo5Vdl7M7VFLMq4xxY/dY99aZx0ZJQYFx0w/6UkbDdFLzN upT7NIN68lZRucImffiWyN7CjH23X3Tni8bS9ubo7OON68NbPz1YIaYaHmnVQCjDyDXkQoKC R82Vf9mf5slj0Vlpf+/Wpsv/TH8X32ajva37oEQTkWNMsDxyw3aPSps6MaMafcN7k60y2Wk/ TCiLsRHFfMHFY6/lq/c0ZdOsGjgpIK0G0z6et9YU6MaPuKwNY4kBdjPNBwHreucrQVUdqRRm RcxmGC6ohvpqVGfhT48ZPZKZEWM+tZky0mO7bhZYxMXyVjBn4EoNTsXy1et9Y1dU3HVJ8fod 5UqrNrzIQFbdeM0/JqSLrtlTcXKJ7cYFa9ZM2AP7UIN9n1UWxq+OPY9YMOewVfYtL8M= Message-ID: <75db110a-db25-e1ff-f74d-997b61532bf7@suse.com> Date: Mon, 25 Mar 2019 18:43:49 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20190325162651.GI10640@twin.jikos.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 25.03.19 г. 18:26 ч., David Sterba wrote: > On Mon, Mar 25, 2019 at 02:31:27PM +0200, Nikolay Borisov wrote: >> From: Jeff Mahoney >> >> The pending chunks list contains chunks that are allocated in the >> current transaction but haven't been created yet. The pinned chunks >> list contains chunks that are being released in the current transaction. >> Both describe chunks that are not reflected on disk as in use but are >> unavailable just the same. >> >> The pending chunks list is anchored by the transaction handle, which >> means that we need to hold a reference to a transaction when working >> with the list. >> >> We use these lists to ensure that we don't end up discarding chunks >> that are allocated or released in the current transaction. What we r >> >> The way we use them is by iterating over both lists to perform >> comparisons on the stripes they describe for each device. This is >> backwards and requires that we keep a transaction handle open while >> we're trimming. >> >> This patchset adds an extent_io_tree to btrfs_device that maintains >> the allocation state of the device. Extents are set dirty when >> chunks are first allocated -- when the extent maps are added to the >> mapping tree. They're cleared when last removed -- when the extent >> maps are removed from the mapping tree. This matches the lifespan >> of the pending and pinned chunks list and allows us to do trims >> on unallocated space safely without pinning the transaction for what >> may be a lengthy operation. We can also use this io tree to mark >> which chunks have already been trimmed so we don't repeat the operation. >> >> Signed-off-by: Nikolay Borisov >> --- >> fs/btrfs/ctree.h | 6 --- >> fs/btrfs/disk-io.c | 11 ----- >> fs/btrfs/extent-tree.c | 28 ----------- >> fs/btrfs/extent_io.c | 2 +- >> fs/btrfs/extent_io.h | 6 ++- >> fs/btrfs/extent_map.c | 36 ++++++++++++++ >> fs/btrfs/extent_map.h | 1 - >> fs/btrfs/free-space-cache.c | 4 -- >> fs/btrfs/transaction.c | 9 ---- >> fs/btrfs/transaction.h | 1 - >> fs/btrfs/volumes.c | 96 +++++++++++++------------------------ >> fs/btrfs/volumes.h | 2 + >> 12 files changed, 76 insertions(+), 126 deletions(-) >> >> --- a/fs/btrfs/extent_io.c >> +++ b/fs/btrfs/extent_io.c >> @@ -918,7 +918,7 @@ static void cache_state(struct extent_state *state, >> * [start, end] is inclusive This takes the tree lock. >> */ >> >> -static int __must_check >> +int __must_check >> __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, >> unsigned bits, unsigned exclusive_bits, >> u64 *failed_start, struct extent_state **cached_state, > > Does this really need to be exported again? There are helpers that can > wrap specific combinations of parameters. This is exported so that __set_extent_bit could be called with GFP_NOWAIT parameter otherwise I was getting lockdep splats since extent_map_device_set_bits (called from add_extent_mapping) is called under a write_lock hence we can't sleep. > >> @@ -335,6 +335,8 @@ void btrfs_free_device(struct btrfs_device *device) >> { >> WARN_ON(!list_empty(&device->post_commit_list)); >> rcu_string_free(device->name); >> + if (!in_softirq()) >> + extent_io_tree_release(&device->alloc_state); This is used to distinguish between btrfs_free_device being called from btrfs_close_devices in close_ctree i.e non rcu (hence no softirq ) context or any of the error handlers and from free_device_rcu. In the latter case the extent tree is already freed in btrfs_close_one_device, hence there is no need to do it in the RCU callback. Furthermore, there is also a comment that the extent io tree cannot be destroyed in RCU context because extent_io_tree_release calls cond_resched_lock which in turn could sleep, but this is forbidden in RCU context. > > This needs a comment > >> bio_put(device->flush_bio); >> kfree(device); >> } > > The commit is quite big but I don't see how to shrink it, the changes > need to be done in several places. So, probably ok. >