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Wed, 11 Dec 2019 05:44:05 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 01F7CAC7D; Wed, 11 Dec 2019 10:43:59 +0000 (UTC) Subject: Re: [PATCH 4/8] btrfs: Switch to iomap_dio_rw() for dio To: Goldwyn Rodrigues , linux-btrfs@vger.kernel.org Cc: hch@infradead.org, darrick.wong@oracle.com, fdmanana@kernel.org, dsterba@suse.cz, jthumshirn@suse.de, linux-fsdevel@vger.kernel.org, Goldwyn Rodrigues References: <20191210230155.22688-1-rgoldwyn@suse.de> <20191210230155.22688-5-rgoldwyn@suse.de> 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: Date: Wed, 11 Dec 2019 12:43:56 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191210230155.22688-5-rgoldwyn@suse.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 11.12.19 г. 1:01 ч., Goldwyn Rodrigues wrote: > From: Goldwyn Rodrigues > > Switch from __blockdev_direct_IO() to iomap_dio_rw(). > Rename btrfs_get_blocks_direct() to btrfs_dio_iomap_begin() and use it > as iomap_begin() for iomap direct I/O functions. This function > allocates and locks all the blocks required for the I/O. > btrfs_submit_direct() is used as the submit_io() hook for direct I/O > ops. > > Since we need direct I/O reads to go through iomap_dio_rw(), we change > file_operations.read_iter() to a btrfs_file_read_iter() which calls > btrfs_direct_IO() for direct reads and falls back to > generic_file_buffered_read() for incomplete reads and buffered reads. > > We don't need address_space.direct_IO() anymore so set it to noop. > Similarly, we don't need flags used in __blockdev_direct_IO(). iomap is > capable of direct I/O reads from a hole, so we don't need to return > -ENOENT. > > BTRFS direct I/O is now done under i_rwsem, shared in case of > reads and exclusive in case of writes. This guards against simultaneous > truncates. > > Signed-off-by: Goldwyn Rodrigues > --- > fs/btrfs/ctree.h | 1 + > fs/btrfs/file.c | 21 ++++++- > fs/btrfs/inode.c | 184 ++++++++++++++++++++++++++----------------------------- > 3 files changed, 107 insertions(+), 99 deletions(-) > > + > +/* > + * btrfs_direct_IO - perform direct I/O > + * inode->i_rwsem must be locked before calling this function, shared or exclusive. Instead of having this as a comment which cannot easily be checked automatically I'd rather it gets codified via lockdep_assert_held. I believe this is in line with Dave's comment comment on patch 3. > + * @iocb - kernel iocb > + * @iter - iter to/from data is copied > + */ > + > +ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) > { > struct file *file = iocb->ki_filp; > struct inode *inode = file->f_mapping->host; > @@ -8662,28 +8676,13 @@ static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) > struct extent_changeset *data_reserved = NULL; > loff_t offset = iocb->ki_pos; > size_t count = 0; > - int flags = 0; > - bool wakeup = true; > bool relock = false; > ssize_t ret; > > if (check_direct_IO(fs_info, iter, offset)) > return 0; > > - inode_dio_begin(inode); > - > - /* > - * The generic stuff only does filemap_write_and_wait_range, which > - * isn't enough if we've written compressed pages to this area, so > - * we need to flush the dirty pages again to make absolutely sure > - * that any outstanding dirty pages are on disk. > - */ > count = iov_iter_count(iter); > - if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT, > - &BTRFS_I(inode)->runtime_flags)) > - filemap_fdatawrite_range(inode->i_mapping, offset, > - offset + count - 1); > - > if (iov_iter_rw(iter) == WRITE) { > /* > * If the write DIO is beyond the EOF, we need update > @@ -8714,17 +8713,11 @@ static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) > dio_data.unsubmitted_oe_range_end = (u64)offset; > current->journal_info = &dio_data; > down_read(&BTRFS_I(inode)->dio_sem); > - } else if (test_bit(BTRFS_INODE_READDIO_NEED_LOCK, > - &BTRFS_I(inode)->runtime_flags)) { > - inode_dio_end(inode); > - flags = DIO_LOCKING | DIO_SKIP_HOLES; > - wakeup = false; > } > > - ret = __blockdev_direct_IO(iocb, inode, > - fs_info->fs_devices->latest_bdev, > - iter, btrfs_get_blocks_direct, NULL, > - btrfs_submit_direct, flags); > + ret = iomap_dio_rw(iocb, iter, &btrfs_dio_iomap_ops, &btrfs_dops, > + is_sync_kiocb(iocb)); > + > if (iov_iter_rw(iter) == WRITE) { > up_read(&BTRFS_I(inode)->dio_sem); > current->journal_info = NULL; > @@ -8751,11 +8744,8 @@ static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) > btrfs_delalloc_release_extents(BTRFS_I(inode), count); > } > out: > - if (wakeup) > - inode_dio_end(inode); > if (relock) > inode_lock(inode); > - > extent_changeset_free(data_reserved); > return ret; > } > @@ -11045,7 +11035,7 @@ static const struct address_space_operations btrfs_aops = { > .writepage = btrfs_writepage, > .writepages = btrfs_writepages, > .readpages = btrfs_readpages, > - .direct_IO = btrfs_direct_IO, > + .direct_IO = noop_direct_IO, > .invalidatepage = btrfs_invalidatepage, > .releasepage = btrfs_releasepage, > .set_page_dirty = btrfs_set_page_dirty, >