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[2403:580d:fda1::299]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-719449b370fsm3465567b3a.0.2024.09.16.03.39.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Sep 2024 03:39:06 -0700 (PDT) Message-ID: <98991e9d-cce0-48ad-b77c-b7d3eff71dca@suse.com> Date: Mon, 16 Sep 2024 20:09:01 +0930 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/3] btrfs: Split remaining space to discard in chunks To: Luca Stefani Cc: Chris Mason , Josef Bacik , David Sterba , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org References: <20240916101615.116164-1-luca.stefani.ge1@gmail.com> <20240916101615.116164-3-luca.stefani.ge1@gmail.com> Content-Language: en-US From: Qu Wenruo Autocrypt: addr=wqu@suse.com; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNGFF1IFdlbnJ1byA8d3F1QHN1c2UuY29tPsLAlAQTAQgAPgIbAwULCQgHAgYVCAkKCwIE FgIDAQIeAQIXgBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJjTSJVBQkNOgemAAoJEMI9kfOh Jf6oapEH/3r/xcalNXMvyRODoprkDraOPbCnULLPNwwp4wLP0/nKXvAlhvRbDpyx1+Ht/3gW p+Klw+S9zBQemxu+6v5nX8zny8l7Q6nAM5InkLaD7U5OLRgJ0O1MNr/UTODIEVx3uzD2X6MR ECMigQxu9c3XKSELXVjTJYgRrEo8o2qb7xoInk4mlleji2rRrqBh1rS0pEexImWphJi+Xgp3 dxRGHsNGEbJ5+9yK9Nc5r67EYG4bwm+06yVT8aQS58ZI22C/UeJpPwcsYrdABcisd7dddj4Q RhWiO4Iy5MTGUD7PdfIkQ40iRcQzVEL1BeidP8v8C4LVGmk4vD1wF6xTjQRKfXHOwE0EWdWB rwEIAKpT62HgSzL9zwGe+WIUCMB+nOEjXAfvoUPUwk+YCEDcOdfkkM5FyBoJs8TCEuPXGXBO Cl5P5B8OYYnkHkGWutAVlUTV8KESOIm/KJIA7jJA+Ss9VhMjtePfgWexw+P8itFRSRrrwyUf E+0WcAevblUi45LjWWZgpg3A80tHP0iToOZ5MbdYk7YFBE29cDSleskfV80ZKxFv6koQocq0 vXzTfHvXNDELAuH7Ms/WJcdUzmPyBf3Oq6mKBBH8J6XZc9LjjNZwNbyvsHSrV5bgmu/THX2n g/3be+iqf6OggCiy3I1NSMJ5KtR0q2H2Nx2Vqb1fYPOID8McMV9Ll6rh8S8AEQEAAcLAfAQY AQgAJgIbDBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJjTSJuBQkNOge/AAoJEMI9kfOhJf6o rq8H/3LJmWxL6KO2y/BgOMYDZaFWE3TtdrlIEG8YIDJzIYbNIyQ4lw61RR+0P4APKstsu5VJ 9E3WR7vfxSiOmHCRIWPi32xwbkD5TwaA5m2uVg6xjb5wbdHm+OhdSBcw/fsg19aHQpsmh1/Q bjzGi56yfTxxt9R2WmFIxe6MIDzLlNw3JG42/ark2LOXywqFRnOHgFqxygoMKEG7OcGy5wJM AavA+Abj+6XoedYTwOKkwq+RX2hvXElLZbhYlE+npB1WsFYn1wJ22lHoZsuJCLba5lehI+// ShSsZT5Tlfgi92e9P7y+I/OzMvnBezAll+p/Ly2YczznKM5tV0gboCWeusM= In-Reply-To: <20240916101615.116164-3-luca.stefani.ge1@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2024/9/16 19:46, Luca Stefani 写道: > Per Qu Wenruo in case we have a very large disk, e.g. 8TiB device, > mostly empty although we will do the split according to our super block > locations, the last super block ends at 256G, we can submit a huge > discard for the range [256G, 8T), causing a super large delay. > > We now split the space left to discard based on BTRFS_MAX_DATA_CHUNK_SIZE > in preparation of introduction of cancellation signals handling. > > 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 > --- > fs/btrfs/extent-tree.c | 24 +++++++++++++++++++----- > 1 file changed, 19 insertions(+), 5 deletions(-) > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index a5966324607d..cbe66d0acff8 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -1239,7 +1239,7 @@ static int btrfs_issue_discard(struct block_device *bdev, u64 start, u64 len, > u64 *discarded_bytes) > { > int j, ret = 0; > - u64 bytes_left, end; > + u64 bytes_left, bytes_to_discard, end; > u64 aligned_start = ALIGN(start, 1 << SECTOR_SHIFT); > > /* Adjust the range to be aligned to 512B sectors if necessary. */ > @@ -1300,13 +1300,27 @@ static int btrfs_issue_discard(struct block_device *bdev, u64 start, u64 len, > bytes_left = end - start; > } > > - if (bytes_left) { > + while (bytes_left) { > + if (bytes_left > BTRFS_MAX_DATA_CHUNK_SIZE) > + bytes_to_discard = BTRFS_MAX_DATA_CHUNK_SIZE; That MAX_DATA_CHUNK_SIZE is only possible for RAID0/RAID10/RAID5/RAID6, by spanning the device extents across multiple devices. For each device, the maximum size is limited to 1G (check init_alloc_chunk_ctl_policy_regular()). So you can just limit it to 1G instead. (If you want, you can also extract that into a macro as a cleanup). Furthermore, you can use min() instead of a if (). So you only need: bytes_to_discard = min(SZ_1G, bytes_left); Otherwise this looks good enough to me. If the 1G size is not good enough, we can later tune it to smaller values. Personally speaking I think 1G would be enough. Thanks, Qu > + else > + bytes_to_discard = bytes_left; > + > ret = blkdev_issue_discard(bdev, start >> SECTOR_SHIFT, > - bytes_left >> SECTOR_SHIFT, > + bytes_to_discard >> SECTOR_SHIFT, > GFP_NOFS); > - if (!ret) > - *discarded_bytes += bytes_left; > + > + if (ret) { > + if (ret != -EOPNOTSUPP) > + break; > + continue; > + } > + > + start += bytes_to_discard; > + bytes_left -= bytes_to_discard; > + *discarded_bytes += bytes_to_discard; > } > + > return ret; > } >