Re: [PATCH] btrfs-progs: Drop the type check in init_alloc_chunk_ctl_policy_regular
From: Qu Wenruo <hidden>
Date: 2021-08-18 05:36:53
On 2021/8/18 下午1:27, Anand Jain wrote:
On 10/08/2021 02:26, Marcos Paulo de Souza wrote:quoted
[PROBLEM] Our documentation says that a DATA block group can have up to 1G of size, or the at most 10% of the filesystem size. Currently, by default, mkfs.btrfs is creating an initial DATA block group of 8M of size, regardless of the filesystem size. It happens because we check for the ctl->type in init_alloc_chunk_ctl_policy_regular to be one of the BTRFS_BLOCK_GROUP_PROFILE_MASK bits, which is not the case for SINGLE (default) DATA block group:quoted
$ mkfs.btrfs -f /storage/btrfs.disk btrfs-progs v4.19.1 See http://btrfs.wiki.kernel.org for more information. Label: (null) UUID: 39e3492f-41f2-4bd7-8c25-93032606b9fe Node size: 16384 Sector size: 4096 Filesystem size: 55.00GiB Block group profiles: Data: single 8.00MiB Metadata: DUP 1.00GiB System: DUP 8.00MiB SSD detected: no Incompat features: extref, skinny-metadata Number of devices: 1 Devices: ID SIZE PATH 1 55.00GiB /storage/btrfs.disk In this case, for single data profile, it should create a data block group of 1G, since the filesystem if bigger than 50G. [FIX] Remove the check for BTRFS_BLOCK_GROUP_PROFILE_MASK in init_alloc_chunk_ctl_policy_regular function. The ctl->stripe_size is later on assigned to ctl.num_bytes, which is used by btrfs_make_block_group to create the block group. By removing the check we allow the code to always configure the correct stripe_size regardless of the PROFILE, looking on the block group TYPE. With the fix applied, it now created the BG correctly: $ ./mkfs.btrfs -f /storage/btrfs.disk btrfs-progs v5.10.1 See http://btrfs.wiki.kernel.org for more information. Label: (null) UUID: 5145e343-5639-462d-82ee-3eb75dc41c31 Node size: 16384 Sector size: 4096 Filesystem size: 55.00GiB Block group profiles: Data: single 1.00GiB Metadata: DUP 1.00GiB System: DUP 8.00MiB SSD detected: no Zoned device: no Incompat features: extref, skinny-metadata Runtime features: Checksum: crc32c Number of devices: 1 Devices: ID SIZE PATH 1 55.00GiB /storage/btrfs.disk Using a disk >50G it creates a 1G single data block group. Another example: $ ./mkfs.btrfs -f /storage/btrfs2.disk btrfs-progs v5.10.1 See http://btrfs.wiki.kernel.org for more information. Label: (null) UUID: c0910857-e512-4e76-9efa-50a475aafc87 Node size: 16384 Sector size: 4096 Filesystem size: 5.00GiB Block group profiles: Data: single 512.00MiB Metadata: DUP 256.00MiB System: DUP 8.00MiB SSD detected: no Zoned device: no Incompat features: extref, skinny-metadata Runtime features: Checksum: crc32c Number of devices: 1 Devices: ID SIZE PATH 1 5.00GiB /storage/btrfs2.disk The code now created a single data block group of 512M, which is exactly 10% of the size of the filesystem, which is 5G in this case. Signed-off-by: Marcos Paulo de Souza <redacted>Looks good to me. I hope there isn't any xfstests/tests/btrfs test case that is hardcoded to the older block group alloc (like swap file test with relocation?). But then the test case will need a fix, not btrfs-progs. So
Well, fsck/025 will fail, and it's not the test case needs a fix... We just suddenly can't mkfs on a 128MiB device due to the enlarged minimal stripe length of data chunks. This still exposes a behavior difference between kernel and btrfs-progs... Thanks, Qu
Reviewed-by: Anand Jain <redacted> Thanks, Anandquoted
--- This change mimics what the kernel currently does, which is set the stripe_size regardless of the profile. Any thoughts on it? Thanks! kernel-shared/volumes.c | 40 +++++++++++++++++++--------------------- 1 file changed, 19 insertions(+), 21 deletions(-)diff --git a/kernel-shared/volumes.c b/kernel-shared/volumes.c index aeeb25fe..3677dd7c 100644 --- a/kernel-shared/volumes.c +++ b/kernel-shared/volumes.c@@ -1105,27 +1105,25 @@ static voidinit_alloc_chunk_ctl_policy_regular(struct btrfs_fs_info *info, u64 type = ctl->type; u64 percent_max; - if (type & BTRFS_BLOCK_GROUP_PROFILE_MASK) { - if (type & BTRFS_BLOCK_GROUP_SYSTEM) { - ctl->stripe_size = SZ_8M; - ctl->max_chunk_size = ctl->stripe_size * 2; - ctl->min_stripe_size = SZ_1M; - ctl->max_stripes = BTRFS_MAX_DEVS_SYS_CHUNK; - } else if (type & BTRFS_BLOCK_GROUP_DATA) { - ctl->stripe_size = SZ_1G; - ctl->max_chunk_size = 10 * ctl->stripe_size; - ctl->min_stripe_size = SZ_64M; - ctl->max_stripes = BTRFS_MAX_DEVS(info); - } else if (type & BTRFS_BLOCK_GROUP_METADATA) { - /* For larger filesystems, use larger metadata chunks */ - if (info->fs_devices->total_rw_bytes > 50ULL * SZ_1G) - ctl->max_chunk_size = SZ_1G; - else - ctl->max_chunk_size = SZ_256M; - ctl->stripe_size = ctl->max_chunk_size; - ctl->min_stripe_size = SZ_32M; - ctl->max_stripes = BTRFS_MAX_DEVS(info); - } + if (type & BTRFS_BLOCK_GROUP_SYSTEM) { + ctl->stripe_size = SZ_8M; + ctl->max_chunk_size = ctl->stripe_size * 2; + ctl->min_stripe_size = SZ_1M; + ctl->max_stripes = BTRFS_MAX_DEVS_SYS_CHUNK; + } else if (type & BTRFS_BLOCK_GROUP_DATA) { + ctl->stripe_size = SZ_1G; + ctl->max_chunk_size = 10 * ctl->stripe_size; + ctl->min_stripe_size = SZ_64M; + ctl->max_stripes = BTRFS_MAX_DEVS(info); + } else if (type & BTRFS_BLOCK_GROUP_METADATA) { + /* For larger filesystems, use larger metadata chunks */ + if (info->fs_devices->total_rw_bytes > 50ULL * SZ_1G) + ctl->max_chunk_size = SZ_1G; + else + ctl->max_chunk_size = SZ_256M; + ctl->stripe_size = ctl->max_chunk_size; + ctl->min_stripe_size = SZ_32M; + ctl->max_stripes = BTRFS_MAX_DEVS(info); } /* We don't want a chunk larger than 10% of the FS */