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authorNaohiro Aota <naohiro.aota@wdc.com>2020-11-10 20:26:10 +0900
committerDavid Sterba <dsterba@suse.com>2020-12-09 19:16:04 +0100
commit5d1ab66c56fed152acbbac1933b16d33ebd47d7f (patch)
tree70930b6e41b3c35a4eb6f3c269d6f3329d754b6c /fs/btrfs/super.c
parent862931c76327e54d49c30d80c333f552dca18489 (diff)
downloadlinux-5d1ab66c56fed152acbbac1933b16d33ebd47d7f.tar.bz2
btrfs: disallow space_cache in ZONED mode
As updates to the space cache v1 are in-place, the space cache cannot be located over sequential zones and there is no guarantees that the device will have enough conventional zones to store this cache. Resolve this problem by disabling completely the space cache v1. This does not introduce any problems with sequential block groups: all the free space is located after the allocation pointer and no free space before the pointer. There is no need to have such cache. Note: we can technically use free-space-tree (space cache v2) on ZONED mode. But, since ZONED mode now always allocates extents in a block group sequentially regardless of underlying device zone type, it's no use to enable and maintain the tree. For the same reason, NODATACOW is also disabled. In summary, ZONED will disable: | Disabled features | Reason | |-------------------+-----------------------------------------------------| | RAID/DUP | Cannot handle two zone append writes to different | | | zones | |-------------------+-----------------------------------------------------| | space_cache (v1) | In-place updating | | NODATACOW | In-place updating | |-------------------+-----------------------------------------------------| | fallocate | Reserved extent will be a write hole | |-------------------+-----------------------------------------------------| | MIXED_BG | Allocated metadata region will be write holes for | | | data writes | Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/super.c')
-rw-r--r--fs/btrfs/super.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index b754205f21d0..7b2970c90ebe 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -565,8 +565,15 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
cache_gen = btrfs_super_cache_generation(info->super_copy);
if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE))
btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE);
- else if (cache_gen)
- btrfs_set_opt(info->mount_opt, SPACE_CACHE);
+ else if (cache_gen) {
+ if (btrfs_is_zoned(info)) {
+ btrfs_info(info,
+ "zoned: clearing existing space cache");
+ btrfs_set_super_cache_generation(info->super_copy, 0);
+ } else {
+ btrfs_set_opt(info->mount_opt, SPACE_CACHE);
+ }
+ }
/*
* Even the options are empty, we still need to do extra check
@@ -1025,6 +1032,8 @@ out:
ret = -EINVAL;
}
+ if (!ret)
+ ret = btrfs_check_mountopts_zoned(info);
if (!ret && btrfs_test_opt(info, SPACE_CACHE))
btrfs_info(info, "disk space caching is enabled");
if (!ret && btrfs_test_opt(info, FREE_SPACE_TREE))