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Sun, 13 Sep 2026 16:13:26 -0700 (PDT) Received: from [172.16.0.229] ([159.196.52.54]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-39d98e602e7sm19188924a91.5.2026.09.13.16.13.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 13 Sep 2026 16:13:25 -0700 (PDT) Message-ID: <42025eb2-da6f-4319-83db-9cbd7ac3a7b9@suse.com> Date: Mon, 14 Sep 2026 08:43:19 +0930 Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 01/16] btrfs: stop enabling the v1 space cache from the on-disk state To: Tal Zussman , David Sterba , Chris Mason Cc: linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260913-btrfs-remove-v1-space-cache-v2-0-186767a7e106@columbia.edu> <20260913-btrfs-remove-v1-space-cache-v2-1-186767a7e106@columbia.edu> 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 FgIDAQIeAQIXgBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJnEXVgBQkQ/lqxAAoJEMI9kfOh Jf6o+jIH/2KhFmyOw4XWAYbnnijuYqb/obGae8HhcJO2KIGcxbsinK+KQFTSZnkFxnbsQ+VY fvtWBHGt8WfHcNmfjdejmy9si2jyy8smQV2jiB60a8iqQXGmsrkuR+AM2V360oEbMF3gVvim 2VSX2IiW9KERuhifjseNV1HLk0SHw5NnXiWh1THTqtvFFY+CwnLN2GqiMaSLF6gATW05/sEd V17MdI1z4+WSk7D57FlLjp50F3ow2WJtXwG8yG8d6S40dytZpH9iFuk12Sbg7lrtQxPPOIEU rpmZLfCNJJoZj603613w/M8EiZw6MohzikTWcFc55RLYJPBWQ+9puZtx1DopW2jOwE0EWdWB rwEIAKpT62HgSzL9zwGe+WIUCMB+nOEjXAfvoUPUwk+YCEDcOdfkkM5FyBoJs8TCEuPXGXBO Cl5P5B8OYYnkHkGWutAVlUTV8KESOIm/KJIA7jJA+Ss9VhMjtePfgWexw+P8itFRSRrrwyUf E+0WcAevblUi45LjWWZgpg3A80tHP0iToOZ5MbdYk7YFBE29cDSleskfV80ZKxFv6koQocq0 vXzTfHvXNDELAuH7Ms/WJcdUzmPyBf3Oq6mKBBH8J6XZc9LjjNZwNbyvsHSrV5bgmu/THX2n g/3be+iqf6OggCiy3I1NSMJ5KtR0q2H2Nx2Vqb1fYPOID8McMV9Ll6rh8S8AEQEAAcLAfAQY AQgAJgIbDBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJnEXWBBQkQ/lrSAAoJEMI9kfOhJf6o cakH+QHwDszsoYvmrNq36MFGgvAHRjdlrHRBa4A1V1kzd4kOUokongcrOOgHY9yfglcvZqlJ qfa4l+1oxs1BvCi29psteQTtw+memmcGruKi+YHD7793zNCMtAtYidDmQ2pWaLfqSaryjlzR /3tBWMyvIeWZKURnZbBzWRREB7iWxEbZ014B3gICqZPDRwwitHpH8Om3eZr7ygZck6bBa4MU o1XgbZcspyCGqu1xF/bMAY2iCDcq6ULKQceuKkbeQ8qxvt9hVxJC2W3lHq8dlK1pkHPDg9wO JoAXek8MF37R8gpLoGWl41FIUb3hFiu3zhDDvslYM4BmzI18QgQTQnotJH8= In-Reply-To: <20260913-btrfs-remove-v1-space-cache-v2-1-186767a7e106@columbia.edu> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2026/9/14 06:51, Tal Zussman 写道: > Since commit 545e560a5b0f ("btrfs: disable v1 space cache") the mount > options can no longer request the v1 space cache, but a filesystem with > an active v1 cache and no free space tree still enables it from > cache_generation, and remount does the same. Drop both, so SPACE_CACHE > can never be set. Oh, this is a bug in that commit, I intended to reject all v1 space cache usage, but lost the case where no "space_cache=" mount option is specified. > > btrfs_start_pre_rw_mount() then sees the on-disk cache as active but > unwanted and cleans it up, as -o nospace_cache does today. That covers > the read-only to read-write remount as well, so drop the toggle in > btrfs_remount_cleanup(), which would otherwise start a transaction on > remounts of a read-only filesystem with an old cache. > > The cleanup is now unconditional, and the first read-write mount fails > if it fails, as it did with -o nospace_cache. This also lets an old > filesystem mount without options when the page size is larger than the > sector size, which btrfs_check_features() rejected once SPACE_CACHE was > set from the superblock. > > Assisted-by: Claude:claude-fable-5-1 > Signed-off-by: Tal Zussman Reviewed-by: Qu Wenruo Thanks, Qu > --- > fs/btrfs/super.c | 16 +++------------- > 1 file changed, 3 insertions(+), 13 deletions(-) > > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c > index 464129b1b0d4..77443ded6db3 100644 > --- a/fs/btrfs/super.c > +++ b/fs/btrfs/super.c > @@ -759,12 +759,12 @@ void btrfs_set_free_space_cache_settings(struct btrfs_fs_info *fs_info) > > /* > * At this point we don't have explicit options set by the user, set > - * them ourselves based on the state of the file system. > + * them ourselves based on the state of the file system. An existing > + * v1 space cache is no longer used and gets cleaned up once the > + * filesystem is mounted read-write. > */ > if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) > btrfs_set_opt(fs_info->mount_opt, FREE_SPACE_TREE); > - else if (btrfs_free_space_cache_v1_active(fs_info)) > - btrfs_set_opt(fs_info->mount_opt, SPACE_CACHE); > } > > static void set_device_specific_options(struct btrfs_fs_info *fs_info) > @@ -1264,8 +1264,6 @@ static inline void btrfs_remount_begin(struct btrfs_fs_info *fs_info, > static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info, > unsigned long long old_opts) > { > - const bool cache_opt = btrfs_test_opt(fs_info, SPACE_CACHE); > - > /* > * We need to cleanup all defraggable inodes if the autodefragment is > * close or the filesystem is read only. > @@ -1282,10 +1280,6 @@ static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info, > else if (btrfs_raw_test_opt(old_opts, DISCARD_ASYNC) && > !btrfs_test_opt(fs_info, DISCARD_ASYNC)) > btrfs_discard_cleanup(fs_info); > - > - /* If we toggled space cache */ > - if (cache_opt != btrfs_free_space_cache_v1_active(fs_info)) > - btrfs_set_free_space_cache_v1_active(fs_info, cache_opt); > } > > static int btrfs_remount_rw(struct btrfs_fs_info *fs_info) > @@ -1535,10 +1529,6 @@ static int btrfs_reconfigure(struct fs_context *fc) > btrfs_set_opt(fs_info->mount_opt, FREE_SPACE_TREE); > btrfs_clear_opt(fs_info->mount_opt, SPACE_CACHE); > } > - if (btrfs_free_space_cache_v1_active(fs_info)) { > - btrfs_clear_opt(fs_info->mount_opt, FREE_SPACE_TREE); > - btrfs_set_opt(fs_info->mount_opt, SPACE_CACHE); > - } > } > > ret = 0; >