From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0591533688A for ; Fri, 16 Oct 2026 15:49:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792165795; cv=none; b=sm7TRZsuhFr46w7fGf1t256m5AvcSzIWyPi3GFmbkp7dCFGfGpQ30ZfBcWHvgnI5HHBUA8KSs8irzKXsiyNMU/d/EvFW1SJgpmUuzBchT4NCFvcPvceCLdCLUqd/Ce4gZBmN+s/duWIPyq9v149z9Nba1pZnjeHQD9JU+CXXkfQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792165795; c=relaxed/simple; bh=5llZ0LIRGBcTgGcaQCLHrtSkrcwcNYvPsxspljIO49Y=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=kzw6NobGF4AEnysduT8p4RHomcxSnBNGEL1CdlsjLyFOf2zuxOfsofhDi9CTakLZV2uad/X2R7IyjkFtLmmIYFI8lKSEa4wMhqpGRst8f1g+mKZKf+myFF1FjnmAJWrdIKc5LKj19oPRoeltRNs8yLXOJ/UV+UDwQ3mniW2ZUu0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=f5cYgEAJ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="f5cYgEAJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 714F51F000C4; Fri, 16 Oct 2026 15:49:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792165793; bh=VFe1fLdI/OdtPw9A1tg+WIziI3PtzKffGPIYi2NBVBo=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=f5cYgEAJn+mlwdohsMTn0zFCemDGQ9v8z3oa0vwZeOTM0HxGC4KHJ4z89Zt8X6SIC uVOvogv0C0cEOmyACROFLNR0pODelo7ZTKHuUbJ1BUggjejcJ+KGyVYSbAONk98lgV 50p6HtVxk359nXbJj0EnbHVMzoN6UFwIQaOEHQUectk4GDYrKHIdE4PBSWw5H7k01Y 3dYIJDHVhp4wLIz53CRKmH1KplmJuEwoHD3wmXth9l2za2BJkjdeFJow+d83544xgQ pVfrICC+WKppEO+LohhiUVDa3iPPQ7pXMi/7cDNeU+eGmArbgJKPM8PECsvITd2Gqf qLzGZvPaq0IbQ== Date: Fri, 16 Oct 2026 15:49:51 +0000 From: Jaegeuk Kim To: Chao Yu Cc: Daeho Jeong , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com, Daeho Jeong Subject: Re: [f2fs-dev] [PATCH v2 2/2] f2fs: introduce reserve_shrink mount option for filesystem shrinkage Message-ID: References: <20260911143549.909867-1-daeho43@gmail.com> <20260911143549.909867-2-daeho43@gmail.com> <3e5f2bd4-f0e6-4f79-b182-6cb8ac331580@kernel.org> <0aedc5af-1273-4510-a8fa-5ddf2281b699@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <0aedc5af-1273-4510-a8fa-5ddf2281b699@kernel.org> Are we waiting for v3 along with sysfs's feature flag, right? On 10/14, Chao Yu wrote: > On 10/14/26 07:27, Daeho Jeong wrote: > > On Tue, Oct 13, 2026 at 8:36 AM Daeho Jeong wrote: > >> > >> On Mon, Oct 12, 2026 at 7:15 PM Daeho Jeong wrote: > >>> > >>> On Mon, Oct 12, 2026 at 6:27 PM Chao Yu wrote: > >>>> > >>>> On 9/15/26 00:24, Daeho Jeong wrote: > >>>>> On Mon, Sep 14, 2026 at 12:15 AM Chao Yu wrote: > >>>>>> > >>>>>> On 9/11/26 22:35, Daeho Jeong wrote: > >>>>>>> From: Daeho Jeong > >>>>>>> > >>>>>>> When preparing for subsequent online filesystem shrinkage (e.g., during > >>>>>>> partition resizing or FOTA updates), sufficient free space must be > >>>>>>> preserved so that valid data blocks can be evacuated and the filesystem > >>>>>>> can safely shrink. > >>>>>>> > >>>>>>> Existing reserve_root cannot prevent space exhaustion by privileged root > >>>>>>> processes (such as OTA updaters, package managers, and system daemons > >>>>>>> running with CAP_SYS_RESOURCE), which can allocate blocks from the root > >>>>>>> reserve and lead to resize failures due to lack of space. Moreover, > >>>>>> > >>>>>> I'm thinking about reusing existing mount option AMAP, is there any problem > >>>>>> to use "reserve_root=" w/ 128mb+shrunk_size_mb when we execute online filesyste > >>>>>> shrinkage? once it is done, recover w/ reserve_root=128mb. > >>>>>> > >>>>>>> runtime configurable reserved_blocks represents permanent GC and metadata > >>>>>>> headroom that must persist after resize, which would cause double-counting > >>>>>>> if inflated for shrinkage. > >>>>>> > >>>>>> I didn't get it, can you please explain a bit more about this issue? > >>>>>> > >>>>>> Thanks, > >>>>> > >>>>> Hi Chao, > >>>>> > >>>>> There are three main reasons why reserve_root cannot be reused: > >>>>> > >>>>> 1. Double-counting in f2fs_resize_fs(): > >>>>> f2fs_resize_fs() checks: > >>>>> shrunk_blocks + valid_user_blocks + root_reserved_blocks + ... > > >>>>> user_block_count > >>>>> Since root_reserved_blocks must persist after > >>>>> resize, inflating it by shrunk_size causes shrunk_size to be counted twice, > >>>>> requiring 2x free space and triggering false -ENOSPC. Resetting it right before > >>>>> resize also introduces a race window where concurrent writes can > >>>>> consume the space. > >>>>> 2. Root can allocate from reserve_root: > >>>>> reserve_root allows root/CAP_SYS_RESOURCE processes to allocate. During OTA, > >>>>> system daemons and updaters can eat into the reserved blocks. > >>>>> reserve_shrink strictly blocks all callers, including root. > >>>> > >>>> Daeho, sorry for the delay. > >>>> > >>>> Thanks for the explanation, I see, it's not appropriate to reuse > >>>> "reserve_root=" option for your requirement. > >>>> > >>>> May I ask that do you need to keep the reservation for a long time before resize, > >>>> e.g. from OTA starts till shrink happens? or is it enough to make it reserved > >>>> during f2fs_resize_fs()? > >>>> > >>>> If the latter, can we just reserve shrunk_blocks in f2fs_resize_fs() > >>>> directly, w/ the same way we did for f2fs_ioc_reserve_dev_alias()? Then > >>>> we don't need a new mount option. Something like: > >>>> > >>>> f2fs_resize_fs() > >>>> spin_lock(&sbi->stat_lock); > >>>> if (shrunk_blocks + valid_user_blocks(sbi) + ... > sbi->user_block_count) > >>>> err = -ENOSPC; > >>>> else > >>>> sbi->resize_reserved_blocks += shrunk_blocks; > >>>> spin_unlock(&sbi->stat_lock); > >>>> > >>>> free_segment_range(sbi, secs, true); > >>>> ... > >>>> freeze_super(); > >>>> ... > >>>> spin_lock(&sbi->stat_lock); > >>>> sbi->user_block_count -= shrunk_blocks; > >>>> sbi->resize_reserved_blocks -= shrunk_blocks; > >>>> spin_unlock(&sbi->stat_lock); > >>>> ... > >>>> /* error path: sbi->resize_reserved_blocks -= shrunk_blocks */ > >>>> > >>>> and in get_available_block_count(), deduct resize_reserved_blocks as we did for > >>>> alias_reserved_blocks, so that no one, including root, can allocate from the > >>>> reserved space during resize. > >>>> > >>>> Thanks, > >>> > >>> Hi Chao, > >>> > >>> Thanks for the suggestion. > >>> > >>> Unfortunately, reserving only inside f2fs_resize_fs() is not enough for > >>> our use case. We need the reservation to be in place for a long time > >>> before the resize, i.e. from the moment we decide to shrink (mount time) > >>> until F2FS_IOC_RESIZE_FS is actually issued. During that window, > >>> privileged processes (OTA updater, package manager, system daemons) keep > >>> writing to the filesystem. If they consume the free space, the ENOSPC > >>> check at the entry of f2fs_resize_fs() fails right away, so there is no > >>> chance to reserve anything inside the ioctl. Also, statfs would keep > >>> reporting space that is going to be cut off. > >>> > >>> That's why it's a mount option: the reservation is applied before any > >>> userspace write can happen, it's honored for all callers including root, > >>> it's reflected in statfs, and it's released automatically once the > >>> shrink succeeds. > >>> > >>> Thanks, > >> > >> Plus, > >> > >> Please think about the FOTA scenario below: > >> > >> 1) The device downloads the FOTA image. At this point, we check that > >> there is enough free space for the shrink. > >> 2) The device reboots to apply the update. > >> 3) After the reboot, /data is mounted and F2FS_IOC_RESIZE_FS is issued > >> to shrink the filesystem. > >> > >> Between 1) and 3), there is a long window that also spans a reboot. > >> > >> Thanks, > > > > Hi Chao, > > > > Sorry for the confusion. Our scenario has recently changed. > > > > Now the shrink is triggered at OTA install time, before the reboot: the > > updater figures out how much space the new partitions need, and issues > > F2FS_IOC_RESIZE_FS on the mounted /data right away. So we don't need to > > keep the reservation for a long time before the resize anymore. What we > > need is to protect the space during f2fs_resize_fs(), between the > > dry-run GC and freeze_super(), where other processes (including root) > > can consume it. > > > > So your suggestion fits the new scenario better. I'll drop the > > reserve_shrink mount option, and send a new patch that reserves > > shrunk_blocks inside f2fs_resize_fs() and deducts it in > > get_available_block_count() for all callers. > > Hi Daeho, > > I see, thanks for the sync-up. > > BTW, could you please add above background information into commit message? > I think it can help developer/reviewer to know more background info. > > Thanks, > > > > > Thanks for the review, > > > >> > >>> > >>>> > >>>>> > >>>>> Thanks, > >>>>> Daeho > >>>>> > >>>>>> > >>>>>>> > >>>>>>> To resolve this, introduce a dedicated reserve_shrink= > >>>>>>> mount option: > >>>>>>> 1. Symmetrically mirrors reserve_root= in block units to > >>>>>>> pre-reserve space specifically for subsequent filesystem shrinkage. > >>>>>>> 2. In get_available_block_count(), unconditionally deducts > >>>>>>> reserve_shrink_blocks for all callers, strictly rejecting all > >>>>>>> allocations (including root / CAP_SYS_RESOURCE) once available blocks > >>>>>>> are exhausted. > >>>>>>> 3. In f2fs_statfs(), deducts reserve_shrink_blocks from f_bfree (and > >>>>>>> f_bavail) so that filesystem statistics accurately reflect usable space. > >>>>>>> 4. In f2fs_resize_fs(), automatically resets reserve_shrink_blocks to 0 > >>>>>>> and clears F2FS_MOUNT_RESERVE_SHRINK upon successful shrink completion, > >>>>>>> releasing any remaining reservation. > >>>>>>> 5. In sysfs: reserved_blocks, subtracts reserve_shrink_blocks when > >>>>>>> validating the upper limit of configurable reserved blocks. > >>>>>>> > >>>>>>> Signed-off-by: Daeho Jeong > >>>>>>> --- > >>>>>>> v2: > >>>>>>> - Split out mount option bitmask expansion (BIT_ULL) into a separate > >>>>>>> prerequisite patch (Patch 1/2). > >>>>>>> --- > >>>>>>> Documentation/filesystems/f2fs.rst | 7 +++++ > >>>>>>> fs/f2fs/f2fs.h | 9 ++++++ > >>>>>>> fs/f2fs/gc.c | 5 ++++ > >>>>>>> fs/f2fs/super.c | 47 ++++++++++++++++++++++++++++++ > >>>>>>> fs/f2fs/sysfs.c | 13 +++++++-- > >>>>>>> 5 files changed, 79 insertions(+), 2 deletions(-) > >>>>>>> > >>>>>>> diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst > >>>>>>> index 771216f45207..dbdc5d5a83ad 100644 > >>>>>>> --- a/Documentation/filesystems/f2fs.rst > >>>>>>> +++ b/Documentation/filesystems/f2fs.rst > >>>>>>> @@ -191,6 +191,13 @@ reserve_node=%d Support configuring reserved nodes which are used for > >>>>>>> gid, the default limit is 12.5% of all nodes. > >>>>>>> resuid=%d The user ID which may use the reserved blocks and nodes. > >>>>>>> resgid=%d The group ID which may use the reserved blocks and nodes. > >>>>>>> +reserve_shrink=%d Support pre-reserving space for subsequent filesystem > >>>>>>> + shrinkage (e.g. during partition resizing or FOTA), > >>>>>>> + unit: blocks. Unlike reserve_root, allocations from > >>>>>>> + this reserved space strictly reject all callers > >>>>>>> + (including root / CAP_SYS_RESOURCE). Once the > >>>>>>> + filesystem is successfully shrunk via resize, this > >>>>>>> + value is automatically reset to 0. > >>>>>>> fault_injection=%d Enable fault injection in all supported types with > >>>>>>> specified injection rate. > >>>>>>> fault_type=%d Support configuring fault injection type, should be > >>>>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > >>>>>>> index 4aaf29de3f6f..48a91771be95 100644 > >>>>>>> --- a/fs/f2fs/f2fs.h > >>>>>>> +++ b/fs/f2fs/f2fs.h > >>>>>>> @@ -145,6 +145,7 @@ enum f2fs_mount_opt { > >>>>>>> */ > >>>>>>> F2FS_MOUNT_LAZYTIME, > >>>>>>> F2FS_MOUNT_RESERVE_NODE, > >>>>>>> + F2FS_MOUNT_RESERVE_SHRINK, > >>>>>>> }; > >>>>>>> > >>>>>>> #define F2FS_OPTION(sbi) ((sbi)->mount_opt) > >>>>>>> @@ -226,6 +227,7 @@ struct f2fs_mount_info { > >>>>>>> unsigned long long opt; > >>>>>>> block_t root_reserved_blocks; /* root reserved blocks */ > >>>>>>> block_t root_reserved_nodes; /* root reserved nodes */ > >>>>>>> + block_t reserve_shrink_blocks; /* reserve blocks for shrink */ > >>>>>>> kuid_t s_resuid; /* reserved blocks for uid */ > >>>>>>> kgid_t s_resgid; /* reserved blocks for gid */ > >>>>>>> int active_logs; /* # of active logs */ > >>>>>>> @@ -2658,6 +2660,13 @@ static inline unsigned int get_available_block_count(struct f2fs_sb_info *sbi, > >>>>>>> if (test_opt(sbi, RESERVE_ROOT) && !__allow_reserved_root(sbi, inode, cap)) > >>>>>>> avail_user_block_count -= F2FS_OPTION(sbi).root_reserved_blocks; > >>>>>>> > >>>>>>> + if (test_opt(sbi, RESERVE_SHRINK)) { > >>>>>>> + if (avail_user_block_count > F2FS_OPTION(sbi).reserve_shrink_blocks) > >>>>>>> + avail_user_block_count -= F2FS_OPTION(sbi).reserve_shrink_blocks; > >>>>>>> + else > >>>>>>> + avail_user_block_count = 0; > >>>>>>> + } > >>>>>>> + > >>>>>>> if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) { > >>>>>>> if (avail_user_block_count > sbi->unusable_block_count) > >>>>>>> avail_user_block_count -= sbi->unusable_block_count; > >>>>>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c > >>>>>>> index bc22dde1cb30..556c4793478d 100644 > >>>>>>> --- a/fs/f2fs/gc.c > >>>>>>> +++ b/fs/f2fs/gc.c > >>>>>>> @@ -2492,6 +2492,11 @@ int f2fs_resize_fs(struct file *filp, __u64 block_count) > >>>>>>> spin_lock(&sbi->stat_lock); > >>>>>>> sbi->user_block_count += shrunk_blocks; > >>>>>>> spin_unlock(&sbi->stat_lock); > >>>>>>> + } else if (test_opt(sbi, RESERVE_SHRINK)) { > >>>>>>> + spin_lock(&sbi->stat_lock); > >>>>>>> + F2FS_OPTION(sbi).reserve_shrink_blocks = 0; > >>>>>>> + clear_opt(sbi, RESERVE_SHRINK); > >>>>>>> + spin_unlock(&sbi->stat_lock); > >>>>>>> } > >>>>>>> out_err: > >>>>>>> f2fs_up_write_trace(&sbi->cp_global_sem, &clc); > >>>>>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c > >>>>>>> index a5e109bdcebc..58f33750b2a8 100644 > >>>>>>> --- a/fs/f2fs/super.c > >>>>>>> +++ b/fs/f2fs/super.c > >>>>>>> @@ -196,6 +196,7 @@ enum { > >>>>>>> Opt_data_flush, > >>>>>>> Opt_reserve_root, > >>>>>>> Opt_reserve_node, > >>>>>>> + Opt_reserve_shrink, > >>>>>>> Opt_resgid, > >>>>>>> Opt_resuid, > >>>>>>> Opt_mode, > >>>>>>> @@ -328,6 +329,7 @@ static const struct fs_parameter_spec f2fs_param_specs[] = { > >>>>>>> fsparam_flag("data_flush", Opt_data_flush), > >>>>>>> fsparam_u32("reserve_root", Opt_reserve_root), > >>>>>>> fsparam_u32("reserve_node", Opt_reserve_node), > >>>>>>> + fsparam_u32("reserve_shrink", Opt_reserve_shrink), > >>>>>>> fsparam_gid("resgid", Opt_resgid), > >>>>>>> fsparam_uid("resuid", Opt_resuid), > >>>>>>> fsparam_enum("mode", Opt_mode, f2fs_param_mode), > >>>>>>> @@ -407,6 +409,7 @@ static match_table_t f2fs_checkpoint_tokens = { > >>>>>>> #define F2FS_SPEC_lookup_mode (1 << 24) > >>>>>>> #define F2FS_SPEC_reserve_node (1 << 25) > >>>>>>> #define F2FS_SPEC_resizable_tail_secno (1 << 26) > >>>>>>> +#define F2FS_SPEC_reserve_shrink (1 << 27) > >>>>>>> > >>>>>>> struct f2fs_fs_context { > >>>>>>> struct f2fs_mount_info info; > >>>>>>> @@ -550,6 +553,27 @@ static inline void limit_reserve_root(struct f2fs_sb_info *sbi) > >>>>>>> F2FS_OPTION(sbi).s_resgid)); > >>>>>>> } > >>>>>>> > >>>>>>> +static inline void limit_reserve_shrink(struct f2fs_sb_info *sbi) > >>>>>>> +{ > >>>>>>> + block_t block_limit; > >>>>>>> + > >>>>>>> + if (!test_opt(sbi, RESERVE_SHRINK)) > >>>>>>> + return; > >>>>>>> + > >>>>>>> + block_limit = sbi->user_block_count - sbi->reserved_blocks; > >>>>>>> + if (test_opt(sbi, RESERVE_ROOT)) { > >>>>>>> + if (block_limit > F2FS_OPTION(sbi).root_reserved_blocks) > >>>>>>> + block_limit -= F2FS_OPTION(sbi).root_reserved_blocks; > >>>>>>> + else > >>>>>>> + block_limit = 0; > >>>>>>> + } > >>>>>>> + if (F2FS_OPTION(sbi).reserve_shrink_blocks > block_limit) { > >>>>>>> + F2FS_OPTION(sbi).reserve_shrink_blocks = block_limit; > >>>>>>> + f2fs_info(sbi, "Reduce reserved blocks for shrink = %u", > >>>>>>> + F2FS_OPTION(sbi).reserve_shrink_blocks); > >>>>>>> + } > >>>>>>> +} > >>>>>>> + > >>>>>>> static inline void adjust_unusable_cap_perc(struct f2fs_sb_info *sbi) > >>>>>>> { > >>>>>>> if (!F2FS_OPTION(sbi).unusable_cap_perc) > >>>>>>> @@ -953,6 +977,14 @@ static int f2fs_parse_param(struct fs_context *fc, struct fs_parameter *param) > >>>>>>> F2FS_CTX_INFO(ctx).root_reserved_nodes = result.uint_32; > >>>>>>> ctx->spec_mask |= F2FS_SPEC_reserve_node; > >>>>>>> break; > >>>>>>> + case Opt_reserve_shrink: > >>>>>>> + if (result.uint_32) > >>>>>>> + ctx_set_opt(ctx, F2FS_MOUNT_RESERVE_SHRINK); > >>>>>>> + else > >>>>>>> + ctx_clear_opt(ctx, F2FS_MOUNT_RESERVE_SHRINK); > >>>>>>> + F2FS_CTX_INFO(ctx).reserve_shrink_blocks = result.uint_32; > >>>>>>> + ctx->spec_mask |= F2FS_SPEC_reserve_shrink; > >>>>>>> + break; > >>>>>>> case Opt_resuid: > >>>>>>> F2FS_CTX_INFO(ctx).s_resuid = result.uid; > >>>>>>> ctx->spec_mask |= F2FS_SPEC_resuid; > >>>>>>> @@ -1775,6 +1807,9 @@ static void f2fs_apply_options(struct fs_context *fc, struct super_block *sb) > >>>>>>> if (ctx->spec_mask & F2FS_SPEC_reserve_node) > >>>>>>> F2FS_OPTION(sbi).root_reserved_nodes = > >>>>>>> F2FS_CTX_INFO(ctx).root_reserved_nodes; > >>>>>>> + if (ctx->spec_mask & F2FS_SPEC_reserve_shrink) > >>>>>>> + F2FS_OPTION(sbi).reserve_shrink_blocks = > >>>>>>> + F2FS_CTX_INFO(ctx).reserve_shrink_blocks; > >>>>>>> if (ctx->spec_mask & F2FS_SPEC_resgid) > >>>>>>> F2FS_OPTION(sbi).s_resgid = F2FS_CTX_INFO(ctx).s_resgid; > >>>>>>> if (ctx->spec_mask & F2FS_SPEC_resuid) > >>>>>>> @@ -2300,6 +2335,13 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf) > >>>>>>> buf->f_bfree = user_block_count - valid_user_blocks(sbi) - > >>>>>>> sbi->current_reserved_blocks; > >>>>>>> > >>>>>>> + if (test_opt(sbi, RESERVE_SHRINK)) { > >>>>>>> + if (buf->f_bfree > F2FS_OPTION(sbi).reserve_shrink_blocks) > >>>>>>> + buf->f_bfree -= F2FS_OPTION(sbi).reserve_shrink_blocks; > >>>>>>> + else > >>>>>>> + buf->f_bfree = 0; > >>>>>>> + } > >>>>>>> + > >>>>>>> if (unlikely(buf->f_bfree <= sbi->unusable_block_count)) > >>>>>>> buf->f_bfree = 0; > >>>>>>> else > >>>>>>> @@ -2524,6 +2566,9 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root) > >>>>>>> F2FS_OPTION(sbi).s_resuid), > >>>>>>> from_kgid_munged(&init_user_ns, > >>>>>>> F2FS_OPTION(sbi).s_resgid)); > >>>>>>> + if (test_opt(sbi, RESERVE_SHRINK)) > >>>>>>> + seq_printf(seq, ",reserve_shrink=%u", > >>>>>>> + F2FS_OPTION(sbi).reserve_shrink_blocks); > >>>>>>> #ifdef CONFIG_F2FS_FAULT_INJECTION > >>>>>>> if (test_opt(sbi, FAULT_INJECTION)) { > >>>>>>> seq_printf(seq, ",fault_injection=%u", > >>>>>>> @@ -3105,6 +3150,7 @@ static int __f2fs_remount(struct fs_context *fc, struct super_block *sb) > >>>>>>> > >>>>>>> adjust_pinned_area_boundary(sbi); > >>>>>>> limit_reserve_root(sbi); > >>>>>>> + limit_reserve_shrink(sbi); > >>>>>>> fc->sb_flags = (flags & ~SB_LAZYTIME) | (sb->s_flags & SB_LAZYTIME); > >>>>>>> > >>>>>>> sbi->umount_lock_holder = NULL; > >>>>>>> @@ -5322,6 +5368,7 @@ static int f2fs_fill_super(struct super_block *sb, struct fs_context *fc) > >>>>>>> sbi->current_reserved_blocks = 0; > >>>>>>> sbi->alias_reserved_blocks = 0; > >>>>>>> limit_reserve_root(sbi); > >>>>>>> + limit_reserve_shrink(sbi); > >>>>>>> adjust_unusable_cap_perc(sbi); > >>>>>>> > >>>>>>> f2fs_init_extent_cache_info(sbi); > >>>>>>> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c > >>>>>>> index aaca9ed9b169..d61940d095b4 100644 > >>>>>>> --- a/fs/f2fs/sysfs.c > >>>>>>> +++ b/fs/f2fs/sysfs.c > >>>>>>> @@ -591,9 +591,18 @@ static ssize_t __sbi_store(struct f2fs_attr *a, > >>>>>>> } > >>>>>>> #endif > >>>>>>> if (a->struct_type == RESERVED_BLOCKS) { > >>>>>>> + unsigned long limit; > >>>>>>> + > >>>>>>> spin_lock(&sbi->stat_lock); > >>>>>>> - if (t > (unsigned long)(sbi->user_block_count - > >>>>>>> - F2FS_OPTION(sbi).root_reserved_blocks)) { > >>>>>>> + limit = sbi->user_block_count - > >>>>>>> + F2FS_OPTION(sbi).root_reserved_blocks; > >>>>>>> + if (test_opt(sbi, RESERVE_SHRINK)) { > >>>>>>> + if (limit > F2FS_OPTION(sbi).reserve_shrink_blocks) > >>>>>>> + limit -= F2FS_OPTION(sbi).reserve_shrink_blocks; > >>>>>>> + else > >>>>>>> + limit = 0; > >>>>>>> + } > >>>>>>> + if (t > limit) { > >>>>>>> spin_unlock(&sbi->stat_lock); > >>>>>>> return -EINVAL; > >>>>>>> } > >>>>>> > >>>> >