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Message-ID: <56424935-bb18-463b-8a18-6503a4cab7cb@vivo.com>
Date: Wed, 30 Jul 2025 09:07:46 +0000
From: Chunhai Guo <guochunhai@...o.com>
To: Chao Yu <chao@...nel.org>, Chunhai Guo <guochunhai@...o.com>,
	"jaegeuk@...nel.org" <jaegeuk@...nel.org>
CC: "linux-f2fs-devel@...ts.sourceforge.net"
	<linux-f2fs-devel@...ts.sourceforge.net>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] f2fs: add reserved nodes for privileged users

在 7/30/2025 3:23 PM, Chao Yu 写道:
> On 2025/7/30 10:42, Chunhai Guo wrote:
>> This patch allows privileged users to reserve nodes via the
>> 'reserve_node' mount option, which is similar to the existing
>> 'reserve_root' option.
>>
>> "-o reserve_node=<N>" means <N> nodes are reserved for privileged
>> users only.
>>
>> Signed-off-by: Chunhai Guo <guochunhai@...o.com>
>> ---
>> v2: Add two missing handling parts.
>> v1: https://lore.kernel.org/linux-f2fs-devel/20250729095238.607433-1-guochunhai@vivo.com/
>> ---
>>    Documentation/filesystems/f2fs.rst |  9 +++++---
>>    fs/f2fs/f2fs.h                     | 15 +++++++-----
>>    fs/f2fs/super.c                    | 37 ++++++++++++++++++++++++++----
>>    3 files changed, 48 insertions(+), 13 deletions(-)
>>
>> diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
>> index 03b1efa6d3b2..95dbcd7ac9a8 100644
>> --- a/Documentation/filesystems/f2fs.rst
>> +++ b/Documentation/filesystems/f2fs.rst
>> @@ -173,9 +173,12 @@ data_flush               Enable data flushing before checkpoint in order to
>>                       persist data of regular and symlink.
>>    reserve_root=%d            Support configuring reserved space which is used for
>>                       allocation from a privileged user with specified uid or
>> -                     gid, unit: 4KB, the default limit is 0.2% of user blocks.
>> -resuid=%d            The user ID which may use the reserved blocks.
>> -resgid=%d            The group ID which may use the reserved blocks.
>> +                     gid, unit: 4KB, the default limit is 12.5% of user blocks.
>> +reserve_node=%d              Support configuring reserved nodes which are used for
>> +                     allocation from a privileged user with specified uid or
>> +                     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.
>>    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 97c1a2a3fbd7..f4c4ea115465 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -131,6 +131,7 @@ extern const char *f2fs_fault_name[FAULT_MAX];
>>     * string rather than using the MS_LAZYTIME flag, so this must remain.
>>     */
>>    #define F2FS_MOUNT_LAZYTIME               0x40000000
>> +#define F2FS_MOUNT_RESERVE_NODE             0x80000000
>>
>>    #define F2FS_OPTION(sbi)  ((sbi)->mount_opt)
>>    #define clear_opt(sbi, option)    (F2FS_OPTION(sbi).opt &= ~F2FS_MOUNT_##option)
>> @@ -171,6 +172,7 @@ struct f2fs_rwsem {
>>
>>    struct f2fs_mount_info {
>>      unsigned int opt;
>> +    unsigned int root_reserved_nodes; /* root reserved nodes */
>>      block_t root_reserved_blocks;   /* root reserved blocks */
> block_t root_reserved_nodes; /* root reserved nodes */
>
>>      kuid_t s_resuid;                /* reserved blocks for uid */
>>      kgid_t s_resgid;                /* reserved blocks for gid */
>> @@ -2355,13 +2357,11 @@ static inline bool f2fs_has_xattr_block(unsigned int ofs)
>>      return ofs == XATTR_NODE_OFFSET;
>>    }
>>
>> -static inline bool __allow_reserved_blocks(struct f2fs_sb_info *sbi,
>> +static inline bool __allow_reserved_root(struct f2fs_sb_info *sbi,
>>                                      struct inode *inode, bool cap)
>>    {
>>      if (!inode)
>>              return true;
>> -    if (!test_opt(sbi, RESERVE_ROOT))
>> -            return false;
>>      if (IS_NOQUOTA(inode))
>>              return true;
>>      if (uid_eq(F2FS_OPTION(sbi).s_resuid, current_fsuid()))
>> @@ -2382,7 +2382,7 @@ static inline unsigned int get_available_block_count(struct f2fs_sb_info *sbi,
>>      avail_user_block_count = sbi->user_block_count -
>>                                      sbi->current_reserved_blocks;
>>
>> -    if (!__allow_reserved_blocks(sbi, inode, cap))
>> +    if (!__allow_reserved_root(sbi, inode, cap))
> if (!test_opt(RESERVE_ROOT) && !__allow_reserved_root()) ?
>
>>              avail_user_block_count -= F2FS_OPTION(sbi).root_reserved_blocks;
>>
>>      if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
>> @@ -2740,7 +2740,7 @@ static inline int inc_valid_node_count(struct f2fs_sb_info *sbi,
>>                                      struct inode *inode, bool is_inode)
>>    {
>>      block_t valid_block_count;
>> -    unsigned int valid_node_count;
>> +    unsigned int valid_node_count, avail_user_node_count;
>>      unsigned int avail_user_block_count;
>>      int err;
>>
>> @@ -2769,8 +2769,11 @@ static inline int inc_valid_node_count(struct f2fs_sb_info *sbi,
>>              goto enospc;
>>      }
>>
>> +    avail_user_node_count = sbi->total_node_count - F2FS_RESERVED_NODE_NUM;
>> +    if (!__allow_reserved_root(sbi, inode, false))
> if (!test_opt(RESERVE_NODE) && !__allow_reserved_root()) ?
>
>> +            avail_user_node_count -= F2FS_OPTION(sbi).root_reserved_nodes;
>>      valid_node_count = sbi->total_valid_node_count + 1;
>> -    if (unlikely(valid_node_count > sbi->total_node_count)) {
>> +    if (unlikely(valid_node_count > avail_user_node_count)) {
>>              spin_unlock(&sbi->stat_lock);
>>              goto enospc;
>>      }
>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>> index 30c038413040..54a40820b3da 100644
>> --- a/fs/f2fs/super.c
>> +++ b/fs/f2fs/super.c
>> @@ -143,6 +143,7 @@ enum {
>>      Opt_extent_cache,
>>      Opt_data_flush,
>>      Opt_reserve_root,
>> +    Opt_reserve_node,
>>      Opt_resgid,
>>      Opt_resuid,
>>      Opt_mode,
>> @@ -265,6 +266,7 @@ static const struct fs_parameter_spec f2fs_param_specs[] = {
>>      fsparam_flag_no("extent_cache", Opt_extent_cache),
>>      fsparam_flag("data_flush", Opt_data_flush),
>>      fsparam_u32("reserve_root", Opt_reserve_root),
>> +    fsparam_u32("reserve_node", Opt_reserve_node),
>>      fsparam_gid("resgid", Opt_resgid),
>>      fsparam_uid("resuid", Opt_resuid),
>>      fsparam_enum("mode", Opt_mode, f2fs_param_mode),
>> @@ -336,6 +338,7 @@ static match_table_t f2fs_checkpoint_tokens = {
>>    #define F2FS_SPEC_discard_unit                    (1 << 21)
>>    #define F2FS_SPEC_memory_mode                     (1 << 22)
>>    #define F2FS_SPEC_errors                  (1 << 23)
>> +#define F2FS_SPEC_reserve_node                      (1 << 24)
>>
>>    struct f2fs_fs_context {
>>      struct f2fs_mount_info info;
>> @@ -439,6 +442,7 @@ static inline void limit_reserve_root(struct f2fs_sb_info *sbi)
>>    {
>>      block_t limit = min((sbi->user_block_count >> 3),
>>                      sbi->user_block_count - sbi->reserved_blocks);
>> +    unsigned int node_limit = sbi->total_node_count >> 3;
> block_t data_limit = ...
> block_t node_limit = sbi->total_node_count >> 3;


Thank you for your prompt reply. I will send the v3 patch as per your
suggestion.

Thanks,

>
> Thanks,
>
>>
>>      /* limit is 12.5% */
>>      if (test_opt(sbi, RESERVE_ROOT) &&
>> @@ -447,12 +451,19 @@ static inline void limit_reserve_root(struct f2fs_sb_info *sbi)
>>              f2fs_info(sbi, "Reduce reserved blocks for root = %u",
>>                        F2FS_OPTION(sbi).root_reserved_blocks);
>>      }
>> -    if (!test_opt(sbi, RESERVE_ROOT) &&
>> +    if (test_opt(sbi, RESERVE_NODE) &&
>> +                    F2FS_OPTION(sbi).root_reserved_nodes > node_limit) {
>> +            F2FS_OPTION(sbi).root_reserved_nodes = node_limit;
>> +            f2fs_info(sbi, "Reduce reserved nodes for root = %u",
>> +                      F2FS_OPTION(sbi).root_reserved_nodes);
>> +    }
>> +    if (!test_opt(sbi, RESERVE_ROOT) && !test_opt(sbi, RESERVE_NODE) &&
>>              (!uid_eq(F2FS_OPTION(sbi).s_resuid,
>>                              make_kuid(&init_user_ns, F2FS_DEF_RESUID)) ||
>>              !gid_eq(F2FS_OPTION(sbi).s_resgid,
>>                              make_kgid(&init_user_ns, F2FS_DEF_RESGID))))
>> -            f2fs_info(sbi, "Ignore s_resuid=%u, s_resgid=%u w/o reserve_root",
>> +            f2fs_info(sbi, "Ignore s_resuid=%u, s_resgid=%u w/o reserve_root"
>> +                            " and reserve_node",
>>                        from_kuid_munged(&init_user_ns,
>>                                         F2FS_OPTION(sbi).s_resuid),
>>                        from_kgid_munged(&init_user_ns,
>> @@ -841,6 +852,11 @@ static int f2fs_parse_param(struct fs_context *fc, struct fs_parameter *param)
>>              F2FS_CTX_INFO(ctx).root_reserved_blocks = result.uint_32;
>>              ctx->spec_mask |= F2FS_SPEC_reserve_root;
>>              break;
>> +    case Opt_reserve_node:
>> +            ctx_set_opt(ctx, F2FS_MOUNT_RESERVE_NODE);
>> +            F2FS_CTX_INFO(ctx).root_reserved_nodes = result.uint_32;
>> +            ctx->spec_mask |= F2FS_SPEC_reserve_node;
>> +            break;
>>      case Opt_resuid:
>>              F2FS_CTX_INFO(ctx).s_resuid = result.uid;
>>              ctx->spec_mask |= F2FS_SPEC_resuid;
>> @@ -1424,6 +1440,14 @@ static int f2fs_check_opt_consistency(struct fs_context *fc,
>>              ctx_clear_opt(ctx, F2FS_MOUNT_RESERVE_ROOT);
>>              ctx->opt_mask &= ~F2FS_MOUNT_RESERVE_ROOT;
>>      }
>> +    if (test_opt(sbi, RESERVE_NODE) &&
>> +                    (ctx->opt_mask & F2FS_MOUNT_RESERVE_NODE) &&
>> +                    ctx_test_opt(ctx, F2FS_MOUNT_RESERVE_NODE)) {
>> +            f2fs_info(sbi, "Preserve previous reserve_node=%u",
>> +                    F2FS_OPTION(sbi).root_reserved_nodes);
>> +            ctx_clear_opt(ctx, F2FS_MOUNT_RESERVE_NODE);
>> +            ctx->opt_mask &= ~F2FS_MOUNT_RESERVE_NODE;
>> +    }
>>
>>      err = f2fs_check_test_dummy_encryption(fc, sb);
>>      if (err)
>> @@ -1623,6 +1647,9 @@ static void f2fs_apply_options(struct fs_context *fc, struct super_block *sb)
>>      if (ctx->spec_mask & F2FS_SPEC_reserve_root)
>>              F2FS_OPTION(sbi).root_reserved_blocks =
>>                                      F2FS_CTX_INFO(ctx).root_reserved_blocks;
>> +    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_resgid)
>>              F2FS_OPTION(sbi).s_resgid = F2FS_CTX_INFO(ctx).s_resgid;
>>      if (ctx->spec_mask & F2FS_SPEC_resuid)
>> @@ -2342,9 +2369,11 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
>>      else if (F2FS_OPTION(sbi).fs_mode == FS_MODE_FRAGMENT_BLK)
>>              seq_puts(seq, "fragment:block");
>>      seq_printf(seq, ",active_logs=%u", F2FS_OPTION(sbi).active_logs);
>> -    if (test_opt(sbi, RESERVE_ROOT))
>> -            seq_printf(seq, ",reserve_root=%u,resuid=%u,resgid=%u",
>> +    if (test_opt(sbi, RESERVE_ROOT) || test_opt(sbi, RESERVE_NODE))
>> +            seq_printf(seq, ",reserve_root=%u,reserve_node=%u,resuid=%u,"
>> +                            "resgid=%u",
>>                              F2FS_OPTION(sbi).root_reserved_blocks,
>> +                            F2FS_OPTION(sbi).root_reserved_nodes,
>>                              from_kuid_munged(&init_user_ns,
>>                                      F2FS_OPTION(sbi).s_resuid),
>>                              from_kgid_munged(&init_user_ns,


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