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Message-ID: <ee0955ae-7d7a-40b7-8bae-f65ca56bd45c@kernel.org>
Date: Tue, 5 Aug 2025 16:56:27 +0800
From: Chao Yu <chao@...nel.org>
To: Chunhai Guo <guochunhai@...o.com>, jaegeuk@...nel.org
Cc: chao@...nel.org, linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] f2fs: add reserved nodes for privileged users
On 7/31/25 16:46, Chao Yu wrote:
> On 7/31/25 15:57, 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>
>> ---
>> v3->v4: Rebase this patch on https://lore.kernel.org/linux-f2fs-devel/20250731060338.1136086-1-chao@kernel.org
>> v2->v3: Apply Chao's suggestion from v2.
>> v1->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 | 14 +++++++---
>> fs/f2fs/super.c | 43 +++++++++++++++++++++++++-----
>> 3 files changed, 52 insertions(+), 14 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 eb372af22edc..b9676ef16246 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)
>> @@ -172,6 +173,7 @@ struct f2fs_rwsem {
>> struct f2fs_mount_info {
>> unsigned int opt;
>> 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 */
>> int active_logs; /* # of active logs */
>> @@ -2355,7 +2357,7 @@ 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)
>> @@ -2380,7 +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 (test_opt(sbi, RESERVE_ROOT) && !__allow_reserved_blocks(sbi, inode, cap))
>> + if (test_opt(sbi, RESERVE_ROOT) && !__allow_reserved_root(sbi, inode, cap))
>> avail_user_block_count -= F2FS_OPTION(sbi).root_reserved_blocks;
>>
>> if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
>> @@ -2738,7 +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;
>>
>> @@ -2767,8 +2769,12 @@ 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 (test_opt(sbi, RESERVE_NODE) &&
>> + !__allow_reserved_root(sbi, inode, false))
>
> Chunhai,
>
> Do we need to pass cap=true to __allow_reserved_root()?
>
> In addition, do we need to change cap as well for below statement?
>
> avail_user_block_count = get_available_block_count(sbi, inode, false);
I meant something like this? not sure.
---
fs/f2fs/f2fs.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 3804b70e5a28..d0aa5766ea66 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2805,7 +2805,8 @@ static inline int inc_valid_node_count(struct f2fs_sb_info *sbi,
spin_lock(&sbi->stat_lock);
valid_block_count = sbi->total_valid_block_count + 1;
- avail_user_block_count = get_available_block_count(sbi, inode, false);
+ avail_user_block_count = get_available_block_count(sbi, inode,
+ test_opt(sbi, RESERVE_NODE));
if (unlikely(valid_block_count > avail_user_block_count)) {
spin_unlock(&sbi->stat_lock);
@@ -2814,7 +2815,7 @@ static inline int inc_valid_node_count(struct f2fs_sb_info *sbi,
avail_user_node_count = sbi->total_node_count - F2FS_RESERVED_NODE_NUM;
if (test_opt(sbi, RESERVE_NODE) &&
- !__allow_reserved_root(sbi, inode, false))
+ !__allow_reserved_root(sbi, inode, true))
avail_user_node_count -= F2FS_OPTION(sbi).root_reserved_nodes;
valid_node_count = sbi->total_valid_node_count + 1;
if (unlikely(valid_node_count > avail_user_node_count)) {
--
2.49.0
Thanks,
>
> Thanks,
>
>> + 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..a24e855a38ed 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;
>> @@ -437,22 +440,30 @@ static void f2fs_destroy_casefold_cache(void) { }
>>
>> static inline void limit_reserve_root(struct f2fs_sb_info *sbi)
>> {
>> - block_t limit = min((sbi->user_block_count >> 3),
>> + block_t block_limit = min((sbi->user_block_count >> 3),
>> sbi->user_block_count - sbi->reserved_blocks);
>> + block_t node_limit = sbi->total_node_count >> 3;
>>
>> /* limit is 12.5% */
>> if (test_opt(sbi, RESERVE_ROOT) &&
>> - F2FS_OPTION(sbi).root_reserved_blocks > limit) {
>> - F2FS_OPTION(sbi).root_reserved_blocks = limit;
>> + F2FS_OPTION(sbi).root_reserved_blocks > block_limit) {
>> + F2FS_OPTION(sbi).root_reserved_blocks = block_limit;
>> 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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