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Message-ID: <526cac92-29eb-42a4-bf56-220e3b1f7c0c@kernel.org>
Date: Thu, 31 Jul 2025 10:56:43 +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 v3] f2fs: add reserved nodes for privileged users
On 7/30/25 22:15, 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->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 | 17 +++++++-----
> fs/f2fs/super.c | 43 +++++++++++++++++++++++++-----
> 3 files changed, 53 insertions(+), 16 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..70f32c118dac 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 */
> @@ -2355,13 +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;
Oh, I just notice this condition is wrong, let me submit a patch
to fix this, as I hope it can go into stable correctly.
Thanks,
> if (IS_NOQUOTA(inode))
> return true;
> if (uid_eq(F2FS_OPTION(sbi).s_resuid, current_fsuid()))
> @@ -2382,7 +2382,8 @@ 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 (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))) {
> @@ -2740,7 +2741,7 @@ 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 +2770,12 @@ 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))
> + 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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