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Message-Id: <20250729095238.607433-1-guochunhai@vivo.com>
Date: Tue, 29 Jul 2025 17:52:38 +0800
From: Chunhai Guo <guochunhai@...o.com>
To: chao@...nel.org,
	jaegeuk@...nel.org
Cc: linux-f2fs-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org,
	Chunhai Guo <guochunhai@...o.com>
Subject: [PATCH] f2fs: add reserved nodes for privileged users

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>
---
 Documentation/filesystems/f2fs.rst |  9 ++++++---
 fs/f2fs/f2fs.h                     | 15 +++++++++------
 fs/f2fs/super.c                    | 30 +++++++++++++++++++++++++++++-
 3 files changed, 44 insertions(+), 10 deletions(-)
 mode change 100644 => 100755 Documentation/filesystems/f2fs.rst

diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
old mode 100644
new mode 100755
index 03b1efa6d3b2..95dbcd7ac9a8
--- 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 */
 	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))
 		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))
+		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..c58992be52a1 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;
 
 	/* limit is 12.5% */
 	if (test_opt(sbi, RESERVE_ROOT) &&
@@ -447,6 +451,12 @@ 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_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) &&
 		(!uid_eq(F2FS_OPTION(sbi).s_resuid,
 				make_kuid(&init_user_ns, F2FS_DEF_RESUID)) ||
@@ -841,6 +851,11 @@ 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 +1439,14 @@ 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 +1646,9 @@ 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)
@@ -2343,8 +2369,10 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
 		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",
+		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,
-- 
2.34.1


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