shmem: Add default quota limit mount options

Allow system administrator to set default global quota limits at tmpfs
mount time.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-Id: <20230725144510.253763-7-cem@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

1 files changed, 61 insertions, 0 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index ec76ce9aea5f..5f2c9e2961c2 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -118,6 +118,7 @@ struct shmem_options {
 	int seen;
 	bool noswap;
 	unsigned short quota_types;
+	struct shmem_quota_limits qlimits;
 #define SHMEM_SEEN_BLOCKS 1
 #define SHMEM_SEEN_INODES 2
 #define SHMEM_SEEN_HUGE 4
@@ -3738,6 +3739,10 @@ enum shmem_param {
 	Opt_quota,
 	Opt_usrquota,
 	Opt_grpquota,
+	Opt_usrquota_block_hardlimit,
+	Opt_usrquota_inode_hardlimit,
+	Opt_grpquota_block_hardlimit,
+	Opt_grpquota_inode_hardlimit,
 };
 
 static const struct constant_table shmem_param_enums_huge[] = {
@@ -3764,6 +3769,10 @@ const struct fs_parameter_spec shmem_fs_parameters[] = {
 	fsparam_flag  ("quota",		Opt_quota),
 	fsparam_flag  ("usrquota",	Opt_usrquota),
 	fsparam_flag  ("grpquota",	Opt_grpquota),
+	fsparam_string("usrquota_block_hardlimit", Opt_usrquota_block_hardlimit),
+	fsparam_string("usrquota_inode_hardlimit", Opt_usrquota_inode_hardlimit),
+	fsparam_string("grpquota_block_hardlimit", Opt_grpquota_block_hardlimit),
+	fsparam_string("grpquota_inode_hardlimit", Opt_grpquota_inode_hardlimit),
 #endif
 	{}
 };
@@ -3874,6 +3883,42 @@ static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
 		ctx->seen |= SHMEM_SEEN_QUOTA;
 		ctx->quota_types |= QTYPE_MASK_GRP;
 		break;
+	case Opt_usrquota_block_hardlimit:
+		size = memparse(param->string, &rest);
+		if (*rest || !size)
+			goto bad_value;
+		if (size > SHMEM_QUOTA_MAX_SPC_LIMIT)
+			return invalfc(fc,
+				       "User quota block hardlimit too large.");
+		ctx->qlimits.usrquota_bhardlimit = size;
+		break;
+	case Opt_grpquota_block_hardlimit:
+		size = memparse(param->string, &rest);
+		if (*rest || !size)
+			goto bad_value;
+		if (size > SHMEM_QUOTA_MAX_SPC_LIMIT)
+			return invalfc(fc,
+				       "Group quota block hardlimit too large.");
+		ctx->qlimits.grpquota_bhardlimit = size;
+		break;
+	case Opt_usrquota_inode_hardlimit:
+		size = memparse(param->string, &rest);
+		if (*rest || !size)
+			goto bad_value;
+		if (size > SHMEM_QUOTA_MAX_INO_LIMIT)
+			return invalfc(fc,
+				       "User quota inode hardlimit too large.");
+		ctx->qlimits.usrquota_ihardlimit = size;
+		break;
+	case Opt_grpquota_inode_hardlimit:
+		size = memparse(param->string, &rest);
+		if (*rest || !size)
+			goto bad_value;
+		if (size > SHMEM_QUOTA_MAX_INO_LIMIT)
+			return invalfc(fc,
+				       "Group quota inode hardlimit too large.");
+		ctx->qlimits.grpquota_ihardlimit = size;
+		break;
 	}
 	return 0;
 
@@ -3987,6 +4032,18 @@ static int shmem_reconfigure(struct fs_context *fc)
 		goto out;
 	}
 
+#ifdef CONFIG_TMPFS_QUOTA
+#define CHANGED_LIMIT(name)						\
+	(ctx->qlimits.name## hardlimit &&				\
+	(ctx->qlimits.name## hardlimit != sbinfo->qlimits.name## hardlimit))
+
+	if (CHANGED_LIMIT(usrquota_b) || CHANGED_LIMIT(usrquota_i) ||
+	    CHANGED_LIMIT(grpquota_b) || CHANGED_LIMIT(grpquota_i)) {
+		err = "Cannot change global quota limit on remount";
+		goto out;
+	}
+#endif /* CONFIG_TMPFS_QUOTA */
+
 	if (ctx->seen & SHMEM_SEEN_HUGE)
 		sbinfo->huge = ctx->huge;
 	if (ctx->seen & SHMEM_SEEN_INUMS)
@@ -4166,6 +4223,10 @@ static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
 		sb->s_qcop = &dquot_quotactl_sysfile_ops;
 		sb->s_quota_types = QTYPE_MASK_USR | QTYPE_MASK_GRP;
 
+		/* Copy the default limits from ctx into sbinfo */
+		memcpy(&sbinfo->qlimits, &ctx->qlimits,
+		       sizeof(struct shmem_quota_limits));
+
 		if (shmem_enable_quotas(sb, ctx->quota_types))
 			goto failed;
 	}