shmem: prepare shmem quota infrastructure (eafc474e) · Commits · EulixOS / Software / Kernel

fs/Kconfig

+12 −0

Original line number	Diff line number	Diff line
		@@ -233,6 +233,18 @@ config TMPFS_INODE64

		If unsure, say N.

		config TMPFS_QUOTA
		bool "Tmpfs quota support"
		depends on TMPFS
		select QUOTA
		help
		Quota support allows to set per user and group limits for tmpfs
		usage. Say Y to enable quota support. Once enabled you can control
		user and group quota enforcement with quota, usrquota and grpquota
		mount options.

		If unsure, say N.

		config ARCH_SUPPORTS_HUGETLBFS
		def_bool n

include/linux/shmem_fs.h

+12 −0

Original line number	Diff line number	Diff line
		@@ -13,6 +13,10 @@

		/* inode in-kernel data */

		#ifdef CONFIG_TMPFS_QUOTA
		#define SHMEM_MAXQUOTAS 2
		#endif

		struct shmem_inode_info {
		spinlock_t lock;
		unsigned int seals; /* shmem seals */
		@@ -172,4 +176,12 @@ extern int shmem_mfill_atomic_pte(pmd_t *dst_pmd,
		#endif /* CONFIG_SHMEM */
		#endif /* CONFIG_USERFAULTFD */

		/*
		* Used space is stored as unsigned 64-bit value in bytes but
		* quota core supports only signed 64-bit values so use that
		* as a limit
		*/
		#define SHMEM_QUOTA_MAX_SPC_LIMIT 0x7fffffffffffffffLL /* 2^63-1 */
		#define SHMEM_QUOTA_MAX_INO_LIMIT 0x7fffffffffffffffLL

		#endif

include/uapi/linux/quota.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -77,6 +77,7 @@
		#define QFMT_VFS_V0 2
		#define QFMT_OCFS2 3
		#define QFMT_VFS_V1 4
		#define QFMT_SHMEM 5

		/* Size of block in which space limits are passed through the quota
		* interface */

mm/Makefile

+1 −1

Original line number	Diff line number	Diff line
		@@ -51,7 +51,7 @@ obj-y := filemap.o mempool.o oom_kill.o fadvise.o \
		readahead.o swap.o truncate.o vmscan.o shmem.o \
		util.o mmzone.o vmstat.o backing-dev.o \
		mm_init.o percpu.o slab_common.o \
		compaction.o show_mem.o\
		compaction.o show_mem.o shmem_quota.o\
		interval_tree.o list_lru.o workingset.o \
		debug.o gup.o mmap_lock.o $(mmu-y)

mm/shmem_quota.c

0 → 100644

+318 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0-only
		/*
		* In memory quota format relies on quota infrastructure to store dquot
		* information for us. While conventional quota formats for file systems
		* with persistent storage can load quota information into dquot from the
		* storage on-demand and hence quota dquot shrinker can free any dquot
		* that is not currently being used, it must be avoided here. Otherwise we
		* can lose valuable information, user provided limits, because there is
		* no persistent storage to load the information from afterwards.
		*
		* One information that in-memory quota format needs to keep track of is
		* a sorted list of ids for each quota type. This is done by utilizing
		* an rb tree which root is stored in mem_dqinfo->dqi_priv for each quota
		* type.
		*
		* This format can be used to support quota on file system without persistent
		* storage such as tmpfs.
		*
		* Author: Lukas Czerner <lczerner@redhat.com>
		* Carlos Maiolino <cmaiolino@redhat.com>
		*
		* Copyright (C) 2023 Red Hat, Inc.
		*/
		#include <linux/errno.h>
		#include <linux/fs.h>
		#include <linux/mount.h>
		#include <linux/kernel.h>
		#include <linux/init.h>
		#include <linux/module.h>
		#include <linux/slab.h>
		#include <linux/rbtree.h>
		#include <linux/shmem_fs.h>

		#include <linux/quotaops.h>
		#include <linux/quota.h>

		#ifdef CONFIG_TMPFS_QUOTA

		/*
		* The following constants define the amount of time given a user
		* before the soft limits are treated as hard limits (usually resulting
		* in an allocation failure). The timer is started when the user crosses
		* their soft limit, it is reset when they go below their soft limit.
		*/
		#define SHMEM_MAX_IQ_TIME 604800 /* (7246060) 1 week /
		#define SHMEM_MAX_DQ_TIME 604800 /* (7246060) 1 week /

		struct quota_id {
		struct rb_node node;
		qid_t id;
		qsize_t bhardlimit;
		qsize_t bsoftlimit;
		qsize_t ihardlimit;
		qsize_t isoftlimit;
		};

		static int shmem_check_quota_file(struct super_block *sb, int type)
		{
		/* There is no real quota file, nothing to do */
		return 1;
		}

		/*
		* There is no real quota file. Just allocate rb_root for quota ids and
		* set limits
		*/
		static int shmem_read_file_info(struct super_block *sb, int type)
		{
		struct quota_info *dqopt = sb_dqopt(sb);
		struct mem_dqinfo *info = &dqopt->info[type];

		info->dqi_priv = kzalloc(sizeof(struct rb_root), GFP_NOFS);
		if (!info->dqi_priv)
		return -ENOMEM;

		info->dqi_max_spc_limit = SHMEM_QUOTA_MAX_SPC_LIMIT;
		info->dqi_max_ino_limit = SHMEM_QUOTA_MAX_INO_LIMIT;

		info->dqi_bgrace = SHMEM_MAX_DQ_TIME;
		info->dqi_igrace = SHMEM_MAX_IQ_TIME;
		info->dqi_flags = 0;

		return 0;
		}

		static int shmem_write_file_info(struct super_block *sb, int type)
		{
		/* There is no real quota file, nothing to do */
		return 0;
		}

		/*
		* Free all the quota_id entries in the rb tree and rb_root.
		*/
		static int shmem_free_file_info(struct super_block *sb, int type)
		{
		struct mem_dqinfo *info = &sb_dqopt(sb)->info[type];
		struct rb_root *root = info->dqi_priv;
		struct quota_id *entry;
		struct rb_node *node;

		info->dqi_priv = NULL;
		node = rb_first(root);
		while (node) {
		entry = rb_entry(node, struct quota_id, node);
		node = rb_next(&entry->node);

		rb_erase(&entry->node, root);
		kfree(entry);
		}

		kfree(root);
		return 0;
		}

		static int shmem_get_next_id(struct super_block sb, struct kqid qid)
		{
		struct mem_dqinfo *info = sb_dqinfo(sb, qid->type);
		struct rb_node node = ((struct rb_root )info->dqi_priv)->rb_node;
		qid_t id = from_kqid(&init_user_ns, *qid);
		struct quota_info *dqopt = sb_dqopt(sb);
		struct quota_id *entry = NULL;
		int ret = 0;

		if (!sb_has_quota_active(sb, qid->type))
		return -ESRCH;

		down_read(&dqopt->dqio_sem);
		while (node) {
		entry = rb_entry(node, struct quota_id, node);

		if (id < entry->id)
		node = node->rb_left;
		else if (id > entry->id)
		node = node->rb_right;
		else
		goto got_next_id;
		}

		if (!entry) {
		ret = -ENOENT;
		goto out_unlock;
		}

		if (id > entry->id) {
		node = rb_next(&entry->node);
		if (!node) {
		ret = -ENOENT;
		goto out_unlock;
		}
		entry = rb_entry(node, struct quota_id, node);
		}

		got_next_id:
		*qid = make_kqid(&init_user_ns, qid->type, entry->id);
		out_unlock:
		up_read(&dqopt->dqio_sem);
		return ret;
		}

		/*
		* Load dquot with limits from existing entry, or create the new entry if
		* it does not exist.
		*/
		static int shmem_acquire_dquot(struct dquot *dquot)
		{
		struct mem_dqinfo *info = sb_dqinfo(dquot->dq_sb, dquot->dq_id.type);
		struct rb_node *n = &((struct rb_root )info->dqi_priv)->rb_node;
		struct rb_node parent = NULL, new_node = NULL;
		struct quota_id new_entry, entry;
		qid_t id = from_kqid(&init_user_ns, dquot->dq_id);
		struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
		int ret = 0;

		mutex_lock(&dquot->dq_lock);

		down_write(&dqopt->dqio_sem);
		while (*n) {
		parent = *n;
		entry = rb_entry(parent, struct quota_id, node);

		if (id < entry->id)
		n = &(*n)->rb_left;
		else if (id > entry->id)
		n = &(*n)->rb_right;
		else
		goto found;
		}

		/* We don't have entry for this id yet, create it */
		new_entry = kzalloc(sizeof(struct quota_id), GFP_NOFS);
		if (!new_entry) {
		ret = -ENOMEM;
		goto out_unlock;
		}

		new_entry->id = id;
		new_node = &new_entry->node;
		rb_link_node(new_node, parent, n);
		rb_insert_color(new_node, (struct rb_root *)info->dqi_priv);
		entry = new_entry;

		found:
		/* Load the stored limits from the tree */
		spin_lock(&dquot->dq_dqb_lock);
		dquot->dq_dqb.dqb_bhardlimit = entry->bhardlimit;
		dquot->dq_dqb.dqb_bsoftlimit = entry->bsoftlimit;
		dquot->dq_dqb.dqb_ihardlimit = entry->ihardlimit;
		dquot->dq_dqb.dqb_isoftlimit = entry->isoftlimit;

		if (!dquot->dq_dqb.dqb_bhardlimit &&
		!dquot->dq_dqb.dqb_bsoftlimit &&
		!dquot->dq_dqb.dqb_ihardlimit &&
		!dquot->dq_dqb.dqb_isoftlimit)
		set_bit(DQ_FAKE_B, &dquot->dq_flags);
		spin_unlock(&dquot->dq_dqb_lock);

		/* Make sure flags update is visible after dquot has been filled */
		smp_mb__before_atomic();
		set_bit(DQ_ACTIVE_B, &dquot->dq_flags);
		out_unlock:
		up_write(&dqopt->dqio_sem);
		mutex_unlock(&dquot->dq_lock);
		return ret;
		}

		/*
		* Store limits from dquot in the tree unless it's fake. If it is fake
		* remove the id from the tree since there is no useful information in
		* there.
		*/
		static int shmem_release_dquot(struct dquot *dquot)
		{
		struct mem_dqinfo *info = sb_dqinfo(dquot->dq_sb, dquot->dq_id.type);
		struct rb_node node = ((struct rb_root )info->dqi_priv)->rb_node;
		qid_t id = from_kqid(&init_user_ns, dquot->dq_id);
		struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
		struct quota_id *entry = NULL;

		mutex_lock(&dquot->dq_lock);
		/* Check whether we are not racing with some other dqget() */
		if (dquot_is_busy(dquot))
		goto out_dqlock;

		down_write(&dqopt->dqio_sem);
		while (node) {
		entry = rb_entry(node, struct quota_id, node);

		if (id < entry->id)
		node = node->rb_left;
		else if (id > entry->id)
		node = node->rb_right;
		else
		goto found;
		}

		/* We should always find the entry in the rb tree */
		WARN_ONCE(1, "quota id %u from dquot %p, not in rb tree!\n", id, dquot);
		up_write(&dqopt->dqio_sem);
		mutex_unlock(&dquot->dq_lock);
		return -ENOENT;

		found:
		if (test_bit(DQ_FAKE_B, &dquot->dq_flags)) {
		/* Remove entry from the tree */
		rb_erase(&entry->node, info->dqi_priv);
		kfree(entry);
		} else {
		/* Store the limits in the tree */
		spin_lock(&dquot->dq_dqb_lock);
		entry->bhardlimit = dquot->dq_dqb.dqb_bhardlimit;
		entry->bsoftlimit = dquot->dq_dqb.dqb_bsoftlimit;
		entry->ihardlimit = dquot->dq_dqb.dqb_ihardlimit;
		entry->isoftlimit = dquot->dq_dqb.dqb_isoftlimit;
		spin_unlock(&dquot->dq_dqb_lock);
		}

		clear_bit(DQ_ACTIVE_B, &dquot->dq_flags);
		up_write(&dqopt->dqio_sem);

		out_dqlock:
		mutex_unlock(&dquot->dq_lock);
		return 0;
		}

		static int shmem_mark_dquot_dirty(struct dquot *dquot)
		{
		return 0;
		}

		static int shmem_dquot_write_info(struct super_block *sb, int type)
		{
		return 0;
		}

		static const struct quota_format_ops shmem_format_ops = {
		.check_quota_file = shmem_check_quota_file,
		.read_file_info = shmem_read_file_info,
		.write_file_info = shmem_write_file_info,
		.free_file_info = shmem_free_file_info,
		};

		struct quota_format_type shmem_quota_format = {
		.qf_fmt_id = QFMT_SHMEM,
		.qf_ops = &shmem_format_ops,
		.qf_owner = THIS_MODULE
		};

		const struct dquot_operations shmem_quota_operations = {
		.acquire_dquot = shmem_acquire_dquot,
		.release_dquot = shmem_release_dquot,
		.alloc_dquot = dquot_alloc,
		.destroy_dquot = dquot_destroy,
		.write_info = shmem_dquot_write_info,
		.mark_dirty = shmem_mark_dquot_dirty,
		.get_next_id = shmem_get_next_id,
		};
		#endif /* CONFIG_TMPFS_QUOTA */