[4/6] shmem: prepare shmem quota infrastructure

Message ID	20230403084759.884681-5-cem@kernel.org (mailing list archive)
State	New
Headers	show Return-Path: <owner-linux-mm@kvack.org> From: cem@kernel.org To: hughd@google.com Cc: jack@suse.cz, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, djwong@kernel.org Subject: [PATCH 4/6] shmem: prepare shmem quota infrastructure Date: Mon, 3 Apr 2023 10:47:57 +0200 Message-Id: <20230403084759.884681-5-cem@kernel.org> In-Reply-To: <20230403084759.884681-1-cem@kernel.org> References: <20230403084759.884681-1-cem@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org Precedence: bulk
Series	shmem: Add user and group quota support for tmpfs \| expand [0/6] shmem: Add user and group quota support for tmpfs [1/6] shmem: make shmem_inode_acct_block() return error [2/6] shmem: make shmem_get_inode() return ERR_PTR instead of NULL [3/6] quota: Check presence of quota operation structures instead of ->quota_read and ->quota_write… [4/6] shmem: prepare shmem quota infrastructure [5/6] shmem: quota support [6/6] Add default quota limit mount options

diff --git a/fs/Kconfig b/fs/Kconfig index e99830c650336..ba809882f1961 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -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 diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h index 103d1000a5a2e..cf38381bdb4c1 100644 --- a/include/linux/shmem_fs.h +++ b/include/linux/shmem_fs.h @@ -163,4 +163,12 @@ extern int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, 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 diff --git a/include/uapi/linux/quota.h b/include/uapi/linux/quota.h index f17c9636a8593..52090105b8282 100644 --- a/include/uapi/linux/quota.h +++ b/include/uapi/linux/quota.h @@ -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 */ diff --git a/mm/Makefile b/mm/Makefile index 8e105e5b3e293..977d2b66775a9 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -52,7 +52,7 @@ 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 \ + compaction.o shmem_quota.o\ interval_tree.o list_lru.o workingset.o \ debug.o gup.o mmap_lock.o $(mmu-y) diff --git a/mm/shmem_quota.c b/mm/shmem_quota.c new file mode 100644 index 0000000000000..c415043a71e67 --- /dev/null +++ b/mm/shmem_quota.c @@ -0,0 +1,318 @@ +// 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 + +#define SHMEM_MAXQUOTAS 2 + +/* + * 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 /* (7*24*60*60) 1 week */ +#define SHMEM_MAX_DQ_TIME 604800 /* (7*24*60*60) 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; + } + + up_write(&dqopt->dqio_sem); + mutex_unlock(&dquot->dq_lock); + return 0; + +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; +} + +int shmem_mark_dquot_dirty(struct dquot *dquot) +{ + return 0; +} + +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 */

[4/6] shmem: prepare shmem quota infrastructure

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