On Thu 20-04-23 10:03:57, cem@xxxxxxxxxx wrote:
> From: Lukas Czerner <lczerner@xxxxxxxxxx>
>
> Add new shmem quota format, its quota_format_ops together with
> dquot_operations
>
> Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx>
> Signed-off-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
Looks good to me. Feel free to add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> V2:
> - define SHMEM_MAXQUOTAS in include/linux/shmem_fs.h instead of
> mm/shmem_quota.c
> - Add a warning and error return if shmem_release_dquot() does
> not find an entry in the rb tree.
>
> fs/Kconfig | 12 ++
> include/linux/shmem_fs.h | 12 ++
> include/uapi/linux/quota.h | 1 +
> mm/Makefile | 2 +-
> mm/shmem_quota.c | 318 +++++++++++++++++++++++++++++++++++++
> 5 files changed, 344 insertions(+), 1 deletion(-)
> create mode 100644 mm/shmem_quota.c
>
> 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..92db49ebd5452 100644
> --- a/include/linux/shmem_fs.h
> +++ b/include/linux/shmem_fs.h
> @@ -12,6 +12,10 @@
>
> /* 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 */
> @@ -163,4 +167,12 @@ 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..c0b531e2ef688
> --- /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@xxxxxxxxxx>
> + * Carlos Maiolino <cmaiolino@xxxxxxxxxx>
> + *
> + * 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 /* (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;
> + }
> +
> + /* 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;
> +}
> +
> +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 */
> --
> 2.30.2
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
