Re: [PATCH 5/6] shmem: quota support

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Apr 03, 2023 at 10:47:58AM +0200, cem@kernel.org wrote:
> From: Lukas Czerner <lczerner@redhat.com>
> 
> Now the basic infra-structure is in place, enable quota support for tmpfs.
> 
> Signed-off-by: Lukas Czerner <lczerner@redhat.com>
> Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
> ---
>  Documentation/filesystems/tmpfs.rst |  12 +++
>  include/linux/shmem_fs.h            |   9 ++
>  mm/shmem.c                          | 162 ++++++++++++++++++++++++++--
>  3 files changed, 174 insertions(+), 9 deletions(-)
> 
> diff --git a/Documentation/filesystems/tmpfs.rst b/Documentation/filesystems/tmpfs.rst
> index 0408c245785e3..3f8d89bb7e1a5 100644
> --- a/Documentation/filesystems/tmpfs.rst
> +++ b/Documentation/filesystems/tmpfs.rst
> @@ -86,6 +86,18 @@ use up all the memory on the machine; but enhances the scalability of
>  that instance in a system with many CPUs making intensive use of it.
>  
>  
> +tmpfs also supports quota with the following mount options
> +
> +========  =============================================================
> +quota     User and group quota accounting and enforcement is enabled on
> +          the mount. Tmpfs is using hidden system quota files that are
> +          initialized on mount.
> +usrquota  User quota accounting and enforcement is enabled on the
> +          mount.
> +grpquota  Group quota accounting and enforcement is enabled on the
> +          mount.
> +========  =============================================================
> +
>  tmpfs has a mount option to set the NUMA memory allocation policy for
>  all files in that instance (if CONFIG_NUMA is enabled) - which can be
>  adjusted on the fly via 'mount -o remount ...'
> diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
> index cf38381bdb4c1..3e7e18726feb5 100644
> --- a/include/linux/shmem_fs.h
> +++ b/include/linux/shmem_fs.h
> @@ -26,6 +26,9 @@ struct shmem_inode_info {
>  	atomic_t		stop_eviction;	/* hold when working on inode */
>  	struct timespec64	i_crtime;	/* file creation time */
>  	unsigned int		fsflags;	/* flags for FS_IOC_[SG]ETFLAGS */
> +#ifdef CONFIG_TMPFS_QUOTA
> +	struct dquot		*i_dquot[MAXQUOTAS];

Why allocate three dquot pointers here...

> +#endif
>  	struct inode		vfs_inode;
>  };
>  
> @@ -171,4 +174,10 @@ extern int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
>  #define SHMEM_QUOTA_MAX_SPC_LIMIT 0x7fffffffffffffffLL /* 2^63-1 */
>  #define SHMEM_QUOTA_MAX_INO_LIMIT 0x7fffffffffffffffLL
>  
> +#ifdef CONFIG_TMPFS_QUOTA
> +#define SHMEM_MAXQUOTAS 2

...when you're only allowing user and group quotas?

(Or: Why not allow project quotas?  But that's outside the scope you
defined.)

--D

> +extern const struct dquot_operations shmem_quota_operations;
> +extern struct quota_format_type shmem_quota_format;
> +#endif /* CONFIG_TMPFS_QUOTA */
> +
>  #endif
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 88e13930fc013..d7529c883eaf5 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -79,6 +79,7 @@ static struct vfsmount *shm_mnt;
>  #include <linux/userfaultfd_k.h>
>  #include <linux/rmap.h>
>  #include <linux/uuid.h>
> +#include <linux/quotaops.h>
>  
>  #include <linux/uaccess.h>
>  
> @@ -116,10 +117,12 @@ struct shmem_options {
>  	bool full_inums;
>  	int huge;
>  	int seen;
> +	unsigned short quota_types;
>  #define SHMEM_SEEN_BLOCKS 1
>  #define SHMEM_SEEN_INODES 2
>  #define SHMEM_SEEN_HUGE 4
>  #define SHMEM_SEEN_INUMS 8
> +#define SHMEM_SEEN_QUOTA 16
>  };
>  
>  #ifdef CONFIG_TMPFS
> @@ -211,8 +214,11 @@ static inline int shmem_inode_acct_block(struct inode *inode, long pages)
>  		if (percpu_counter_compare(&sbinfo->used_blocks,
>  					   sbinfo->max_blocks - pages) > 0)
>  			goto unacct;
> +		if ((err = dquot_alloc_block_nodirty(inode, pages)) != 0)
> +			goto unacct;
>  		percpu_counter_add(&sbinfo->used_blocks, pages);
> -	}
> +	} else if ((err = dquot_alloc_block_nodirty(inode, pages)) != 0)
> +		goto unacct;
>  
>  	return 0;
>  
> @@ -226,6 +232,8 @@ static inline void shmem_inode_unacct_blocks(struct inode *inode, long pages)
>  	struct shmem_inode_info *info = SHMEM_I(inode);
>  	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
>  
> +	dquot_free_block_nodirty(inode, pages);
> +
>  	if (sbinfo->max_blocks)
>  		percpu_counter_sub(&sbinfo->used_blocks, pages);
>  	shmem_unacct_blocks(info->flags, pages);
> @@ -254,6 +262,47 @@ bool vma_is_shmem(struct vm_area_struct *vma)
>  static LIST_HEAD(shmem_swaplist);
>  static DEFINE_MUTEX(shmem_swaplist_mutex);
>  
> +#ifdef CONFIG_TMPFS_QUOTA
> +
> +static int shmem_enable_quotas(struct super_block *sb,
> +			       unsigned short quota_types)
> +{
> +	int type, err = 0;
> +
> +	sb_dqopt(sb)->flags |= DQUOT_QUOTA_SYS_FILE | DQUOT_NOLIST_DIRTY;
> +	for (type = 0; type < SHMEM_MAXQUOTAS; type++) {
> +		if (!(quota_types & (1 << type)))
> +			continue;
> +		err = dquot_load_quota_sb(sb, type, QFMT_SHMEM,
> +					  DQUOT_USAGE_ENABLED |
> +					  DQUOT_LIMITS_ENABLED);
> +		if (err)
> +			goto out_err;
> +	}
> +	return 0;
> +
> +out_err:
> +	pr_warn("tmpfs: failed to enable quota tracking (type=%d, err=%d)\n",
> +		type, err);
> +	for (type--; type >= 0; type--)
> +		dquot_quota_off(sb, type);
> +	return err;
> +}
> +
> +static void shmem_disable_quotas(struct super_block *sb)
> +{
> +	int type;
> +
> +	for (type = 0; type < SHMEM_MAXQUOTAS; type++)
> +		dquot_quota_off(sb, type);
> +}
> +
> +static struct dquot **shmem_get_dquots(struct inode *inode)
> +{
> +	return SHMEM_I(inode)->i_dquot;
> +}
> +#endif /* CONFIG_TMPFS_QUOTA */
> +
>  /*
>   * shmem_reserve_inode() performs bookkeeping to reserve a shmem inode, and
>   * produces a novel ino for the newly allocated inode.
> @@ -360,7 +409,6 @@ static void shmem_recalc_inode(struct inode *inode)
>  	freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
>  	if (freed > 0) {
>  		info->alloced -= freed;
> -		inode->i_blocks -= freed * BLOCKS_PER_PAGE;
>  		shmem_inode_unacct_blocks(inode, freed);
>  	}
>  }
> @@ -378,7 +426,6 @@ bool shmem_charge(struct inode *inode, long pages)
>  
>  	spin_lock_irqsave(&info->lock, flags);
>  	info->alloced += pages;
> -	inode->i_blocks += pages * BLOCKS_PER_PAGE;
>  	shmem_recalc_inode(inode);
>  	spin_unlock_irqrestore(&info->lock, flags);
>  
> @@ -394,7 +441,6 @@ void shmem_uncharge(struct inode *inode, long pages)
>  
>  	spin_lock_irqsave(&info->lock, flags);
>  	info->alloced -= pages;
> -	inode->i_blocks -= pages * BLOCKS_PER_PAGE;
>  	shmem_recalc_inode(inode);
>  	spin_unlock_irqrestore(&info->lock, flags);
>  
> @@ -1133,6 +1179,15 @@ static int shmem_setattr(struct mnt_idmap *idmap,
>  		}
>  	}
>  
> +	/* Transfer quota accounting */
> +	if (i_uid_needs_update(idmap, attr, inode) ||
> +	    i_gid_needs_update(idmap, attr,inode)) {
> +		error = dquot_transfer(idmap, inode, attr);
> +
> +		if (error)
> +			return error;
> +	}
> +
>  	setattr_copy(idmap, inode, attr);
>  	if (attr->ia_valid & ATTR_MODE)
>  		error = posix_acl_chmod(idmap, dentry, inode->i_mode);
> @@ -1178,7 +1233,9 @@ static void shmem_evict_inode(struct inode *inode)
>  	simple_xattrs_free(&info->xattrs);
>  	WARN_ON(inode->i_blocks);
>  	shmem_free_inode(inode->i_sb);
> +	dquot_free_inode(inode);
>  	clear_inode(inode);
> +	dquot_drop(inode);
>  }
>  
>  static int shmem_find_swap_entries(struct address_space *mapping,
> @@ -1975,7 +2032,6 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
>  
>  	spin_lock_irq(&info->lock);
>  	info->alloced += folio_nr_pages(folio);
> -	inode->i_blocks += (blkcnt_t)BLOCKS_PER_PAGE << folio_order(folio);
>  	shmem_recalc_inode(inode);
>  	spin_unlock_irq(&info->lock);
>  	alloced = true;
> @@ -2346,9 +2402,10 @@ static void shmem_set_inode_flags(struct inode *inode, unsigned int fsflags)
>  #define shmem_initxattrs NULL
>  #endif
>  
> -static struct inode *shmem_get_inode(struct mnt_idmap *idmap, struct super_block *sb,
> -				     struct inode *dir, umode_t mode, dev_t dev,
> -				     unsigned long flags)
> +static struct inode *shmem_get_inode_noquota(struct mnt_idmap *idmap,
> +					     struct super_block *sb,
> +					     struct inode *dir, umode_t mode,
> +					     dev_t dev, unsigned long flags)
>  {
>  	struct inode *inode;
>  	struct shmem_inode_info *info;
> @@ -2422,6 +2479,37 @@ static struct inode *shmem_get_inode(struct mnt_idmap *idmap, struct super_block
>  	return inode;
>  }
>  
> +static struct inode *shmem_get_inode(struct mnt_idmap *idmap,
> +				     struct super_block *sb, struct inode *dir,
> +				     umode_t mode, dev_t dev, unsigned long flags)
> +{
> +	int err;
> +	struct inode *inode;
> +
> +	inode = shmem_get_inode_noquota(idmap, sb, dir, mode, dev, flags);
> +	if (IS_ERR(inode))
> +		return inode;
> +
> +	err = dquot_initialize(inode);
> +	if (err)
> +		goto errout;
> +
> +	err = dquot_alloc_inode(inode);
> +	if (err) {
> +		dquot_drop(inode);
> +		goto errout;
> +	}
> +	return inode;
> +
> +errout:
> +	inode->i_flags |= S_NOQUOTA;
> +	iput(inode);
> +	shmem_free_inode(sb);
> +	if (err)
> +		return ERR_PTR(err);
> +	return NULL;
> +}
> +
>  #ifdef CONFIG_USERFAULTFD
>  int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
>  			   pmd_t *dst_pmd,
> @@ -2525,7 +2613,6 @@ int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
>  
>  	spin_lock_irq(&info->lock);
>  	info->alloced++;
> -	inode->i_blocks += BLOCKS_PER_PAGE;
>  	shmem_recalc_inode(inode);
>  	spin_unlock_irq(&info->lock);
>  
> @@ -3372,6 +3459,7 @@ static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
>  
>  static const struct inode_operations shmem_short_symlink_operations = {
>  	.getattr	= shmem_getattr,
> +	.setattr	= shmem_setattr,
>  	.get_link	= simple_get_link,
>  #ifdef CONFIG_TMPFS_XATTR
>  	.listxattr	= shmem_listxattr,
> @@ -3380,6 +3468,7 @@ static const struct inode_operations shmem_short_symlink_operations = {
>  
>  static const struct inode_operations shmem_symlink_inode_operations = {
>  	.getattr	= shmem_getattr,
> +	.setattr	= shmem_setattr,
>  	.get_link	= shmem_get_link,
>  #ifdef CONFIG_TMPFS_XATTR
>  	.listxattr	= shmem_listxattr,
> @@ -3478,6 +3567,9 @@ enum shmem_param {
>  	Opt_uid,
>  	Opt_inode32,
>  	Opt_inode64,
> +	Opt_quota,
> +	Opt_usrquota,
> +	Opt_grpquota,
>  };
>  
>  static const struct constant_table shmem_param_enums_huge[] = {
> @@ -3499,6 +3591,11 @@ const struct fs_parameter_spec shmem_fs_parameters[] = {
>  	fsparam_u32   ("uid",		Opt_uid),
>  	fsparam_flag  ("inode32",	Opt_inode32),
>  	fsparam_flag  ("inode64",	Opt_inode64),
> +#ifdef CONFIG_TMPFS_QUOTA
> +	fsparam_flag  ("quota",		Opt_quota),
> +	fsparam_flag  ("usrquota",	Opt_usrquota),
> +	fsparam_flag  ("grpquota",	Opt_grpquota),
> +#endif
>  	{}
>  };
>  
> @@ -3582,6 +3679,18 @@ static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
>  		ctx->full_inums = true;
>  		ctx->seen |= SHMEM_SEEN_INUMS;
>  		break;
> +	case Opt_quota:
> +		ctx->seen |= SHMEM_SEEN_QUOTA;
> +		ctx->quota_types |= (QTYPE_MASK_USR | QTYPE_MASK_GRP);
> +		break;
> +	case Opt_usrquota:
> +		ctx->seen |= SHMEM_SEEN_QUOTA;
> +		ctx->quota_types |= QTYPE_MASK_USR;
> +		break;
> +	case Opt_grpquota:
> +		ctx->seen |= SHMEM_SEEN_QUOTA;
> +		ctx->quota_types |= QTYPE_MASK_GRP;
> +		break;
>  	}
>  	return 0;
>  
> @@ -3681,6 +3790,12 @@ static int shmem_reconfigure(struct fs_context *fc)
>  		goto out;
>  	}
>  
> +	if (ctx->seen & SHMEM_SEEN_QUOTA &&
> +	    !sb_any_quota_loaded(fc->root->d_sb)) {
> +		err = "Cannot enable quota on remount";
> +		goto out;
> +	}
> +
>  	if (ctx->seen & SHMEM_SEEN_HUGE)
>  		sbinfo->huge = ctx->huge;
>  	if (ctx->seen & SHMEM_SEEN_INUMS)
> @@ -3763,6 +3878,9 @@ static void shmem_put_super(struct super_block *sb)
>  {
>  	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
>  
> +#ifdef CONFIG_TMPFS_QUOTA
> +	shmem_disable_quotas(sb);
> +#endif
>  	free_percpu(sbinfo->ino_batch);
>  	percpu_counter_destroy(&sbinfo->used_blocks);
>  	mpol_put(sbinfo->mpol);
> @@ -3841,6 +3959,17 @@ static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
>  #endif
>  	uuid_gen(&sb->s_uuid);
>  
> +#ifdef CONFIG_TMPFS_QUOTA
> +	if (ctx->seen & SHMEM_SEEN_QUOTA) {
> +		sb->dq_op = &shmem_quota_operations;
> +		sb->s_qcop = &dquot_quotactl_sysfile_ops;
> +		sb->s_quota_types = QTYPE_MASK_USR | QTYPE_MASK_GRP;
> +
> +		if (shmem_enable_quotas(sb, ctx->quota_types))
> +			goto failed;
> +	}
> +#endif /* CONFIG_TMPFS_QUOTA */
> +
>  	inode = shmem_get_inode(&nop_mnt_idmap, sb, NULL, S_IFDIR | sbinfo->mode, 0,
>  				VM_NORESERVE);
>  	if (IS_ERR(inode)) {
> @@ -4016,6 +4145,9 @@ static const struct super_operations shmem_ops = {
>  #ifdef CONFIG_TMPFS
>  	.statfs		= shmem_statfs,
>  	.show_options	= shmem_show_options,
> +#endif
> +#ifdef CONFIG_TMPFS_QUOTA
> +	.get_dquots	= shmem_get_dquots,
>  #endif
>  	.evict_inode	= shmem_evict_inode,
>  	.drop_inode	= generic_delete_inode,
> @@ -4082,6 +4214,14 @@ void __init shmem_init(void)
>  
>  	shmem_init_inodecache();
>  
> +#ifdef CONFIG_TMPFS_QUOTA
> +	error = register_quota_format(&shmem_quota_format);
> +	if (error < 0) {
> +		pr_err("Could not register quota format\n");
> +		goto out3;
> +	}
> +#endif
> +
>  	error = register_filesystem(&shmem_fs_type);
>  	if (error) {
>  		pr_err("Could not register tmpfs\n");
> @@ -4106,6 +4246,10 @@ void __init shmem_init(void)
>  out1:
>  	unregister_filesystem(&shmem_fs_type);
>  out2:
> +#ifdef CONFIG_TMPFS_QUOTA
> +	unregister_quota_format(&shmem_quota_format);
> +#endif
> +out3:
>  	shmem_destroy_inodecache();
>  	shm_mnt = ERR_PTR(error);
>  }
> -- 
> 2.30.2
>