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

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

On Tue, Apr 04, 2023 at 03:41:19PM +0200, Carlos Maiolino wrote:
> Hi.
> 
> > >  	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?
> 
> My bad, I should have used SHMEM_MAXQUOTAS to define the i_dquot
> 
> > 
> > (Or: Why not allow project quotas?  But that's outside the scope you
> > defined.)
> 
> This is indeed on my plan, which I want to do later, I want to deal with the
> 'avoid users to consume all memory' issue, then I want to add prjquotas here. I
> want to limit the scope of this series by now to avoid it snowballing with more
> and more features.

Ok.  This all mostly looks fine to me ... to the extent that I know
anything about tmpfs. ;)

--D

> > 
> > --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
> > >
> 
> -- 
> Carlos Maiolino