On Tue, Nov 08, 2022 at 08:35:28AM -0800, Darrick J. Wong wrote:
> On Tue, Nov 08, 2022 at 02:30:10PM +0100, Lukas Czerner wrote:
> > Implement a set of mount options for setting glopbal quota limits on
> > tmpfs.
> >
> > quota_ubh_limit - global user quota block hard limit
>
> Is this the default per-user limit until the sysadmin runs setquota -u
> or something to change a per-user limit? Or is this a global limit for
> all users and it's never possible to change it?
This is a global limit for all users, except root. The way it works is
that the limit is applied when dquot is first allocated for the
user/group - this is typically the first time user/group allocates
blocks, or creates an inode. It can be changed the same way as it would
be normally.
>
> (Are there any plans for a soft limit?)
I have no plans for soft limit, but I also don't want to make the naming
confusing once someone decides they'd like to have soft limits in future.
>
> > quota_uih_limit - global user quota inode hard limit
> > quota_gbh_limit - global group quota block hard limit
> > quota_gih_limit - global group quota inode hard limit
>
> I don't really like these names, only 2/15 letters in the whole name
> actually distinguish them.
Yes, exactly my feeling as well. I am bad at naming things ;) I was
hoping I'd get some suggestions here, and that exactly what I got.
Thanks!
>
> usrquota_block_hardlimit?
> usrquota_inode_hardlimit? 8/24...
I like it.
>
> usrquota_block_limit?
> usrquota_inode_limit? 8/20...
I like it even more, but with hypothetical introduction of soft limits
in future it wouldn't be as obvious it is a hard limit. But maybe it's
not an issue at all.
Thanks!
-Lukas
>
> (The mechanical changes below here looked ok to me...)
>
> --D
>
> >
> > All of the above mount options will take an effect for any and all
> > users/groups except for root and can be changed using standard ways of
> > setting quota limits. Along with setting the limits, quota enforcement
> > will be enabled as well.
> >
> > None of the mount options can be set or changed on remount.
>
> > Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx>
> > ---
> > Documentation/filesystems/tmpfs.rst | 23 ++--
> > include/linux/shmem_fs.h | 4 +
> > mm/shmem.c | 166 +++++++++++++++++++++++++---
> > 3 files changed, 171 insertions(+), 22 deletions(-)
> >
> > diff --git a/Documentation/filesystems/tmpfs.rst b/Documentation/filesystems/tmpfs.rst
> > index 9c4f228ef4f3..be4aa964863d 100644
> > --- a/Documentation/filesystems/tmpfs.rst
> > +++ b/Documentation/filesystems/tmpfs.rst
> > @@ -88,14 +88,21 @@ that instance in a system with many CPUs making intensive use of it.
> >
> > tmpfs also supports quota with the following mount options
> >
> > -======== =============================================================
> > -quota Quota accounting is enabled on the mount. Tmpfs is using
> > - hidden system quota files that are initialized on mount.
> > - Quota limits can quota enforcement can be enabled using
> > - standard quota tools.
> > -usrquota Same as quota option. Exists for compatibility reasons.
> > -grpquota Same as quota option. Exists for compatibility reasons.
> > -======== =============================================================
> > +=============== ======================================================
> > +quota Quota accounting is enabled on the mount. Tmpfs is
> > + using hidden system quota files that are initialized
> > + on mount. Quota limits can quota enforcement can be
> > + enabled using standard quota tools.
> > +usrquota Same as quota option. Exists for compatibility.
> > +grpquota Same as quota option. Exists for compatibility.
> > +quota_ubh_limit Set global user quota block hard limit.
> > +quota_uih_limit Set global user quota inode hard limit.
> > +quota_gbh_limit Set global group quota block hard limit.
> > +quota_gih_limit Set global group quota inode hard limit.
> > +=============== ======================================================
> > +
> > +Quota limit parameters accept a suffix k, m or g for kilo, mega and
> > +giga and can't be changed on remount.
> >
> >
> > tmpfs has a mount option to set the NUMA memory allocation policy for
> > diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
> > index 02a328c98d3a..eb5e2dc2dc4c 100644
> > --- a/include/linux/shmem_fs.h
> > +++ b/include/linux/shmem_fs.h
> > @@ -39,6 +39,10 @@ struct shmem_inode_info {
> >
> > struct shmem_sb_info {
> > unsigned long max_blocks; /* How many blocks are allowed */
> > + unsigned long quota_ubh_limit; /* Default user quota block hard limit */
> > + unsigned long quota_uih_limit; /* Default user quota inode hard limit */
> > + unsigned long quota_gbh_limit; /* Default group quota block hard limit */
> > + unsigned long quota_gih_limit; /* Default group quota inode hard limit */
> > struct percpu_counter used_blocks; /* How many are allocated */
> > unsigned long max_inodes; /* How many inodes are allowed */
> > unsigned long free_inodes; /* How many are left for allocation */
> > diff --git a/mm/shmem.c b/mm/shmem.c
> > index ec16659c2255..f1d6a3931b0a 100644
> > --- a/mm/shmem.c
> > +++ b/mm/shmem.c
> > @@ -99,6 +99,10 @@ static struct vfsmount *shm_mnt;
> > /* Symlink up to this size is kmalloc'ed instead of using a swappable page */
> > #define SHORT_SYMLINK_LEN 128
> >
> > +#if defined(CONFIG_TMPFS) && defined(CONFIG_QUOTA)
> > +#define SHMEM_QUOTA_TMPFS
> > +#endif
> > +
> > /*
> > * shmem_fallocate communicates with shmem_fault or shmem_writepage via
> > * inode->i_private (with i_rwsem making sure that it has only one user at
> > @@ -115,6 +119,12 @@ struct shmem_falloc {
> > struct shmem_options {
> > unsigned long long blocks;
> > unsigned long long inodes;
> > +#ifdef SHMEM_QUOTA_TMPFS
> > + unsigned long long quota_ubh_limit;
> > + unsigned long long quota_uih_limit;
> > + unsigned long long quota_gbh_limit;
> > + unsigned long long quota_gih_limit;
> > +#endif
> > struct mempolicy *mpol;
> > kuid_t uid;
> > kgid_t gid;
> > @@ -147,10 +157,6 @@ static unsigned long shmem_default_max_inodes(void)
> > }
> > #endif
> >
> > -#if defined(CONFIG_TMPFS) && defined(CONFIG_QUOTA)
> > -#define SHMEM_QUOTA_TMPFS
> > -#endif
> > -
> > static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
> > struct folio **foliop, enum sgp_type sgp,
> > gfp_t gfp, struct vm_area_struct *vma,
> > @@ -285,6 +291,54 @@ static DEFINE_MUTEX(shmem_swaplist_mutex);
> > #define QUOTABLOCK_BITS 10
> > #define QUOTABLOCK_SIZE (1 << QUOTABLOCK_BITS)
> >
> > +struct kmem_cache *shmem_dquot_cachep;
> > +
> > +struct dquot *shmem_dquot_alloc(struct super_block *sb, int type)
> > +{
> > + struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
> > + struct dquot *dquot = NULL;
> > +
> > + dquot = kmem_cache_zalloc(shmem_dquot_cachep, GFP_NOFS);
> > + if (!dquot)
> > + return NULL;
> > +
> > + if (type == USRQUOTA) {
> > + dquot->dq_dqb.dqb_bhardlimit =
> > + (sbinfo->quota_ubh_limit << PAGE_SHIFT);
> > + dquot->dq_dqb.dqb_ihardlimit = sbinfo->quota_uih_limit;
> > + } else if (type == GRPQUOTA) {
> > + dquot->dq_dqb.dqb_bhardlimit =
> > + (sbinfo->quota_gbh_limit << PAGE_SHIFT);
> > + dquot->dq_dqb.dqb_ihardlimit = sbinfo->quota_gih_limit;
> > + }
> > + /*
> > + * This is a bit a of a hack to allow setting global default
> > + * limits on new files, by setting the limits here and preventing
> > + * quota from initializing everything to zero. It won't ever be
> > + * read from quota file because existing inodes in tmpfs are always
> > + * kept in memory (or swap) so we know we're getting dquot for a
> > + * new inode with no pre-existing dquot.
> > + */
> > + set_bit(DQ_READ_B, &dquot->dq_flags);
> > + return dquot;
> > +}
> > +
> > +static void shmem_dquot_destroy(struct dquot *dquot)
> > +{
> > + kmem_cache_free(shmem_dquot_cachep, dquot);
> > +}
> > +
> > +const struct dquot_operations shmem_dquot_operations = {
> > + .write_dquot = dquot_commit,
> > + .acquire_dquot = dquot_acquire,
> > + .release_dquot = dquot_release,
> > + .mark_dirty = dquot_mark_dquot_dirty,
> > + .write_info = dquot_commit_info,
> > + .alloc_dquot = shmem_dquot_alloc,
> > + .destroy_dquot = shmem_dquot_destroy,
> > + .get_next_id = dquot_get_next_id,
> > +};
> > +
> > static ssize_t shmem_quota_write_inode(struct inode *inode, int type,
> > const char *data, size_t len, loff_t off)
> > {
> > @@ -343,7 +397,7 @@ static ssize_t shmem_quota_write(struct super_block *sb, int type,
> > return shmem_quota_write_inode(inode, type, data, len, off);
> > }
> >
> > -static int shmem_enable_quotas(struct super_block *sb)
> > +static int shmem_enable_quotas(struct super_block *sb, unsigned int dquot_flags)
> > {
> > int type, err = 0;
> > struct inode *inode;
> > @@ -389,7 +443,7 @@ static int shmem_enable_quotas(struct super_block *sb)
> > shmem_set_inode_flags(inode, FS_NOATIME_FL | FS_IMMUTABLE_FL);
> >
> > err = dquot_load_quota_inode(inode, type, QFMT_VFS_V1,
> > - DQUOT_USAGE_ENABLED);
> > + dquot_flags);
> > iput(inode);
> > if (err)
> > goto out_err;
> > @@ -3720,6 +3774,10 @@ enum shmem_param {
> > Opt_inode32,
> > Opt_inode64,
> > Opt_quota,
> > + Opt_quota_ubh_limit,
> > + Opt_quota_uih_limit,
> > + Opt_quota_gbh_limit,
> > + Opt_quota_gih_limit,
> > };
> >
> > static const struct constant_table shmem_param_enums_huge[] = {
> > @@ -3744,6 +3802,10 @@ const struct fs_parameter_spec shmem_fs_parameters[] = {
> > fsparam_flag ("quota", Opt_quota),
> > fsparam_flag ("usrquota", Opt_quota),
> > fsparam_flag ("grpquota", Opt_quota),
> > + fsparam_string("quota_ubh_limit", Opt_quota_ubh_limit),
> > + fsparam_string("quota_uih_limit", Opt_quota_uih_limit),
> > + fsparam_string("quota_gbh_limit", Opt_quota_gbh_limit),
> > + fsparam_string("quota_gih_limit", Opt_quota_gih_limit),
> > {}
> > };
> >
> > @@ -3827,13 +3889,44 @@ 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:
> > #ifdef CONFIG_QUOTA
> > + case Opt_quota:
> > + ctx->seen |= SHMEM_SEEN_QUOTA;
> > + break;
> > + case Opt_quota_ubh_limit:
> > + size = memparse(param->string, &rest);
> > + if (*rest || !size)
> > + goto bad_value;
> > + ctx->quota_ubh_limit = DIV_ROUND_UP(size, PAGE_SIZE);
> > + ctx->seen |= SHMEM_SEEN_QUOTA;
> > + break;
> > + case Opt_quota_gbh_limit:
> > + size = memparse(param->string, &rest);
> > + if (*rest || !size)
> > + goto bad_value;
> > + ctx->quota_gbh_limit = DIV_ROUND_UP(size, PAGE_SIZE);
> > + ctx->seen |= SHMEM_SEEN_QUOTA;
> > + break;
> > + case Opt_quota_uih_limit:
> > + ctx->quota_uih_limit = memparse(param->string, &rest);
> > + if (*rest || !ctx->quota_uih_limit)
> > + goto bad_value;
> > + ctx->seen |= SHMEM_SEEN_QUOTA;
> > + break;
> > + case Opt_quota_gih_limit:
> > + ctx->quota_gih_limit = memparse(param->string, &rest);
> > + if (*rest || !ctx->quota_gih_limit)
> > + goto bad_value;
> > ctx->seen |= SHMEM_SEEN_QUOTA;
> > + break;
> > #else
> > + case Opt_quota:
> > + case Opt_quota_ubh_limit:
> > + case Opt_quota_gbh_limit:
> > + case Opt_quota_uih_limit:
> > + case Opt_quota_gih_limit:
> > goto unsupported_parameter;
> > #endif
> > - break;
> > }
> > return 0;
> >
> > @@ -3933,12 +4026,24 @@ static int shmem_reconfigure(struct fs_context *fc)
> > goto out;
> > }
> >
> > +#ifdef CONFIG_QUOTA
> > if (ctx->seen & SHMEM_SEEN_QUOTA &&
> > !sb_any_quota_loaded(fc->root->d_sb)) {
> > err = "Cannot enable quota on remount";
> > goto out;
> > }
> >
> > +#define CHANGED_LIMIT(name) \
> > + (ctx->quota_##name##_limit && \
> > + (ctx->quota_##name##_limit != sbinfo->quota_ ##name##_limit))
> > +
> > + if (CHANGED_LIMIT(ubh) || CHANGED_LIMIT(uih) ||
> > + CHANGED_LIMIT(gbh) || CHANGED_LIMIT(gih)) {
> > + err = "Cannot change global quota limit on remount";
> > + goto out;
> > + }
> > +#endif /* CONFIG_QUOTA */
> > +
> > if (ctx->seen & SHMEM_SEEN_HUGE)
> > sbinfo->huge = ctx->huge;
> > if (ctx->seen & SHMEM_SEEN_INUMS)
> > @@ -4103,11 +4208,22 @@ static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
> >
> > #ifdef SHMEM_QUOTA_TMPFS
> > if (ctx->seen & SHMEM_SEEN_QUOTA) {
> > - sb->dq_op = &dquot_operations;
> > + unsigned int dquot_flags;
> > +
> > + sb->dq_op = &shmem_dquot_operations;
> > sb->s_qcop = &dquot_quotactl_sysfile_ops;
> > sb->s_quota_types = QTYPE_MASK_USR | QTYPE_MASK_GRP;
> >
> > - if (shmem_enable_quotas(sb))
> > + dquot_flags = DQUOT_USAGE_ENABLED;
> > + /*
> > + * If any of the global quota limits are set, enable
> > + * quota enforcement
> > + */
> > + if (ctx->quota_ubh_limit || ctx->quota_uih_limit ||
> > + ctx->quota_gbh_limit || ctx->quota_gih_limit)
> > + dquot_flags |= DQUOT_LIMITS_ENABLED;
> > +
> > + if (shmem_enable_quotas(sb, dquot_flags))
> > goto failed;
> > }
> > #endif /* SHMEM_QUOTA_TMPFS */
> > @@ -4121,6 +4237,17 @@ static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
> > if (!sb->s_root)
> > goto failed;
> >
> > +#ifdef SHMEM_QUOTA_TMPFS
> > + /*
> > + * Set quota hard limits after shmem_get_inode() to avoid setting
> > + * it for root
> > + */
> > + sbinfo->quota_ubh_limit = ctx->quota_ubh_limit;
> > + sbinfo->quota_uih_limit = ctx->quota_uih_limit;
> > + sbinfo->quota_gbh_limit = ctx->quota_gbh_limit;
> > + sbinfo->quota_gih_limit = ctx->quota_gih_limit;
> > +#endif /* SHMEM_QUOTA_TMPFS */
> > +
> > return 0;
> >
> > failed:
> > @@ -4183,16 +4310,27 @@ static void shmem_init_inode(void *foo)
> > inode_init_once(&info->vfs_inode);
> > }
> >
> > -static void shmem_init_inodecache(void)
> > +static void shmem_init_mem_caches(void)
> > {
> > shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
> > sizeof(struct shmem_inode_info),
> > 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode);
> > +
> > +#ifdef SHMEM_QUOTA_TMPFS
> > + shmem_dquot_cachep = kmem_cache_create("shmem_dquot",
> > + sizeof(struct dquot), sizeof(unsigned long) * 4,
> > + (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
> > + SLAB_MEM_SPREAD|SLAB_PANIC),
> > + NULL);
> > +#endif
> > }
> >
> > -static void shmem_destroy_inodecache(void)
> > +static void shmem_destroy_mem_caches(void)
> > {
> > kmem_cache_destroy(shmem_inode_cachep);
> > +#ifdef SHMEM_QUOTA_TMPFS
> > + kmem_cache_destroy(shmem_dquot_cachep);
> > +#endif
> > }
> >
> > /* Keep the page in page cache instead of truncating it */
> > @@ -4340,7 +4478,7 @@ void __init shmem_init(void)
> > {
> > int error;
> >
> > - shmem_init_inodecache();
> > + shmem_init_mem_caches();
> >
> > error = register_filesystem(&shmem_fs_type);
> > if (error) {
> > @@ -4366,7 +4504,7 @@ void __init shmem_init(void)
> > out1:
> > unregister_filesystem(&shmem_fs_type);
> > out2:
> > - shmem_destroy_inodecache();
> > + shmem_destroy_mem_caches();
> > shm_mnt = ERR_PTR(error);
> > }
> >
> > --
> > 2.38.1
> >
>
