Re: [RFC PATCH v3 2/3] ceph: quotas: support for ceph.quota.max_files

["Yan, Zheng" <ukernel@gmail.com>]

On Wed, Dec 20, 2017 at 11:18 PM, Luis Henriques <lhenriques@suse.com> wrote:
> This patch adds support for the max_files quota.  It hooks into all the
> ceph functions that add new filesystem objects that need to be checked
> against the quota limits.  When these limits are hit, -EDQUOT is returned.
>
> Note that we're not checking quotas on ceph_link().  ceph_link doesn't
> really create a new inode,  and since the MDS doesn't update the directory
> statistics when a new (hard) link is created (only with symlinks), they
> are not accounted as a new file.
>
> Link: http://tracker.ceph.com/issues/22372
> Signed-off-by: Luis Henriques <lhenriques@suse.com>
> ---
>  fs/ceph/dir.c   | 11 +++++++++
>  fs/ceph/file.c  |  4 +++-
>  fs/ceph/quota.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  fs/ceph/super.h |  1 +
>  4 files changed, 84 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
> index 8a5266699b67..66550d92b1ac 100644
> --- a/fs/ceph/dir.c
> +++ b/fs/ceph/dir.c
> @@ -818,6 +818,9 @@ static int ceph_mknod(struct inode *dir, struct dentry *dentry,
>         if (ceph_snap(dir) != CEPH_NOSNAP)
>                 return -EROFS;
>
> +       if (ceph_quota_is_max_files_exceeded(dir))
> +               return -EDQUOT;
> +
>         err = ceph_pre_init_acls(dir, &mode, &acls);
>         if (err < 0)
>                 return err;
> @@ -871,6 +874,9 @@ static int ceph_symlink(struct inode *dir, struct dentry *dentry,
>         if (ceph_snap(dir) != CEPH_NOSNAP)
>                 return -EROFS;
>
> +       if (ceph_quota_is_max_files_exceeded(dir))
> +               return -EDQUOT;
> +
>         dout("symlink in dir %p dentry %p to '%s'\n", dir, dentry, dest);
>         req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_SYMLINK, USE_AUTH_MDS);
>         if (IS_ERR(req)) {
> @@ -920,6 +926,11 @@ static int ceph_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
>                 goto out;
>         }
>
> +       if (ceph_quota_is_max_files_exceeded(dir)) {
> +               err = -EDQUOT;
> +               goto out;
> +       }
> +
>         mode |= S_IFDIR;
>         err = ceph_pre_init_acls(dir, &mode, &acls);
>         if (err < 0)
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index 5c17125f45c7..5a77a66e3d6b 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -371,7 +371,7 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
>         struct ceph_mds_request *req;
>         struct dentry *dn;
>         struct ceph_acls_info acls = {};
> -       int mask;
> +       int mask;
>         int err;
>
>         dout("atomic_open %p dentry %p '%pd' %s flags %d mode 0%o\n",
> @@ -382,6 +382,8 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
>                 return -ENAMETOOLONG;
>
>         if (flags & O_CREAT) {
> +               if (ceph_quota_is_max_files_exceeded(dir))
> +                       return -EDQUOT;
>                 err = ceph_pre_init_acls(dir, &mode, &acls);
>                 if (err < 0)
>                         return err;
> diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c
> index 7bde6e85b609..06b3268f8f7f 100644
> --- a/fs/ceph/quota.c
> +++ b/fs/ceph/quota.c
> @@ -61,3 +61,72 @@ void ceph_handle_quota(struct ceph_mds_client *mdsc,
>
>         iput(inode);
>  }
> +
> +enum quota_check_op {
> +       QUOTA_CHECK_MAX_FILES_OP /* check quota max_files limit */
> +};
> +
> +/*
> + * check_quota_exceeded() will walk up the snaprealm hierarchy and, for each
> + * realm, it will execute quota check operation defined by the 'op' parameter.
> + * The snaprealm walk is interrupted if the quota check detects that the quota
> + * is exceeded or if the root inode is reached.
> + */
> +static bool check_quota_exceeded(struct inode *inode, enum quota_check_op op,
> +                                loff_t size)
> +{
> +       struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
> +       struct ceph_inode_info *ci;
> +       struct ceph_snap_realm *realm, *next;
> +       struct ceph_vino vino;
> +       struct inode *ino;

It's better to use name 'in'

> +       u64 max = 0, rvalue = 0;
> +       bool quota_exceeded = false, is_root = false;
> +
> +       WARN_ON(!S_ISDIR(inode->i_mode));
> +
> +       down_read(&mdsc->snap_rwsem);
> +       realm = ceph_inode(inode)->i_snap_realm;
> +       ceph_get_snap_realm(mdsc, realm);
> +       while (realm) {
> +               vino.ino = realm->ino;
> +               vino.snap = CEPH_NOSNAP;
> +               ino = ceph_find_inode(inode->i_sb, vino);
> +               if (!ino) {
> +                       pr_warn("Failed to find inode for %llu\n", vino.ino);
> +                       break;
> +               }
> +               ci = ceph_inode(ino);
> +               switch(op) {
> +               case QUOTA_CHECK_MAX_FILES_OP:
> +                       spin_lock(&ci->i_ceph_lock);
> +                       max = ci->i_max_files;
> +                       rvalue = ci->i_rfiles + ci->i_rsubdirs;
> +                       is_root = (ci->i_vino.ino == CEPH_INO_ROOT);
> +                       spin_unlock(&ci->i_ceph_lock);
> +                       quota_exceeded = (max && (rvalue >= max));
> +                       break;
> +               default:
> +                       /* Shouldn't happen */
> +                       pr_warn("Invalid quota check op (%d)\n", op);
> +                       is_root = true; /* Just break the loop */
> +               }
> +               iput(ino);
> +
> +               if (quota_exceeded || is_root)
> +                       break;
> +               next = realm->parent;
> +               ceph_get_snap_realm(mdsc, next);
> +               ceph_put_snap_realm(mdsc, realm);
> +               realm = next;
> +       }
> +       ceph_put_snap_realm(mdsc, realm);
> +       up_read(&mdsc->snap_rwsem);
> +
> +       return quota_exceeded;
> +}
> +
> +bool ceph_quota_is_max_files_exceeded(struct inode *inode)
> +{
> +       return check_quota_exceeded(inode, QUOTA_CHECK_MAX_FILES_OP, 0);
> +}
> diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> index f998b7f076cf..20197e29a7f0 100644
> --- a/fs/ceph/super.h
> +++ b/fs/ceph/super.h
> @@ -1026,5 +1026,6 @@ extern void ceph_fs_debugfs_cleanup(struct ceph_fs_client *client);
>  extern void ceph_handle_quota(struct ceph_mds_client *mdsc,
>                               struct ceph_mds_session *session,
>                               struct ceph_msg *msg);
> +extern bool ceph_quota_is_max_files_exceeded(struct inode *inode);
>
>  #endif /* _FS_CEPH_SUPER_H */
> --
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