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SubjectRe: [PATCH] ocfs2: mount shared volume without ha stack
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Hi Gang,

On 2020/4/23 13:33, Gang He wrote:
> Usually we create and use a ocfs2 shared volume on the top of
> ha stack. For pcmk based ha stack, which includes DLM, corosync
> and pacemaker services.
> The customers complained they could not mount existent ocfs2
> volume in the single node without ha stack, e.g. single node
> backup/restore scenario.
> Like this case, the customers just want to access the data
> from the existent ocfs2 volume quickly, but do not want to
> restart or setup ha stack.
> Then, I'd like to add a mount option "nocluster", if the users
> use this option to mount a ocfs2 shared volume, the whole mount
> will not depend on the ha related services. the command will mount
> the existent ocfs2 volume directly (like local mount), for avoiding
> setup the ha stack.
>
> Signed-off-by: Gang He <ghe@suse.com>
> ---
> fs/ocfs2/ocfs2.h | 4 +++-
> fs/ocfs2/slot_map.c | 46 ++++++++++++++++++++++++++-------------------
> fs/ocfs2/super.c | 21 +++++++++++++++++++++
> 3 files changed, 51 insertions(+), 20 deletions(-)
>
> diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
> index 9150cfa4df7d..ee5d98516212 100644
> --- a/fs/ocfs2/ocfs2.h
> +++ b/fs/ocfs2/ocfs2.h
> @@ -279,6 +279,7 @@ enum ocfs2_mount_options
> OCFS2_MOUNT_JOURNAL_ASYNC_COMMIT = 1 << 15, /* Journal Async Commit */
> OCFS2_MOUNT_ERRORS_CONT = 1 << 16, /* Return EIO to the calling process on error */
> OCFS2_MOUNT_ERRORS_ROFS = 1 << 17, /* Change filesystem to read-only on error */
> + OCFS2_MOUNT_NOCLUSTER = 1 << 18, /* No cluster aware filesystem mount */
> };
>
> #define OCFS2_OSB_SOFT_RO 0x0001
> @@ -673,7 +674,8 @@ static inline int ocfs2_cluster_o2cb_global_heartbeat(struct ocfs2_super *osb)
>
> static inline int ocfs2_mount_local(struct ocfs2_super *osb)
> {
> - return (osb->s_feature_incompat & OCFS2_FEATURE_INCOMPAT_LOCAL_MOUNT);
> + return ((osb->s_feature_incompat & OCFS2_FEATURE_INCOMPAT_LOCAL_MOUNT)
> + || (osb->s_mount_opt & OCFS2_MOUNT_NOCLUSTER));

Could we set the feature bit when mount with "nocluster"?

> }
>
> static inline int ocfs2_uses_extended_slot_map(struct ocfs2_super *osb)
> diff --git a/fs/ocfs2/slot_map.c b/fs/ocfs2/slot_map.c
> index 8caeceeaeda7..4da0e4b1e79b 100644
> --- a/fs/ocfs2/slot_map.c
> +++ b/fs/ocfs2/slot_map.c
> @@ -254,14 +254,16 @@ static int __ocfs2_find_empty_slot(struct ocfs2_slot_info *si,
> int i, ret = -ENOSPC;
>
> if ((preferred >= 0) && (preferred < si->si_num_slots)) {
> - if (!si->si_slots[preferred].sl_valid) {
> + if (!si->si_slots[preferred].sl_valid ||
> + !si->si_slots[preferred].sl_node_num) {

Why specially handle node num 0 here?
It seems breaks original logic.

> ret = preferred;
> goto out;
> }
> }
>
> for(i = 0; i < si->si_num_slots; i++) {
> - if (!si->si_slots[i].sl_valid) {
> + if (!si->si_slots[i].sl_valid ||
> + !si->si_slots[i].sl_node_num) {
> ret = i;
> break;
> }
> @@ -456,24 +458,30 @@ int ocfs2_find_slot(struct ocfs2_super *osb)
> spin_lock(&osb->osb_lock);
> ocfs2_update_slot_info(si);
>
> - /* search for ourselves first and take the slot if it already
> - * exists. Perhaps we need to mark this in a variable for our
> - * own journal recovery? Possibly not, though we certainly
> - * need to warn to the user */
> - slot = __ocfs2_node_num_to_slot(si, osb->node_num);
> - if (slot < 0) {
> - /* if no slot yet, then just take 1st available
> - * one. */
> - slot = __ocfs2_find_empty_slot(si, osb->preferred_slot);
> + if (ocfs2_mount_local(osb))
> + /* use slot 0 directly in local mode */
> + slot = 0;

Could you please elaborate more why we need this?

Thanks,
Joseph

> + else {
> + /* search for ourselves first and take the slot if it already
> + * exists. Perhaps we need to mark this in a variable for our
> + * own journal recovery? Possibly not, though we certainly
> + * need to warn to the user */
> + slot = __ocfs2_node_num_to_slot(si, osb->node_num);
> if (slot < 0) {
> - spin_unlock(&osb->osb_lock);
> - mlog(ML_ERROR, "no free slots available!\n");
> - status = -EINVAL;
> - goto bail;
> - }
> - } else
> - printk(KERN_INFO "ocfs2: Slot %d on device (%s) was already "
> - "allocated to this node!\n", slot, osb->dev_str);
> + /* if no slot yet, then just take 1st available
> + * one. */
> + slot = __ocfs2_find_empty_slot(si, osb->preferred_slot);
> + if (slot < 0) {
> + spin_unlock(&osb->osb_lock);
> + mlog(ML_ERROR, "no free slots available!\n");
> + status = -EINVAL;
> + goto bail;
> + }
> + } else
> + printk(KERN_INFO "ocfs2: Slot %d on device (%s) was "
> + "already allocated to this node!\n",
> + slot, osb->dev_str);
> + }
>
> ocfs2_set_slot(si, slot, osb->node_num);
> osb->slot_num = slot;
> diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
> index ac61eeaf3837..71ea9ce71a6b 100644
> --- a/fs/ocfs2/super.c
> +++ b/fs/ocfs2/super.c
> @@ -175,6 +175,7 @@ enum {
> Opt_dir_resv_level,
> Opt_journal_async_commit,
> Opt_err_cont,
> + Opt_nocluster,
> Opt_err,
> };
>
> @@ -208,6 +209,7 @@ static const match_table_t tokens = {
> {Opt_dir_resv_level, "dir_resv_level=%u"},
> {Opt_journal_async_commit, "journal_async_commit"},
> {Opt_err_cont, "errors=continue"},
> + {Opt_nocluster, "nocluster"},
> {Opt_err, NULL}
> };
>
> @@ -619,6 +621,13 @@ static int ocfs2_remount(struct super_block *sb, int *flags, char *data)
> goto out;
> }
>
> + tmp = OCFS2_MOUNT_NOCLUSTER;
> + if ((osb->s_mount_opt & tmp) != (parsed_options.mount_opt & tmp)) {
> + ret = -EINVAL;
> + mlog(ML_ERROR, "Cannot change nocluster option on remount\n");
> + goto out;
> + }
> +
> tmp = OCFS2_MOUNT_HB_LOCAL | OCFS2_MOUNT_HB_GLOBAL |
> OCFS2_MOUNT_HB_NONE;
> if ((osb->s_mount_opt & tmp) != (parsed_options.mount_opt & tmp)) {
> @@ -859,6 +868,7 @@ static int ocfs2_verify_userspace_stack(struct ocfs2_super *osb,
> }
>
> if (ocfs2_userspace_stack(osb) &&
> + !(osb->s_mount_opt & OCFS2_MOUNT_NOCLUSTER) &&
> strncmp(osb->osb_cluster_stack, mopt->cluster_stack,
> OCFS2_STACK_LABEL_LEN)) {
> mlog(ML_ERROR,
> @@ -1139,6 +1149,11 @@ static int ocfs2_fill_super(struct super_block *sb, void *data, int silent)
> osb->s_mount_opt & OCFS2_MOUNT_DATA_WRITEBACK ? "writeback" :
> "ordered");
>
> + if ((osb->s_mount_opt & OCFS2_MOUNT_NOCLUSTER) &&
> + !(osb->s_feature_incompat & OCFS2_FEATURE_INCOMPAT_LOCAL_MOUNT))
> + printk(KERN_NOTICE "ocfs2: The shared device (%s) is mounted "
> + "without cluster aware mode.\n", osb->dev_str);
> +
> atomic_set(&osb->vol_state, VOLUME_MOUNTED);
> wake_up(&osb->osb_mount_event);
>
> @@ -1445,6 +1460,9 @@ static int ocfs2_parse_options(struct super_block *sb,
> case Opt_journal_async_commit:
> mopt->mount_opt |= OCFS2_MOUNT_JOURNAL_ASYNC_COMMIT;
> break;
> + case Opt_nocluster:
> + mopt->mount_opt |= OCFS2_MOUNT_NOCLUSTER;
> + break;
> default:
> mlog(ML_ERROR,
> "Unrecognized mount option \"%s\" "
> @@ -1556,6 +1574,9 @@ static int ocfs2_show_options(struct seq_file *s, struct dentry *root)
> if (opts & OCFS2_MOUNT_JOURNAL_ASYNC_COMMIT)
> seq_printf(s, ",journal_async_commit");
>
> + if (opts & OCFS2_MOUNT_NOCLUSTER)
> + seq_printf(s, ",nocluster");
> +
> return 0;
> }
>
>

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