[Ocfs2-devel] [PATCH] ocfs2: mount shared volume without ha stack
Gang He
GHe at suse.com
Tue Apr 28 01:12:18 PDT 2020
Hello Joseph,
Thank for your taking the time to review the patch.
Please see my comments inline.
> -----Original Message-----
> From: Joseph Qi [mailto:joseph.qi at linux.alibaba.com]
> Sent: 2020年4月27日 17:48
> To: Gang He <GHe at suse.com>; mark at fasheh.com; jlbec at evilplan.org
> Cc: linux-kernel at vger.kernel.org; ocfs2-devel at oss.oracle.com;
> akpm at linux-foundation.org
> Subject: Re: [PATCH] ocfs2: mount shared volume without ha stack
>
> 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 at 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"?
I feel this code change should belong to mount behavior, we do not change disk layout.
Then, I feel we should not set this option to the feature bit, since the feature bit is usually saved/loaded to/from the disk.
>
> > }
> >
> > 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.
Since in local(or nocluster) mode, the code will not invoke any DLM/cluster related interfaces.
The node_num is set to 0 directly.
In the past, local mount/cluster mount will not happen on the same volume.
But, after nocluster option is introduced, local(nocluster) mount/cluster mount will possibly happen(not at the same time) on the same volume.
If we mount the shared volume with the cluster mode after a local (nocluster mode) mount crash,
We have to use that slot(slot 0, which was used by the last local mount), otherwise, there is possibly not more slot available.
>
> > 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?
I do not change the existed logic.
In the past, in local mode, the code always use slot 0, even if there are more than one slots.
Now, I just make the logic more clear.
In nocluster mode, we do the same logic, use slot 0 directly, need not to find any available slot.
Because we know only this node will use the file system.
Secondly, we cannot get the DLM node_num(since no dlm service) here, we need not to match node_num like cluster mode.
Thanks
Gang
>
> 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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