NFS4.1: Add lseg to struct nfs4_fl_commit_bucket

Also create a commit_info structure to hold the bucket array and push
it up from the lseg to the layout where it really belongs.

While we are at it, fix a refcounting bug due to an (incorrect)
implicit assumption that filelayout_scan_ds_commit_list always
completely emptied the src list.

This clarifies refcounting, removes the ugly find_only_write_lseg
functions, and pushes the file layout commit code along on the path to
supporting multiple lsegs.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

2 files changed, 144 insertions, 92 deletions

diff --git a/fs/nfs/nfs4filelayout.c b/fs/nfs/nfs4filelayout.c
index 5acfd9ea8a31..15aeba20d57d 100644
--- a/fs/nfs/nfs4filelayout.c
+++ b/fs/nfs/nfs4filelayout.c
@@ -650,10 +650,66 @@ filelayout_free_lseg(struct pnfs_layout_segment *lseg)
 
         dprintk("--> %s\n", __func__);
         nfs4_fl_put_deviceid(fl->dsaddr);
-        kfree(fl->commit_buckets);
+        /* This assumes a single RW lseg */
+        if (lseg->pls_range.iomode == IOMODE_RW) {
+                struct nfs4_filelayout *flo;
+
+                flo = FILELAYOUT_FROM_HDR(lseg->pls_layout);
+                flo->commit_info.nbuckets = 0;
+                kfree(flo->commit_info.buckets);
+                flo->commit_info.buckets = NULL;
+        }
         _filelayout_free_lseg(fl);
 }
 
+static int
+filelayout_alloc_commit_info(struct pnfs_layout_segment *lseg,
+                             gfp_t gfp_flags)
+{
+        struct nfs4_filelayout_segment *fl = FILELAYOUT_LSEG(lseg);
+        struct nfs4_filelayout *flo = FILELAYOUT_FROM_HDR(lseg->pls_layout);
+
+        struct nfs4_fl_commit_bucket *buckets;
+        int size;
+
+        if (fl->commit_through_mds)
+                return 0;
+        if (flo->commit_info.nbuckets != 0) {
+                /* This assumes there is only one IOMODE_RW lseg.  What
+                 * we really want to do is have a layout_hdr level
+                 * dictionary of <multipath_list4, fh> keys, each
+                 * associated with a struct list_head, populated by calls
+                 * to filelayout_write_pagelist().
+                 * */
+                return 0;
+        }
+
+        size = (fl->stripe_type == STRIPE_SPARSE) ?
+                fl->dsaddr->ds_num : fl->dsaddr->stripe_count;
+
+        buckets = kcalloc(size, sizeof(struct nfs4_fl_commit_bucket),
+                          gfp_flags);
+        if (!buckets)
+                return -ENOMEM;
+        else {
+                int i;
+
+                spin_lock(&lseg->pls_layout->plh_inode->i_lock);
+                if (flo->commit_info.nbuckets != 0)
+                        kfree(buckets);
+                else {
+                        flo->commit_info.buckets = buckets;
+                        flo->commit_info.nbuckets = size;
+                        for (i = 0; i < size; i++) {
+                                INIT_LIST_HEAD(&buckets[i].written);
+                                INIT_LIST_HEAD(&buckets[i].committing);
+                        }
+                }
+                spin_unlock(&lseg->pls_layout->plh_inode->i_lock);
+                return 0;
+        }
+}
+
 static struct pnfs_layout_segment *
 filelayout_alloc_lseg(struct pnfs_layout_hdr *layoutid,
                       struct nfs4_layoutget_res *lgr,
@@ -673,29 +729,6 @@ filelayout_alloc_lseg(struct pnfs_layout_hdr *layoutid,
                 _filelayout_free_lseg(fl);
                 return NULL;
         }
-
-        /* This assumes there is only one IOMODE_RW lseg.  What
-         * we really want to do is have a layout_hdr level
-         * dictionary of <multipath_list4, fh> keys, each
-         * associated with a struct list_head, populated by calls
-         * to filelayout_write_pagelist().
-         * */
-        if ((!fl->commit_through_mds) && (lgr->range.iomode == IOMODE_RW)) {
-                int i;
-                int size = (fl->stripe_type == STRIPE_SPARSE) ?
-                        fl->dsaddr->ds_num : fl->dsaddr->stripe_count;
-
-                fl->commit_buckets = kcalloc(size, sizeof(struct nfs4_fl_commit_bucket), gfp_flags);
-                if (!fl->commit_buckets) {
-                        filelayout_free_lseg(&fl->generic_hdr);
-                        return NULL;
-                }
-                fl->number_of_buckets = size;
-                for (i = 0; i < size; i++) {
-                        INIT_LIST_HEAD(&fl->commit_buckets[i].written);
-                        INIT_LIST_HEAD(&fl->commit_buckets[i].committing);
-                }
-        }
         return &fl->generic_hdr;
 }
 
@@ -747,6 +780,8 @@ static void
 filelayout_pg_init_write(struct nfs_pageio_descriptor *pgio,
                          struct nfs_page *req)
 {
+        int status;
+
         BUG_ON(pgio->pg_lseg != NULL);
 
         pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
@@ -757,7 +792,16 @@ filelayout_pg_init_write(struct nfs_pageio_descriptor *pgio,
                                            GFP_NOFS);
         /* If no lseg, fall back to write through mds */
         if (pgio->pg_lseg == NULL)
-                nfs_pageio_reset_write_mds(pgio);
+                goto out_mds;
+        status = filelayout_alloc_commit_info(pgio->pg_lseg, GFP_NOFS);
+        if (status < 0) {
+                put_lseg(pgio->pg_lseg);
+                pgio->pg_lseg = NULL;
+                goto out_mds;
+        }
+        return;
+out_mds:
+        nfs_pageio_reset_write_mds(pgio);
 }
 
 static const struct nfs_pageio_ops filelayout_pg_read_ops = {
@@ -793,17 +837,13 @@ filelayout_clear_request_commit(struct nfs_page *req)
         if (!test_and_clear_bit(PG_COMMIT_TO_DS, &req->wb_flags))
                 goto out;
         if (list_is_singular(&req->wb_list)) {
-                struct pnfs_layout_segment *lseg;
+                struct nfs4_fl_commit_bucket *bucket;
 
-                /* From here we can find the bucket, but for the moment,
-                 * since there is only one relevant lseg...
-                 */
-                list_for_each_entry(lseg, &NFS_I(inode)->layout->plh_segs, pls_list) {
-                        if (lseg->pls_range.iomode == IOMODE_RW) {
-                                freeme = lseg;
-                                break;
-                        }
-                }
+                bucket = list_first_entry(&req->wb_list,
+                                          struct nfs4_fl_commit_bucket,
+                                          written);
+                freeme = bucket->wlseg;
+                bucket->wlseg = NULL;
         }
 out:
         nfs_request_remove_commit_list(req);
@@ -818,6 +858,7 @@ filelayout_choose_commit_list(struct nfs_page *req,
         struct nfs4_filelayout_segment *fl = FILELAYOUT_LSEG(lseg);
         u32 i, j;
         struct list_head *list;
+        struct nfs4_fl_commit_bucket *buckets;
 
         if (fl->commit_through_mds)
                 return &NFS_I(req->wb_context->dentry->d_inode)->commit_list;
@@ -831,15 +872,16 @@ filelayout_choose_commit_list(struct nfs_page *req,
         j = nfs4_fl_calc_j_index(lseg,
                                  (loff_t)req->wb_index << PAGE_CACHE_SHIFT);
         i = select_bucket_index(fl, j);
-        list = &fl->commit_buckets[i].written;
+        buckets = FILELAYOUT_FROM_HDR(lseg->pls_layout)->commit_info.buckets;
+        list = &buckets[i].written;
         if (list_empty(list)) {
                 /* Non-empty buckets hold a reference on the lseg.  That ref
                  * is normally transferred to the COMMIT call and released
                  * there.  It could also be released if the last req is pulled
                  * off due to a rewrite, in which case it will be done in
-                 * filelayout_remove_commit_req
+                 * filelayout_clear_request_commit
                  */
-                get_lseg(lseg);
+                buckets[i].wlseg = get_lseg(lseg);
         }
         set_bit(PG_COMMIT_TO_DS, &req->wb_flags);
         return list;
@@ -908,32 +950,6 @@ static int filelayout_initiate_commit(struct nfs_write_data *data, int how)
                                    &filelayout_commit_call_ops, how);
 }
 
-/*
- * This is only useful while we are using whole file layouts.
- */
-static struct pnfs_layout_segment *
-find_only_write_lseg_locked(struct inode *inode)
-{
-        struct pnfs_layout_segment *lseg;
-
-        list_for_each_entry(lseg, &NFS_I(inode)->layout->plh_segs, pls_list)
-                if (lseg->pls_range.iomode == IOMODE_RW)
-                        return lseg;
-        return NULL;
-}
-
-static struct pnfs_layout_segment *find_only_write_lseg(struct inode *inode)
-{
-        struct pnfs_layout_segment *rv;
-
-        spin_lock(&inode->i_lock);
-        rv = find_only_write_lseg_locked(inode);
-        if (rv)
-                get_lseg(rv);
-        spin_unlock(&inode->i_lock);
-        return rv;
-}
-
 static int
 filelayout_scan_ds_commit_list(struct nfs4_fl_commit_bucket *bucket, int max,
                 spinlock_t *lock)
@@ -955,6 +971,13 @@ filelayout_scan_ds_commit_list(struct nfs4_fl_commit_bucket *bucket, int max,
                 if (ret == max)
                         break;
         }
+        if (ret) {
+                bucket->clseg = bucket->wlseg;
+                if (list_empty(src))
+                        bucket->wlseg = NULL;
+                else
+                        get_lseg(bucket->clseg);
+        }
         return ret;
 }
 
@@ -964,18 +987,14 @@ filelayout_scan_ds_commit_list(struct nfs4_fl_commit_bucket *bucket, int max,
 static int filelayout_scan_commit_lists(struct inode *inode, int max,
                 spinlock_t *lock)
 {
-        struct pnfs_layout_segment *lseg;
-        struct nfs4_filelayout_segment *fl;
+        struct nfs4_fl_commit_info *fl_cinfo;
         int i, rv = 0, cnt;
 
-        lseg = find_only_write_lseg_locked(inode);
-        if (!lseg)
-                goto out_done;
-        fl = FILELAYOUT_LSEG(lseg);
-        if (fl->commit_through_mds)
+        fl_cinfo = &FILELAYOUT_FROM_HDR(NFS_I(inode)->layout)->commit_info;
+        if (fl_cinfo->nbuckets == 0)
                 goto out_done;
-        for (i = 0; i < fl->number_of_buckets && max != 0; i++) {
-                cnt = filelayout_scan_ds_commit_list(&fl->commit_buckets[i],
+        for (i = 0; i < fl_cinfo->nbuckets && max != 0; i++) {
+                cnt = filelayout_scan_ds_commit_list(&fl_cinfo->buckets[i],
                                 max, lock);
                 max -= cnt;
                 rv += cnt;
@@ -987,38 +1006,35 @@ out_done:
 static unsigned int
 alloc_ds_commits(struct inode *inode, struct list_head *list)
 {
-        struct pnfs_layout_segment *lseg;
-        struct nfs4_filelayout_segment *fl;
+        struct nfs4_fl_commit_info *fl_cinfo;
+        struct nfs4_fl_commit_bucket *bucket;
         struct nfs_write_data *data;
         int i, j;
         unsigned int nreq = 0;
 
-        /* Won't need this when non-whole file layout segments are supported
-         * instead we will use a pnfs_layout_hdr structure */
-        lseg = find_only_write_lseg(inode);
-        if (!lseg)
-                return 0;
-        fl = FILELAYOUT_LSEG(lseg);
-        for (i = 0; i < fl->number_of_buckets; i++) {
-                if (list_empty(&fl->commit_buckets[i].committing))
+        fl_cinfo = &FILELAYOUT_FROM_HDR(NFS_I(inode)->layout)->commit_info;
+        bucket = fl_cinfo->buckets;
+        for (i = 0; i < fl_cinfo->nbuckets; i++, bucket++) {
+                if (list_empty(&bucket->committing))
                         continue;
                 data = nfs_commitdata_alloc();
                 if (!data)
                         break;
                 data->ds_commit_index = i;
-                data->lseg = lseg;
+                data->lseg = bucket->clseg;
+                bucket->clseg = NULL;
                 list_add(&data->pages, list);
                 nreq++;
         }
 
         /* Clean up on error */
-        for (j = i; j < fl->number_of_buckets; j++) {
-                if (list_empty(&fl->commit_buckets[i].committing))
+        for (j = i; j < fl_cinfo->nbuckets; j++, bucket++) {
+                if (list_empty(&bucket->committing))
                         continue;
-                nfs_retry_commit(&fl->commit_buckets[i].committing, lseg);
-                put_lseg(lseg);  /* associated with emptying bucket */
+                nfs_retry_commit(&bucket->committing, bucket->clseg);
+                put_lseg(bucket->clseg);
+                bucket->clseg = NULL;
         }
-        put_lseg(lseg);
         /* Caller will clean up entries put on list */
         return nreq;
 }
@@ -1058,7 +1074,10 @@ filelayout_commit_pagelist(struct inode *inode, struct list_head *mds_pages,
                         nfs_initiate_commit(data, NFS_CLIENT(inode),
                                             data->mds_ops, how);
                 } else {
-                        nfs_init_commit(data, &FILELAYOUT_LSEG(data->lseg)->commit_buckets[data->ds_commit_index].committing, data->lseg);
+                        struct nfs4_fl_commit_info *fl_cinfo;
+
+                        fl_cinfo = &FILELAYOUT_FROM_HDR(data->lseg->pls_layout)->commit_info;
+                        nfs_init_commit(data, &fl_cinfo->buckets[data->ds_commit_index].committing, data->lseg);
                         filelayout_initiate_commit(data, how);
                 }
         }
@@ -1072,10 +1091,27 @@ filelayout_free_deveiceid_node(struct nfs4_deviceid_node *d)
         nfs4_fl_free_deviceid(container_of(d, struct nfs4_file_layout_dsaddr, id_node));
 }
 
+static struct pnfs_layout_hdr *
+filelayout_alloc_layout_hdr(struct inode *inode, gfp_t gfp_flags)
+{
+        struct nfs4_filelayout *flo;
+
+        flo = kzalloc(sizeof(*flo), gfp_flags);
+        return &flo->generic_hdr;
+}
+
+static void
+filelayout_free_layout_hdr(struct pnfs_layout_hdr *lo)
+{
+        kfree(FILELAYOUT_FROM_HDR(lo));
+}
+
 static struct pnfs_layoutdriver_type filelayout_type = {
         .id                     = LAYOUT_NFSV4_1_FILES,
         .name                   = "LAYOUT_NFSV4_1_FILES",
         .owner                  = THIS_MODULE,
+        .alloc_layout_hdr       = filelayout_alloc_layout_hdr,
+        .free_layout_hdr        = filelayout_free_layout_hdr,
         .alloc_lseg             = filelayout_alloc_lseg,
         .free_lseg              = filelayout_free_lseg,
         .pg_read_ops            = &filelayout_pg_read_ops,
diff --git a/fs/nfs/nfs4filelayout.h b/fs/nfs/nfs4filelayout.h
index 21190bb1f5e3..333a3ac97606 100644
--- a/fs/nfs/nfs4filelayout.h
+++ b/fs/nfs/nfs4filelayout.h
@@ -77,6 +77,13 @@ struct nfs4_file_layout_dsaddr {
 struct nfs4_fl_commit_bucket {
         struct list_head written;
         struct list_head committing;
+        struct pnfs_layout_segment *wlseg;
+        struct pnfs_layout_segment *clseg;
+};
+
+struct nfs4_fl_commit_info {
+        int nbuckets;
+        struct nfs4_fl_commit_bucket *buckets;
 };
 
 struct nfs4_filelayout_segment {
@@ -89,10 +96,19 @@ struct nfs4_filelayout_segment {
         struct nfs4_file_layout_dsaddr *dsaddr; /* Point to GETDEVINFO data */
         unsigned int num_fh;
         struct nfs_fh **fh_array;
-        struct nfs4_fl_commit_bucket *commit_buckets; /* Sort commits to ds */
-        int number_of_buckets;
 };
 
+struct nfs4_filelayout {
+        struct pnfs_layout_hdr generic_hdr;
+        struct nfs4_fl_commit_info commit_info;
+};
+
+static inline struct nfs4_filelayout *
+FILELAYOUT_FROM_HDR(struct pnfs_layout_hdr *lo)
+{
+        return container_of(lo, struct nfs4_filelayout, generic_hdr);
+}
+
 static inline struct nfs4_filelayout_segment *
 FILELAYOUT_LSEG(struct pnfs_layout_segment *lseg)
 {