pnfs-obj: objio_osd device information retrieval and caching

When a new layout is received in objio_alloc_lseg all device_ids
referenced are retrieved. The device information is queried for from MDS
and then the osd_device is looked-up from the osd-initiator library. The
devices are cached in a per-mount-point list, for later use. At unmount
all devices are "put" back to the library.

objlayout_get_deviceinfo(), objlayout_put_deviceinfo() middleware
API for retrieving device information given a device_id.

TODO: The device cache can get big. Cap its size. Keep an LRU and start
      to return devices which were not used, when list gets to big, or
      when new entries allocation fail.

[pnfs-obj: Bugs in new global-device-cache code]
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
[gfp_flags]
[use global device cache]
[use layout driver in global device cache]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>

1 files changed, 68 insertions, 0 deletions

diff --git a/fs/nfs/objlayout/objlayout.c b/fs/nfs/objlayout/objlayout.c
index 946526763d38..10e5fca3b7fb 100644
--- a/fs/nfs/objlayout/objlayout.c
+++ b/fs/nfs/objlayout/objlayout.c
@@ -102,3 +102,71 @@ objlayout_free_lseg(struct pnfs_layout_segment *lseg)
         objio_free_lseg(lseg);
 }
 
+/*
+ * Get Device Info API for io engines
+ */
+struct objlayout_deviceinfo {
+        struct page *page;
+        struct pnfs_osd_deviceaddr da; /* This must be last */
+};
+
+/* Initialize and call nfs_getdeviceinfo, then decode and return a
+ * "struct pnfs_osd_deviceaddr *" Eventually objlayout_put_deviceinfo()
+ * should be called.
+ */
+int objlayout_get_deviceinfo(struct pnfs_layout_hdr *pnfslay,
+        struct nfs4_deviceid *d_id, struct pnfs_osd_deviceaddr **deviceaddr,
+        gfp_t gfp_flags)
+{
+        struct objlayout_deviceinfo *odi;
+        struct pnfs_device pd;
+        struct super_block *sb;
+        struct page *page, **pages;
+        u32 *p;
+        int err;
+
+        page = alloc_page(gfp_flags);
+        if (!page)
+                return -ENOMEM;
+
+        pages = &page;
+        pd.pages = pages;
+
+        memcpy(&pd.dev_id, d_id, sizeof(*d_id));
+        pd.layout_type = LAYOUT_OSD2_OBJECTS;
+        pd.pages = &page;
+        pd.pgbase = 0;
+        pd.pglen = PAGE_SIZE;
+        pd.mincount = 0;
+
+        sb = pnfslay->plh_inode->i_sb;
+        err = nfs4_proc_getdeviceinfo(NFS_SERVER(pnfslay->plh_inode), &pd);
+        dprintk("%s nfs_getdeviceinfo returned %d\n", __func__, err);
+        if (err)
+                goto err_out;
+
+        p = page_address(page);
+        odi = kzalloc(sizeof(*odi), gfp_flags);
+        if (!odi) {
+                err = -ENOMEM;
+                goto err_out;
+        }
+        pnfs_osd_xdr_decode_deviceaddr(&odi->da, p);
+        odi->page = page;
+        *deviceaddr = &odi->da;
+        return 0;
+
+err_out:
+        __free_page(page);
+        return err;
+}
+
+void objlayout_put_deviceinfo(struct pnfs_osd_deviceaddr *deviceaddr)
+{
+        struct objlayout_deviceinfo *odi = container_of(deviceaddr,
+                                                struct objlayout_deviceinfo,
+                                                da);
+
+        __free_page(odi->page);
+        kfree(odi);
+}