pnfsblock: bl_find_get_extent

Implement bl_find_get_extent(), one of the core extent manipulation
routines.

[pnfsblock: Lookup list entry of layouts and tags in reverse order]
Signed-off-by: Zhang Jingwang <zhangjingwang@nrchpc.ac.cn>
Signed-off-by: Fred Isaman <iisaman@citi.umich.edu>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Jim Rees <rees@umich.edu>

pnfsblock: fix print format warnings for sector_t and size_t

gcc spews warnings about these on x86_64, e.g.:
fs/nfs/blocklayout/blocklayout.c:74: warning: format ‘%Lu’ expects type ‘long long unsigned int’, but argument 2 has type ‘sector_t’
fs/nfs/blocklayout/blocklayout.c:388: warning: format ‘%d’ expects type ‘int’, but argument 5 has type ‘size_t’

Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
Signed-off-by: Jim Rees <rees@umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

2 files changed, 50 insertions, 0 deletions

diff --git a/fs/nfs/blocklayout/blocklayout.h b/fs/nfs/blocklayout/blocklayout.h
index d645880f61a0..3e1b5fc152d7 100644
--- a/fs/nfs/blocklayout/blocklayout.h
+++ b/fs/nfs/blocklayout/blocklayout.h
@@ -153,6 +153,9 @@ int nfs4_blk_process_layoutget(struct pnfs_layout_hdr *lo,
 void bl_free_block_dev(struct pnfs_block_dev *bdev);
 
 /* extents.c */
+struct pnfs_block_extent *
+bl_find_get_extent(struct pnfs_block_layout *bl, sector_t isect,
+                struct pnfs_block_extent **cow_read);
 void bl_put_extent(struct pnfs_block_extent *be);
 struct pnfs_block_extent *bl_alloc_extent(void);
 int bl_add_merge_extent(struct pnfs_block_layout *bl,
diff --git a/fs/nfs/blocklayout/extents.c b/fs/nfs/blocklayout/extents.c
index ee4891f32492..8fa93e23cb24 100644
--- a/fs/nfs/blocklayout/extents.c
+++ b/fs/nfs/blocklayout/extents.c
@@ -193,3 +193,50 @@ bl_add_merge_extent(struct pnfs_block_layout *bl,
         bl_put_extent(new);
         return -EIO;
 }
+
+/* Returns extent, or NULL.  If a second READ extent exists, it is returned
+ * in cow_read, if given.
+ *
+ * The extents are kept in two seperate ordered lists, one for READ and NONE,
+ * one for READWRITE and INVALID.  Within each list, we assume:
+ * 1. Extents are ordered by file offset.
+ * 2. For any given isect, there is at most one extents that matches.
+ */
+struct pnfs_block_extent *
+bl_find_get_extent(struct pnfs_block_layout *bl, sector_t isect,
+            struct pnfs_block_extent **cow_read)
+{
+        struct pnfs_block_extent *be, *cow, *ret;
+        int i;
+
+        dprintk("%s enter with isect %llu\n", __func__, (u64)isect);
+        cow = ret = NULL;
+        spin_lock(&bl->bl_ext_lock);
+        for (i = 0; i < EXTENT_LISTS; i++) {
+                list_for_each_entry_reverse(be, &bl->bl_extents[i], be_node) {
+                        if (isect >= be->be_f_offset + be->be_length)
+                                break;
+                        if (isect >= be->be_f_offset) {
+                                /* We have found an extent */
+                                dprintk("%s Get %p (%i)\n", __func__, be,
+                                        atomic_read(&be->be_refcnt.refcount));
+                                kref_get(&be->be_refcnt);
+                                if (!ret)
+                                        ret = be;
+                                else if (be->be_state != PNFS_BLOCK_READ_DATA)
+                                        bl_put_extent(be);
+                                else
+                                        cow = be;
+                                break;
+                        }
+                }
+                if (ret &&
+                    (!cow_read || ret->be_state != PNFS_BLOCK_INVALID_DATA))
+                        break;
+        }
+        spin_unlock(&bl->bl_ext_lock);
+        if (cow_read)
+                *cow_read = cow;
+        print_bl_extent(ret);
+        return ret;
+}