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pnfsblock: merge rw extents 

Signed-off-by: Fred Isaman <iisaman@citi.umich.edu>
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>
This commit is contained in:
Fred Isaman 2011-07-30 20:52:50 -04:00 committed by Trond Myklebust
parent c1c2a4cd35
commit 9f3770422c
1 changed files with 47 additions and 0 deletions
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47
fs/nfs/blocklayout/extents.c
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@ -493,3 +493,50 @@ bl_find_get_extent(struct pnfs_block_layout *bl, sector_t isect,
print_bl_extent(ret);
return ret;
}
/* Helper function to set_to_rw that initialize a new extent */
static void
_prep_new_extent(struct pnfs_block_extent *new,
struct pnfs_block_extent *orig,
sector_t offset, sector_t length, int state)
{
kref_init(&new->be_refcnt);
/* don't need to INIT_LIST_HEAD(&new->be_node) */
memcpy(&new->be_devid, &orig->be_devid, sizeof(struct nfs4_deviceid));
new->be_mdev = orig->be_mdev;
new->be_f_offset = offset;
new->be_length = length;
new->be_v_offset = orig->be_v_offset - orig->be_f_offset + offset;
new->be_state = state;
new->be_inval = orig->be_inval;
}
/* Tries to merge be with extent in front of it in list.
* Frees storage if not used.
*/
static struct pnfs_block_extent *
_front_merge(struct pnfs_block_extent *be, struct list_head *head,
struct pnfs_block_extent *storage)
{
struct pnfs_block_extent *prev;
if (!storage)
goto no_merge;
if (&be->be_node == head || be->be_node.prev == head)
goto no_merge;
prev = list_entry(be->be_node.prev, struct pnfs_block_extent, be_node);
if ((prev->be_f_offset + prev->be_length != be->be_f_offset) ||
!extents_consistent(prev, be))
goto no_merge;
_prep_new_extent(storage, prev, prev->be_f_offset,
prev->be_length + be->be_length, prev->be_state);
list_replace(&prev->be_node, &storage->be_node);
bl_put_extent(prev);
list_del(&be->be_node);
bl_put_extent(be);
return storage;
no_merge:
kfree(storage);
return be;
}