[GFS2] Reduce inode size by moving i_alloc out of line
It is possible to reduce the size of GFS2 inodes by taking the i_alloc
structure out of the gfs2_inode. This patch allocates the i_alloc
structure whenever its needed, and frees it afterward. This decreases
the amount of low memory we use at the expense of requiring a memory
allocation for each page or partial page that we write. A quick test
with postmark shows that the overhead is not measurable and I also note
that OCFS2 use the same approach.
In the future I'd like to solve the problem by shrinking down the size
of the members of the i_alloc structure, but for now, this reduces the
immediate problem of using too much low-memory on x86 and doesn't add
too much overhead.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 2241141..73dfad7 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -683,7 +683,7 @@
if (metadata)
revokes = (height) ? sdp->sd_inptrs : sdp->sd_diptrs;
- error = gfs2_rindex_hold(sdp, &ip->i_alloc.al_ri_gh);
+ error = gfs2_rindex_hold(sdp, &ip->i_alloc->al_ri_gh);
if (error)
return error;
@@ -785,7 +785,7 @@
out_rlist:
gfs2_rlist_free(&rlist);
out:
- gfs2_glock_dq_uninit(&ip->i_alloc.al_ri_gh);
+ gfs2_glock_dq_uninit(&ip->i_alloc->al_ri_gh);
return error;
}
