GFS2: Extend the life of the reservations

This patch lengthens the lifespan of the reservations structure for
inodes. Before, they were allocated and deallocated for every write
operation. With this patch, they are allocated when the first write
occurs, and deallocated when the last process closes the file.
It's more efficient to do it this way because it saves GFS2 a lot of
unnecessary allocates and frees. It also gives us more flexibility
for the future: (1) we can now fold the qadata structure back into
the structure and save those alloc/frees, (2) we can use this for
multi-block reservations.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 37 insertions, 31 deletions

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index f74fb9b..e944fef 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -417,6 +417,39 @@ void gfs2_free_clones(struct gfs2_rgrpd *rgd)
 	}
 }
 
+/**
+ * gfs2_rs_alloc - make sure we have a reservation assigned to the inode
+ * @ip: the inode for this reservation
+ */
+int gfs2_rs_alloc(struct gfs2_inode *ip)
+{
+	int error = 0;
+
+	down_write(&ip->i_rw_mutex);
+	if (!ip->i_res) {
+		ip->i_res = kmem_cache_zalloc(gfs2_rsrv_cachep, GFP_NOFS);
+		if (!ip->i_res)
+			error = -ENOMEM;
+	}
+	up_write(&ip->i_rw_mutex);
+	return error;
+}
+
+/**
+ * gfs2_rs_delete - delete a reservation
+ * @ip: The inode for this reservation
+ *
+ */
+void gfs2_rs_delete(struct gfs2_inode *ip)
+{
+	down_write(&ip->i_rw_mutex);
+	if (ip->i_res) {
+		kmem_cache_free(gfs2_rsrv_cachep, ip->i_res);
+		ip->i_res = NULL;
+	}
+	up_write(&ip->i_rw_mutex);
+}
+
 void gfs2_clear_rgrpd(struct gfs2_sbd *sdp)
 {
 	struct rb_node *n;
@@ -993,22 +1026,6 @@ struct gfs2_qadata *gfs2_qadata_get(struct gfs2_inode *ip)
 }
 
 /**
- * gfs2_blkrsv_get - get the struct gfs2_blkreserv structure for an inode
- * @ip: the incore GFS2 inode structure
- *
- * Returns: the struct gfs2_qadata
- */
-
-static int gfs2_blkrsv_get(struct gfs2_inode *ip)
-{
-	BUG_ON(ip->i_res != NULL);
-	ip->i_res = kmem_cache_zalloc(gfs2_rsrv_cachep, GFP_NOFS);
-	if (!ip->i_res)
-		return -ENOMEM;
-	return 0;
-}
-
-/**
  * try_rgrp_fit - See if a given reservation will fit in a given RG
  * @rgd: the RG data
  * @ip: the inode
@@ -1162,13 +1179,6 @@ static int get_local_rgrp(struct gfs2_inode *ip, u64 *last_unlinked)
 	return -ENOSPC;
 }
 
-static void gfs2_blkrsv_put(struct gfs2_inode *ip)
-{
-	BUG_ON(ip->i_res == NULL);
-	kmem_cache_free(gfs2_rsrv_cachep, ip->i_res);
-	ip->i_res = NULL;
-}
-
 /**
  * gfs2_inplace_reserve - Reserve space in the filesystem
  * @ip: the inode to reserve space for
@@ -1181,14 +1191,10 @@ int gfs2_inplace_reserve(struct gfs2_inode *ip, u32 requested)
 {
 	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
 	struct gfs2_blkreserv *rs;
-	int error;
+	int error = 0;
 	u64 last_unlinked = NO_BLOCK;
 	int tries = 0;
 
-	error = gfs2_blkrsv_get(ip);
-	if (error)
-		return error;
-
 	rs = ip->i_res;
 	rs->rs_requested = requested;
 	if (gfs2_assert_warn(sdp, requested)) {
@@ -1213,7 +1219,7 @@ int gfs2_inplace_reserve(struct gfs2_inode *ip, u32 requested)
 
 out:
 	if (error)
-		gfs2_blkrsv_put(ip);
+		rs->rs_requested = 0;
 	return error;
 }
 
@@ -1230,7 +1236,7 @@ void gfs2_inplace_release(struct gfs2_inode *ip)
 
 	if (rs->rs_rgd_gh.gh_gl)
 		gfs2_glock_dq_uninit(&rs->rs_rgd_gh);
-	gfs2_blkrsv_put(ip);
+	rs->rs_requested = 0;
 }
 
 /**
@@ -1496,7 +1502,7 @@ int gfs2_alloc_blocks(struct gfs2_inode *ip, u64 *bn, unsigned int *nblocks,
 	/* Only happens if there is a bug in gfs2, return something distinctive
 	 * to ensure that it is noticed.
 	 */
-	if (ip->i_res == NULL)
+	if (ip->i_res->rs_requested == 0)
 		return -ECANCELED;
 
 	rgd = ip->i_rgd;