ocfs2: use allocation reservations for directory data

Use the reservations system for unindexed dir tree allocations. We don't
bother with the indexed tree as reads from it are mostly random anyway.
Directory reservations are marked seperately, to allow the reservations code
a chance to optimize their window sizes. This patch allocates only 8 bits
for directory windows as they generally are not expected to grow as quickly
as file data. Future improvements to dir window sizing can trivially be
made.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

fs/ocfs2/dir.c

@@ -2977,6 +2977,7 @@ static int ocfs2_expand_inline_dir(struct inode *dir, struct buffer_head *di_bh,
 	 * if we only get one now, that's enough to continue. The rest
 	 * will be claimed after the conversion to extents.
 	 */
+	data_ac->ac_resv = &oi->ip_la_data_resv;
 	ret = ocfs2_claim_clusters(osb, handle, data_ac, 1, &bit_off, &len);
 	if (ret) {
 		mlog_errno(ret);
@@ -3347,6 +3348,8 @@ static int ocfs2_extend_dir(struct ocfs2_super *osb,
 			goto bail;
 		}
 
+		data_ac->ac_resv = &OCFS2_I(dir)->ip_la_data_resv;
+
 		credits = ocfs2_calc_extend_credits(sb, el, 1);
 	} else {
 		spin_unlock(&OCFS2_I(dir)->ip_lock);

fs/ocfs2/inode.c

@@ -377,6 +377,10 @@ void ocfs2_populate_inode(struct inode *inode, struct ocfs2_dinode *fe,
 
 	OCFS2_I(inode)->ip_last_used_slot = 0;
 	OCFS2_I(inode)->ip_last_used_group = 0;
+
+	if (S_ISDIR(inode->i_mode))
+		ocfs2_resv_set_type(&OCFS2_I(inode)->ip_la_data_resv,
+				    OCFS2_RESV_FLAG_DIR);
 	mlog_exit_void();
 }
 

fs/ocfs2/reservations.c

@@ -44,6 +44,7 @@ DEFINE_SPINLOCK(resv_lock);
 
 #define	OCFS2_MIN_RESV_WINDOW_BITS	8
 #define	OCFS2_MAX_RESV_WINDOW_BITS	1024
+#define	OCFS2_RESV_DIR_WINDOW_BITS	OCFS2_MIN_RESV_WINDOW_BITS
 
 static unsigned int ocfs2_resv_window_bits(struct ocfs2_reservation_map *resmap,
 					   struct ocfs2_alloc_reservation *resv)
@@ -51,8 +52,11 @@ static unsigned int ocfs2_resv_window_bits(struct ocfs2_reservation_map *resmap,
 	struct ocfs2_super *osb = resmap->m_osb;
 	unsigned int bits;
 
-	/* 8, 16, 32, 64, 128, 256, 512, 1024 */
-	bits = 4 << osb->osb_resv_level;
+	if (!(resv->r_flags & OCFS2_RESV_FLAG_DIR)) {
+		/* 8, 16, 32, 64, 128, 256, 512, 1024 */
+		bits = 4 << osb->osb_resv_level;
+	} else
+		bits = OCFS2_RESV_DIR_WINDOW_BITS;
 
 	return bits;
 }

fs/ocfs2/reservations.h

@@ -42,6 +42,8 @@ struct ocfs2_alloc_reservation {
 #define	OCFS2_RESV_FLAG_INUSE	0x01	/* Set when r_node is part of a btree */
 #define	OCFS2_RESV_FLAG_TMP	0x02	/* Temporary reservation, will be
 					 * destroyed immedately after use */
+#define	OCFS2_RESV_FLAG_DIR	0x04	/* Reservation is for an unindexed
+					 * directory btree */
 
 struct ocfs2_reservation_map {
 	struct rb_root		m_reservations;
@@ -61,7 +63,7 @@ struct ocfs2_reservation_map {
 
 void ocfs2_resv_init_once(struct ocfs2_alloc_reservation *resv);
 
-#define OCFS2_RESV_TYPES	(OCFS2_RESV_FLAG_TMP)
+#define OCFS2_RESV_TYPES	(OCFS2_RESV_FLAG_TMP|OCFS2_RESV_FLAG_DIR)
 void ocfs2_resv_set_type(struct ocfs2_alloc_reservation *resv,
 			 unsigned int flags);
 

fs/ocfs2/suballoc.c

@@ -130,6 +130,7 @@ void ocfs2_free_ac_resource(struct ocfs2_alloc_context *ac)
 	}
 	brelse(ac->ac_bh);
 	ac->ac_bh = NULL;
+	ac->ac_resv = NULL;
 }
 
 void ocfs2_free_alloc_context(struct ocfs2_alloc_context *ac)