1 files changed, 161 insertions, 40 deletions

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 3cc402ce6fea..b7eff078fe90 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -16,6 +16,7 @@
 #include <linux/prefetch.h>
 #include <linux/blkdev.h>
 #include <linux/rbtree.h>
+#include <linux/random.h>
 
 #include "gfs2.h"
 #include "incore.h"
@@ -251,22 +252,25 @@ static u32 gfs2_bitfit(const u8 *buf, const unsigned int len,
 static int gfs2_rbm_from_block(struct gfs2_rbm *rbm, u64 block)
 {
 	u64 rblock = block - rbm->rgd->rd_data0;
-	u32 goal = (u32)rblock;
-	int x;
+	u32 x;
 
 	if (WARN_ON_ONCE(rblock > UINT_MAX))
 		return -EINVAL;
 	if (block >= rbm->rgd->rd_data0 + rbm->rgd->rd_data)
 		return -E2BIG;
 
-	for (x = 0; x < rbm->rgd->rd_length; x++) {
-		rbm->bi = rbm->rgd->rd_bits + x;
-		if (goal < (rbm->bi->bi_start + rbm->bi->bi_len) * GFS2_NBBY) {
-			rbm->offset = goal - (rbm->bi->bi_start * GFS2_NBBY);
-			break;
-		}
-	}
+	rbm->bi = rbm->rgd->rd_bits;
+	rbm->offset = (u32)(rblock);
+	/* Check if the block is within the first block */
+	if (rbm->offset < (rbm->bi->bi_start + rbm->bi->bi_len) * GFS2_NBBY)
+		return 0;
 
+	/* Adjust for the size diff between gfs2_meta_header and gfs2_rgrp */
+	rbm->offset += (sizeof(struct gfs2_rgrp) -
+			sizeof(struct gfs2_meta_header)) * GFS2_NBBY;
+	x = rbm->offset / rbm->rgd->rd_sbd->sd_blocks_per_bitmap;
+	rbm->offset -= x * rbm->rgd->rd_sbd->sd_blocks_per_bitmap;
+	rbm->bi += x;
 	return 0;
 }
 
@@ -346,10 +350,14 @@ static u32 gfs2_free_extlen(const struct gfs2_rbm *rrbm, u32 len)
 		BUG_ON(len < chunk_size);
 		len -= chunk_size;
 		block = gfs2_rbm_to_block(&rbm);
-		gfs2_rbm_from_block(&rbm, block + chunk_size);
-		n_unaligned = 3;
-		if (ptr)
+		if (gfs2_rbm_from_block(&rbm, block + chunk_size)) {
+			n_unaligned = 0;
+			break;
+		}
+		if (ptr) {
+			n_unaligned = 3;
 			break;
+		}
 		n_unaligned = len & 3;
 	}
 
@@ -554,24 +562,21 @@ void gfs2_free_clones(struct gfs2_rgrpd *rgd)
 int gfs2_rs_alloc(struct gfs2_inode *ip)
 {
 	int error = 0;
-	struct gfs2_blkreserv *res;
 
+	down_write(&ip->i_rw_mutex);
 	if (ip->i_res)
-		return 0;
+		goto out;
 
-	res = kmem_cache_zalloc(gfs2_rsrv_cachep, GFP_NOFS);
-	if (!res)
+	ip->i_res = kmem_cache_zalloc(gfs2_rsrv_cachep, GFP_NOFS);
+	if (!ip->i_res) {
 		error = -ENOMEM;
+		goto out;
+	}
 
-	RB_CLEAR_NODE(&res->rs_node);
-
-	down_write(&ip->i_rw_mutex);
-	if (ip->i_res)
-		kmem_cache_free(gfs2_rsrv_cachep, res);
-	else
-		ip->i_res = res;
+	RB_CLEAR_NODE(&ip->i_res->rs_node);
+out:
 	up_write(&ip->i_rw_mutex);
-	return error;
+	return 0;
 }
 
 static void dump_rs(struct seq_file *seq, const struct gfs2_blkreserv *rs)
@@ -876,7 +881,7 @@ static int read_rindex_entry(struct gfs2_inode *ip)
 		goto fail;
 
 	rgd->rd_gl->gl_object = rgd;
-	rgd->rd_rgl = (struct gfs2_rgrp_lvb *)rgd->rd_gl->gl_lvb;
+	rgd->rd_rgl = (struct gfs2_rgrp_lvb *)rgd->rd_gl->gl_lksb.sb_lvbptr;
 	rgd->rd_flags &= ~GFS2_RDF_UPTODATE;
 	if (rgd->rd_data > sdp->sd_max_rg_data)
 		sdp->sd_max_rg_data = rgd->rd_data;
@@ -1263,7 +1268,9 @@ int gfs2_fitrim(struct file *filp, void __user *argp)
 	int ret = 0;
 	u64 amt;
 	u64 trimmed = 0;
+	u64 start, end, minlen;
 	unsigned int x;
+	unsigned bs_shift = sdp->sd_sb.sb_bsize_shift;
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
@@ -1271,19 +1278,25 @@ int gfs2_fitrim(struct file *filp, void __user *argp)
 	if (!blk_queue_discard(q))
 		return -EOPNOTSUPP;
 
-	if (argp == NULL) {
-		r.start = 0;
-		r.len = ULLONG_MAX;
-		r.minlen = 0;
-	} else if (copy_from_user(&r, argp, sizeof(r)))
+	if (copy_from_user(&r, argp, sizeof(r)))
 		return -EFAULT;
 
 	ret = gfs2_rindex_update(sdp);
 	if (ret)
 		return ret;
 
-	rgd = gfs2_blk2rgrpd(sdp, r.start, 0);
-	rgd_end = gfs2_blk2rgrpd(sdp, r.start + r.len, 0);
+	start = r.start >> bs_shift;
+	end = start + (r.len >> bs_shift);
+	minlen = max_t(u64, r.minlen,
+		       q->limits.discard_granularity) >> bs_shift;
+
+	rgd = gfs2_blk2rgrpd(sdp, start, 0);
+	rgd_end = gfs2_blk2rgrpd(sdp, end - 1, 0);
+
+	if (end <= start ||
+	    minlen > sdp->sd_max_rg_data ||
+	    start > rgd_end->rd_data0 + rgd_end->rd_data)
+		return -EINVAL;
 
 	while (1) {
 
@@ -1295,7 +1308,9 @@ int gfs2_fitrim(struct file *filp, void __user *argp)
 			/* Trim each bitmap in the rgrp */
 			for (x = 0; x < rgd->rd_length; x++) {
 				struct gfs2_bitmap *bi = rgd->rd_bits + x;
-				ret = gfs2_rgrp_send_discards(sdp, rgd->rd_data0, NULL, bi, r.minlen, &amt);
+				ret = gfs2_rgrp_send_discards(sdp,
+						rgd->rd_data0, NULL, bi, minlen,
+						&amt);
 				if (ret) {
 					gfs2_glock_dq_uninit(&gh);
 					goto out;
@@ -1324,7 +1339,7 @@ int gfs2_fitrim(struct file *filp, void __user *argp)
 
 out:
 	r.len = trimmed << 9;
-	if (argp && copy_to_user(argp, &r, sizeof(r)))
+	if (copy_to_user(argp, &r, sizeof(r)))
 		return -EFAULT;
 
 	return ret;
@@ -1411,6 +1426,9 @@ static void rg_mblk_search(struct gfs2_rgrpd *rgd, struct gfs2_inode *ip,
 		rs->rs_free = extlen;
 		rs->rs_inum = ip->i_no_addr;
 		rs_insert(ip);
+	} else {
+		if (goal == rgd->rd_last_alloc + rgd->rd_data0)
+			rgd->rd_last_alloc = 0;
 	}
 }
 
@@ -1669,13 +1687,105 @@ static void try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked, u64 skip
 	return;
 }
 
+/**
+ * gfs2_rgrp_congested - Use stats to figure out whether an rgrp is congested
+ * @rgd: The rgrp in question
+ * @loops: An indication of how picky we can be (0=very, 1=less so)
+ *
+ * This function uses the recently added glock statistics in order to
+ * figure out whether a parciular resource group is suffering from
+ * contention from multiple nodes. This is done purely on the basis
+ * of timings, since this is the only data we have to work with and
+ * our aim here is to reject a resource group which is highly contended
+ * but (very important) not to do this too often in order to ensure that
+ * we do not land up introducing fragmentation by changing resource
+ * groups when not actually required.
+ *
+ * The calculation is fairly simple, we want to know whether the SRTTB
+ * (i.e. smoothed round trip time for blocking operations) to acquire
+ * the lock for this rgrp's glock is significantly greater than the
+ * time taken for resource groups on average. We introduce a margin in
+ * the form of the variable @var which is computed as the sum of the two
+ * respective variences, and multiplied by a factor depending on @loops
+ * and whether we have a lot of data to base the decision on. This is
+ * then tested against the square difference of the means in order to
+ * decide whether the result is statistically significant or not.
+ *
+ * Returns: A boolean verdict on the congestion status
+ */
+
+static bool gfs2_rgrp_congested(const struct gfs2_rgrpd *rgd, int loops)
+{
+	const struct gfs2_glock *gl = rgd->rd_gl;
+	const struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct gfs2_lkstats *st;
+	s64 r_dcount, l_dcount;
+	s64 r_srttb, l_srttb;
+	s64 srttb_diff;
+	s64 sqr_diff;
+	s64 var;
+
+	preempt_disable();
+	st = &this_cpu_ptr(sdp->sd_lkstats)->lkstats[LM_TYPE_RGRP];
+	r_srttb = st->stats[GFS2_LKS_SRTTB];
+	r_dcount = st->stats[GFS2_LKS_DCOUNT];
+	var = st->stats[GFS2_LKS_SRTTVARB] +
+	      gl->gl_stats.stats[GFS2_LKS_SRTTVARB];
+	preempt_enable();
+
+	l_srttb = gl->gl_stats.stats[GFS2_LKS_SRTTB];
+	l_dcount = gl->gl_stats.stats[GFS2_LKS_DCOUNT];
+
+	if ((l_dcount < 1) || (r_dcount < 1) || (r_srttb == 0))
+		return false;
+
+	srttb_diff = r_srttb - l_srttb;
+	sqr_diff = srttb_diff * srttb_diff;
+
+	var *= 2;
+	if (l_dcount < 8 || r_dcount < 8)
+		var *= 2;
+	if (loops == 1)
+		var *= 2;
+
+	return ((srttb_diff < 0) && (sqr_diff > var));
+}
+
+/**
+ * gfs2_rgrp_used_recently
+ * @rs: The block reservation with the rgrp to test
+ * @msecs: The time limit in milliseconds
+ *
+ * Returns: True if the rgrp glock has been used within the time limit
+ */
+static bool gfs2_rgrp_used_recently(const struct gfs2_blkreserv *rs,
+				    u64 msecs)
+{
+	u64 tdiff;
+
+	tdiff = ktime_to_ns(ktime_sub(ktime_get_real(),
+                            rs->rs_rbm.rgd->rd_gl->gl_dstamp));
+
+	return tdiff > (msecs * 1000 * 1000);
+}
+
+static u32 gfs2_orlov_skip(const struct gfs2_inode *ip)
+{
+	const struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
+	u32 skip;
+
+	get_random_bytes(&skip, sizeof(skip));
+	return skip % sdp->sd_rgrps;
+}
+
 static bool gfs2_select_rgrp(struct gfs2_rgrpd **pos, const struct gfs2_rgrpd *begin)
 {
 	struct gfs2_rgrpd *rgd = *pos;
+	struct gfs2_sbd *sdp = rgd->rd_sbd;
 
 	rgd = gfs2_rgrpd_get_next(rgd);
 	if (rgd == NULL)
-		rgd = gfs2_rgrpd_get_next(NULL);
+		rgd = gfs2_rgrpd_get_first(sdp);
 	*pos = rgd;
 	if (rgd != begin) /* If we didn't wrap */
 		return true;
@@ -1690,14 +1800,15 @@ static bool gfs2_select_rgrp(struct gfs2_rgrpd **pos, const struct gfs2_rgrpd *b
  * Returns: errno
  */
 
-int gfs2_inplace_reserve(struct gfs2_inode *ip, u32 requested)
+int gfs2_inplace_reserve(struct gfs2_inode *ip, u32 requested, u32 aflags)
 {
 	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
 	struct gfs2_rgrpd *begin = NULL;
 	struct gfs2_blkreserv *rs = ip->i_res;
-	int error = 0, rg_locked, flags = LM_FLAG_TRY;
+	int error = 0, rg_locked, flags = 0;
 	u64 last_unlinked = NO_BLOCK;
 	int loops = 0;
+	u32 skip = 0;
 
 	if (sdp->sd_args.ar_rgrplvb)
 		flags |= GL_SKIP;
@@ -1711,6 +1822,8 @@ int gfs2_inplace_reserve(struct gfs2_inode *ip, u32 requested)
 	} else {
 		rs->rs_rbm.rgd = begin = gfs2_blk2rgrpd(sdp, ip->i_goal, 1);
 	}
+	if (S_ISDIR(ip->i_inode.i_mode) && (aflags & GFS2_AF_ORLOV))
+		skip = gfs2_orlov_skip(ip);
 	if (rs->rs_rbm.rgd == NULL)
 		return -EBADSLT;
 
@@ -1719,13 +1832,20 @@ int gfs2_inplace_reserve(struct gfs2_inode *ip, u32 requested)
 
 		if (!gfs2_glock_is_locked_by_me(rs->rs_rbm.rgd->rd_gl)) {
 			rg_locked = 0;
+			if (skip && skip--)
+				goto next_rgrp;
+			if (!gfs2_rs_active(rs) && (loops < 2) &&
+			     gfs2_rgrp_used_recently(rs, 1000) &&
+			     gfs2_rgrp_congested(rs->rs_rbm.rgd, loops))
+				goto next_rgrp;
 			error = gfs2_glock_nq_init(rs->rs_rbm.rgd->rd_gl,
 						   LM_ST_EXCLUSIVE, flags,
 						   &rs->rs_rgd_gh);
-			if (error == GLR_TRYFAILED)
-				goto next_rgrp;
 			if (unlikely(error))
 				return error;
+			if (!gfs2_rs_active(rs) && (loops < 2) &&
+			    gfs2_rgrp_congested(rs->rs_rbm.rgd, loops))
+				goto skip_rgrp;
 			if (sdp->sd_args.ar_rgrplvb) {
 				error = update_rgrp_lvb(rs->rs_rbm.rgd);
 				if (unlikely(error)) {
@@ -1772,12 +1892,13 @@ next_rgrp:
 		/* Find the next rgrp, and continue looking */
 		if (gfs2_select_rgrp(&rs->rs_rbm.rgd, begin))
 			continue;
+		if (skip)
+			continue;
 
 		/* If we've scanned all the rgrps, but found no free blocks
 		 * then this checks for some less likely conditions before
 		 * trying again.
 		 */
-		flags &= ~LM_FLAG_TRY;
 		loops++;
 		/* Check that fs hasn't grown if writing to rindex */
 		if (ip == GFS2_I(sdp->sd_rindex) && !sdp->sd_rindex_uptodate) {