#include <linux/prefetch.h>
#include <linux/blkdev.h>
#include <linux/rbtree.h>
+#include <linux/random.h>
#include "gfs2.h"
#include "incore.h"
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;
}
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;
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;
* 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;
} 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;
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)) {
/* 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) {
projects / firefly-linux-kernel-4.4.55.git / blobdiff