[PATCH 03/24] GFS2: Implement a "rgrp has no extents longer than X" scheme

From: Steven Whitehouse
Date: Mon Jan 20 2014 - 07:30:34 EST


From: Bob Peterson <rpeterso@xxxxxxxxxx>

With the preceding patch, we started accepting block reservations
smaller than the ideal size, which requires a lot more parsing of the
bitmaps. To reduce the amount of bitmap searching, this patch
implements a scheme whereby each rgrp keeps track of the point
at this multi-block reservations will fail.

Signed-off-by: Bob Peterson <rpeterso@xxxxxxxxxx>
Signed-off-by: Steven Whitehouse <swhiteho@xxxxxxxxxx>

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index ba1ea67..0132816 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -93,6 +93,7 @@ struct gfs2_rgrpd {
struct gfs2_rgrp_lvb *rd_rgl;
u32 rd_last_alloc;
u32 rd_flags;
+ u32 rd_extfail_pt; /* extent failure point */
#define GFS2_RDF_CHECK 0x10000000 /* check for unlinked inodes */
#define GFS2_RDF_UPTODATE 0x20000000 /* rg is up to date */
#define GFS2_RDF_ERROR 0x40000000 /* error in rg */
diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index 010b9fb..cdadb92 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -83,6 +83,7 @@ static void maybe_release_space(struct gfs2_bufdata *bd)
bd->bd_bh->b_data + bi->bi_offset, bi->bi_len);
clear_bit(GBF_FULL, &bi->bi_flags);
rgd->rd_free_clone = rgd->rd_free;
+ rgd->rd_extfail_pt = rgd->rd_free;
}

/**
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 1ccf89a..797f1d3 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -641,9 +641,13 @@ static void __rs_deltree(struct gfs2_blkreserv *rs)
/* return reserved blocks to the rgrp */
BUG_ON(rs->rs_rbm.rgd->rd_reserved < rs->rs_free);
rs->rs_rbm.rgd->rd_reserved -= rs->rs_free;
+ /* The rgrp extent failure point is likely not to increase;
+ it will only do so if the freed blocks are somehow
+ contiguous with a span of free blocks that follows. Still,
+ it will force the number to be recalculated later. */
+ rgd->rd_extfail_pt += rs->rs_free;
rs->rs_free = 0;
clear_bit(GBF_FULL, &bi->bi_flags);
- smp_mb__after_clear_bit();
}
}

@@ -1132,6 +1136,8 @@ int gfs2_rgrp_bh_get(struct gfs2_rgrpd *rgd)
gfs2_rgrp_in(rgd, (rgd->rd_bits[0].bi_bh)->b_data);
rgd->rd_flags |= (GFS2_RDF_UPTODATE | GFS2_RDF_CHECK);
rgd->rd_free_clone = rgd->rd_free;
+ /* max out the rgrp allocation failure point */
+ rgd->rd_extfail_pt = rgd->rd_free;
}
if (cpu_to_be32(GFS2_MAGIC) != rgd->rd_rgl->rl_magic) {
rgd->rd_rgl->rl_unlinked = cpu_to_be32(count_unlinked(rgd));
@@ -1593,6 +1599,8 @@ fail:
* Side effects:
* - If looking for free blocks, we set GBF_FULL on each bitmap which
* has no free blocks in it.
+ * - If looking for free blocks, we set rd_extfail_pt on each rgrp which
+ * has come up short on a free block search.
*
* Returns: 0 on success, -ENOSPC if there is no block of the requested state
*/
@@ -1604,6 +1612,8 @@ static int gfs2_rbm_find(struct gfs2_rbm *rbm, u8 state, u32 *minext,
struct buffer_head *bh;
int initial_bii;
u32 initial_offset;
+ int first_bii = rbm->bii;
+ u32 first_offset = rbm->offset;
u32 offset;
u8 *buffer;
int n = 0;
@@ -1679,6 +1689,13 @@ next_iter:
if (minext == NULL || state != GFS2_BLKST_FREE)
return -ENOSPC;

+ /* If the extent was too small, and it's smaller than the smallest
+ to have failed before, remember for future reference that it's
+ useless to search this rgrp again for this amount or more. */
+ if ((first_offset == 0) && (first_bii == 0) &&
+ (*minext < rbm->rgd->rd_extfail_pt))
+ rbm->rgd->rd_extfail_pt = *minext;
+
/* If the maximum extent we found is big enough to fulfill the
minimum requirements, use it anyway. */
if (maxext.len) {
@@ -1924,7 +1941,9 @@ int gfs2_inplace_reserve(struct gfs2_inode *ip, const struct gfs2_alloc_parms *a
}

/* Skip unuseable resource groups */
- if (rs->rs_rbm.rgd->rd_flags & (GFS2_RGF_NOALLOC | GFS2_RDF_ERROR))
+ if ((rs->rs_rbm.rgd->rd_flags & (GFS2_RGF_NOALLOC |
+ GFS2_RDF_ERROR)) ||
+ (ap && (ap->target > rs->rs_rbm.rgd->rd_extfail_pt)))
goto skip_rgrp;

if (sdp->sd_args.ar_rgrplvb)
@@ -2106,10 +2125,10 @@ int gfs2_rgrp_dump(struct seq_file *seq, const struct gfs2_glock *gl)

if (rgd == NULL)
return 0;
- gfs2_print_dbg(seq, " R: n:%llu f:%02x b:%u/%u i:%u r:%u\n",
+ gfs2_print_dbg(seq, " R: n:%llu f:%02x b:%u/%u i:%u r:%u e:%u\n",
(unsigned long long)rgd->rd_addr, rgd->rd_flags,
rgd->rd_free, rgd->rd_free_clone, rgd->rd_dinodes,
- rgd->rd_reserved);
+ rgd->rd_reserved, rgd->rd_extfail_pt);
spin_lock(&rgd->rd_rsspin);
for (n = rb_first(&rgd->rd_rstree); n; n = rb_next(&trs->rs_node)) {
trs = rb_entry(n, struct gfs2_blkreserv, rs_node);
@@ -2228,9 +2247,10 @@ int gfs2_alloc_blocks(struct gfs2_inode *ip, u64 *bn, unsigned int *nblocks,

/* Since all blocks are reserved in advance, this shouldn't happen */
if (error) {
- fs_warn(sdp, "inum=%llu error=%d, nblocks=%u, full=%d\n",
+ fs_warn(sdp, "inum=%llu error=%d, nblocks=%u, full=%d fail_pt=%d\n",
(unsigned long long)ip->i_no_addr, error, *nblocks,
- test_bit(GBF_FULL, &rbm.rgd->rd_bits->bi_flags));
+ test_bit(GBF_FULL, &rbm.rgd->rd_bits->bi_flags),
+ rbm.rgd->rd_extfail_pt);
goto rgrp_error;
}

--
1.8.3.1

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