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authorBob Peterson <rpeterso@redhat.com>2011-08-31 09:53:19 +0100
committerSteven Whitehouse <swhiteho@redhat.com>2011-10-21 12:39:31 +0100
commit7c9ca621137cde26be05448133fc1a554345f4f8 (patch)
tree9c0779d2ca6fa8a1c6dab7ff6391bef8f444f1b3 /fs/gfs2/lops.c
parent9453615a1a7ef3fa910c6464a619595556cfcd63 (diff)
GFS2: Use rbtree for resource groups and clean up bitmap buffer ref count scheme
Here is an update of Bob's original rbtree patch which, in addition, also resolves the rather strange ref counting that was being done relating to the bitmap blocks. Originally we had a dual system for journaling resource groups. The metadata blocks were journaled and also the rgrp itself was added to a list. The reason for adding the rgrp to the list in the journal was so that the "repolish clones" code could be run to update the free space, and potentially send any discard requests when the log was flushed. This was done by comparing the "cloned" bitmap with what had been written back on disk during the transaction commit. Due to this, there was a requirement to hang on to the rgrps' bitmap buffers until the journal had been flushed. For that reason, there was a rather complicated set up in the ->go_lock ->go_unlock functions for rgrps involving both a mutex and a spinlock (the ->sd_rindex_spin) to maintain a reference count on the buffers. However, the journal maintains a reference count on the buffers anyway, since they are being journaled as metadata buffers. So by moving the code which deals with the post-journal accounting for bitmap blocks to the metadata journaling code, we can entirely dispense with the rather strange buffer ref counting scheme and also the requirement to journal the rgrps. The net result of all this is that the ->sd_rindex_spin is left to do exactly one job, and that is to look after the rbtree or rgrps. This patch is designed to be a stepping stone towards using RCU for the rbtree of resource groups, however the reduction in the number of uses of the ->sd_rindex_spin is likely to have benefits for multi-threaded workloads, anyway. The patch retains ->go_lock and ->go_unlock for rgrps, however these maybe also be removed in future in favour of calling the functions directly where required in the code. That will allow locking of resource groups without needing to actually read them in - something that could be useful in speeding up statfs. In the mean time though it is valid to dereference ->bi_bh only when the rgrp is locked. This is basically the same rule as before, modulo the references not being valid until the following journal flush. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com> Signed-off-by: Bob Peterson <rpeterso@redhat.com> Cc: Benjamin Marzinski <bmarzins@redhat.com>
Diffstat (limited to 'fs/gfs2/lops.c')
-rw-r--r--fs/gfs2/lops.c64
1 files changed, 26 insertions, 38 deletions
diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index 05bbb124699f..de05b4d66ef3 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -60,6 +60,29 @@ static void gfs2_pin(struct gfs2_sbd *sdp, struct buffer_head *bh)
trace_gfs2_pin(bd, 1);
}
+static bool buffer_is_rgrp(const struct gfs2_bufdata *bd)
+{
+ return bd->bd_gl->gl_name.ln_type == LM_TYPE_RGRP;
+}
+
+static void maybe_release_space(struct gfs2_bufdata *bd)
+{
+ struct gfs2_glock *gl = bd->bd_gl;
+ struct gfs2_sbd *sdp = gl->gl_sbd;
+ struct gfs2_rgrpd *rgd = gl->gl_object;
+ unsigned int index = bd->bd_bh->b_blocknr - gl->gl_name.ln_number;
+ struct gfs2_bitmap *bi = rgd->rd_bits + index;
+
+ if (bi->bi_clone == 0)
+ return;
+ if (sdp->sd_args.ar_discard)
+ gfs2_rgrp_send_discards(sdp, rgd->rd_data0, bd->bd_bh, bi);
+ memcpy(bi->bi_clone + bi->bi_offset,
+ 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;
+}
+
/**
* gfs2_unpin - Unpin a buffer
* @sdp: the filesystem the buffer belongs to
@@ -81,6 +104,9 @@ static void gfs2_unpin(struct gfs2_sbd *sdp, struct buffer_head *bh,
mark_buffer_dirty(bh);
clear_buffer_pinned(bh);
+ if (buffer_is_rgrp(bd))
+ maybe_release_space(bd);
+
spin_lock(&sdp->sd_ail_lock);
if (bd->bd_ail) {
list_del(&bd->bd_ail_st_list);
@@ -469,42 +495,6 @@ static void revoke_lo_after_scan(struct gfs2_jdesc *jd, int error, int pass)
gfs2_revoke_clean(sdp);
}
-static void rg_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
-{
- struct gfs2_rgrpd *rgd;
- struct gfs2_trans *tr = current->journal_info;
-
- tr->tr_touched = 1;
-
- rgd = container_of(le, struct gfs2_rgrpd, rd_le);
-
- gfs2_log_lock(sdp);
- if (!list_empty(&le->le_list)){
- gfs2_log_unlock(sdp);
- return;
- }
- gfs2_rgrp_bh_hold(rgd);
- sdp->sd_log_num_rg++;
- list_add(&le->le_list, &sdp->sd_log_le_rg);
- gfs2_log_unlock(sdp);
-}
-
-static void rg_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
-{
- struct list_head *head = &sdp->sd_log_le_rg;
- struct gfs2_rgrpd *rgd;
-
- while (!list_empty(head)) {
- rgd = list_entry(head->next, struct gfs2_rgrpd, rd_le.le_list);
- list_del_init(&rgd->rd_le.le_list);
- sdp->sd_log_num_rg--;
-
- gfs2_rgrp_repolish_clones(rgd);
- gfs2_rgrp_bh_put(rgd);
- }
- gfs2_assert_warn(sdp, !sdp->sd_log_num_rg);
-}
-
/**
* databuf_lo_add - Add a databuf to the transaction.
*
@@ -771,8 +761,6 @@ const struct gfs2_log_operations gfs2_revoke_lops = {
};
const struct gfs2_log_operations gfs2_rg_lops = {
- .lo_add = rg_lo_add,
- .lo_after_commit = rg_lo_after_commit,
.lo_name = "rg",
};