Hi,
Before this patch, function gfs2_rgrp_bh_get would only update the
rgrp info from the buffer if the GFS2_RDF_UPTODATE flag was clear.
This went back to the days when gfs2 kept rgrp version numbers, and
re-read the buffer_heads constantly, not just when needed.
The problem is, RDF_UPTODATE is a local flag, but lvbs are changed
dynamically throughout the cluster. This is a serious problem when
using the rgrplvb mount option because of scenarios like this:
1. Node A mounts the file system, sets RDF_UPTODATE for rgrp X.
2. Node B mounts the file system, sets RDF_UPTODATE for rgrp X.
3. Node A deletes a large file, freeing up lots of blocks,
so the lvb gets updated.
4. Node B now re-reads the rgrp, but because it's marked UPTODATE,
it decides not to update its in-core copy of rgrp X.
At this point, Node B will have the wrong value for rgd->rd_free,
the amount of free space in the rgrp.
But there's no good reason not to grab the most recent values from
the buffer: it only costs us a few cpu cycles to read them.
This patch removes the UPTODATE check in favor of just always
reading the rgrp values in from the buffer we just read.
Signed-off-by: Bob Peterson <rpete...@redhat.com>
---
fs/gfs2/rgrp.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 1ad3256b9cbc..6eec634eae2d 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -1177,15 +1177,14 @@ static int gfs2_rgrp_bh_get(struct gfs2_rgrpd *rgd)
}
}
- if (!(rgd->rd_flags & GFS2_RDF_UPTODATE)) {
- for (x = 0; x < length; x++)
- clear_bit(GBF_FULL, &rgd->rd_bits[x].bi_flags);
- 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;
- }
+ for (x = 0; x < length; x++)
+ clear_bit(GBF_FULL, &rgd->rd_bits[x].bi_flags);
+ 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));
gfs2_rgrp_ondisk2lvb(rgd->rd_rgl,
