gfs2: Fix loop in gfs2_rbm_find (v2)

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Fix the resource group wrap-around logic in gfs2_rbm_find that commit
e579ed4f44 broke.  The bug can lead to unnecessary repeated scanning of the
same bitmaps; there is a risk that future changes will turn this into an
endless loop.

This is an updated version of commit 2d29f6b96d ("gfs2: Fix loop in
gfs2_rbm_find") which ended up being reverted because it introduced a
performance regression in iozone (see commit e74c98ca2d).  Changes since v1:

 - Simplify the wrap-around logic.

 - Handle the case where each resource group only has a single bitmap block
   (small filesystem).

 - Update rd_extfail_pt whenever we scan the entire bitmap, even when we don't
   start the scan at the very beginning of the bitmap.

Fixes: e579ed4f44 ("GFS2: Introduce rbm field bii")
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

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This commit is contained in:

Andreas Gruenbacher 2019-03-14 16:48:48 +01:00

parent b4b52b881c

commit 71921ef859

1 changed files with 25 additions and 29 deletions

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fs/gfs2/rgrp.c

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