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Subject[PATCH 50/58] [GFS2] Fix assert in log code
Date
From: Steven Whitehouse <swhiteho@redhat.com>

Although the values were all being calculated correctly, there was a
race in the assert due to the way it was using atomic variables. This
changes the value we assert on so that we get the same effect by testing
a different variable. This prevents the assert triggering when it shouldn't.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 40c51bf..6e6a104 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -749,7 +749,7 @@ void __gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
{
unsigned int reserved;
- unsigned int old;
+ unsigned int unused;

gfs2_log_lock(sdp);

@@ -761,14 +761,11 @@ static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
sdp->sd_log_commited_revoke += tr->tr_num_revoke - tr->tr_num_revoke_rm;
gfs2_assert_withdraw(sdp, ((int)sdp->sd_log_commited_revoke) >= 0);
reserved = calc_reserved(sdp);
- old = atomic_read(&sdp->sd_log_blks_free);
- atomic_add(tr->tr_reserved - (reserved - sdp->sd_log_blks_reserved),
- &sdp->sd_log_blks_free);
-
- gfs2_assert_withdraw(sdp, atomic_read(&sdp->sd_log_blks_free) >= old);
+ unused = sdp->sd_log_blks_reserved - reserved + tr->tr_reserved;
+ gfs2_assert_withdraw(sdp, unused >= 0);
+ atomic_add(unused, &sdp->sd_log_blks_free);
gfs2_assert_withdraw(sdp, atomic_read(&sdp->sd_log_blks_free) <=
sdp->sd_jdesc->jd_blocks);
-
sdp->sd_log_blks_reserved = reserved;

gfs2_log_unlock(sdp);
--
1.5.1.2


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