GFS2: Allow the number of committed revokes to temporarily be negative (2e95e3f6) · Commits · 戴 / test

GFS2 tracks the number of revokes and unrevokes that are part of committed transactions via sd_log_commited_revoke. It is possible for one process to add revokes during its transaction, while another process unrevokes them during its transaction. If the second process finishes its transaction first, sd_log_commited_revoke will be decremented by the number of unrevokes that the second process did, without first being incremented by the number of revokes the first process did. This is fine, since all started transactions must be completed before the journal can be flushed. However, sd_log_commited_revoke is an unsigned integer, and log_refund() causes an assertion failure if it would go negative at the end of a transaction. This patch makes sd_log_commited_revoke a signed integer and allows it to go negative. __gfs2_log_flush() still checks that it mataches the actual number of revokes. Signed-off-by:

Benjamin Marzinski <bmarzins@redhat.com> Signed-off-by:

Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/incore.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -616,7 +616,7 @@ struct gfs2_sbd {
		unsigned int sd_log_blks_reserved;
		unsigned int sd_log_commited_buf;
		unsigned int sd_log_commited_databuf;
		unsigned int sd_log_commited_revoke;
		int sd_log_commited_revoke;

		unsigned int sd_log_num_buf;
		unsigned int sd_log_num_revoke;

fs/gfs2/log.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -417,7 +417,7 @@ static unsigned int calc_reserved(struct gfs2_sbd *sdp)
		databufhdrs_needed = (sdp->sd_log_commited_databuf +
		(dbuf_limit - 1)) / dbuf_limit;

		if (sdp->sd_log_commited_revoke)
		if (sdp->sd_log_commited_revoke > 0)
		revokes = gfs2_struct2blk(sdp, sdp->sd_log_commited_revoke,
		sizeof(u64));

		@@ -790,7 +790,6 @@ static void log_refund(struct gfs2_sbd sdp, struct gfs2_trans tr)
		gfs2_assert_withdraw(sdp, (((int)sdp->sd_log_commited_buf) >= 0) \|\|
		(((int)sdp->sd_log_commited_databuf) >= 0));
		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);
		gfs2_assert_withdraw(sdp, sdp->sd_log_blks_reserved + tr->tr_reserved >= reserved);
		unused = sdp->sd_log_blks_reserved - reserved + tr->tr_reserved;

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