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Commit 8a2e70c4 authored by Tao Ma's avatar Tao Ma Committed by Joel Becker
Browse files

ocfs2: Count more refcount records in file system fragmentation. 



The refcount record calculation in ocfs2_calc_refcount_meta_credits
is too optimistic that we can always allocate contiguous clusters
and handle an already existed refcount rec as a whole. Actually
because of file system fragmentation, we may have the chance to split
a refcount record into 3 parts during the transaction. So consider
the worst case in record calculation.

Cc: stable@kernel.org
Signed-off-by: default avatarTao Ma <tao.ma@oracle.com>
Signed-off-by: default avatarJoel Becker <joel.becker@oracle.com>
parent 7beaf243

fs/ocfs2/refcounttree.c

+15 −5
Original line number Original line Diff line number Diff line
@@ -2436,16 +2436,26 @@ static int ocfs2_calc_refcount_meta_credits(struct super_block *sb, 
		len = min((u64)cpos + clusters, le64_to_cpu(rec.r_cpos) +

		len = min((u64)cpos + clusters, le64_to_cpu(rec.r_cpos) +

			  le32_to_cpu(rec.r_clusters)) - cpos;

			  le32_to_cpu(rec.r_clusters)) - cpos;

		/*

		/*

		 * If the refcount rec already exist, cool. We just need

		 * to check whether there is a split. Otherwise we just need

		 * to increase the refcount.

		 * If we will insert one, increases recs_add.

		 *

		 * We record all the records which will be inserted to the

		 * We record all the records which will be inserted to the

		 * same refcount block, so that we can tell exactly whether

		 * same refcount block, so that we can tell exactly whether

		 * we need a new refcount block or not.

		 * we need a new refcount block or not.

		 *

		 * If we will insert a new one, this is easy and only happens

		 * during adding refcounted flag to the extent, so we don't

		 * have a chance of spliting. We just need one record.

		 *

		 * If the refcount rec already exists, that would be a little

		 * complicated. we may have to:

		 * 1) split at the beginning if the start pos isn't aligned.

		 *    we need 1 more record in this case.

		 * 2) split int the end if the end pos isn't aligned.

		 *    we need 1 more record in this case.

		 * 3) split in the middle because of file system fragmentation.

		 *    we need 2 more records in this case(we can't detect this

		 *    beforehand, so always think of the worst case).

		 */

		 */

		if (rec.r_refcount) {

		if (rec.r_refcount) {

			recs_add += 2;

			/* Check whether we need a split at the beginning. */

			/* Check whether we need a split at the beginning. */

			if (cpos == start_cpos &&

			if (cpos == start_cpos &&

			    cpos != le64_to_cpu(rec.r_cpos))

			    cpos != le64_to_cpu(rec.r_cpos))