xfs: fix multi-AG deadlock in xfs_bunmapi (5b094d6d) · Commits · 戴 / test

Just like in the allocator we must avoid touching multiple AGs out of order when freeing blocks, as freeing still locks the AGF and can cause the same AB-BA deadlocks as in the allocation path. Signed-off-by:

Christoph Hellwig <hch@lst.de> Reported-by:

Nikolay Borisov <n.borisov.lkml@gmail.com> Reviewed-by:

Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by:

Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/libxfs/xfs_bmap.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -5435,6 +5435,7 @@ __xfs_bunmapi(
		xfs_fsblock_t sum;
		xfs_filblks_t len = rlen; / length to unmap in file */
		xfs_fileoff_t max_len;
		xfs_agnumber_t prev_agno = NULLAGNUMBER, agno;

		trace_xfs_bunmap(ip, bno, len, flags, _RET_IP_);

		@@ -5534,6 +5535,17 @@ __xfs_bunmapi(
		*/
		del = got;
		wasdel = isnullstartblock(del.br_startblock);

		/*
		* Make sure we don't touch multiple AGF headers out of order
		* in a single transaction, as that could cause AB-BA deadlocks.
		*/
		if (!wasdel) {
		agno = XFS_FSB_TO_AGNO(mp, del.br_startblock);
		if (prev_agno != NULLAGNUMBER && prev_agno > agno)
		break;
		prev_agno = agno;
		}
		if (got.br_startoff < start) {
		del.br_startoff = start;
		del.br_blockcount -= start - got.br_startoff;

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