xfs: avoid buffer deadlocks when walking fs inodes

mainline-inclusion
from mainline-v5.14-rc4
commit a6343e4d
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4KIAO
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a6343e4d9278b3919c809fab9945c4d8f04fadf5



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When we're servicing an INUMBERS or BULKSTAT request or running
quotacheck, grab an empty transaction so that we can use its inherent
recursive buffer locking abilities to detect inode btree cycles without
hitting ABBA buffer deadlocks.  This patch requires the deferred inode
inactivation patchset because xfs_irele cannot directly call
xfs_inactive when the iwalk itself has an (empty) transaction.

Found by fuzzing an inode btree pointer to introduce a cycle into the
tree (xfs/365).

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Lihong Kou <koulihong@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>