xfs: wait for the write the superblock on unmount (9a57fa8e) · Commits · 戴 / test

v2: Add the xfs_buf_lock to xfs_quiesce_attr(). Add explaination why xfs_buf_lock() is used to wait for write. xfs_wait_buftarg() does not wait for the completion of the write of the uncached superblock. This write can race with the shutdown of the log and causes a panic if the write does not win the race. During the log write, xfsaild_push() will lock the buffer and set the XBF_ASYNC flag. Because the XBF_FLAG is set, complete() is not performed on the buffer's iowait entry, we cannot call xfs_buf_iowait() to wait for the write to complete. The buffer's lock is held until the write is complete, so we can block on a xfs_buf_lock() request to be notified that the write is complete. Signed-off-by:

Mark Tinguely <tinguely@sgi.com> Reviewed-by:

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

Ben Myers <bpm@sgi.com>

fs/xfs/xfs_mount.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -1529,6 +1529,15 @@ xfs_unmountfs(
		xfs_ail_push_all_sync(mp->m_ail);
		xfs_wait_buftarg(mp->m_ddev_targp);

		/*
		* The superblock buffer is uncached and xfsaild_push() will lock and
		* set the XBF_ASYNC flag on the buffer. We cannot do xfs_buf_iowait()
		* here but a lock on the superblock buffer will block until iodone()
		* has completed.
		*/
		xfs_buf_lock(mp->m_sb_bp);
		xfs_buf_unlock(mp->m_sb_bp);

		xfs_log_unmount_write(mp);
		xfs_log_unmount(mp);
		xfs_uuid_unmount(mp);

fs/xfs/xfs_sync.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -359,6 +359,15 @@ xfs_quiesce_attr(
		* added an item to the AIL, thus flush it again.
		*/
		xfs_ail_push_all_sync(mp->m_ail);

		/*
		* The superblock buffer is uncached and xfsaild_push() will lock and
		* set the XBF_ASYNC flag on the buffer. We cannot do xfs_buf_iowait()
		* here but a lock on the superblock buffer will block until iodone()
		* has completed.
		*/
		xfs_buf_lock(mp->m_sb_bp);
		xfs_buf_unlock(mp->m_sb_bp);
		}

		static void

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