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Commit 9a57fa8e authored by Mark Tinguely's avatar Mark Tinguely Committed by Ben Myers
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xfs: wait for the write the superblock on unmount 



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: default avatarMark Tinguely <tinguely@sgi.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarBen Myers <bpm@sgi.com>
parent 8375f922

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