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authorNeilBrown <neilb@suse.de>2008-08-31 22:32:52 -0400
committerNeilBrown <neilb@suse.de>2008-08-31 22:32:52 -0400
commit271f5a9b8f8ae0db95de72779d115c9d0b9d3cc5 (patch)
tree814bfe03f1c5ae97da163c8f6b24a0cf67cfd783 /Documentation/cgroups.txt
parentbef69ea0dcce574a425feb0a5aa4c63dd108b9a6 (diff)
Remove invalidate_partition call from do_md_stop.
When stopping an md array, or just switching to read-only, we currently call invalidate_partition while holding the mddev lock. The main reason for this is probably to ensure all dirty buffers are flushed (invalidate_partition calls fsync_bdev). However if any dirty buffers are found, it will almost certainly cause a deadlock as starting writeout will require an update to the superblock, and performing that updates requires taking the mddev lock - which is already held. This deadlock can be demonstrated by running "reboot -f -n" with a root filesystem on md/raid, and some dirty buffers in memory. All other calls to stop an array should already happen after a flush. The normal sequence is to stop using the array (e.g. umount) which will cause __blkdev_put to call sync_blockdev. Then open the array and issue the STOP_ARRAY ioctl while the buffers are all still clean. So this invalidate_partition is normally a no-op, except for one case where it will cause a deadlock. So remove it. This patch possibly addresses the regression recored in http://bugzilla.kernel.org/show_bug.cgi?id=11460 and http://bugzilla.kernel.org/show_bug.cgi?id=11452 though it isn't yet clear how it ever worked. Signed-off-by: NeilBrown <neilb@suse.de>
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