Konstantin Belousov 2cc7d26f7f Cylinder group bitmaps and blocks containing inode for a snapshot ... file are after snaplock, while other ffs device buffers are before snaplock in global lock order. By itself, this could cause deadlock when bdwrite() tries to flush dirty buffers on snapshotted ffs. If, during the flush, COW activity for snapshot needs to allocate block and ffs_alloccg() selects the cylinder group that is being written by bdwrite(), then kernel would panic due to recursive buffer lock acquision. Avoid dealing with buffers in bdwrite() that are from other side of snaplock divisor in the lock order then the buffer being written. Add new BOP, bop_bdwrite(), to do dirty buffer flushing for same vnode in the bdwrite(). Default implementation, bufbdflush(), refactors the code from bdwrite(). For ffs device buffers, specialized implementation is used. Reviewed by: tegge, jeff, Russell Cattelan (cattelan xfs org, xfs changes) Tested by: Peter Holm X-MFC after: 3 weeks (if ever: it changes ABI)		2007-01-23 10:01:19 +00:00
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ffs	Cylinder group bitmaps and blocks containing inode for a snapshot	2007-01-23 10:01:19 +00:00
ufs	Fix build. chkdquot() should not return anything.	2007-01-20 13:54:28 +00:00