From 80641dc66a2d6dfb22af4413227a92b8ab84c7bb Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 19 Oct 2009 04:00:03 +0000 Subject: xfs: I/O completion handlers must use NOFS allocations When completing I/O requests we must not allow the memory allocator to recurse into the filesystem, as we might deadlock on waiting for the I/O completion otherwise. The only thing currently allocating normal GFP_KERNEL memory is the allocation of the transaction structure for the unwritten extent conversion. Add a memflags argument to _xfs_trans_alloc to allow controlling the allocator behaviour. Signed-off-by: Christoph Hellwig Reported-by: Thomas Neumann Tested-by: Thomas Neumann Reviewed-by: Alex Elder Signed-off-by: Alex Elder --- fs/xfs/xfs_iomap.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'fs/xfs/xfs_iomap.c') diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 67ae5555a30a..7294abce6ef2 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -860,8 +860,15 @@ xfs_iomap_write_unwritten( * set up a transaction to convert the range of extents * from unwritten to real. Do allocations in a loop until * we have covered the range passed in. + * + * Note that we open code the transaction allocation here + * to pass KM_NOFS--we can't risk to recursing back into + * the filesystem here as we might be asked to write out + * the same inode that we complete here and might deadlock + * on the iolock. */ - tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE); + xfs_wait_for_freeze(mp, SB_FREEZE_TRANS); + tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS); tp->t_flags |= XFS_TRANS_RESERVE; error = xfs_trans_reserve(tp, resblks, XFS_WRITE_LOG_RES(mp), 0, -- cgit v1.2.3