tree 5462388cdb6b36b2f0f1cf75dc6ee60a7c643a23
parent a8d770d987ee20b59fba6c37d7f0f2a351913c4b
author Dave Chinner <david@fromorbit.com> 1239036344 +0200
committer Christoph Hellwig <hch@brick.lst.de> 1239036344 +0200

xfs: make inode flush at ENOSPC synchronous

When we are writing to a single file and hit ENOSPC, we trigger a background
flush of the inode and try again.  Because we hold page locks and the iolock,
the flush won't proceed until after we release these locks. This occurs once
we've given up and ENOSPC has been reported. Hence if this one is the only
dirty inode in the system, we'll get an ENOSPC prematurely.

To fix this, remove the async flush from the allocation routines and move
it to the top of the write path where we can do a synchronous flush
and retry the write again. Only retry once as a second ENOSPC indicates
that we really are ENOSPC.

This avoids a page cache deadlock when trying to do this flush synchronously
in the allocation layer that was identified by Mikulas Patocka.

Signed-off-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>