From: Miklos Szeredi <mszeredi@suse.cz>
Date: Tue, 19 May 2009 09:37:46 +0000 (+0200)
Subject: splice: fix kmaps in default_file_splice_write()
X-Git-Tag: v2.6.31-rc1~389^2~46
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b2858d7d1639c04ca3c54988d76c5f7300b76f1c;p=pandora-kernel.git

splice: fix kmaps in default_file_splice_write()

Unfortunately multiple kmap() within a single thread are deadlockable,
so writing out multiple buffers with writev() isn't possible.

Change the implementation so that it does a separate write() for each
buffer.  This actually simplifies the code a lot since the
splice_from_pipe() helper can be used.

This limitation is caused by HIGHMEM pages, and so only affects a
subset of architectures and configurations.  In the future it may be
worth to implement default_file_splice_write() in a more efficient way
on configs that allow it.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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