From: Michael Holzheu Date: Wed, 14 Oct 2009 10:43:45 +0000 (+0200) Subject: [S390] tape390: Fix request queue handling in block driver X-Git-Tag: v2.6.32-rc5~19^2~6 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=03cadd36d51c737d7ad6aa21e2524296be6fe57f;p=pandora-kernel.git [S390] tape390: Fix request queue handling in block driver When setting a channel attached tape online under Linux 2.6.31, the "vol_id" process from udev hangs in sync_page(): 2 sync_page+144 [0x1dfaac] 3 __wait_on_bit_lock+194 [0x58c23e] 4 __lock_page+116 [0x1df9dc] 5 truncate_inode_pages_range+728 [0x1ed7cc] 6 __blkdev_put+244 [0x25f738] 7 __fput+300 [0x229c4c] 8 filp_close+122 [0x225a3a] The reason for that is an error in the request queue handling. It can happen that we fetch a request, but do not process it further because the number of queued requests exceeds TAPEBLOCK_MIN_REQUEUE. To fix this, we should call blk_peek_request() instead of blk_fetch_request() in the while condition and fetch the request in the loop body afterwards. This bug was introduced with the patch "block: implement and enforce request peek/start/fetch" (9934c8c04561413609d2bc38c6b9f268cba774a4) Signed-off-by: Michael Holzheu Signed-off-by: Martin Schwidefsky --- Reading git-diff-tree failed