linux/block, branch v2.6.16.54

elevator: move clearing of unplug flag earlier

2007-04-20T22:13:30Z

A flag was recently added to the elevator code to avoid performing an unplug when reuests are being re-queued. The goal of this flag was to avoid a deep recursion that can occur when re-queueing requests after a SCSI device/host reset. See http://lkml.org/lkml/2006/5/17/254 However, that fix added the flag near the bottom of a case statement, where an earlier break (in an if statement) could transport one out of the case, without setting the flag. This patch sets the flag earlier in the case statement. I re-discovered the deep recursion recently during testing; I was told that it was a known problem, and the fix to it was in the kernel I was testing. Indeed it was ... but it didn't fix the bug. With the patch below, I no longer see the bug. Signed-off by: Linas Vepstas Signed-off-by: Jens Axboe Signed-off-by: Adrian Bunk

scsi: clear garbage after CDBs on SG_IO

2006-12-17T20:32:00Z

ATAPI devices transfer fixed number of bytes for CDBs (12 or 16). Some ATAPI devices choke when shorter CDB is used and the left bytes contain garbage. Block SG_IO cleared left bytes but SCSI SG_IO didn't. This patch makes SCSI SG_IO clear it and simplify CDB clearing in block SG_IO. Signed-off-by: Tejun Heo Acked-by: Jens Axboe Signed-off-by: Adrian Bunk

block layer: elv_iosched_show should get elv_list_lock

2006-11-29T13:04:14Z

elv_iosched_show function iterates other elv_list, hence elv_list_lock should be got. Also the question is: in elv_iosched_show, elv_iosched_store q->elevator->elevator_type construction is used without locking q->queue_lock. Is it expected?.. Signed-off-by: Vasily Tarasov Acked-by: Jens Axboe Signed-off-by: Adrian Bunk

block: Fix bad data direction in SG_IO

2006-11-29T13:01:40Z

Contrary to what the name misleads you to believe, SG_DXFER_TO_FROM_DEV is really just a normal read seen from the device side. This patch fixes http://lkml.org/lkml/2006/10/13/100 Signed-off-by: Jens Axboe Signed-off-by: Adrian Bunk

BLOCK: Fix bounce limit address check

2006-08-07T19:26:18Z

This fixes some OOMs on 64bit systems with <4GB of RAM when accessing the cdrom. Do a safer check for when to enable DMA. Currently we enable ISA DMA for cases that do not need it, resulting in OOM conditions when ZONE_DMA runs out of space. Signed-off-by: Andi Kleen Signed-off-by: Jens Axboe Signed-off-by: Adrian Bunk

[PATCH] limit request_fn recursion

2006-05-20T22:00:31Z

Don't recurse back into the driver even if the unplug threshold is met, when the driver asks for a requeue. This is both silly from a logical point of view (requeues typically happen due to driver/hardware shortage), and also dangerous since we could hit an endless request_fn -> requeue -> unplug -> request_fn loop and crash on stack overrun. Also limit blk_run_queue() to one level of recursion, similar to how blk_start_queue() works. This patch fixed a real problem with SLES10 and lpfc, and it could hit any SCSI lld that returns non-zero from it's ->queuecommand() handler. Signed-off-by: Jens Axboe Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman Signed-off-by: Chris Wright

[PATCH] Simplify proc/devices and fix early termination regression

2006-05-01T19:03:43Z

Repair /proc/devices early-termination regression. 2.6.16 broke /proc/devices. An application often gets an EOF before the end of data is reached, if that application uses a series of short read(2)s to access the data. I have used read buffers of varying sizes with varying degrees of unsuccess (larger sizes get further into the data than smaller sizes, following a simple pattern). It appears that the only safe way to get the data is to use a single read buffer larger than all the data in /proc/devices. The following example demonstates the problem: # dd if=/proc/devices bs=1 Character devices: 1 mem 27+0 records in 27+0 records out This patch is a backport of the fix recently accepted to Linus's tree: commit 68eef3b4791572ecb70249c7fb145bb3742dd899 [PATCH] Simplify proc/devices and fix early termination regression It replaces the complex, state-machine algorithm introduced in 2.6.16 with a simple algorithm, modeled on the implementation of /proc/interrupts. [akpm@osdl.org: cleanups, simplifications] Signed-off-by: Joe Korty Signed-off-by: Greg Kroah-Hartman

[PATCH] block: disable block layer bouncing for most memory on 64bit systems

2006-03-09T02:10:31Z

The low level PCI DMA mapping functions should handle it in most cases. This should fix problems with depleting the DMA zone early. The old code used precious GFP_DMA memory in many cases where it was not needed. Signed-off-by: Andi Kleen Cc: Jens Axboe Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] cfq-iosched: slice expiry fixups

2006-02-28T08:38:02Z

During testing of SLES10, we encountered a hang in the CFQ io scheduler. Turns out the deferred slice expiry logic is buggy, so remove that for now. We could be left with an idle queue that would never wake up. So kill that logic, always expire immediately. Also fix a potential timer race condition. Patch looks bigger than it is, because it moves a function. Signed-off-by: Jens Axboe Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://brick.kernel.dk/data/git/linux-2.6-block

2006-02-08T15:58:18Z