linux-toradex.git/drivers/block/aoe/aoedev.c, branch v4.4.26

block: add a bi_error field to struct bio

2015-07-29T14:55:15+00:00

Currently we have two different ways to signal an I/O error on a BIO:

 (1) by clearing the BIO_UPTODATE flag
 (2) by returning a Linux errno value to the bi_end_io callback

The first one has the drawback of only communicating a single possible
error (-EIO), and the second one has the drawback of not beeing persistent
when bios are queued up, and are not passed along from child to parent
bio in the ever more popular chaining scenario.  Having both mechanisms
available has the additional drawback of utterly confusing driver authors
and introducing bugs where various I/O submitters only deal with one of
them, and the others have to add boilerplate code to deal with both kinds
of error returns.

So add a new bi_error field to store an errno value directly in struct
bio and remove the existing mechanisms to clean all this up.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Hannes Reinecke 
Reviewed-by: NeilBrown 
Signed-off-by: Jens Axboe

aoe: remove custom implementation of kbasename()

2013-09-11T22:59:26+00:00

In the kernel we have a nice helper that may be used here. This patch
substitutes the custom implementation by the native function call.

Signed-off-by: Andy Shevchenko 
Cc: Ed Cashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: add AoE-target files to debugfs

2013-09-11T22:59:23+00:00

Signed-off-by: Ed Cashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: update copyright date

2013-07-03T23:08:05+00:00

Signed-off-by: Ed Cashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: perform I/O completions in parallel

2013-07-03T23:08:05+00:00

Some users have a large AoE target while others like to use many AoE
targets at the same time.  In the latter case, there is an opportunity to
greatly improve aggregate throughput by allowing different threads to
complete the I/O associated with each target.  For 36 targets, 4 KiB read
throughput roughly doubles, for example, with these changes in place.

Signed-off-by: Ed Cashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: fix use after free in aoedev_by_aoeaddr()

2012-12-18T01:15:26+00:00

We should return NULL on failure instead of returning a freed pointer.

Signed-off-by: Dan Carpenter 
Cc: Ed Cashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: use dynamic number of remote ports for AoE storage target

2012-12-18T01:15:25+00:00

Many AoE targets have four or fewer network ports, but some existing
storage devices have many, and the AoE protocol sets no limit.

This patch allows the use of more than eight remote MAC addresses per AoE
target, while reducing the amount of memory used by the aoe driver in
cases where there are many AoE targets with fewer than eight MAC addresses
each.

Signed-off-by: Ed Cashin 
Cc: Jens Axboe 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: avoid races between device destruction and discovery

2012-12-18T01:15:25+00:00

This change avoids a race that could result in a NULL pointer derference
following a WARNing from kobject_add_internal, "don't try to register
things with the same name in the same directory."

The problem was found with a test that forgets and discovers an
aoe device in a loop:

  while test ! -r /tmp/stop; do
	aoe-flush -a
	aoe-discover
  done

The race was between aoedev_flush taking aoedevs out of the devlist,
allowing a new discovery of the same AoE target to take place before the
driver gets around to calling sysfs_remove_group.  Fixing that one
revealed another race between do_open and add_disk, and this patch avoids
that, too.

The fix required some care, because for flushing (forgetting) an aoedev,
some of the steps must be performed under lock and some must be able to
sleep.  Also, for discovering a new aoedev, some steps might sleep.

The check for a bad aoedev pointer remains from a time when about half of
this patch was done, and it was possible for the
bdev->bd_disk->private_data to become corrupted.  The check should be
removed eventually, but it is not expected to add significant overhead,
occurring in the aoeblk_open routine.

Signed-off-by: Ed Cashin 
Cc: Jens Axboe 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: improve handling of misbehaving network paths

2012-12-18T01:15:25+00:00

An AoE target can have multiple network ports used for AoE, and in the
aoe driver, those are tracked by the aoetgt struct.  These changes allow
the aoe driver to handle network paths, or aoetgts, that are not working
well, compared to the others.

Paths that do not get responses despite the retransmission of AoE
commands are marked as "tainted", and non-tainted paths are preferred.

Meanwhile, the aoe driver attempts to "probe" the tainted path in the
background by issuing reads of LBA 0 that are padded out to full
(possibly jumbo-frame) size.  If the probes get responses, then the path
is "redeemed", and its taint is removed.

This mechanism has been shown to be helpful in transparently handling
and recovering from real-world network "brown outs" in ways that the
earlier "shoot the help-needing target in the head" mechanism could not.

Signed-off-by: Ed Cashin 
Cc: Jens Axboe 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: return real minor number for static minors

2012-12-18T01:15:25+00:00

The value returned by the static minor device number number allocator is
the real minor number, so it must be multiplied by the supported number
of partitions per aoedev.

Without this fix the support for systems without udev is incomplete, and
the few users of aoe on such systems will have surprising results when
device nodes names do not match the AoE target.

Signed-off-by: Ed Cashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds