linux.git/drivers/mtd/mtd_blkdevs.c, branch v4.2

mtd: blktrans: use better error code for unimplemented ioctl()

2015-05-21T17:44:32+00:00

In commit 50183936254b ("mtd: blktrans: change blktrans_getgeo return
value") we fixed the problem that ioctl(HDIO_GETGEO) might return 0
(success) for mtdblock devices which did not implement the feature and
would leave a blank (zero) result.

But now, let's get the error code right. Other code paths on this ioctl
tend to use -ENOTTY to notify the user that the ioctl() is not supported
for the device, so let's use that instead of -EOPNOTSUPP.

Suggested-by: Richard Weinberger 
Signed-off-by: Brian Norris

mtd: blktrans: change blktrans_getgeo return value

2015-05-21T07:26:41+00:00

Modify function blktrans_getgeo()'s return value to -EOPNOTSUPP when
dev->tr->getgeo == NULL.

We shouldn't make the return value to 0 when dev->tr->getgeo == NULL,
because the function blktrans_getgeo() has an output value "hd_geometry"
which is usually used by some application, if returns 0 (i.e.,
"success"), it will make some application get the wrong information.

Signed-off-by: Wenlin Kang 
Signed-off-by: Brian Norris

mtd: fix: avoid race condition when accessing mtd->usecount

2015-05-12T17:59:53+00:00

On A MIPS 32-cores machine a BUG_ON was triggered because some acesses to
mtd->usecount were done without taking mtd_table_mutex.
kernel: Call Trace:
kernel: [] __put_mtd_device+0x20/0x50
kernel: [] blktrans_release+0x8c/0xd8
kernel: [] __blkdev_put+0x1a8/0x200
kernel: [] blkdev_close+0x1c/0x30
kernel: [] __fput+0xac/0x250
kernel: [] task_work_run+0xd8/0x120
kernel: [] work_notifysig+0x10/0x18
kernel:
kernel:
        Code: 2442ffff  ac8202d8  000217fe <00020336> dc820128  10400003
               00000000  0040f809  00000000
kernel: ---[ end trace 080fbb4579b47a73 ]---

Fixed by taking the mutex in blktrans_open and blktrans_release.

Note that this locking is already suggested in
include/linux/mtd/blktrans.h:

struct mtd_blktrans_ops {
...
	/* Called with mtd_table_mutex held; no race with add/remove */
	int (*open)(struct mtd_blktrans_dev *dev);
	void (*release)(struct mtd_blktrans_dev *dev);
...
};

But we weren't following it.

Originally reported by (and patched by) Zhang and Giuseppe,
independently. Improved and rewritten.

Cc: stable@vger.kernel.org
Reported-by: Zhang Xingcai 
Reported-by: Giuseppe Cantavenera 
Tested-by: Giuseppe Cantavenera 
Acked-by: Alexander Sverdlin 
Signed-off-by: Brian Norris

mtd: blkdevs: remove dead code

2015-03-11T22:21:48+00:00

The only exit (break) from the preceding loop is nested within a
condition which yields req == NULL. This code is dead.

Coverity CID #752669

Signed-off-by: Brian Norris

block: disable entropy contributions for nonrot devices

2014-10-04T16:55:32+00:00

Clear QUEUE_FLAG_ADD_RANDOM in all block drivers that set
QUEUE_FLAG_NONROT.

Historically, all block devices have automatically made entropy
contributions.  But as previously stated in commit e2e1a148 ("block: add
sysfs knob for turning off disk entropy contributions"):
    - On SSD disks, the completion times aren't as random as they
      are for rotational drives. So it's questionable whether they
      should contribute to the random pool in the first place.
    - Calling add_disk_randomness() has a lot of overhead.

There are more reliable sources for randomness than non-rotational block
devices.  From a security perspective it is better to err on the side of
caution than to allow entropy contributions from unreliable "random"
sources.

Signed-off-by: Mike Snitzer 
Signed-off-by: Jens Axboe

Merge tag 'for-linus-20140610' of git://git.infradead.org/linux-mtd

2014-06-11T15:35:34+00:00

Pull MTD updates from Brian Norris:
 - refactor m25p80.c driver for use as a general SPI NOR framework for
   other drivers which may speak to SPI NOR flash without providing full
   SPI support (i.e., not part of drivers/spi/)
 - new Freescale QuadSPI driver (utilizing new SPI NOR framework)
 - updates for the STMicro "FSM" SPI NOR driver
 - fix sync/flush behavior on mtd_blkdevs
 - fixup subpage write support on a few NAND drivers
 - correct the MTD OOB test for odd-sized OOB areas
 - add BCH-16 support for OMAP NAND
 - fix warnings and trivial refactoring
 - utilize new ECC DT bindings in pxa3xx NAND driver
 - new LPDDR NVM driver
 - address a few assorted bugs caught by Coverity
 - add new imx6sx support for GPMI NAND
 - use a bounce buffer for NAND when non-DMA-able buffers are used

* tag 'for-linus-20140610' of git://git.infradead.org/linux-mtd: (77 commits)
  mtd: gpmi: add gpmi support for imx6sx
  mtd: maps: remove check for CONFIG_MTD_SUPERH_RESERVE
  mtd: bf5xx_nand: use the managed version of kzalloc
  mtd: pxa3xx_nand: make the driver work on big-endian systems
  mtd: nand: omap: fix omap_calculate_ecc_bch() for-loop error
  mtd: nand: r852: correct write_buf loop bounds
  mtd: nand_bbt: handle error case for nand_create_badblock_pattern()
  mtd: nand_bbt: remove unused variable
  mtd: maps: sc520cdp: fix warnings
  mtd: slram: fix unused variable warning
  mtd: pfow: remove unused variable
  mtd: lpddr: fix Kconfig dependency, for I/O accessors
  mtd: nand: pxa3xx: Add supported ECC strength and step size to the DT binding
  mtd: nand: pxa3xx: Use ECC strength and step size devicetree binding
  mtd: nand: pxa3xx: Clean pxa_ecc_init() error handling
  mtd: nand: Warn the user if the selected ECC strength is too weak
  mtd: nand: omap: Documentation: How to select correct ECC scheme for your device ?
  mtd: nand: omap: add support for BCH16_ECC - NAND driver updates
  mtd: nand: omap: add support for BCH16_ECC - ELM driver updates
  mtd: nand: omap: add support for BCH16_ECC - GPMC driver updates
  ...

mtd: mtd_blkdevs: handle REQ_FLUSH request and do explicit flush of writeback buffer

2014-04-16T06:25:37+00:00

mtd_blkdevs is device with volatile cache (writeback buffer), so it should support
REQ_FLUSH to do explicit flush.

Without this patch 'sync' does not guarantee that writeback buffer will be flushed
on disk in case of power off, e.g.:

  $ cp some_file /mnt
  $ sync

  ### POWER OFF

In case of this sequence writeback buffer will not be flushed on disk.

This patch fixes this behaviour and explicitly reports to block layer that flush
requests are being supported.

Signed-off-by: Roman Peniaev 
Cc: David Woodhouse 
Cc: linux-mtd@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Brian Norris

block: remove struct request buffer member

2014-04-15T20:03:02+00:00

This was used in the olden days, back when onions were proper
yellow. Basically it mapped to the current buffer to be
transferred. With highmem being added more than a decade ago,
most drivers map pages out of a bio, and rq->buffer isn't
pointing at anything valid.

Convert old style drivers to just use bio_data().

For the discard payload use case, just reference the page
in the bio.

Signed-off-by: Jens Axboe

mtd: delete non-required instances of include

2014-03-11T05:42:22+00:00

None of these files are actually using any __init type directives
and hence don't need to include .  Most are just a
left over from __devinit and __cpuinit removal, or simply due to
code getting copied from one driver to the next.

Cc: David Woodhouse 
Cc: Brian Norris 
Cc: linux-mtd@lists.infradead.org
Signed-off-by: Paul Gortmaker 
[Brian: dropped one incorrect hunk]
Signed-off-by: Brian Norris

block_device_operations->release() should return void

2013-05-07T06:16:21+00:00

The value passed is 0 in all but "it can never happen" cases (and those
only in a couple of drivers) *and* it would've been lost on the way
out anyway, even if something tried to pass something meaningful.
Just don't bother.

Signed-off-by: Al Viro