Update FMODE_NDELAY before each ioctl call so that we can kill the
magic FMODE_NDELAY_NOW. It would be even better to do this directly
in setfl(), but for that we'd need to have FMODE_NDELAY for all files,
not just block special files.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
To keep the size of changesets sane we split the switch by drivers;
to keep the damn thing bisectable we do the following:
1) rename the affected methods, add ones with correct
prototypes, make (few) callers handle both. That's this changeset.
2) for each driver convert to new methods. *ALL* drivers
are converted in this series.
3) kill the old (renamed) methods.
Note that it _is_ a flagday; all in-tree drivers are converted and by the
end of this series no trace of old methods remain. The only reason why
we do that this way is to keep the damn thing bisectable and allow per-driver
debugging if anything goes wrong.
New methods:
open(bdev, mode)
release(disk, mode)
ioctl(bdev, mode, cmd, arg) /* Called without BKL */
compat_ioctl(bdev, mode, cmd, arg)
locked_ioctl(bdev, mode, cmd, arg) /* Called with BKL, legacy */
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Right now SCSI and others do their own command timeout handling.
Move those bits to the block layer.
Instead of having a timer per command, we try to be a bit more clever
and simply have one per-queue. This avoids the overhead of having to
tear down and setup a timer for each command, so it will result in a lot
less timer fiddling.
Signed-off-by: Mike Anderson <andmike@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* Implement disk_devt() and part_devt() and use them to directly
access devt instead of computing it from ->major and ->first_minor.
Note that all references to ->major and ->first_minor outside of
block layer is used to determine devt of the disk (the part0) and as
->major and ->first_minor will continue to represent devt for the
disk, converting these users aren't strictly necessary. However,
convert them for consistency.
* Implement disk_max_parts() to avoid directly deferencing
genhd->minors.
* Update bdget_disk() such that it doesn't assume consecutive minor
space.
* Move devt computation from register_disk() to add_disk() and make it
the only one (all other usages use the initially determined value).
These changes clean up the code and will help disk->part dereference
fix and extended block device numbers.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
We still have life time issues with the sysfs command filter kobject,
so disable it for 2.6.27 release. We can revisit this and make it work
properly for 2.6.28, for 2.6.27 release it's too risky.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This patch remove blk_register_filter and blk_unregister_filter in
gendisk, and adds them to sd.c, sr.c. and ide-cd.c
The commit abf5439370 moved cmdfilter
from gendisk to request_queue. It turned out that in some subsystems
multiple gendisks share a single request_queue. So we get:
Using physmap partition information
Creating 3 MTD partitions on "physmap-flash":
0x00000000-0x01c00000 : "User FS"
0x01c00000-0x01c40000 : "booter"
kobject (8511c410): tried to init an initialized object, something is seriously wrong.
Call Trace:
[<8036644c>] dump_stack+0x8/0x34
[<8021f050>] kobject_init+0x50/0xcc
[<8021fa18>] kobject_init_and_add+0x24/0x58
[<8021d20c>] blk_register_filter+0x4c/0x64
[<8021c194>] add_disk+0x78/0xe0
[<8027d14c>] add_mtd_blktrans_dev+0x254/0x278
[<8027c8f0>] blktrans_notify_add+0x40/0x78
[<80279c00>] add_mtd_device+0xd0/0x150
[<8027b090>] add_mtd_partitions+0x568/0x5d8
[<80285458>] physmap_flash_probe+0x2ac/0x334
[<802644f8>] driver_probe_device+0x12c/0x244
[<8026465c>] __driver_attach+0x4c/0x84
[<80263c64>] bus_for_each_dev+0x58/0xac
[<802633ec>] bus_add_driver+0xc4/0x24c
[<802648e0>] driver_register+0xcc/0x184
[<80100460>] _stext+0x60/0x1bc
In the long term, we need to fix such subsystems but we need a quick
fix now. This patch add the command filter support to only sd and sr
though it might be useful for other SG_IO users (such as cciss).
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Reported-by: Manuel Lauss <mano@roarinelk.homelinux.net>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
blk_rq_map_kern can handle the stack buffers correctly (avoid DMA
from/to the stack buffers by using the bounce buffer) so we don't need
to complicate the code by allocating just 8 bytes.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Tejun Heo <htejun@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Reported-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
If you delay 30s or more before mounting a CD after inserting it then
the kernel has the wrong value for the CD size.
http://marc.info/?t=121276133000001
The problem is in sr_test_unit_ready(): the function eats unit
attentions without adjusting the sdev->changed status. This means
that when the CD signals changed media via unit attention, we can
ignore it. Fix by making sr_test_unit_ready() adjust the changed
status.
Tested-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Cc: Stable Tree <stable@kernel.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Initialize the "state changed" flag, so we do not send a change event
immediately after registering a new device.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Commit 210ba1d172 updated sr.c to use
the scsi_test_unit_ready() function. Unfortunately, this has the
wrong characteristic of eating NOT_READY returns which sr.c relies on
for tray status.
Fix by rolling an internal sr_test_unit_ready() that doesn't do this.
Tested-by: Daniel Drake <dsd@gentoo.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
In preparation for bidi we abstract all IO members of scsi_cmnd,
that will need to duplicate, into a substructure.
- Group all IO members of scsi_cmnd into a scsi_data_buffer
structure.
- Adjust accessors to new members.
- scsi_{alloc,free}_sgtable receive a scsi_data_buffer instead of
scsi_cmnd. And work on it.
- Adjust scsi_init_io() and scsi_release_buffers() for above
change.
- Fix other parts of scsi_lib/scsi.c to members migration. Use
accessors where appropriate.
- fix Documentation about scsi_cmnd in scsi_host.h
- scsi_error.c
* Changed needed members of struct scsi_eh_save.
* Careful considerations in scsi_eh_prep/restore_cmnd.
- sd.c and sr.c
* sd and sr would adjust IO size to align on device's block
size so code needs to change once we move to scsi_data_buff
implementation.
* Convert code to use scsi_for_each_sg
* Use data accessors where appropriate.
- tgt: convert libsrp to use scsi_data_buffer
- isd200: This driver still bangs on scsi_cmnd IO members,
so need changing
[jejb: rebased on top of sg_table patches fixed up conflicts
and used the synergy to eliminate use_sg and sg_count]
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Based on an original patch from: David Martin <tasio@tasio.net>
When trying to get the drive status via ioctl CDROM_DRIVE_STATUS, with
no disk it gives CDS_TRAY_OPEN even if the tray is closed.
ioctl works as expected with ide-cd driver.
Gentoo bug report: http://bugs.gentoo.org/show_bug.cgi?id=196879
Cc: Maarten Bressers <mbres@gentoo.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
The current scsi_test_unit_ready() is updated to return sense code
information (in struct scsi_sense_hdr). The sd and sr drivers are
changed to interpret the sense code return asc 0x3a as no media and
adjust the device status accordingly.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
This will send for a card reader slot (remove/add media):
UEVENT[1187091572.155884] change /devices/pci0000:00/0000:00:1d.7/usb5/5-2/5-2:1.0/host7/target7:0:0/7:0:0:0 (scsi)
UEVENT[1187091572.162314] remove /block/sdb/sdb1 (block)
UEVENT[1187091572.172464] add /block/sdb/sdb1 (block)
UEVENT[1187091572.175408] change /devices/pci0000:00/0000:00:1d.7/usb5/5-2/5-2:1.0/host7/target7:0:0/7:0:0:0 (scsi)
and for a DVD drive (add/eject media):
UEVENT[1187091590.189159] change /devices/pci0000:00/0000:00:1f.1/host4/target4:0:0/4:0:0:0 (scsi)
UEVENT[1187091590.957124] add /module/isofs (module)
UEVENT[1187091604.468207] change /devices/pci0000:00/0000:00:1f.1/host4/target4:0:0/4:0:0:0 (scsi)
Userspace gets events, even for unpartitioned media. This unifies
the event handling for asynchronoous events (AN) and events caused by
perodical polling the device from userspace.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
[jejb: modified for new event API]
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
This reverts commit ac40532ef0, which gets
us back the original cleanup of 6f5391c283.
It turns out that the bug that was triggered by that commit was
apparently not actually triggered by that commit at all, and just the
testing conditions had changed enough to make it appear to be due to it.
The real problem seems to have been found by Peter Osterlund:
"pktcdvd sets it [block device size] when opening the /dev/pktcdvd
device, but when the drive is later opened as /dev/scd0, there is
nothing that sets it back. (Btw, 40944 is possible if the disk is a
CDRW that was formatted with "cdrwtool -m 10236".)
The problem is that pktcdvd opens the cd device in non-blocking mode
when pktsetup is run, and doesn't close it again until pktsetup -d is
run. The effect is that if you meanwhile open the cd device,
blkdev.c:do_open() doesn't call bd_set_size() because
bdev->bd_openers is non-zero."
In particular, to repeat the bug (regardless of whether commit
6f5391c283 is applied or not):
" 1. Start with an empty drive.
2. pktsetup 0 /dev/scd0
3. Insert a CD containing an isofs filesystem.
4. mount /dev/pktcdvd/0 /mnt/tmp
5. umount /mnt/tmp
6. Press the eject button.
7. Insert a DVD containing a non-writable filesystem.
8. mount /dev/scd0 /mnt/tmp
9. find /mnt/tmp -type f -print0 | xargs -0 sha1sum >/dev/null
10. If the DVD contains data beyond the physical size of a CD, you
get I/O errors in the terminal, and dmesg reports lots of
"attempt to access beyond end of device" errors."
which in turn is because the nested open after the media change won't
cause the size to be set properly (because the original open still holds
the block device, and we only do the bd_set_size() when we don't have
other people holding the device open).
The proper fix for that is probably to just do something like
bdev->bd_inode->i_size = (loff_t)get_capacity(disk)<<9;
in fs/block_dev.c:do_open() even for the cases where we're not the
original opener (but *not* call bd_set_size(), since that will also
change the block size of the device).
Cc: Peter Osterlund <petero2@telia.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit 6f5391c283 ("[SCSI]
Get rid of scsi_cmnd->done") that was supposed to be a cleanup commit,
but apparently it causes regressions:
Bug 9370 - v2.6.24-rc2-409-g9418d5d: attempt to access beyond end of device
http://bugzilla.kernel.org/show_bug.cgi?id=9370
this patch should be reintroduced in a more split-up form to make
testing of it easier.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Matthew Wilcox <matthew@wil.cx>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The ULD ->done callback moves into the scsi_driver. By moving the call
to scsi_io_completion() from scsi_blk_pc_done() to scsi_finish_command(),
we can eliminate the latter entirely. By returning 'good_bytes' from
the ->done callback (rather than invoking scsi_io_completion()), we can
stop exporting scsi_io_completion().
Also move the prototypes from sd.h to sd.c as they're all internal anyway.
Rename sd_rw_intr to sd_done and rw_intr to sr_done.
Inspired-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
One of the intents of the block prep function was to allow ULDs to use
it for preprocessing. The original SCSI model was to have a single prep
function and add a pointer indirect filter to build the necessary
commands. This patch reverses that, does away with the init_command
field of the scsi_driver structure and makes ULDs attach directly to the
prep function instead. The value is really that it allows us to begin
to separate the ULDs from the SCSI mid layer (as long as they don't use
any core functions---which is hard at the moment---a ULD doesn't even
need SCSI to bind).
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Some of the code has been gradually transitioned to using the proper
struct request_queue, but there's lots left. So do a full sweet of
the kernel and get rid of this typedef and replace its uses with
the proper type.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This patch contains the following cleanups:
- make needlessly global functions static
- every file should #include the headers containing the prototypes for
it's global functions
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Sweep registered blkdev when scsi_register_driver has failed.
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
The following patch adds support for sysfs/uevent modalias
attribute for scsi devices (like disks, tapes, cdroms etc),
based on whatever current sd.c, sr.c, st.c and osst.c drivers
supports.
The modalias format is like this:
scsi:type-0x04
(for TYPE_WORM, handled by sr.c now).
Several comments.
o This hexadecimal type value is because all TYPE_XXX constants
in include/scsi/scsi.h are given in hex, but __stringify() will
not convert them to decimal (so it will NOT be scsi:type-4).
Since it does not really matter in which format it is, while
both modalias in module and modalias attribute match each other,
I descided to go for that 0x%02x format (and added a comment in
include/scsi/scsi.h to keep them that way), instead of changing
them all to decimal.
o There was no .uevent routine for SCSI bus. It might be a good
idea to add some more ueven environment variables in there.
o osst.c driver handles tapes too, like st.c, but only SOME tapes.
With this setup, hotplug scripts (or whatever is used by the
user) will try to load both st and osst modules for all SCSI
tapes found, because both modules have scsi:type-0x01 alias).
It is not harmful, but one extra module is no good either.
It is possible to solve this, by exporting more info in
modalias attribute, including vendor and device identification
strings, so that modalias becomes something like
scsi:type-0x12:vendor-Adaptec LTD:device-OnStream Tape Drive
and having that, match for all 3 attributes, not only device
type. But oh well, vendor and device strings may be large,
and they do contain spaces and whatnot.
So I left them for now, awaiting for comments first.
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
After Al Viro (finally) succeeded in removing the sched.h #include in module.h
recently, it makes sense again to remove other superfluous sched.h includes.
There are quite a lot of files which include it but don't actually need
anything defined in there. Presumably these includes were once needed for
macros that used to live in sched.h, but moved to other header files in the
course of cleaning it up.
To ease the pain, this time I did not fiddle with any header files and only
removed #includes from .c-files, which tend to cause less trouble.
Compile tested against 2.6.20-rc2 and 2.6.20-rc2-mm2 (with offsets) on alpha,
arm, i386, ia64, mips, powerpc, and x86_64 with allnoconfig, defconfig,
allmodconfig, and allyesconfig as well as a few randconfigs on x86_64 and all
configs in arch/arm/configs on arm. I also checked that no new warnings were
introduced by the patch (actually, some warnings are removed that were emitted
by unnecessarily included header files).
Signed-off-by: Tim Schmielau <tim@physik3.uni-rostock.de>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
sr_block_ioctl() should proceed to SCSI ioctls if cdrom_ioctl()
returns -ENOSYS. However it tested for ENOSYS instead of -ENOSYS
rendering all SCSI ioctls other than GET_IDLUN and GET_BUS_NUMBER
inaccessible. Fix it.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Currently struct scsi_cmnd has various fields that are used to backup
original data after the corresponding fields have been overridden for
EH commands. This means drivers can easily get at it and misuse it.
Due to the old_ naming this doesn't happen for most of them, but two
that have different names have been used wrong a lot (see previous
patch). Another downside is that they unessecarily bloat the scsi_cmnd
size.
This patch moves them onstack in scsi_send_eh_cmnd to fix those two
issues aswell as allowing future EH fixes like moving the EH command
submissions to use SG lists like everything else.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This patch simplifies "good_bytes" computation in sd_rw_intr().
sd: "good_bytes" computation is always done in terms of the resolution
of the device's medium, since after that it is the number of good bytes
we pass around and other layers/contexts (as opposed ot sd) can translate
that to their own resolution (block layer:512). It also makes
scsi_io_completion() processing more straightforward, eliminating the
3rd argument to the function.
It also fixes a couple of bugs like not checking return value,
using "break" instead of "return;", etc.
I've been running with this patch for some time now on a
test (do-it-all) system.
Signed-off-by: Luben Tuikov <ltuikov@yahoo.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Various scsi drivers use scsi_cmnd.buffer and scsi_cmnd.bufflen in their
queuecommand functions. Those fields are internal storage for the
midlayer only and are used to restore the original payload after
request_buffer and request_bufflen have been overwritten for EH. Using
the buffer and bufflen fields means they do very broken things in error
handling.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Since early 2.4.x all cdrom drivers implement the block_device methods
themselves, so they can handle additional ioctls directly instead of going
through the cdrom layer.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
As devfs has been disabled from the kernel tree for a number of months
now (5 to be exact), here's a patch against 2.6.16-rc1-git1 that removes
support for it from the SCSI subsystem.
The patch also removes the scsi_disk devfs_name field as it's no longer
needed.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Change the core SCSI code to use kzalloc rather than kmalloc+memset
where possible.
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Remove the "inline" keyword from a bunch of big functions in the kernel with
the goal of shrinking it by 30kb to 40kb
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Jeff Garzik <jgarzik@pobox.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
LLDDs should never see REQ_BLOCK_PC requests, we can handle them just
fine in the core code. There is a small behaviour change in that some
check in sr's rw_intr are bypassed, but I consider the old behaviour
a bug.
Mike found this cleanup opportunity and provdided early patches, so all
the credit goes to him, even if I redid the patches from scratch beause
that was easier than forward-porting the old patches.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
SCSI-1 CD drives can't do MRW or be opened for writing, so mask off
those capabilities.
Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Acked-by: Jens Axboe <axboe@suse.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
the scsi layer is using semaphores in a mutex way, this patch converts
these into using mutexes instead
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This merge is pretty extensive. The conflict is over the new
req->retries parameter, so I had to change the prototype to
scsi_setup_blk_pc_cmnd() and the usage in sd, sr and st.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This follows on from Jens' patch and consolidates all of the ULD
separate handlers for REQ_BLOCK_PC into a single call which has his
fix for our direction bug.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
patch below marks a few scsi core datastructures as const, so that they end up
in the .rodata section and don't cacheline share with things that get dirtied
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This patch fixes an issue reported in drivers/scsi/sr.c by Coverity
Error reported: Pointer returned from "scsi_cd" is never used
Patch description:
Remove the scsi_cd() call as it does not have any effect.
Signed-off-by: Jayachandran C. <c.jayachandran@gmail.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This should eliminate (at least in the mid layer) to make numeric
assumptions about any of the enumeration variables. As a side effect,
it will also make all the messages consistent and line us up nicely for
the error logging strategy (if it ever shows itself again).
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This fixes an issue in scsi command initialization from a request
where sd, sr, st, and scsi_lib all fail to copy the request's
cmd_len to the scsi command's cmd_len field.
Signed-off-by: Timothy Thelin <timothy.thelin@wdc.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This follows almost the identical model to sd, except that there's one
ioctl which returns raw sense data, so it had to use scsi_execute()
instead.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
After this, we just have some drivers, all the ULDs and the SPI
transport class using scsi_wait_req().
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Here's the problem. Try to do this on 2.6.12:
- Kill udev and HAL
- Insert a CD-ROM into a SCSI or USB CD-ROM drive
- Run dd if=/dev/scd0
- cat /sys/block/sr0/size
- Eject the CD, insert a different one
- Run dd if=/dev/scd0
This is likely to do "access beyond the end of device", if you let it
- cat /sys/block/sr0/size
This shows the size of a previous CD, even though dd was supposed
to revalidate the device.
- Run dd if=/dev/scd0
The second run of dd works correctly!
The bug was introduced in 2.5.31, when Al fixes the recursive opens
in partitioning. Before, the code worked like this:
- Block layer called cdrom_open directly
- cdrom_open called sr_open
- sr_open called check_disk_change
- check_disk_change called sr_media_change
- sr_media_change did cd->needs_disk_change=1
- before returning sr_open tested cd->needs_disk_change
and called get_sector_size.
In 2.6.12, the check_disk_change is called from cdrom_open only. Thus:
- Block layer calls sr_bd_open
- sr_bd_open calls cdrom_open
- cdrom_open calls sr_open
- sr_open tests cd->needs_disk_change, which wasn't set yet; returns
- cdrom_open calls check_disk_change
- check_disk_change calls sr_media_change
- sr_media_change does cd->needs_disk_change=1, but nobody cares
Acked by: Alexander Viro <aviro@redhat.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Christoph Hellwig