An error occurred fetching the project authors.
- 15 Apr, 2010 1 commit
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Divyesh Shah authored
After merging the block tree, 20100414's linux-next build (x86_64 allmodconfig) failed like this: ERROR: "get_gendisk" [block/blk-cgroup.ko] undefined! ERROR: "sched_clock" [block/blk-cgroup.ko] undefined! This happens because the two symbols aren't exported and hence not available when blk-cgroup code is built as a module. I've tried to stay consistent with the use of EXPORT_SYMBOL or EXPORT_SYMBOL_GPL with the other symbols in the respective files. Signed-off-by:
Divyesh Shah <dpshah@google.com> Acked-by:
Gui Jianfeng <guijianfeng@cn.fujitsu.cn> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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- 11 Jan, 2010 1 commit
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Martin K. Petersen authored
Discard alignment reporting for partitions was incorrect. Update to match the algorithm used elsewhere. The alignment can be negative (misaligned). Fix format string accordingly. Signed-off-by:
Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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- 10 Nov, 2009 1 commit
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Martin K. Petersen authored
While SSDs track block usage on a per-sector basis, RAID arrays often have allocation blocks that are bigger. Allow the discard granularity and alignment to be set and teach the topology stacking logic how to handle them. Signed-off-by:
Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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- 06 Oct, 2009 1 commit
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Nikanth Karthikesan authored
Commit a9327cac added seperate read and write statistics of in_flight requests. And exported the number of read and write requests in progress seperately through sysfs. But Corrado Zoccolo <czoccolo@gmail.com> reported getting strange output from "iostat -kx 2". Global values for service time and utilization were garbage. For interval values, utilization was always 100%, and service time is higher than normal. So this was reverted by commit 0f78ab98 The problem was in part_round_stats_single(), I missed the following: if (now == part->stamp) return; - if (part->in_flight) { + if (part_in_flight(part)) { __part_stat_add(cpu, part, time_in_queue, part_in_flight(part) * (now - part->stamp)); __part_stat_add(cpu, part, io_ticks, (now - part->stamp)); With this chunk included, the reported regression gets fixed. Signed-off-by:
Nikanth Karthikesan <knikanth@suse.de> -- Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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- 04 Oct, 2009 1 commit
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Jens Axboe authored
This reverts commit a9327cac. Corrado Zoccolo <czoccolo@gmail.com> reports: "with 2.6.32-rc1 I started getting the following strange output from "iostat -kx 2": Linux 2.6.31bisect (et2) 04/10/2009 _i686_ (2 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 10,70 0,00 3,16 15,75 0,00 70,38 Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util sda 18,22 0,00 0,67 0,01 14,77 0,02 43,94 0,01 10,53 39043915,03 2629219,87 sdb 60,89 9,68 50,79 3,04 1724,43 50,52 65,95 0,70 13,06 488437,47 2629219,87 avg-cpu: %user %nice %system %iowait %steal %idle 2,72 0,00 0,74 0,00 0,00 96,53 Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util sda 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 100,00 sdb 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 100,00 avg-cpu: %user %nice %system %iowait %steal %idle 6,68 0,00 0,99 0,00 0,00 92,33 Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util sda 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 100,00 sdb 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 100,00 avg-cpu: %user %nice %system %iowait %steal %idle 4,40 0,00 0,73 1,47 0,00 93,40 Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util sda 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 100,00 sdb 0,00 4,00 0,00 3,00 0,00 28,00 18,67 0,06 19,50 333,33 100,00 Global values for service time and utilization are garbage. For interval values, utilization is always 100%, and service time is higher than normal. I bisected it down to: [a9327cac] Seperate read and write statistics of in_flight requests and verified that reverting just that commit indeed solves the issue on 2.6.32-rc1." So until this is debugged, revert the bad commit. Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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- 19 Sep, 2009 1 commit
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Kay Sievers authored
This allows subsytems to provide devtmpfs with non-default permissions for the device node. Instead of the default mode of 0600, null, zero, random, urandom, full, tty, ptmx now have a mode of 0666, which allows non-privileged processes to access standard device nodes in case no other userspace process applies the expected permissions. This also fixes a wrong assignment in pktcdvd and a checkpatch.pl complain. Signed-off-by:
Kay Sievers <kay.sievers@vrfy.org> Signed-off-by:
Greg Kroah-Hartman <gregkh@suse.de>
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- 15 Sep, 2009 1 commit
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David Brownell authored
Let attribute group vectors be declared "const". We'd like to let most attribute metadata live in read-only sections... this is a start. Signed-off-by:
David Brownell <dbrownell@users.sourceforge.net> Signed-off-by:
Greg Kroah-Hartman <gregkh@suse.de>
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- 14 Sep, 2009 1 commit
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Nikanth Karthikesan authored
Currently, there is a single in_flight counter measuring the number of requests in the request_queue. But some monitoring tools would like to know how many read requests and write requests are in progress. Split the current in_flight counter into two seperate counters for read and write. This information is exported as a sysfs attribute, as changing the currently available stat files would break the existing tools. Signed-off-by:
Nikanth Karthikesan <knikanth@suse.de> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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- 11 Sep, 2009 1 commit
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Hannes Reinecke authored
Whenever a block device changes it's read-only attribute notify the userspace about it. Signed-off-by:
Hannes Reinecke <hare@suse.de> Signed-off-by:
Nikanth Karthikesan <knikanth@suse.de> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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- 16 Jun, 2009 1 commit
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Kay Sievers authored
This adds support for block drivers to report their requested nodename to userspace. It also updates a number of block drivers to provide the needed subdirectory and device name to be used for them. Signed-off-by:
Kay Sievers <kay.sievers@vrfy.org> Signed-off-by:
Jan Blunck <jblunck@suse.de> Signed-off-by:
Greg Kroah-Hartman <gregkh@suse.de>
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- 22 May, 2009 1 commit
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Martin K. Petersen authored
To support devices with physical block sizes bigger than 512 bytes we need to ensure proper alignment. This patch adds support for exposing I/O topology characteristics as devices are stacked. logical_block_size is the smallest unit the device can address. physical_block_size indicates the smallest I/O the device can write without incurring a read-modify-write penalty. The io_min parameter is the smallest preferred I/O size reported by the device. In many cases this is the same as the physical block size. However, the io_min parameter can be scaled up when stacking (RAID5 chunk size > physical block size). The io_opt characteristic indicates the optimal I/O size reported by the device. This is usually the stripe width for arrays. The alignment_offset parameter indicates the number of bytes the start of the device/partition is offset from the device's natural alignment. Partition tools and MD/DM utilities can use this to pad their offsets so filesystems start on proper boundaries. Signed-off-by:
Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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- 22 Apr, 2009 1 commit
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Tejun Heo authored
/proc/diskstats used to show stats for all disks whether they're zero-sized or not and their non-zero partitions. Commit 074a7aca accidentally changed the behavior such that it doesn't print out zero sized disks. This patch implements DISK_PITER_INCL_EMPTY_PART0 flag to partition iterator and uses it in diskstats_show() such that empty part0 is shown in /proc/diskstats. Reported and bisectd by Dianel Collins. Signed-off-by:
Tejun Heo <tj@kernel.org> Reported-by:
Daniel Collins <solemnwarning@solemnwarning.no-ip.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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- 26 Feb, 2009 1 commit
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Márton Németh authored
Add documentation for register_blkdev() function and for the parameters. Signed-off-by:
Márton Németh <nm127@freemail.hu> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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- 18 Feb, 2009 1 commit
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Neil Brown authored
Hi Tejun, it looks like your commit: block: don't depend on consecutive minor space f331c029 broke a particular case for booting from partitioned md/raid devices. That is the second time this has been broken recently. The previous time was fixed by block: do_mounts - accept root=<non-existant partition> 30f2f0eb Because the data isn't available when an md device is first created (we add disks and set it up after creation), the initial partition scan finds nothing. It is not until the device is opened that another partition scan happens and finds something. So at the point where the kernel parameter "root=/dev/md_d0p1" is being parsed, md_d0 exists, but md_d0p1 does not. However if we let blk_lookup_devt return the correct device number even though the device doesn't exist, then the attempt to mount it will successfully find the partition. I have tried in the past to find a way to get the partition table to be read as soon as the array is assembled but that proved impossible (at the time). I don't remember the details, and could possibly revisit it. However it would be really nice if blk_lookup_devt could be adjusted to again accept non existant partitions. Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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- 06 Jan, 2009 1 commit
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Kay Sievers authored
Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by:
Kay Sievers <kay.sievers@vrfy.org> Signed-off-by:
Greg Kroah-Hartman <gregkh@suse.de>
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- 29 Dec, 2008 1 commit
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Jens Axboe authored
disk_map_sector_rcu() returns a partition from a sector offset, which we use for IO statistics on a per-partition basis. The lookup itself is an O(N) list lookup, where N is the number of partitions. This actually hurts performance quite a bit, even on the lower end partitions. On higher numbered partitions, it can get pretty bad. Solve this by adding a one-hit cache for partition lookup. This makes the lookup O(1) for the case where we do most IO to one partition. Even for mixed partition workloads, amortized cost is pretty close to O(1) since the natural IO batching makes the one-hit cache last for lots of IOs. Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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- 03 Dec, 2008 1 commit
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Cheng Renquan authored
disk->node_id will be refered in allocating in disk_expand_part_tbl, so we should set it before disk->node_id is refered. Signed-off-by:
Cheng Renquan <crquan@gmail.com> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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- 18 Nov, 2008 1 commit
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Zhang, Yanmin authored
We run into system boot failure with kernel 2.6.28-rc. We found it on a couple of machines, including T61 notebook, nehalem machine, and another HPC NX6325 notebook. All the machines use FedoraCore 8 or FedoraCore 9. With kernel prior to 2.6.28-rc, system boot doesn't fail. I debug it and locate the root cause. Pls. see http://bugzilla.kernel.org/show_bug.cgi?id=11899 https://bugzilla.redhat.com/show_bug.cgi?id=471517 As a matter of fact, there are 2 bugs. 1)root=/dev/sda1, system boot randomly fails. Mostly, boot for 5 times and fails once. nash has a bug. Some of its functions misuse return value 0. Sometimes, 0 means timeout and no uevent available. Sometimes, 0 means nash gets an uevent, but the uevent isn't block-related (for exmaple, usb). If by coincidence, kernel tells nash that uevents are available, but kernel also set timeout, nash might stops collecting other uevents in queue if current uevent isn't block-related. I work out a patch for nash to fix it. http://bugzilla.kernel.org/attachment.cgi?id=18858 2) root=LABEL=/, system always can't boot. initrd init reports switchroot fails. Here is an executation branch of nash when booting: (1) nash read /sys/block/sda/dev; Assume major is 8 (on my desktop) (2) nash query /proc/devices with the major number; It found line "8 sd"; (3) nash use 'sd' to search its own probe table to find device (DISK) type for the device and add it to its own list; (4) Later on, it probes all devices in its list to get filesystem labels; scsi register "8 sd" always. When major is 259, nash fails to find the device(DISK) type. I enables CONFIG_DEBUG_BLOCK_EXT_DEVT=y when compiling kernel, so 259 is picked up for device /dev/sda1, which causes nash to fail to find device (DISK) type. To fixing issue 2), I create a patch for nash and another patch for kernel. http://bugzilla.kernel.org/attachment.cgi?id=18859 http://bugzilla.kernel.org/attachment.cgi?id=18837 Below is the patch for kernel 2.6.28-rc4. It registers blkext, a new block device in proc/devices. With 2 patches on nash and 1 patch on kernel, I boot my machines for dozens of times without failure. Signed-off-by Zhang Yanmin <yanmin.zhang@linux.intel.com> Acked-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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- 23 Oct, 2008 2 commits
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Alexey Dobriyan authored
Signed-off-by:
Alexey Dobriyan <adobriyan@gmail.com> Acked-by:
Jens Axboe <jens.axboe@oracle.com>
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Alexey Dobriyan authored
Signed-off-by:
Alexey Dobriyan <adobriyan@gmail.com> Acked-by:
Jens Axboe <jens.axboe@oracle.com>
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- 17 Oct, 2008 2 commits
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Randy Dunlap authored
Fix block kernel-doc warnings: Warning(linux-2.6.27-git4//fs/block_dev.c:1272): No description found for parameter 'path' Warning(linux-2.6.27-git4//block/blk-core.c:1021): No description found for parameter 'cpu' Warning(linux-2.6.27-git4//block/blk-core.c:1021): No description found for parameter 'part' Warning(/var/linsrc/linux-2.6.27-git4//block/genhd.c:544): No description found for parameter 'partno' Signed-off-by:
Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Li Zefan authored
No argument 'gfp_mask' for blk_alloc_devt(). Signed-off-by:
Li Zefan <lizf@cn.fujitsu.com> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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- 09 Oct, 2008 18 commits
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Jens Axboe authored
Only works for the generic request timer handling. Allows one to sporadically ignore request completions, thus exercising the timeout handling. Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
seqf can be started multiple times for a read and the header should be printed only for the initial one. Fix it. Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
bdget_disk() and blk_lookup_devt() never cared whether the specified partition (or disk) is zero sized or not. I got confused while converting those not to depend on consecutive minor numbers in commit 5a6411b1178baf534aa9138052864dfa89d3eada and later when dev0 was added it broke callers which expected to get valid return for zero sized disk devices. So, they never needed nr_sects checks in the first place. Kill them. This problem was spotted and debugged by Bartlmoiej Zolnierkiewicz. Signed-off-by:
Tejun Heo <tj@kernel.org> Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Harvey Harrison authored
Noticed by sparse: block/blk-softirq.c:156:12: warning: symbol 'blk_softirq_init' was not declared. Should it be static? block/genhd.c:583:28: warning: function 'bdget_disk' with external linkage has definition block/genhd.c:659:17: warning: incorrect type in argument 1 (different base types) block/genhd.c:659:17: expected unsigned int [unsigned] [usertype] size block/genhd.c:659:17: got restricted gfp_t block/genhd.c:659:29: warning: incorrect type in argument 2 (different base types) block/genhd.c:659:29: expected restricted gfp_t [usertype] flags block/genhd.c:659:29: got unsigned int block: kmalloc args reversed Signed-off-by:
Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
Now that disk and partition handlings are mostly unified, it's easy to allow disk to have extended device number. This patch makes add_disk() use extended device number if disk->minors is zero. Both sd and ide-disk are updated to use this. * sd_format_disk_name() is implemented which can generically determine the drive name. This removes disk number restriction stemming from limited device names. * If sd index goes over SD_MAX_DISKS (which can be increased now BTW), sd simply doesn't initialize minors letting block layer choose extended device number. * If CONFIG_DEBUG_EXT_DEVT is set, both sd and ide-disk always set minors to 0 and use extended device numbers. Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
With previous changes, it's meaningless to limit the number of partitions. Replace @ext_minors with GENHD_FL_EXT_DEVT such that setting the flag allows the disk to have maximum number of allowed partitions (only limited by the number of entries in parsed_partitions as determined by MAX_PART constant). This kills not-too-pretty alloc_disk_ext[_node]() functions and makes @minors parameter to alloc_disk[_node]() unnecessary. The parameter is left alone to avoid disturbing the users. Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
disk->__part used to be statically allocated to the maximum possible number of partitions. This patch makes partition array allocation dynamic. The added overhead is minimal as only real change is one memory dereference changed to RCU one. This saves both a bit of memory and cpu cycles iterating through unoccupied slots and makes increasing partition limit easier. Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
Move stats related fields - stamp, in_flight, dkstats - from disk to part0 and unify stat handling such that... * part_stat_*() now updates part0 together if the specified partition is not part0. ie. part_stat_*() are now essentially all_stat_*(). * {disk|all}_stat_*() are gone. * part_round_stats() is updated similary. It handles part0 stats automatically and disk_round_stats() is killed. * part_{inc|dec}_in_fligh() is implemented which automatically updates part0 stats for parts other than part0. * disk_map_sector_rcu() is updated to return part0 if no part matches. Combined with the above changes, this makes NULL special case handling in callers unnecessary. * Separate stats show code paths for disk are collapsed into part stats show code paths. * Rename disk_stat_lock/unlock() to part_stat_lock/unlock() While at it, reposition stat handling macros a bit and add missing parentheses around macro parameters. Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
GENHD_FL_FAIL for disk is what make_it_fail is for parts. Kill it and use part0->make_it_fail. Sysfs node handling is unified too. Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
Move disk->policy to part0->policy. Implement and use get_disk_ro(). Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
Now that capacity and __dev are moved to part0, part0 and others can share the same method. Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
Move disk->__dev to part0->__dev. This simplifies bdget_disk() and lookup_devt() and allows common sysfs attributes to be unified. part_to_disk() is updated to handle part0 -> disk. Updated to include a fix from Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>, he writes: "part0 is a "special" partition and doesn't need to have capacity set - this fixes regression caused by "block: move __dev from disk to part0" commit." Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
genhd and partition code handled disk and partitions separately. All information about the whole disk was in struct genhd and partitions in struct hd_struct. However, the whole disk (part0) and other partitions have a lot in common and the data structures end up having good number of common fields and thus separate code paths doing the same thing. Also, the partition array was indexed by partno - 1 which gets pretty confusing at times. This patch introduces partition 0 and makes the partition array indexed by partno. Following patches will unify the handling of disk and parts piece-by-piece. This patch also implements disk_partitionable() which tests whether a disk is partitionable. With coming dynamic partition array change, the most common usage of disk_max_parts() will be testing whether a disk is partitionable and the number of max partitions will become much less important. Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
Implement {disk|part}_to_dev() and use them to access generic device instead of directly dereferencing {disk|part}->dev. To make sure no user is left behind, rename generic devices fields to __dev. This is in preparation of unifying partition 0 handling with other partitions. Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
Extended devt introduces non-contiguos device numbers. This patch implements a debug option which forces most devt allocations to be from the extended area and spreads them out. This is enabled by default if DEBUG_KERNEL is set and achieves... 1. Detects code paths in kernel or userland which expect predetermined consecutive device numbers. 2. When something goes wrong, avoid corruption as adding to the minor of earlier partition won't lead to the wrong but valid device. Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
With extended minors and the soon-to-follow debug feature, large minor numbers for block devices will be common. This patch does the followings to make printouts pretty. * Adapt print formats such that large minors don't break the formatting. * For extended MAJ:MIN, %02x%02x for MAJ:MIN used in printk_all_partitions() doesn't cut it anymore. Update it such that %03x:%05x is used if either MAJ or MIN doesn't fit in %02x. * Implement ext_range sysfs attribute which shows total minors the device can use including both conventional minor space and the extended one. Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
Implement extended device numbers. A block driver can tell block layer that it wants to use extended device numbers. After the usual minor space is used up, block layer automatically allocates devt's from EXT_BLOCK_MAJOR. Currently only one major number is allocated for this but as the allocation is strictly on-demand, ~1mil minor space under it should suffice unless the system actually has more than ~1mil partitions and if that ever happens adding more majors to the extended devt area is easy. Due to internal implementation issues, the first partition can't be allocated on the extended area. In other words, genhd->minors should at least be 1. This limitation will be lifted by later changes. Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Tejun Heo authored
There are two variants of stat functions - ones prefixed with double underbars which don't care about preemption and ones without which disable preemption before manipulating per-cpu counters. It's unclear whether the underbarred ones assume that preemtion is disabled on entry as some callers don't do that. This patch unifies diskstats access by implementing disk_stat_lock() and disk_stat_unlock() which take care of both RCU (for partition access) and preemption (for per-cpu counter access). diskstats access should always be enclosed between the two functions. As such, there's no need for the versions which disables preemption. They're removed and double underbars ones are renamed to drop the underbars. As an extra argument is added, there's no danger of using the old version unconverted. disk_stat_lock() uses get_cpu() and returns the cpu index and all diskstat functions which access per-cpu counters now has @cpu argument to help RT. This change adds RCU or preemption operations at some places but also collapses several preemption ops into one at others. Overall, the performance difference should be negligible as all involved ops are very lightweight per-cpu ones. Signed-off-by:
Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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