dm: add log writes target
Introduce a new target that is meant for file system developers to test file system integrity at particular points in the life of a file system. We capture all write requests and associated data and log them to a separate device for later replay. There is a userspace utility to do this replay. The idea behind this is to give file system developers a tool to verify that the file system is always consistent. Signed-off-by: Josef Bacik <jbacik@fb.com> Reviewed-by: Zach Brown <zab@zabbo.net> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Josef Bacik
Mike Snitzer
parent
7f61f5a022
commit
0e9cebe724
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@ -0,0 +1,140 @@
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dm-log-writes
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=============
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This target takes 2 devices, one to pass all IO to normally, and one to log all
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of the write operations to. This is intended for file system developers wishing
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to verify the integrity of metadata or data as the file system is written to.
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There is a log_write_entry written for every WRITE request and the target is
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able to take arbitrary data from userspace to insert into the log. The data
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that is in the WRITE requests is copied into the log to make the replay happen
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exactly as it happened originally.
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Log Ordering
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============
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We log things in order of completion once we are sure the write is no longer in
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cache. This means that normal WRITE requests are not actually logged until the
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next REQ_FLUSH request. This is to make it easier for userspace to replay the
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log in a way that correlates to what is on disk and not what is in cache, to
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make it easier to detect improper waiting/flushing.
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This works by attaching all WRITE requests to a list once the write completes.
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Once we see a REQ_FLUSH request we splice this list onto the request and once
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the FLUSH request completes we log all of the WRITEs and then the FLUSH. Only
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completed WRITEs, at the time the REQ_FLUSH is issued, are added in order to
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simulate the worst case scenario with regard to power failures. Consider the
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following example (W means write, C means complete):
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W1,W2,W3,C3,C2,Wflush,C1,Cflush
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The log would show the following
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W3,W2,flush,W1....
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Again this is to simulate what is actually on disk, this allows us to detect
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cases where a power failure at a particular point in time would create an
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inconsistent file system.
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Any REQ_FUA requests bypass this flushing mechanism and are logged as soon as
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they complete as those requests will obviously bypass the device cache.
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Any REQ_DISCARD requests are treated like WRITE requests. Otherwise we would
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have all the DISCARD requests, and then the WRITE requests and then the FLUSH
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request. Consider the following example:
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WRITE block 1, DISCARD block 1, FLUSH
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If we logged DISCARD when it completed, the replay would look like this
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DISCARD 1, WRITE 1, FLUSH
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which isn't quite what happened and wouldn't be caught during the log replay.
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Target interface
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================
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i) Constructor
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log-writes <dev_path> <log_dev_path>
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dev_path : Device that all of the IO will go to normally.
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log_dev_path : Device where the log entries are written to.
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ii) Status
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<#logged entries> <highest allocated sector>
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#logged entries : Number of logged entries
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highest allocated sector : Highest allocated sector
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iii) Messages
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mark <description>
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You can use a dmsetup message to set an arbitrary mark in a log.
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For example say you want to fsck a file system after every
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write, but first you need to replay up to the mkfs to make sure
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we're fsck'ing something reasonable, you would do something like
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this:
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mkfs.btrfs -f /dev/mapper/log
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dmsetup message log 0 mark mkfs
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<run test>
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This would allow you to replay the log up to the mkfs mark and
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then replay from that point on doing the fsck check in the
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interval that you want.
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Every log has a mark at the end labeled "dm-log-writes-end".
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Userspace component
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===================
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There is a userspace tool that will replay the log for you in various ways.
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It can be found here: https://github.com/josefbacik/log-writes
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Example usage
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=============
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Say you want to test fsync on your file system. You would do something like
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this:
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TABLE="0 $(blockdev --getsz /dev/sdb) log-writes /dev/sdb /dev/sdc"
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dmsetup create log --table "$TABLE"
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mkfs.btrfs -f /dev/mapper/log
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dmsetup message log 0 mark mkfs
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mount /dev/mapper/log /mnt/btrfs-test
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<some test that does fsync at the end>
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dmsetup message log 0 mark fsync
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md5sum /mnt/btrfs-test/foo
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umount /mnt/btrfs-test
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dmsetup remove log
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replay-log --log /dev/sdc --replay /dev/sdb --end-mark fsync
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mount /dev/sdb /mnt/btrfs-test
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md5sum /mnt/btrfs-test/foo
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<verify md5sum's are correct>
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Another option is to do a complicated file system operation and verify the file
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system is consistent during the entire operation. You could do this with:
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TABLE="0 $(blockdev --getsz /dev/sdb) log-writes /dev/sdb /dev/sdc"
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dmsetup create log --table "$TABLE"
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mkfs.btrfs -f /dev/mapper/log
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dmsetup message log 0 mark mkfs
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mount /dev/mapper/log /mnt/btrfs-test
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<fsstress to dirty the fs>
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btrfs filesystem balance /mnt/btrfs-test
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umount /mnt/btrfs-test
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dmsetup remove log
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replay-log --log /dev/sdc --replay /dev/sdb --end-mark mkfs
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btrfsck /dev/sdb
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replay-log --log /dev/sdc --replay /dev/sdb --start-mark mkfs \
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--fsck "btrfsck /dev/sdb" --check fua
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And that will replay the log until it sees a FUA request, run the fsck command
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and if the fsck passes it will replay to the next FUA, until it is completed or
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the fsck command exists abnormally.
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@ -443,4 +443,20 @@ config DM_SWITCH
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If unsure, say N.
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config DM_LOG_WRITES
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tristate "Log writes target support"
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depends on BLK_DEV_DM
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---help---
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This device-mapper target takes two devices, one device to use
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normally, one to log all write operations done to the first device.
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This is for use by file system developers wishing to verify that
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their fs is writing a consitent file system at all times by allowing
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them to replay the log in a variety of ways and to check the
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contents.
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To compile this code as a module, choose M here: the module will
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be called dm-log-writes.
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If unsure, say N.
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endif # MD
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@ -55,6 +55,7 @@ obj-$(CONFIG_DM_CACHE) += dm-cache.o
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obj-$(CONFIG_DM_CACHE_MQ) += dm-cache-mq.o
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obj-$(CONFIG_DM_CACHE_CLEANER) += dm-cache-cleaner.o
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obj-$(CONFIG_DM_ERA) += dm-era.o
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obj-$(CONFIG_DM_LOG_WRITES) += dm-log-writes.o
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ifeq ($(CONFIG_DM_UEVENT),y)
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dm-mod-objs += dm-uevent.o
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@ -0,0 +1,825 @@
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/*
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* Copyright (C) 2014 Facebook. All rights reserved.
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*
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* This file is released under the GPL.
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*/
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#include <linux/device-mapper.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/blkdev.h>
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#include <linux/bio.h>
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#include <linux/slab.h>
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#include <linux/kthread.h>
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#include <linux/freezer.h>
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#define DM_MSG_PREFIX "log-writes"
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/*
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* This target will sequentially log all writes to the target device onto the
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* log device. This is helpful for replaying writes to check for fs consistency
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* at all times. This target provides a mechanism to mark specific events to
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* check data at a later time. So for example you would:
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*
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* write data
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* fsync
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* dmsetup message /dev/whatever mark mymark
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* unmount /mnt/test
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*
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* Then replay the log up to mymark and check the contents of the replay to
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* verify it matches what was written.
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*
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* We log writes only after they have been flushed, this makes the log describe
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* close to the order in which the data hits the actual disk, not its cache. So
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* for example the following sequence (W means write, C means complete)
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*
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* Wa,Wb,Wc,Cc,Ca,FLUSH,FUAd,Cb,CFLUSH,CFUAd
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*
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* Would result in the log looking like this:
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*
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* c,a,flush,fuad,b,<other writes>,<next flush>
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*
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* This is meant to help expose problems where file systems do not properly wait
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* on data being written before invoking a FLUSH. FUA bypasses cache so once it
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* completes it is added to the log as it should be on disk.
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*
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* We treat DISCARDs as if they don't bypass cache so that they are logged in
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* order of completion along with the normal writes. If we didn't do it this
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* way we would process all the discards first and then write all the data, when
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* in fact we want to do the data and the discard in the order that they
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* completed.
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*/
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#define LOG_FLUSH_FLAG (1 << 0)
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#define LOG_FUA_FLAG (1 << 1)
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#define LOG_DISCARD_FLAG (1 << 2)
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#define LOG_MARK_FLAG (1 << 3)
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#define WRITE_LOG_VERSION 1
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#define WRITE_LOG_MAGIC 0x6a736677736872
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/*
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* The disk format for this is braindead simple.
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*
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* At byte 0 we have our super, followed by the following sequence for
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* nr_entries:
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*
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* [ 1 sector ][ entry->nr_sectors ]
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* [log_write_entry][ data written ]
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*
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* The log_write_entry takes up a full sector so we can have arbitrary length
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* marks and it leaves us room for extra content in the future.
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*/
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/*
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* Basic info about the log for userspace.
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*/
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struct log_write_super {
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__le64 magic;
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__le64 version;
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__le64 nr_entries;
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__le32 sectorsize;
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};
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/*
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* sector - the sector we wrote.
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* nr_sectors - the number of sectors we wrote.
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* flags - flags for this log entry.
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* data_len - the size of the data in this log entry, this is for private log
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* entry stuff, the MARK data provided by userspace for example.
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*/
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struct log_write_entry {
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__le64 sector;
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__le64 nr_sectors;
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__le64 flags;
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__le64 data_len;
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};
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struct log_writes_c {
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struct dm_dev *dev;
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struct dm_dev *logdev;
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u64 logged_entries;
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u32 sectorsize;
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atomic_t io_blocks;
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atomic_t pending_blocks;
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sector_t next_sector;
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sector_t end_sector;
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bool logging_enabled;
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bool device_supports_discard;
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spinlock_t blocks_lock;
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struct list_head unflushed_blocks;
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struct list_head logging_blocks;
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wait_queue_head_t wait;
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struct task_struct *log_kthread;
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};
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struct pending_block {
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int vec_cnt;
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u64 flags;
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sector_t sector;
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sector_t nr_sectors;
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char *data;
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u32 datalen;
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struct list_head list;
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struct bio_vec vecs[0];
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};
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struct per_bio_data {
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struct pending_block *block;
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};
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static void put_pending_block(struct log_writes_c *lc)
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{
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if (atomic_dec_and_test(&lc->pending_blocks)) {
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smp_mb__after_atomic();
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if (waitqueue_active(&lc->wait))
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wake_up(&lc->wait);
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}
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}
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static void put_io_block(struct log_writes_c *lc)
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{
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if (atomic_dec_and_test(&lc->io_blocks)) {
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smp_mb__after_atomic();
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if (waitqueue_active(&lc->wait))
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wake_up(&lc->wait);
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}
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}
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static void log_end_io(struct bio *bio, int err)
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{
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struct log_writes_c *lc = bio->bi_private;
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struct bio_vec *bvec;
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int i;
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if (err) {
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unsigned long flags;
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DMERR("Error writing log block, error=%d", err);
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spin_lock_irqsave(&lc->blocks_lock, flags);
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lc->logging_enabled = false;
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spin_unlock_irqrestore(&lc->blocks_lock, flags);
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}
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bio_for_each_segment_all(bvec, bio, i)
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__free_page(bvec->bv_page);
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put_io_block(lc);
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bio_put(bio);
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}
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/*
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* Meant to be called if there is an error, it will free all the pages
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* associated with the block.
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*/
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static void free_pending_block(struct log_writes_c *lc,
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struct pending_block *block)
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{
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int i;
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for (i = 0; i < block->vec_cnt; i++) {
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if (block->vecs[i].bv_page)
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__free_page(block->vecs[i].bv_page);
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}
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kfree(block->data);
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kfree(block);
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put_pending_block(lc);
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}
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static int write_metadata(struct log_writes_c *lc, void *entry,
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size_t entrylen, void *data, size_t datalen,
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sector_t sector)
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{
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struct bio *bio;
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struct page *page;
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void *ptr;
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size_t ret;
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bio = bio_alloc(GFP_KERNEL, 1);
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if (!bio) {
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DMERR("Couldn't alloc log bio");
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goto error;
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}
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bio->bi_iter.bi_size = 0;
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bio->bi_iter.bi_sector = sector;
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bio->bi_bdev = lc->logdev->bdev;
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bio->bi_end_io = log_end_io;
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bio->bi_private = lc;
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set_bit(BIO_UPTODATE, &bio->bi_flags);
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page = alloc_page(GFP_KERNEL);
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if (!page) {
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DMERR("Couldn't alloc log page");
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bio_put(bio);
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goto error;
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}
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ptr = kmap_atomic(page);
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memcpy(ptr, entry, entrylen);
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if (datalen)
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memcpy(ptr + entrylen, data, datalen);
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memset(ptr + entrylen + datalen, 0,
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lc->sectorsize - entrylen - datalen);
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kunmap_atomic(ptr);
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ret = bio_add_page(bio, page, lc->sectorsize, 0);
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if (ret != lc->sectorsize) {
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DMERR("Couldn't add page to the log block");
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goto error_bio;
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}
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submit_bio(WRITE, bio);
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return 0;
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error_bio:
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bio_put(bio);
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__free_page(page);
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error:
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put_io_block(lc);
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return -1;
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}
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static int log_one_block(struct log_writes_c *lc,
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struct pending_block *block, sector_t sector)
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{
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struct bio *bio;
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struct log_write_entry entry;
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size_t ret;
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int i;
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entry.sector = cpu_to_le64(block->sector);
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entry.nr_sectors = cpu_to_le64(block->nr_sectors);
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entry.flags = cpu_to_le64(block->flags);
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entry.data_len = cpu_to_le64(block->datalen);
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if (write_metadata(lc, &entry, sizeof(entry), block->data,
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block->datalen, sector)) {
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free_pending_block(lc, block);
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return -1;
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}
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if (!block->vec_cnt)
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goto out;
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sector++;
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bio = bio_alloc(GFP_KERNEL, block->vec_cnt);
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if (!bio) {
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DMERR("Couldn't alloc log bio");
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goto error;
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}
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atomic_inc(&lc->io_blocks);
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bio->bi_iter.bi_size = 0;
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bio->bi_iter.bi_sector = sector;
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bio->bi_bdev = lc->logdev->bdev;
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bio->bi_end_io = log_end_io;
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bio->bi_private = lc;
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set_bit(BIO_UPTODATE, &bio->bi_flags);
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for (i = 0; i < block->vec_cnt; i++) {
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/*
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* The page offset is always 0 because we allocate a new page
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* for every bvec in the original bio for simplicity sake.
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*/
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ret = bio_add_page(bio, block->vecs[i].bv_page,
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block->vecs[i].bv_len, 0);
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if (ret != block->vecs[i].bv_len) {
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atomic_inc(&lc->io_blocks);
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submit_bio(WRITE, bio);
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bio = bio_alloc(GFP_KERNEL, block->vec_cnt - i);
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if (!bio) {
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DMERR("Couldn't alloc log bio");
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goto error;
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}
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bio->bi_iter.bi_size = 0;
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bio->bi_iter.bi_sector = sector;
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bio->bi_bdev = lc->logdev->bdev;
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bio->bi_end_io = log_end_io;
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bio->bi_private = lc;
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set_bit(BIO_UPTODATE, &bio->bi_flags);
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ret = bio_add_page(bio, block->vecs[i].bv_page,
|
||||
block->vecs[i].bv_len, 0);
|
||||
if (ret != block->vecs[i].bv_len) {
|
||||
DMERR("Couldn't add page on new bio?");
|
||||
bio_put(bio);
|
||||
goto error;
|
||||
}
|
||||
}
|
||||
sector += block->vecs[i].bv_len >> SECTOR_SHIFT;
|
||||
}
|
||||
submit_bio(WRITE, bio);
|
||||
out:
|
||||
kfree(block->data);
|
||||
kfree(block);
|
||||
put_pending_block(lc);
|
||||
return 0;
|
||||
error:
|
||||
free_pending_block(lc, block);
|
||||
put_io_block(lc);
|
||||
return -1;
|
||||
}
|
||||
|
||||
static int log_super(struct log_writes_c *lc)
|
||||
{
|
||||
struct log_write_super super;
|
||||
|
||||
super.magic = cpu_to_le64(WRITE_LOG_MAGIC);
|
||||
super.version = cpu_to_le64(WRITE_LOG_VERSION);
|
||||
super.nr_entries = cpu_to_le64(lc->logged_entries);
|
||||
super.sectorsize = cpu_to_le32(lc->sectorsize);
|
||||
|
||||
if (write_metadata(lc, &super, sizeof(super), NULL, 0, 0)) {
|
||||
DMERR("Couldn't write super");
|
||||
return -1;
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static inline sector_t logdev_last_sector(struct log_writes_c *lc)
|
||||
{
|
||||
return i_size_read(lc->logdev->bdev->bd_inode) >> SECTOR_SHIFT;
|
||||
}
|
||||
|
||||
static int log_writes_kthread(void *arg)
|
||||
{
|
||||
struct log_writes_c *lc = (struct log_writes_c *)arg;
|
||||
sector_t sector = 0;
|
||||
|
||||
while (!kthread_should_stop()) {
|
||||
bool super = false;
|
||||
bool logging_enabled;
|
||||
struct pending_block *block = NULL;
|
||||
int ret;
|
||||
|
||||
spin_lock_irq(&lc->blocks_lock);
|
||||
if (!list_empty(&lc->logging_blocks)) {
|
||||
block = list_first_entry(&lc->logging_blocks,
|
||||
struct pending_block, list);
|
||||
list_del_init(&block->list);
|
||||
if (!lc->logging_enabled)
|
||||
goto next;
|
||||
|
||||
sector = lc->next_sector;
|
||||
if (block->flags & LOG_DISCARD_FLAG)
|
||||
lc->next_sector++;
|
||||
else
|
||||
lc->next_sector += block->nr_sectors + 1;
|
||||
|
||||
/*
|
||||
* Apparently the size of the device may not be known
|
||||
* right away, so handle this properly.
|
||||
*/
|
||||
if (!lc->end_sector)
|
||||
lc->end_sector = logdev_last_sector(lc);
|
||||
if (lc->end_sector &&
|
||||
lc->next_sector >= lc->end_sector) {
|
||||
DMERR("Ran out of space on the logdev");
|
||||
lc->logging_enabled = false;
|
||||
goto next;
|
||||
}
|
||||
lc->logged_entries++;
|
||||
atomic_inc(&lc->io_blocks);
|
||||
|
||||
super = (block->flags & (LOG_FUA_FLAG | LOG_MARK_FLAG));
|
||||
if (super)
|
||||
atomic_inc(&lc->io_blocks);
|
||||
}
|
||||
next:
|
||||
logging_enabled = lc->logging_enabled;
|
||||
spin_unlock_irq(&lc->blocks_lock);
|
||||
if (block) {
|
||||
if (logging_enabled) {
|
||||
ret = log_one_block(lc, block, sector);
|
||||
if (!ret && super)
|
||||
ret = log_super(lc);
|
||||
if (ret) {
|
||||
spin_lock_irq(&lc->blocks_lock);
|
||||
lc->logging_enabled = false;
|
||||
spin_unlock_irq(&lc->blocks_lock);
|
||||
}
|
||||
} else
|
||||
free_pending_block(lc, block);
|
||||
continue;
|
||||
}
|
||||
|
||||
if (!try_to_freeze()) {
|
||||
set_current_state(TASK_INTERRUPTIBLE);
|
||||
if (!kthread_should_stop() &&
|
||||
!atomic_read(&lc->pending_blocks))
|
||||
schedule();
|
||||
__set_current_state(TASK_RUNNING);
|
||||
}
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* Construct a log-writes mapping:
|
||||
* log-writes <dev_path> <log_dev_path>
|
||||
*/
|
||||
static int log_writes_ctr(struct dm_target *ti, unsigned int argc, char **argv)
|
||||
{
|
||||
struct log_writes_c *lc;
|
||||
struct dm_arg_set as;
|
||||
const char *devname, *logdevname;
|
||||
|
||||
as.argc = argc;
|
||||
as.argv = argv;
|
||||
|
||||
if (argc < 2) {
|
||||
ti->error = "Invalid argument count";
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
lc = kzalloc(sizeof(struct log_writes_c), GFP_KERNEL);
|
||||
if (!lc) {
|
||||
ti->error = "Cannot allocate context";
|
||||
return -ENOMEM;
|
||||
}
|
||||
spin_lock_init(&lc->blocks_lock);
|
||||
INIT_LIST_HEAD(&lc->unflushed_blocks);
|
||||
INIT_LIST_HEAD(&lc->logging_blocks);
|
||||
init_waitqueue_head(&lc->wait);
|
||||
lc->sectorsize = 1 << SECTOR_SHIFT;
|
||||
atomic_set(&lc->io_blocks, 0);
|
||||
atomic_set(&lc->pending_blocks, 0);
|
||||
|
||||
devname = dm_shift_arg(&as);
|
||||
if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &lc->dev)) {
|
||||
ti->error = "Device lookup failed";
|
||||
goto bad;
|
||||
}
|
||||
|
||||
logdevname = dm_shift_arg(&as);
|
||||
if (dm_get_device(ti, logdevname, dm_table_get_mode(ti->table), &lc->logdev)) {
|
||||
ti->error = "Log device lookup failed";
|
||||
dm_put_device(ti, lc->dev);
|
||||
goto bad;
|
||||
}
|
||||
|
||||
lc->log_kthread = kthread_run(log_writes_kthread, lc, "log-write");
|
||||
if (!lc->log_kthread) {
|
||||
ti->error = "Couldn't alloc kthread";
|
||||
dm_put_device(ti, lc->dev);
|
||||
dm_put_device(ti, lc->logdev);
|
||||
goto bad;
|
||||
}
|
||||
|
||||
/* We put the super at sector 0, start logging at sector 1 */
|
||||
lc->next_sector = 1;
|
||||
lc->logging_enabled = true;
|
||||
lc->end_sector = logdev_last_sector(lc);
|
||||
lc->device_supports_discard = true;
|
||||
|
||||
ti->num_flush_bios = 1;
|
||||
ti->flush_supported = true;
|
||||
ti->num_discard_bios = 1;
|
||||
ti->discards_supported = true;
|
||||
ti->per_bio_data_size = sizeof(struct per_bio_data);
|
||||
ti->private = lc;
|
||||
return 0;
|
||||
|
||||
bad:
|
||||
kfree(lc);
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
static int log_mark(struct log_writes_c *lc, char *data)
|
||||
{
|
||||
struct pending_block *block;
|
||||
size_t maxsize = lc->sectorsize - sizeof(struct log_write_entry);
|
||||
|
||||
block = kzalloc(sizeof(struct pending_block), GFP_KERNEL);
|
||||
if (!block) {
|
||||
DMERR("Error allocating pending block");
|
||||
return -ENOMEM;
|
||||
}
|
||||
|
||||
block->data = kstrndup(data, maxsize, GFP_KERNEL);
|
||||
if (!block->data) {
|
||||
DMERR("Error copying mark data");
|
||||
kfree(block);
|
||||
return -ENOMEM;
|
||||
}
|
||||
atomic_inc(&lc->pending_blocks);
|
||||
block->datalen = strlen(block->data);
|
||||
block->flags |= LOG_MARK_FLAG;
|
||||
spin_lock_irq(&lc->blocks_lock);
|
||||
list_add_tail(&block->list, &lc->logging_blocks);
|
||||
spin_unlock_irq(&lc->blocks_lock);
|
||||
wake_up_process(lc->log_kthread);
|
||||
return 0;
|
||||
}
|
||||
|
||||
static void log_writes_dtr(struct dm_target *ti)
|
||||
{
|
||||
struct log_writes_c *lc = ti->private;
|
||||
|
||||
spin_lock_irq(&lc->blocks_lock);
|
||||
list_splice_init(&lc->unflushed_blocks, &lc->logging_blocks);
|
||||
spin_unlock_irq(&lc->blocks_lock);
|
||||
|
||||
/*
|
||||
* This is just nice to have since it'll update the super to include the
|
||||
* unflushed blocks, if it fails we don't really care.
|
||||
*/
|
||||
log_mark(lc, "dm-log-writes-end");
|
||||
wake_up_process(lc->log_kthread);
|
||||
wait_event(lc->wait, !atomic_read(&lc->io_blocks) &&
|
||||
!atomic_read(&lc->pending_blocks));
|
||||
kthread_stop(lc->log_kthread);
|
||||
|
||||
WARN_ON(!list_empty(&lc->logging_blocks));
|
||||
WARN_ON(!list_empty(&lc->unflushed_blocks));
|
||||
dm_put_device(ti, lc->dev);
|
||||
dm_put_device(ti, lc->logdev);
|
||||
kfree(lc);
|
||||
}
|
||||
|
||||
static void normal_map_bio(struct dm_target *ti, struct bio *bio)
|
||||
{
|
||||
struct log_writes_c *lc = ti->private;
|
||||
|
||||
bio->bi_bdev = lc->dev->bdev;
|
||||
}
|
||||
|
||||
static int log_writes_map(struct dm_target *ti, struct bio *bio)
|
||||
{
|
||||
struct log_writes_c *lc = ti->private;
|
||||
struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
|
||||
struct pending_block *block;
|
||||
struct bvec_iter iter;
|
||||
struct bio_vec bv;
|
||||
size_t alloc_size;
|
||||
int i = 0;
|
||||
bool flush_bio = (bio->bi_rw & REQ_FLUSH);
|
||||
bool fua_bio = (bio->bi_rw & REQ_FUA);
|
||||
bool discard_bio = (bio->bi_rw & REQ_DISCARD);
|
||||
|
||||
pb->block = NULL;
|
||||
|
||||
/* Don't bother doing anything if logging has been disabled */
|
||||
if (!lc->logging_enabled)
|
||||
goto map_bio;
|
||||
|
||||
/*
|
||||
* Map reads as normal.
|
||||
*/
|
||||
if (bio_data_dir(bio) == READ)
|
||||
goto map_bio;
|
||||
|
||||
/* No sectors and not a flush? Don't care */
|
||||
if (!bio_sectors(bio) && !flush_bio)
|
||||
goto map_bio;
|
||||
|
||||
/*
|
||||
* Discards will have bi_size set but there's no actual data, so just
|
||||
* allocate the size of the pending block.
|
||||
*/
|
||||
if (discard_bio)
|
||||
alloc_size = sizeof(struct pending_block);
|
||||
else
|
||||
alloc_size = sizeof(struct pending_block) + sizeof(struct bio_vec) * bio_segments(bio);
|
||||
|
||||
block = kzalloc(alloc_size, GFP_NOIO);
|
||||
if (!block) {
|
||||
DMERR("Error allocating pending block");
|
||||
spin_lock_irq(&lc->blocks_lock);
|
||||
lc->logging_enabled = false;
|
||||
spin_unlock_irq(&lc->blocks_lock);
|
||||
return -ENOMEM;
|
||||
}
|
||||
INIT_LIST_HEAD(&block->list);
|
||||
pb->block = block;
|
||||
atomic_inc(&lc->pending_blocks);
|
||||
|
||||
if (flush_bio)
|
||||
block->flags |= LOG_FLUSH_FLAG;
|
||||
if (fua_bio)
|
||||
block->flags |= LOG_FUA_FLAG;
|
||||
if (discard_bio)
|
||||
block->flags |= LOG_DISCARD_FLAG;
|
||||
|
||||
block->sector = bio->bi_iter.bi_sector;
|
||||
block->nr_sectors = bio_sectors(bio);
|
||||
|
||||
/* We don't need the data, just submit */
|
||||
if (discard_bio) {
|
||||
WARN_ON(flush_bio || fua_bio);
|
||||
if (lc->device_supports_discard)
|
||||
goto map_bio;
|
||||
bio_endio(bio, 0);
|
||||
return DM_MAPIO_SUBMITTED;
|
||||
}
|
||||
|
||||
/* Flush bio, splice the unflushed blocks onto this list and submit */
|
||||
if (flush_bio && !bio_sectors(bio)) {
|
||||
spin_lock_irq(&lc->blocks_lock);
|
||||
list_splice_init(&lc->unflushed_blocks, &block->list);
|
||||
spin_unlock_irq(&lc->blocks_lock);
|
||||
goto map_bio;
|
||||
}
|
||||
|
||||
/*
|
||||
* We will write this bio somewhere else way later so we need to copy
|
||||
* the actual contents into new pages so we know the data will always be
|
||||
* there.
|
||||
*
|
||||
* We do this because this could be a bio from O_DIRECT in which case we
|
||||
* can't just hold onto the page until some later point, we have to
|
||||
* manually copy the contents.
|
||||
*/
|
||||
bio_for_each_segment(bv, bio, iter) {
|
||||
struct page *page;
|
||||
void *src, *dst;
|
||||
|
||||
page = alloc_page(GFP_NOIO);
|
||||
if (!page) {
|
||||
DMERR("Error allocing page");
|
||||
free_pending_block(lc, block);
|
||||
spin_lock_irq(&lc->blocks_lock);
|
||||
lc->logging_enabled = false;
|
||||
spin_unlock_irq(&lc->blocks_lock);
|
||||
return -ENOMEM;
|
||||
}
|
||||
|
||||
src = kmap_atomic(bv.bv_page);
|
||||
dst = kmap_atomic(page);
|
||||
memcpy(dst, src + bv.bv_offset, bv.bv_len);
|
||||
kunmap_atomic(dst);
|
||||
kunmap_atomic(src);
|
||||
block->vecs[i].bv_page = page;
|
||||
block->vecs[i].bv_len = bv.bv_len;
|
||||
block->vec_cnt++;
|
||||
i++;
|
||||
}
|
||||
|
||||
/* Had a flush with data in it, weird */
|
||||
if (flush_bio) {
|
||||
spin_lock_irq(&lc->blocks_lock);
|
||||
list_splice_init(&lc->unflushed_blocks, &block->list);
|
||||
spin_unlock_irq(&lc->blocks_lock);
|
||||
}
|
||||
map_bio:
|
||||
normal_map_bio(ti, bio);
|
||||
return DM_MAPIO_REMAPPED;
|
||||
}
|
||||
|
||||
static int normal_end_io(struct dm_target *ti, struct bio *bio, int error)
|
||||
{
|
||||
struct log_writes_c *lc = ti->private;
|
||||
struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
|
||||
|
||||
if (bio_data_dir(bio) == WRITE && pb->block) {
|
||||
struct pending_block *block = pb->block;
|
||||
unsigned long flags;
|
||||
|
||||
spin_lock_irqsave(&lc->blocks_lock, flags);
|
||||
if (block->flags & LOG_FLUSH_FLAG) {
|
||||
list_splice_tail_init(&block->list, &lc->logging_blocks);
|
||||
list_add_tail(&block->list, &lc->logging_blocks);
|
||||
wake_up_process(lc->log_kthread);
|
||||
} else if (block->flags & LOG_FUA_FLAG) {
|
||||
list_add_tail(&block->list, &lc->logging_blocks);
|
||||
wake_up_process(lc->log_kthread);
|
||||
} else
|
||||
list_add_tail(&block->list, &lc->unflushed_blocks);
|
||||
spin_unlock_irqrestore(&lc->blocks_lock, flags);
|
||||
}
|
||||
|
||||
return error;
|
||||
}
|
||||
|
||||
/*
|
||||
* INFO format: <logged entries> <highest allocated sector>
|
||||
*/
|
||||
static void log_writes_status(struct dm_target *ti, status_type_t type,
|
||||
unsigned status_flags, char *result,
|
||||
unsigned maxlen)
|
||||
{
|
||||
unsigned sz = 0;
|
||||
struct log_writes_c *lc = ti->private;
|
||||
|
||||
switch (type) {
|
||||
case STATUSTYPE_INFO:
|
||||
DMEMIT("%llu %llu", lc->logged_entries,
|
||||
(unsigned long long)lc->next_sector - 1);
|
||||
if (!lc->logging_enabled)
|
||||
DMEMIT(" logging_disabled");
|
||||
break;
|
||||
|
||||
case STATUSTYPE_TABLE:
|
||||
DMEMIT("%s %s", lc->dev->name, lc->logdev->name);
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
static int log_writes_ioctl(struct dm_target *ti, unsigned int cmd,
|
||||
unsigned long arg)
|
||||
{
|
||||
struct log_writes_c *lc = ti->private;
|
||||
struct dm_dev *dev = lc->dev;
|
||||
int r = 0;
|
||||
|
||||
/*
|
||||
* Only pass ioctls through if the device sizes match exactly.
|
||||
*/
|
||||
if (ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
|
||||
r = scsi_verify_blk_ioctl(NULL, cmd);
|
||||
|
||||
return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
|
||||
}
|
||||
|
||||
static int log_writes_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
|
||||
struct bio_vec *biovec, int max_size)
|
||||
{
|
||||
struct log_writes_c *lc = ti->private;
|
||||
struct request_queue *q = bdev_get_queue(lc->dev->bdev);
|
||||
|
||||
if (!q->merge_bvec_fn)
|
||||
return max_size;
|
||||
|
||||
bvm->bi_bdev = lc->dev->bdev;
|
||||
bvm->bi_sector = dm_target_offset(ti, bvm->bi_sector);
|
||||
|
||||
return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
|
||||
}
|
||||
|
||||
static int log_writes_iterate_devices(struct dm_target *ti,
|
||||
iterate_devices_callout_fn fn,
|
||||
void *data)
|
||||
{
|
||||
struct log_writes_c *lc = ti->private;
|
||||
|
||||
return fn(ti, lc->dev, 0, ti->len, data);
|
||||
}
|
||||
|
||||
/*
|
||||
* Messages supported:
|
||||
* mark <mark data> - specify the marked data.
|
||||
*/
|
||||
static int log_writes_message(struct dm_target *ti, unsigned argc, char **argv)
|
||||
{
|
||||
int r = -EINVAL;
|
||||
struct log_writes_c *lc = ti->private;
|
||||
|
||||
if (argc != 2) {
|
||||
DMWARN("Invalid log-writes message arguments, expect 2 arguments, got %d", argc);
|
||||
return r;
|
||||
}
|
||||
|
||||
if (!strcasecmp(argv[0], "mark"))
|
||||
r = log_mark(lc, argv[1]);
|
||||
else
|
||||
DMWARN("Unrecognised log writes target message received: %s", argv[0]);
|
||||
|
||||
return r;
|
||||
}
|
||||
|
||||
static void log_writes_io_hints(struct dm_target *ti, struct queue_limits *limits)
|
||||
{
|
||||
struct log_writes_c *lc = ti->private;
|
||||
struct request_queue *q = bdev_get_queue(lc->dev->bdev);
|
||||
|
||||
if (!q || !blk_queue_discard(q)) {
|
||||
lc->device_supports_discard = false;
|
||||
limits->discard_granularity = 1 << SECTOR_SHIFT;
|
||||
limits->max_discard_sectors = (UINT_MAX >> SECTOR_SHIFT);
|
||||
}
|
||||
}
|
||||
|
||||
static struct target_type log_writes_target = {
|
||||
.name = "log-writes",
|
||||
.version = {1, 0, 0},
|
||||
.module = THIS_MODULE,
|
||||
.ctr = log_writes_ctr,
|
||||
.dtr = log_writes_dtr,
|
||||
.map = log_writes_map,
|
||||
.end_io = normal_end_io,
|
||||
.status = log_writes_status,
|
||||
.ioctl = log_writes_ioctl,
|
||||
.merge = log_writes_merge,
|
||||
.message = log_writes_message,
|
||||
.iterate_devices = log_writes_iterate_devices,
|
||||
.io_hints = log_writes_io_hints,
|
||||
};
|
||||
|
||||
static int __init dm_log_writes_init(void)
|
||||
{
|
||||
int r = dm_register_target(&log_writes_target);
|
||||
|
||||
if (r < 0)
|
||||
DMERR("register failed %d", r);
|
||||
|
||||
return r;
|
||||
}
|
||||
|
||||
static void __exit dm_log_writes_exit(void)
|
||||
{
|
||||
dm_unregister_target(&log_writes_target);
|
||||
}
|
||||
|
||||
module_init(dm_log_writes_init);
|
||||
module_exit(dm_log_writes_exit);
|
||||
|
||||
MODULE_DESCRIPTION(DM_NAME " log writes target");
|
||||
MODULE_AUTHOR("Josef Bacik <jbacik@fb.com>");
|
||||
MODULE_LICENSE("GPL");
|
||||
Loading…
Reference in New Issue