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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>
hifive-unleashed-5.1
Josef Bacik 2015-03-20 10:50:37 -04:00 committed by Mike Snitzer
parent 7f61f5a022
commit 0e9cebe724
4 changed files with 982 additions and 0 deletions
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140
Documentation/device-mapper/log-writes.txt 100644
View File

@ -0,0 +1,140 @@
dm-log-writes
=============
This target takes 2 devices, one to pass all IO to normally, and one to log all
of the write operations to. This is intended for file system developers wishing
to verify the integrity of metadata or data as the file system is written to.
There is a log_write_entry written for every WRITE request and the target is
able to take arbitrary data from userspace to insert into the log. The data
that is in the WRITE requests is copied into the log to make the replay happen
exactly as it happened originally.
Log Ordering
============
We log things in order of completion once we are sure the write is no longer in
cache. This means that normal WRITE requests are not actually logged until the
next REQ_FLUSH request. This is to make it easier for userspace to replay the
log in a way that correlates to what is on disk and not what is in cache, to
make it easier to detect improper waiting/flushing.
This works by attaching all WRITE requests to a list once the write completes.
Once we see a REQ_FLUSH request we splice this list onto the request and once
the FLUSH request completes we log all of the WRITEs and then the FLUSH. Only
completed WRITEs, at the time the REQ_FLUSH is issued, are added in order to
simulate the worst case scenario with regard to power failures. Consider the
following example (W means write, C means complete):
W1,W2,W3,C3,C2,Wflush,C1,Cflush
The log would show the following
W3,W2,flush,W1....
Again this is to simulate what is actually on disk, this allows us to detect
cases where a power failure at a particular point in time would create an
inconsistent file system.
Any REQ_FUA requests bypass this flushing mechanism and are logged as soon as
they complete as those requests will obviously bypass the device cache.
Any REQ_DISCARD requests are treated like WRITE requests. Otherwise we would
have all the DISCARD requests, and then the WRITE requests and then the FLUSH
request. Consider the following example:
WRITE block 1, DISCARD block 1, FLUSH
If we logged DISCARD when it completed, the replay would look like this
DISCARD 1, WRITE 1, FLUSH
which isn't quite what happened and wouldn't be caught during the log replay.
Target interface
================
i) Constructor
log-writes <dev_path> <log_dev_path>
dev_path : Device that all of the IO will go to normally.
log_dev_path : Device where the log entries are written to.
ii) Status
<#logged entries> <highest allocated sector>
#logged entries : Number of logged entries
highest allocated sector : Highest allocated sector
iii) Messages
mark <description>
You can use a dmsetup message to set an arbitrary mark in a log.
For example say you want to fsck a file system after every
write, but first you need to replay up to the mkfs to make sure
we're fsck'ing something reasonable, you would do something like
this:
mkfs.btrfs -f /dev/mapper/log
dmsetup message log 0 mark mkfs
<run test>
This would allow you to replay the log up to the mkfs mark and
then replay from that point on doing the fsck check in the
interval that you want.
Every log has a mark at the end labeled "dm-log-writes-end".
Userspace component
===================
There is a userspace tool that will replay the log for you in various ways.
It can be found here: https://github.com/josefbacik/log-writes
Example usage
=============
Say you want to test fsync on your file system. You would do something like
this:
TABLE="0 $(blockdev --getsz /dev/sdb) log-writes /dev/sdb /dev/sdc"
dmsetup create log --table "$TABLE"
mkfs.btrfs -f /dev/mapper/log
dmsetup message log 0 mark mkfs
mount /dev/mapper/log /mnt/btrfs-test
<some test that does fsync at the end>
dmsetup message log 0 mark fsync
md5sum /mnt/btrfs-test/foo
umount /mnt/btrfs-test
dmsetup remove log
replay-log --log /dev/sdc --replay /dev/sdb --end-mark fsync
mount /dev/sdb /mnt/btrfs-test
md5sum /mnt/btrfs-test/foo
<verify md5sum's are correct>
Another option is to do a complicated file system operation and verify the file
system is consistent during the entire operation. You could do this with:
TABLE="0 $(blockdev --getsz /dev/sdb) log-writes /dev/sdb /dev/sdc"
dmsetup create log --table "$TABLE"
mkfs.btrfs -f /dev/mapper/log
dmsetup message log 0 mark mkfs
mount /dev/mapper/log /mnt/btrfs-test
<fsstress to dirty the fs>
btrfs filesystem balance /mnt/btrfs-test
umount /mnt/btrfs-test
dmsetup remove log
replay-log --log /dev/sdc --replay /dev/sdb --end-mark mkfs
btrfsck /dev/sdb
replay-log --log /dev/sdc --replay /dev/sdb --start-mark mkfs \
--fsck "btrfsck /dev/sdb" --check fua
And that will replay the log until it sees a FUA request, run the fsck command
and if the fsck passes it will replay to the next FUA, until it is completed or
the fsck command exists abnormally.

16
drivers/md/Kconfig
View File

@ -443,4 +443,20 @@ config DM_SWITCH
If unsure, say N.
config DM_LOG_WRITES
tristate "Log writes target support"
depends on BLK_DEV_DM
---help---
This device-mapper target takes two devices, one device to use
normally, one to log all write operations done to the first device.
This is for use by file system developers wishing to verify that
their fs is writing a consitent file system at all times by allowing
them to replay the log in a variety of ways and to check the
contents.
To compile this code as a module, choose M here: the module will
be called dm-log-writes.
If unsure, say N.
endif # MD

1
drivers/md/Makefile
View File

@ -55,6 +55,7 @@ obj-$(CONFIG_DM_CACHE) += dm-cache.o
obj-$(CONFIG_DM_CACHE_MQ) += dm-cache-mq.o
obj-$(CONFIG_DM_CACHE_CLEANER) += dm-cache-cleaner.o
obj-$(CONFIG_DM_ERA) += dm-era.o
obj-$(CONFIG_DM_LOG_WRITES) += dm-log-writes.o
ifeq ($(CONFIG_DM_UEVENT),y)
dm-mod-objs += dm-uevent.o

825
drivers/md/dm-log-writes.c 100644
View File

@ -0,0 +1,825 @@
/*
* Copyright (C) 2014 Facebook. All rights reserved.
*
* This file is released under the GPL.
*/
#include <linux/device-mapper.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
#define DM_MSG_PREFIX "log-writes"
/*
* This target will sequentially log all writes to the target device onto the
* log device. This is helpful for replaying writes to check for fs consistency
* at all times. This target provides a mechanism to mark specific events to
* check data at a later time. So for example you would:
*
* write data
* fsync
* dmsetup message /dev/whatever mark mymark
* unmount /mnt/test
*
* Then replay the log up to mymark and check the contents of the replay to
* verify it matches what was written.
*
* We log writes only after they have been flushed, this makes the log describe
* close to the order in which the data hits the actual disk, not its cache. So
* for example the following sequence (W means write, C means complete)
*
* Wa,Wb,Wc,Cc,Ca,FLUSH,FUAd,Cb,CFLUSH,CFUAd
*
* Would result in the log looking like this:
*
* c,a,flush,fuad,b,<other writes>,<next flush>
*
* This is meant to help expose problems where file systems do not properly wait
* on data being written before invoking a FLUSH. FUA bypasses cache so once it
* completes it is added to the log as it should be on disk.
*
* We treat DISCARDs as if they don't bypass cache so that they are logged in
* order of completion along with the normal writes. If we didn't do it this
* way we would process all the discards first and then write all the data, when
* in fact we want to do the data and the discard in the order that they
* completed.
*/
#define LOG_FLUSH_FLAG (1 << 0)
#define LOG_FUA_FLAG (1 << 1)
#define LOG_DISCARD_FLAG (1 << 2)
#define LOG_MARK_FLAG (1 << 3)
#define WRITE_LOG_VERSION 1
#define WRITE_LOG_MAGIC 0x6a736677736872
/*
* The disk format for this is braindead simple.
*
* At byte 0 we have our super, followed by the following sequence for
* nr_entries:
*
* [ 1 sector ][ entry->nr_sectors ]
* [log_write_entry][ data written ]
*
* The log_write_entry takes up a full sector so we can have arbitrary length
* marks and it leaves us room for extra content in the future.
*/
/*
* Basic info about the log for userspace.
*/
struct log_write_super {
__le64 magic;
__le64 version;
__le64 nr_entries;
__le32 sectorsize;
};
/*
* sector - the sector we wrote.
* nr_sectors - the number of sectors we wrote.
* flags - flags for this log entry.
* data_len - the size of the data in this log entry, this is for private log
* entry stuff, the MARK data provided by userspace for example.
*/
struct log_write_entry {
__le64 sector;
__le64 nr_sectors;
__le64 flags;
__le64 data_len;
};
struct log_writes_c {
struct dm_dev *dev;
struct dm_dev *logdev;
u64 logged_entries;
u32 sectorsize;
atomic_t io_blocks;
atomic_t pending_blocks;
sector_t next_sector;
sector_t end_sector;
bool logging_enabled;
bool device_supports_discard;
spinlock_t blocks_lock;
struct list_head unflushed_blocks;
struct list_head logging_blocks;
wait_queue_head_t wait;
struct task_struct *log_kthread;
};
struct pending_block {
int vec_cnt;
u64 flags;
sector_t sector;
sector_t nr_sectors;
char *data;
u32 datalen;
struct list_head list;
struct bio_vec vecs[0];
};
struct per_bio_data {
struct pending_block *block;
};
static void put_pending_block(struct log_writes_c *lc)
{
if (atomic_dec_and_test(&lc->pending_blocks)) {
smp_mb__after_atomic();
if (waitqueue_active(&lc->wait))
wake_up(&lc->wait);
}
}
static void put_io_block(struct log_writes_c *lc)
{
if (atomic_dec_and_test(&lc->io_blocks)) {
smp_mb__after_atomic();
if (waitqueue_active(&lc->wait))
wake_up(&lc->wait);
}
}
static void log_end_io(struct bio *bio, int err)
{
struct log_writes_c *lc = bio->bi_private;
struct bio_vec *bvec;
int i;
if (err) {
unsigned long flags;
DMERR("Error writing log block, error=%d", err);
spin_lock_irqsave(&lc->blocks_lock, flags);
lc->logging_enabled = false;
spin_unlock_irqrestore(&lc->blocks_lock, flags);
}
bio_for_each_segment_all(bvec, bio, i)
__free_page(bvec->bv_page);
put_io_block(lc);
bio_put(bio);
}
/*
* Meant to be called if there is an error, it will free all the pages
* associated with the block.
*/
static void free_pending_block(struct log_writes_c *lc,
struct pending_block *block)
{
int i;
for (i = 0; i < block->vec_cnt; i++) {
if (block->vecs[i].bv_page)
__free_page(block->vecs[i].bv_page);
}
kfree(block->data);
kfree(block);
put_pending_block(lc);
}
static int write_metadata(struct log_writes_c *lc, void *entry,
size_t entrylen, void *data, size_t datalen,
sector_t sector)
{
struct bio *bio;
struct page *page;
void *ptr;
size_t ret;
bio = bio_alloc(GFP_KERNEL, 1);
if (!bio) {
DMERR("Couldn't alloc log bio");
goto error;
}
bio->bi_iter.bi_size = 0;
bio->bi_iter.bi_sector = sector;
bio->bi_bdev = lc->logdev->bdev;
bio->bi_end_io = log_end_io;
bio->bi_private = lc;
set_bit(BIO_UPTODATE, &bio->bi_flags);
page = alloc_page(GFP_KERNEL);
if (!page) {
DMERR("Couldn't alloc log page");
bio_put(bio);
goto error;
}
ptr = kmap_atomic(page);
memcpy(ptr, entry, entrylen);
if (datalen)
memcpy(ptr + entrylen, data, datalen);
memset(ptr + entrylen + datalen, 0,
lc->sectorsize - entrylen - datalen);
kunmap_atomic(ptr);
ret = bio_add_page(bio, page, lc->sectorsize, 0);
if (ret != lc->sectorsize) {
DMERR("Couldn't add page to the log block");
goto error_bio;
}
submit_bio(WRITE, bio);
return 0;
error_bio:
bio_put(bio);
__free_page(page);
error:
put_io_block(lc);
return -1;
}
static int log_one_block(struct log_writes_c *lc,
struct pending_block *block, sector_t sector)
{
struct bio *bio;
struct log_write_entry entry;
size_t ret;
int i;
entry.sector = cpu_to_le64(block->sector);
entry.nr_sectors = cpu_to_le64(block->nr_sectors);
entry.flags = cpu_to_le64(block->flags);
entry.data_len = cpu_to_le64(block->datalen);
if (write_metadata(lc, &entry, sizeof(entry), block->data,
block->datalen, sector)) {
free_pending_block(lc, block);
return -1;
}
if (!block->vec_cnt)
goto out;
sector++;
bio = bio_alloc(GFP_KERNEL, block->vec_cnt);
if (!bio) {
DMERR("Couldn't alloc log bio");
goto error;
}
atomic_inc(&lc->io_blocks);
bio->bi_iter.bi_size = 0;
bio->bi_iter.bi_sector = sector;
bio->bi_bdev = lc->logdev->bdev;
bio->bi_end_io = log_end_io;
bio->bi_private = lc;
set_bit(BIO_UPTODATE, &bio->bi_flags);
for (i = 0; i < block->vec_cnt; i++) {
/*
* The page offset is always 0 because we allocate a new page
* for every bvec in the original bio for simplicity sake.
*/
ret = bio_add_page(bio, block->vecs[i].bv_page,
block->vecs[i].bv_len, 0);
if (ret != block->vecs[i].bv_len) {
atomic_inc(&lc->io_blocks);
submit_bio(WRITE, bio);
bio = bio_alloc(GFP_KERNEL, block->vec_cnt - i);
if (!bio) {
DMERR("Couldn't alloc log bio");
goto error;
}
bio->bi_iter.bi_size = 0;
bio->bi_iter.bi_sector = sector;
bio->bi_bdev = lc->logdev->bdev;
bio->bi_end_io = log_end_io;
bio->bi_private = lc;
set_bit(BIO_UPTODATE, &bio->bi_flags);
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");