Commit Graph

336366 Commits

Author SHA1 Message Date
Josef Bacik d6393786cd Btrfs: add path->really_keep_locks
You'd think path->keep_locks would keep all the locks wouldn't you?  You'd
be wrong.  It only keeps them if the slot is pointing to the last item in
the node.  This is for use with btrfs_next_leaf, which needs this sort of
thing.  But the horrible horrible things I'm going to do to the tree log
means I really need everything held from root to leaf so I can add and
delete items in the same search.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:24 -05:00
Josef Bacik b11e234d21 Btrfs: do not mark ems as prealloc if we are writing to them
We are going to use EM's to log extents in the future, so we need to not
mark them as prealloc if they aren't actually prealloc extents.  Instead
mark them with FILLING so we know to ammend mod_start/mod_len and that way
we don't confuse the extent logging code.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:23 -05:00
Josef Bacik b493968096 Btrfs: keep track of the extents original block length
If we've written to a prealloc extent we need to know the original block len
for the extent.  We can't figure this out currently since ->block_len is
just set to the extent length.  So introduce ->orig_block_len so that we
know how many bytes were in the original extent for proper extent logging
that future patches will need.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:23 -05:00
Josef Bacik b812ce2879 Btrfs: inline csums if we're fsyncing
The tree logging stuff needs the csums to be on the ordered extents in order
to log them properly, so mark that we're sync and inline the csum creation
so we don't have to wait on the csumming to be done when logging extents
that are still in flight.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:22 -05:00
Josef Bacik a95249b392 Btrfs: don't bother copying if we're only logging the inode
We don't copy inode items anwyay, we just copy them straight into the log
from the in memory inode.  So if we know we're only logging the inode, don't
bother dropping anything, just try to insert it and either if it succeeds or
we get EEXIST we can update the inode item in the log and carry on.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:22 -05:00
Josef Bacik e997615149 Btrfs: only log the inode item if we can get away with it
Currently we copy all the file information into the log, inode item, the
refs, xattrs etc.  Except most of this doesn't change from fsync to fsync,
just the inode item changes.  So set a flag if an xattr changes or a link is
added, and otherwise only log the inode item.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:21 -05:00
Anand Jain 5f3ab90a72 Btrfs: rename root_times_lock to root_item_lock
Originally root_times_lock was introduced as part of send/receive
code however newly developed patch to label the subvol reused
the same lock, so renaming it for a meaningful name.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:21 -05:00
Lukas Czerner b8b8ff590f btrfs: Notify udev when removing device
Currently udev does not know about the device being removed from the
file system. This may result in the situation where we're unable to
mount the file system by UUID or by LABEL because the by-uuid and
by-label links may still point to the device which is no longer part of
the btrfs file system and hence does not have any btrfs super block.

It can be easily reproduced by the following:

mkfs.btrfs -L bugfs /dev/loop[0-6]
mount /dev/loop0 /mnt/test
btrfs device delete /dev/loop0 /mnt/test
umount /mnt/test

mount LABEL=bugfs /mnt/test <---- this fails

then see:

ls -l /dev/disk/by-label/bugfs

which will still point to the /dev/loop0

We did not noticed this before because libblkid would send the udev
event for us when it notice that the link does not fit the reality,
however it does not do that anymore and completely relies on udev
information.

Fix this by sending the KOBJ_CHANGE event to the bdev kobject after
successful device removal.

Note that this does not affect device addition, because we will open the
device prior the addition from userspace and udev will notice that and
reread the device afterwards.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:21 -05:00
Miao Xie ac6a2b36f9 Btrfs: fix wrong return value of btrfs_truncate_page()
ret variant may be set to 0 if we read page successfully, but it might be
released before we lock it again. On this case, if we fail to allocate a
new page, we will return 0, it is wrong, fix it.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:20 -05:00
Miao Xie 7426cc04d4 Btrfs: punch hole past the end of the file
Since we can pre-allocate the space past EOF, we should be able to reclaim
that space if we need. This patch implements it by removing the EOF check.

Though the manual of fallocate command says we can use truncate command to
reclaim the pre-allocated space which past EOF, but because truncate command
changes the file size, we must run several commands to reclaim the space if we
don't want to change the file size, so it is not a good choice.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:20 -05:00
Miao Xie 0061280d2c Btrfs: fix the page that is beyond EOF
Steps to reproduce:
 # mkfs.btrfs <disk>
 # mount <disk> <mnt>
 # dd if=/dev/zero of=<mnt>/<file> bs=512 seek=5 count=8
 # fallocate -p -o 2048 -l 16384 <mnt>/<file>
 # dd if=/dev/zero of=<mnt>/<file> bs=4096 seek=3 count=8 conv=notrunc,nocreat
 # umount <mnt>
 # dmesg
 WARNING: at fs/btrfs/inode.c:7140 btrfs_destroy_inode+0x2eb/0x330

The reason is that we inputed a range which is beyond the end of the file. And
because the end of this range was not page-aligned, we had to truncate the last
page in this range, this operation is similar to a buffered file write. In other
words, we reserved enough space and clear the data which was in the hole range
on that page. But when we expanded that test file, write the data into the same
page, we forgot that we have reserved enough space for the buffered write of
that page because in most cases there is no page that is beyond the end of
the file. As a result, we reserved the space twice.

In fact, we needn't truncate the page if it is beyond the end of the file, just
release the allocated space in that range. Fix the above problem by this way.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:19 -05:00
Miao Xie 6347b3c433 Btrfs: fix off-by-one error of the same page check in btrfs_punch_hole()
(start + len) is the start of the adjacent extent, not the end of the current
extent, so we should not use it to check the hole is on the same page or not.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:19 -05:00
Miao Xie 4b5829a8e3 Btrfs: fix missing reserved space release in error path of delalloc reservation
We forget to release the reserved space in the error path of delalloc
reservatiom, fix it.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:18 -05:00
Miao Xie 543eabd5e1 Btrfs: don't auto defrag a file when doing directIO
If we runt the direct IO, we should not run auto defrag, because it may
introduce buffered IO vs direcIO problem, and make direct IO slow down.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:18 -05:00
Liu Bo fb57dc817c Btrfs: parse parent 0 into correct value in tracepoint
Value 0 is not a tree id, so besides an upper limit, a lower limit is
necessary as well while parsing root types of tracepoint.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:18 -05:00
Wang Sheng-Hui 960097622d Btrfs: use ctl->unit for free space calculation instead of block_group->sectorsize
We should use ctl->unit for free space calculation instead of block_group->sectorsize
even though for free space use_bitmap or free space cluster we only have sectorsize assigned to ctl->unit currently. Also, we can keep it consisten in code style.

Signed-off-by: Wang Sheng-Hui <shhuiw@gmail.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:17 -05:00
Filipe Brandenburger 43baa579b3 Btrfs: refactor error handling to drop inode in btrfs_create()
Refactor it by checking whether the inode has been created and needs to be
dropped (drop_inode_on_err) and also if the err variable is set. That way the
variable doesn't need to be set on each and every error handling block.

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:17 -05:00
Filipe Brandenburger 2794ed013b Btrfs: fix permissions of empty files not affected by umask
When a new file is created with btrfs_create(), the inode will initially be
created with permissions 0666 and later on in btrfs_init_acl() it will be
adapted to mask out the umask bits. The problem is that this change won't make
it into the btrfs_inode unless there's another change to the inode (e.g. writing
content changing the size or touching the file changing the mtime.)

This fix adds a call to btrfs_update_inode() to btrfs_create() to make sure that
the change will not get lost if the in-memory inode is flushed before other
changes are made to the file.

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:16 -05:00
Tsutomu Itoh 05dadc09f5 Btrfs: add fiemap's flag check
When the flag not supported is specified, it is necessary to return the error
to the caller.
So, we add the validity check of the fiemap's flag.

Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:16 -05:00
Liu Bo 01e6deb25a Btrfs: don't add a NULL extended attribute
Passing a null extended attribute value means to remove the attribute,
but we don't have to add a new NULL extended attribute.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:15 -05:00
Liu Bo 755ac67f83 Btrfs: skip adding an acl attribute if we don't have to
If the acl can be exactly represented in the traditional file
mode permission bits, we don't set another acl attribute.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:15 -05:00
Miao Xie 0ff6fabdb0 Btrfs: fix off-by-one error of the reserved size of btrfs_allocate()
alloc_end is not the real end of the current extent, it is the start of the
next adjoining extent. So we needn't +1 when calculating the size the space
that is about to be reserved.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:15 -05:00
Miao Xie 797f427711 Btrfs: use existing align macros in btrfs_allocate()
The kernel developers have implemented some often-used align macros, we should
use them instead of the complex code.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:14 -05:00
Stefan Behrens af1be4f851 Btrfs: fix a scrub regression in case of write errors
This regression was introduced by the device-replace patches.
Scrub immediately stops checking those disks that have write errors.
This is nothing that happens in the real world, but it is wrong
since scrub is the tool to detect and repair defects. Fix it.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:14 -05:00
Stefan Behrens f9c83748de Btrfs: fix a build warning for an unused label
This issue was detected by the "0-DAY kernel build testing".

fs/btrfs/volumes.c: In function 'btrfs_rm_device':
fs/btrfs/volumes.c:1505:1: warning: label 'error_close' defined but not used [-Wunused-label]

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:13 -05:00
Stefan Behrens cb3806ec88 Btrfs: fix race in check-integrity caused by usage of bitfield
The structure member mirror_num is modified concurrently to the
structure member is_iodone. This doesn't require any locking by
design, unless everything is stored in the same 32 bits of a
bit field. This was the case and xfstest 284 was able to
trigger false warnings from the checker code. This patch
seperates the bits and fixes the race.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:13 -05:00
Miao Xie b66f00da0c Btrfs: fix freeze vs auto defrag
If we freeze the fs, the auto defragment should not run. Fix it.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:12 -05:00
Miao Xie 26176e7c2a Btrfs: restructure btrfs_run_defrag_inodes()
This patch restructure btrfs_run_defrag_inodes() and make the code of the auto
defragment more readable.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:12 -05:00
Miao Xie 8ddc473433 Btrfs: fix unprotected defragable inode insertion
We forget to get the defrag lock when we re-add the defragable inode,
Fix it.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:12 -05:00
Miao Xie 9247f3170b Btrfs: use slabs for auto defrag allocation
The auto defrag allocation is in the fast path of the IO, so use slabs
to improve the speed of the allocation.

And besides that, it can do check for leaked objects when the module is removed.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:11 -05:00
Miao Xie 905b0dda06 Btrfs: get write access for qgroup operations
We need get write access for qgroup operations, or we will modify the R/O fs.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:11 -05:00
Miao Xie b8e95489bf Btrfs: get write access for scrub
We need get write access for scrub, or we will modify the R/O fs.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:10 -05:00
Miao Xie da24927b1e Btrfs: get write access when removing a device
Steps to reproduce:
 # mkfs.btrfs -d single -m single <disk0> <disk1>
 # mount -o ro <disk0> <mnt0>
 # mount -o ro <disk0> <mnt1>
 # mount -o remount,rw <mnt0>
 # umount <mnt0>
 # btrfs device delete <disk1> <mnt1>

We can remove a device from a R/O filesystem. The reason is that we just check
the R/O flag of the super block object. It is not enough, because the kernel
may set the R/O flag only for the mount point. We need invoke

	mnt_want_write_file()

to do a full check.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:09 -05:00
Miao Xie 198605a8e2 Btrfs: get write access when doing resize fs
Steps to reproduce:
 # mkfs.btrfs <partition>
 # mount -o ro <partition> <mnt0>
 # mount -o ro <partition> <mnt1>
 # mount -o remount,rw <mnt0>
 # umount <mnt0>
 # btrfs fi resize 10g <mnt1>

We re-sized a R/O filesystem. The reason is that we just check the R/O flag
of the super block object. It is not enough, because the kernel may set the
R/O flag only for the mount point. We need invoke mnt_want_write_file() to
do a full check.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:09 -05:00
Miao Xie 3c04ce0105 Btrfs: get write access when setting the default subvolume
When wen want to set the default subvolume, we must get write access, or
we will change the R/O file system.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:09 -05:00
Miao Xie 8cd2807f79 Btrfs: fix wrong return value of btrfs_wait_for_commit()
If the id of the existed transaction is more than the one we specified, it
means the specified transaction was commited, so we should return 0, not
EINVAL.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:08 -05:00
Miao Xie ff7c1d3355 Btrfs: don't start a new transaction when starting sync
If there is no running transaction in the fs, we needn't start a new one when
we want to start sync.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:08 -05:00
Miao Xie 9a8c28bec1 Btrfs: pass root object into btrfs_ioctl_{start, wait}_sync()
Since we have gotten the root in the caller, just pass it into
btrfs_ioctl_{start, wait}_sync() directly.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:07 -05:00
Liu Bo db2254bce4 Btrfs: fix an while-loop of listxattr
If we found an invalid xattr dir item, we'd better try the next one instead.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:07 -05:00
Wang Sheng-Hui 071401258a Btrfs: do not warn_on io_ctl->cur in io_ctl_map_page
io_ctl_map_page is called by many functions in free-space-cache.
In most scenarios, the ->cur is not null, e.g. io_ctl_add_entry.
I think we'd better remove the warn_on here.

Signed-off-by: Wang Sheng-Hui <shhuiw@gmail.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:06 -05:00
Stefan Behrens 3f6bcfbd41 Btrfs: add support for device replace ioctls
This is the commit that allows to start the device replace
procedure.

An ioctl() interface is added that supports starting and
canceling the device replace procedure, and to retrieve
the status and progress.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-16 20:46:06 -05:00
Stefan Behrens ad6d620e2a Btrfs: allow repair code to include target disk when searching mirrors
Make the target disk of a running device replace operation
available for reading. This is only used as a last ressort for
the defect repair procedure. And it is dependent on the location
of the data block to read, because during an ongoing device
replace operation, the target drive is only partially filled
with the filesystem data.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-12 17:15:45 -05:00
Stefan Behrens 72d7aefccd Btrfs: increase BTRFS_MAX_MIRRORS by one for dev replace
This change of the define is effective in all modes, it
is required and used only in the case when a device replace
procedure is running. The reason is that during an active
device replace procedure, the target device of the copy
operation is a mirror for the filesystem data as well that
can be used to read data in order to repair read errors on
other disks.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-12 17:15:44 -05:00
Stefan Behrens 30d9861ff9 Btrfs: optionally avoid reads from device replace source drive
It is desirable to be able to configure the device replace
procedure to avoid reading the source drive (the one to be
copied) whenever possible. This is useful when the number of
read errors on this disk is high, because it would delay the
copy procedure alot. Therefore there is an option to avoid
reading from the source disk unless the repair procedure
really needs to access it. The regular read req asks for
mapping the block with mirror_num == 0, in this case the
source disk is avoided whenever possible. The repair code
selects the mirror_num explicitly (mirror_num != 0), this
case is not changed by this commit.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-12 17:15:44 -05:00
Stefan Behrens 472262f35a Btrfs: changes to live filesystem are also written to replacement disk
During a running dev replace operation, all write requests to
the live filesystem are duplicated to also write to the target
drive. Therefore btrfs_map_block() is changed to duplicate
stripes that are written to the source disk of a device replace
procedure to be written to the target disk as well.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-12 17:15:43 -05:00
Stefan Behrens 29a8d9a0bc Btrfs: introduce GET_READ_MIRRORS functionality for btrfs_map_block()
Before this commit, btrfs_map_block() was called with REQ_WRITE
in order to retrieve the list of mirrors for a disk block.
This needs to be changed for the device replace procedure since
it makes a difference whether you are asking for read mirrors
or for locations to write to.
GET_READ_MIRRORS is introduced as a new interface to call
btrfs_map_block().
In the current commit, the functionality is not yet changed,
only the interface for GET_READ_MIRRORS is introduced and all
the places that should use this new interface are adapted.

The reason that REQ_WRITE cannot be abused anymore to retrieve
a list of read mirrors is that during a running dev replace
operation all write requests to the live filesystem are
duplicated to also write to the target drive.
Keep in mind that the target disk is only partially a valid
copy of the source disk while the operation is ongoing. All
writes go to the target disk, but not all reads would return
valid data on the target disk. Therefore it is not possible
anymore to abuse a REQ_WRITE interface to find valid mirrors
for a REQ_READ.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-12 17:15:43 -05:00
Stefan Behrens 8dabb7420f Btrfs: change core code of btrfs to support the device replace operations
This commit contains all the essential changes to the core code
of Btrfs for support of the device replace procedure.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-12 17:15:42 -05:00
Stefan Behrens e93c89c1aa Btrfs: add new sources for device replace code
This adds a new file to the sources together with the header file
and the changes to ioctl.h and ctree.h that are required by the
new C source file. Additionally, 4 new functions are added to
volume.c that deal with device creation and destruction.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-12 17:15:41 -05:00
Stefan Behrens ff023aac31 Btrfs: add code to scrub to copy read data to another disk
The device replace procedure makes use of the scrub code. The scrub
code is the most efficient code to read the allocated data of a disk,
i.e. it reads sequentially in order to avoid disk head movements, it
skips unallocated blocks, it uses read ahead mechanisms, and it
contains all the code to detect and repair defects.
This commit adds code to scrub to allow the scrub code to copy read
data to another disk.
One goal is to be able to perform as fast as possible. Therefore the
write requests are collected until huge bios are built, and the
write process is decoupled from the read process with some kind of
flow control, of course, in order to limit the allocated memory.
The best performance on spinning disks could by reached when the
head movements are avoided as much as possible. Therefore a single
worker is used to interface the read process with the write process.
The regular scrub operation works as fast as before, it is not
negatively influenced and actually it is more or less unchanged.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-12 17:15:41 -05:00
Stefan Behrens 618919236b Btrfs: handle errors from btrfs_map_bio() everywhere
With the addition of the device replace procedure, it is possible
for btrfs_map_bio(READ) to report an error. This happens when the
specific mirror is requested which is located on the target disk,
and the copy operation has not yet copied this block. Hence the
block cannot be read and this error state is indicated by
returning EIO.
Some background information follows now. A new mirror is added
while the device replace procedure is running.
btrfs_get_num_copies() returns one more, and
btrfs_map_bio(GET_READ_MIRROR) adds one more mirror if a disk
location is involved that was already handled by the device
replace copy operation. The assigned mirror num is the highest
mirror number, e.g. the value 3 in case of RAID1.
If btrfs_map_bio() is invoked with mirror_num == 0 (i.e., select
any mirror), the copy on the target drive is never selected
because that disk shall be able to perform the write requests as
quickly as possible. The parallel execution of read requests would
only slow down the disk copy procedure. Second case is that
btrfs_map_bio() is called with mirror_num > 0. This is done from
the repair code only. In this case, the highest mirror num is
assigned to the target disk, since it is used last. And when this
mirror is not available because the copy procedure has not yet
handled this area, an error is returned. Everywhere in the code
the handling of such errors is added now.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2012-12-12 17:15:40 -05:00