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* Btrfs: change core code of btrfs to support the device replace operationsStefan Behrens2012-12-12
| | | | | | | | 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>
* Btrfs: add new sources for device replace codeStefan Behrens2012-12-12
| | | | | | | | | | 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>
* Btrfs: handle errors from btrfs_map_bio() everywhereStefan Behrens2012-12-12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* Btrfs: disallow some operations on the device replace target deviceStefan Behrens2012-12-12
| | | | | | | | This patch adds some code to disallow operations on the device that is used as the target for the device replace operation. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
* Btrfs: disallow mutually exclusive admin operations from user modeStefan Behrens2012-12-12
| | | | | | | | | | Btrfs admin operations that are manually started from user mode and that cannot be executed at the same time return -EINPROGRESS. A common way to enter and leave this locked section is introduced since it used to be specific to the balance operation. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
* Btrfs: pass fs_info instead of rootStefan Behrens2012-12-12
| | | | | | | | | | | | A small number of functions that are used in a device replace procedure when the operation is resumed at mount time are unable to pass the same root pointer that would be used in the regular (ioctl) context. And since the root pointer is not required, only the fs_info is, the root pointer argument is replaced with the fs_info pointer argument. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
* Btrfs: add btrfs_scratch_superblock() functionStefan Behrens2012-12-12
| | | | | | | | This new function is used by the device replace procedure in a later patch. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
* Btrfs: pass fs_info to btrfs_map_block() instead of mapping_treeStefan Behrens2012-12-12
| | | | | | | | | This is required for the device replace procedure in a later step. Two calling functions also had to be changed to have the fs_info pointer: repair_io_failure() and scrub_setup_recheck_block(). Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
* Btrfs: Pass fs_info to btrfs_num_copies() instead of mapping_treeStefan Behrens2012-12-12
| | | | | | | This is required for the device replace procedure in a later step. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
* Btrfs: add two more find_device() methodsStefan Behrens2012-12-12
| | | | | | | | | | | | | | The new function btrfs_find_device_missing_or_by_path() will be used for the device replace procedure. This function itself calls the second new function btrfs_find_device_by_path(). Unfortunately, it is not possible to currently make the rest of the code use these functions as well, since all functions that look similar at first view are all a little bit different in what they are doing. But in the future, new code could benefit from these two new functions, and currently, device replace uses them. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
* Btrfs: move some common code into a subfunctionStefan Behrens2012-12-12
| | | | | | | | | | Some code to open block devices, to read the superblock and to handle errors was repeated multiple times in 3 places, and the following patch makes use of it as well. This code is now moved into a subfunction. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
* Btrfs: protect devices list with its mutexLiu Bo2012-12-12
| | | | | | | | Since we've kill the bigger one volume_mutex, we need to add devices list mutex back. Signed-off-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
* Btrfs: Don't trust the superblock label and simply printk("%s") itStefan Behrens2012-12-12
| | | | | | | | | | | | Someone who is root or capable(CAP_SYS_ADMIN) could corrupt the superblock and make Btrfs printk("%s") crash while holding the uuid_mutex since nobody forces a limit on the string. Since the uuid_mutex is significant, the system would be unusable afterwards. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de> Reviewed-by: David Sterba <dsterba@suse.cz> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
* fs/btrfs: use WARNJulia Lawall2012-12-12
| | | | | | | | | | | | | | | | | | | | | | Use WARN rather than printk followed by WARN_ON(1), for conciseness. A simplified version of the semantic patch that makes this transformation is as follows: (http://coccinelle.lip6.fr/) // <smpl> @@ expression list es; @@ -printk( +WARN(1, es); -WARN_ON(1); // </smpl> Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr> Reviewed-by: David Sterba <dsterba@suse.cz> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
* Btrfs: Fix typo in fs/btrfsMasanari Iida2012-12-12
| | | | | | | Correct spelling typo in btrfs. Signed-off-by: Masanari Iida <standby24x7@gmail.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
* Btrfs: Remove the invalid shrink size check up from btrfs_shrink_dev()jeff.liu2012-12-12
| | | | | | | | | | | | Remove an invalid size check up from btrfs_shrink_dev(). The new size should not larger than the device->total_bytes as it was already verified before coming to here(i.e. new_size < old_size). Remove invalid check up for btrfs_shrink_dev(). Signed-off-by: Jie Liu <jeff.liu@oracle.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
* Btrfs: recheck bio against block device when we map the bioJosef Bacik2012-12-11
| | | | | | | | | | | | | Alex reported a problem where we were writing between chunks on a rbd device. The thing is we do bio_add_page using logical offsets, but the physical offset may be different. So when we map the bio now check to see if the bio is still ok with the physical offset, and if it is not split the bio up and redo the bio_add_page with the physical sector. This fixes the problem for Alex and doesn't affect performance in the normal case. Thanks, Reported-and-tested-by: Alex Elder <elder@inktank.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
* Btrfs: cleanup duplicated division functionsMiao Xie2012-12-11
| | | | | | | | | div_factor{_fine} has been implemented for two times, cleanup it. And I move them into a independent file named math.h because they are common math functions. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
* Btrfs: fix deadlock caused by the nested chunk allocationMiao Xie2012-10-25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Steps to reproduce: # mkfs.btrfs -m raid1 <disk1> <disk2> # btrfstune -S 1 <disk1> # mount <disk1> <mnt> # btrfs device add <disk3> <disk4> <mnt> # mount -o remount,rw <mnt> # dd if=/dev/zero of=<mnt>/tmpfile bs=1M count=1 Deadlock happened. It is because of the nested chunk allocation. When we wrote the data into the filesystem, we would allocate the data chunk because there was no data chunk in the filesystem. At the end of the data chunk allocation, we should insert the metadata of the data chunk into the extent tree, but there was no raid1 chunk, so we tried to lock the chunk allocation mutex to allocate the new chunk, but we had held the mutex, the deadlock happened. By rights, we would allocate the raid1 chunk when we added the second device because the profile of the seed filesystem is raid1 and we had two devices. But we didn't do that in fact. It is because the last step of the first device insertion didn't commit the transaction. So when we added the second device, we didn't cow the tree, and just inserted the relative metadata into the leaves which were generated by the first device insertion, and its profile was dup. So, I fix this problem by commiting the transaction at the end of the first device insertion. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
* Btrfs: make filesystem read-only when submitting barrier failsStefan Behrens2012-10-09
| | | | | | | | | | | | | | | | | | | | | | | So far the return code of barrier_all_devices() is ignored, which means that errors are ignored. The result can be a corrupt filesystem which is not consistent. This commit adds code to evaluate the return code of barrier_all_devices(). The normal btrfs_error() mechanism is used to switch the filesystem into read-only mode when errors are detected. In order to decide whether barrier_all_devices() should return error or success, the number of disks that are allowed to fail the barrier submission is calculated. This calculation accounts for the worst RAID level of metadata, system and data. If single, dup or RAID0 is in use, a single disk error is already considered to be fatal. Otherwise a single disk error is tolerated. The calculation of the number of disks that are tolerated to fail the barrier operation is performed when the filesystem gets mounted, when a balance operation is started and finished, and when devices are added or removed. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
* btrfs: fix message printingDaniel J Blueman2012-10-09
| | | | | | Fix various messages to include newline and module prefix. Signed-off-by: Daniel J Blueman <daniel@quora.org>
* btrfs: move transaction aborts to the point of failureDavid Sterba2012-10-08
| | | | | | | | Call btrfs_abort_transaction as early as possible when an error condition is detected, that way the line number reported is useful and we're not clueless anymore which error path led to the abort. Signed-off-by: David Sterba <dsterba@suse.cz>
* Merge branch 'for-linus' of ↵Linus Torvalds2012-08-29
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs Pull btrfs fixes from Chris Mason: "I've split out the big send/receive update from my last pull request and now have just the fixes in my for-linus branch. The send/recv branch will wander over to linux-next shortly though. The largest patches in this pull are Josef's patches to fix DIO locking problems and his patch to fix a crash during balance. They are both well tested. The rest are smaller fixes that we've had queued. The last rc came out while I was hacking new and exciting ways to recover from a misplaced rm -rf on my dev box, so these missed rc3." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (25 commits) Btrfs: fix that repair code is spuriously executed for transid failures Btrfs: fix ordered extent leak when failing to start a transaction Btrfs: fix a dio write regression Btrfs: fix deadlock with freeze and sync V2 Btrfs: revert checksum error statistic which can cause a BUG() Btrfs: remove superblock writing after fatal error Btrfs: allow delayed refs to be merged Btrfs: fix enospc problems when deleting a subvol Btrfs: fix wrong mtime and ctime when creating snapshots Btrfs: fix race in run_clustered_refs Btrfs: don't run __tree_mod_log_free_eb on leaves Btrfs: increase the size of the free space cache Btrfs: barrier before waitqueue_active Btrfs: fix deadlock in wait_for_more_refs btrfs: fix second lock in btrfs_delete_delayed_items() Btrfs: don't allocate a seperate csums array for direct reads Btrfs: do not strdup non existent strings Btrfs: do not use missing devices when showing devname Btrfs: fix that error value is changed by mistake Btrfs: lock extents as we map them in DIO ...
| * Btrfs: revert checksum error statistic which can cause a BUG()Stefan Behrens2012-08-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 442a4f6308e694e0fa6025708bd5e4e424bbf51c added btrfs device statistic counters for detected IO and checksum errors to Linux 3.5. The statistic part that counts checksum errors in end_bio_extent_readpage() can cause a BUG() in a subfunction: "kernel BUG at fs/btrfs/volumes.c:3762!" That part is reverted with the current patch. However, the counting of checksum errors in the scrub context remains active, and the counting of detected IO errors (read, write or flush errors) in all contexts remains active. Cc: stable <stable@vger.kernel.org> # 3.5 Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de> Signed-off-by: Chris Mason <chris.mason@oracle.com>
| * Btrfs: barrier before waitqueue_activeJosef Bacik2012-08-28
| | | | | | | | | | | | | | | | | | | | We need a barrir before calling waitqueue_active otherwise we will miss wakeups. So in places that do atomic_dec(); then atomic_read() use atomic_dec_return() which imply a memory barrier (see memory-barriers.txt) and then add an explicit memory barrier everywhere else that need them. Thanks, Signed-off-by: Josef Bacik <jbacik@fusionio.com>
| * Btrfs: do not strdup non existent stringsJosef Bacik2012-08-28
| | | | | | | | | | | | | | | | | | When we close devices we add back empty devices for some reason that escapes me. In the case of a missing dev we don't allocate an rcu_string for it's name, so check to see if the device has a name and if it doesn't don't bother strdup()'ing it. Thanks, Signed-off-by: Josef Bacik <jbacik@fusionio.com>
* | btrfs: nuke write_super from commentsArtem Bityutskiy2012-08-04
|/ | | | | | | | | | The '->write_super' superblock method is gone, and this patch removes all the references to 'write_super' from btrfs. Cc: Chris Mason <chris.mason@fusionio.com> Cc: linux-btrfs@vger.kernel.org Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Btrfs: suppress printk() if all device I/O stats are zeroStefan Behrens2012-07-23
| | | | | | | Code is added to suppress the I/O stats printing at mount time if all statistic values are zero. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
* Btrfs: remove unwanted printk() for btrfs device I/O statsStefan Behrens2012-07-23
| | | | | | | | | | | | People complained about the annoying kernel log message "btrfs: no dev_stats entry found ... (OK on first mount after mkfs)" everytime a filesystem is mounted for the first time after running mkfs. Since the distribution of the btrfs-progs is not synchronized to the kernel version, mkfs like it is now will be used also in the future. Then this message is not useful to find errors, it is just annoying. This commit removes the printk(). Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
* Btrfs: add DEVICE_READY ioctlJosef Bacik2012-07-23
| | | | | | | | | | This will be used in conjunction with btrfs device ready <dev>. This is needed for initrd's to have a nice and lightweight way to tell if all of the devices needed for a file system are in the cache currently. This keeps them from having to do mount+sleep loops waiting for devices to show up. Thanks, Signed-off-by: Josef Bacik <jbacik@fusionio.com>
* btrfs: join DEV_STATS ioctls to oneDavid Sterba2012-07-23
| | | | | | | | | | | | | | | | Commit c11d2c236cc260b36 (Btrfs: add ioctl to get and reset the device stats) introduced two ioctls doing almost the same thing distinguished by just the ioctl number which encodes "do reset after read". I have suggested http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg16604.html to implement it via the ioctl args. This hasn't happen, and I think we should use a more clean way to pass flags and should not waste ioctl numbers. CC: Stefan Behrens <sbehrens@giantdisaster.de> Signed-off-by: David Sterba <dsterba@suse.cz>
* Btrfs: resume balance on rw (re)mounts properlyIlya Dryomov2012-07-02
| | | | | | | | This introduces btrfs_resume_balance_async(), which, given that restriper state was recovered earlier by btrfs_recover_balance(), resumes balance in btrfs-balance kthread. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
* Btrfs: restore restriper state on all mountsIlya Dryomov2012-07-02
| | | | | | | | | | Fix a bug that triggered asserts in btrfs_balance() in both normal and resume modes -- restriper state was not properly restored on read-only mounts. This factors out resuming code from btrfs_restore_balance(), which is now also called earlier in the mount sequence to avoid the problem of some early writes getting the old profile. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
* Btrfs: don't count I/O statistic read errors for missing devicesStefan Behrens2012-07-02
| | | | | | | | | | | It is normal behaviour of the low level btrfs function btrfs_map_bio() to complete a bio with -EIO if the device is missing, instead of just preventing the bio creation in an earlier step. This used to cause I/O statistic read error increments and annoying printk_ratelimited messages. This commit fixes the issue. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de> Reported-by: Carey Underwood <cwillu@cwillu.com>
* Btrfs: use rcu to protect device->nameJosef Bacik2012-06-14
| | | | | | | | | | | | | | Al pointed out that we can just toss out the old name on a device and add a new one arbitrarily, so anybody who uses device->name in printk could possibly use free'd memory. Instead of adding locking around all of this he suggested doing it with RCU, so I've introduced a struct rcu_string that does just that and have gone through and protected all accesses to device->name that aren't under the uuid_mutex with rcu_read_lock(). This protects us and I will use it for dealing with removing the device that we used to mount the file system in a later patch. Thanks, Reviewed-by: David Sterba <dsterba@suse.cz> Signed-off-by: Josef Bacik <josef@redhat.com>
* Btrfs: read device stats on mount, write modified ones during commitStefan Behrens2012-05-30
| | | | | | | | | | The device statistics are written into the device tree with each transaction commit. Only modified statistics are written. When a filesystem is mounted, the device statistics for each involved device are read from the device tree and used to initialize the counters. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
* Btrfs: add ioctl to get and reset the device statsStefan Behrens2012-05-30
| | | | | | | An ioctl interface is added to get the device statistic counters. A second ioctl is added to atomically get and reset these counters. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
* Btrfs: add device counters for detected IO and checksum errorsStefan Behrens2012-05-30
| | | | | | | | | | The goal is to detect when drives start to get an increased error rate, when drives should be replaced soon. Therefore statistic counters are added that count IO errors (read, write and flush). Additionally, the software detected errors like checksum errors and corrupted blocks are counted. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
* Btrfs: fix wrong error returned by adding a deviceLiu Bo2012-05-30
| | | | | | | | | | | | | | Reproduce: $ mkfs.btrfs /dev/sdb7 $ mount /dev/sdb7 /mnt/btrfs -o ro $ btrfs dev add /dev/sdb8 /mnt/btrfs ERROR: error adding the device '/dev/sdb8' - Invalid argument Since we mount with readonly options, and /dev/sdb7 is not a seeding one, a readonly notification is preferred. Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com> Reviewed-by: Josef Bacik <josef@redhat.com>
* Btrfs: fix repair code for RAID10Jan Schmidt2012-04-27
| | | | | | | | | btrfs_map_block sets mirror_num, so that the repair code knows eventually which device gave us the read error. For RAID10, mirror_num must be 1 or 2. Before this fix mirror_num was incorrectly related to our stripe index. Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net> Signed-off-by: Chris Mason <chris.mason@oracle.com>
* fs/btrfs/volumes.c: add missing free_fs_devicesJulia Lawall2012-04-18
| | | | | | Free fs_devices as done in the error-handling code just below. Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
* Btrfs: fix max chunk size check in chunk allocatorIlya Dryomov2012-04-18
| | | | | | | | | Fix a bug, where in case we need to adjust stripe_size so that the length of the resulting chunk is less than or equal to max_chunk_size, DUP chunks turn out to be only half as big as they could be. Cc: Arne Jansen <sensille@gmx.net> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
* Btrfs: fix eof while discarding extentsLiu Bo2012-04-12
| | | | | | | | | We miscalculate the length of extents we're discarding, and it leads to an eof of device. Reported-by: Daniel Blueman <daniel@quora.org> Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Btrfs: flush out and clean up any block device pages during mountChris Mason2012-03-28
| | | | | | | | | | | | | | Btrfs puts the filesystem metadata into its own address space, and somehow the block device address space isn't getting onto disk properly before a mount. The end result is that a loop of mkfs and mounting the filesystem will sometimes find stale or incorrect data. This commit should fix it by sprinkling fdatawrites and invalidate_bdev calls around. This is a short term measure to make sure it is fixed. The block devices really should be flushed and cleaned up higher in the stack. Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Merge branch 'for-chris' of git://github.com/idryomov/btrfs-unstable into ↵Chris Mason2012-03-28
|\ | | | | | | for-linus
| * Btrfs: fix infinite loop in btrfs_shrink_device()Ilya Dryomov2012-03-27
| | | | | | | | | | | | | | | | If relocate of block group 0 fails with ENOSPC we end up infinitely looping because key.offset -= 1 statement in that case brings us back to where we started. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
| * Btrfs: allow dup for data chunks in mixed modeIlya Dryomov2012-03-27
| | | | | | | | | | | | | | Generally we don't allow dup for data, but mixed chunks are special and people seem to think this has its use cases. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
| * Btrfs: validate target profiles only if we are going to use themIlya Dryomov2012-03-27
| | | | | | | | | | | | | | | | Do not run sanity checks on all target profiles unless they all will be used. This came up because alloc_profile_is_valid() is now more strict than it used to be. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
| * Btrfs: move alloc_profile_is_valid() to volumes.cIlya Dryomov2012-03-27
| | | | | | | | | | | | | | | | | | Header file is not a good place to define functions. This also moves a call to alloc_profile_is_valid() down the stack and removes a redundant check from __btrfs_alloc_chunk() - alloc_profile_is_valid() takes it into account. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
| * Btrfs: make profile_is_valid() check more strictIlya Dryomov2012-03-27
| | | | | | | | | | | | | | | | | | | | "0" is a valid value for an on-disk chunk profile, but it is not a valid extended profile. (We have a separate bit for single chunks in extended case) Also rename it to alloc_profile_is_valid() for clarity. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>