- 17 Dec, 2018 40 commits
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Nikolay Borisov authored
This patch lands the last case which needs to be handled by the fsid change code. Namely, this is the case where a multidisk filesystem has already undergone at least one successful fsid change i.e all disks have the METADATA_UUID incompat bit and power failure occurs as another fsid change is in progress. When such an event occurs, disks could be split in 2 groups. One of the groups will have both METADATA_UUID and CHANGING_FSID_V2 flags set coupled with old fsid/metadata_uuid pairs. The other group of disks will have only METADATA_UUID bit set and their fsid will be different than the one in disks in the first group. Here we look at the following cases: a) A disk from the first group is scanned first, so fs_devices is created with stale fsid/metdata_uuid. Then when a disk from the second group is scanned it needs to first check whether there exists such an fs_devices that has fsid_change set to true (because it was created with a disk having the CHANGING_FSID_V2 flag), the metadata_uuid and fsid of the fs_devices will be different (since it was created by a disk which already has had at least 1 successful fsid change) and finally the metadata_uuid of the fs_devices will equal that of the currently scanned disk (because metadata_uuid never really changes). When the correct fs_devices is found the information from the scanned disk will replace the current one in fs_devices since the scanned disk will have higher generation number. b) A disk from the second group is scanned so fs_devices is created as usual with differing fsid/metdata_uid. Then when a disk from the first group is scanned the code detects that it has both CHANGING_FSID_V2 and METADATA_UUID flags set and will search for fs_devices that has differing metadata_uuid/fsid and whose metadata_uuid is the same as that of the scanned device. Signed-off-by:
Nikolay Borisov <nborisov@suse.com> Signed-off-by:
David Sterba <dsterba@suse.com>
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Nikolay Borisov authored
This commit continues hardening the scanning code to handle cases where power loss could have caused disks in a multi-disk filesystem to be in inconsistent state. Namely handle the situation that can occur when some of the disks in multi-disk fs have completed their fsid change i.e they have METADATA_UUID incompat flag set, have cleared the CHANGING_FSID_V2 flag and their fsid/metadata_uuid are different. At the same time the other half of the disks will have their fsid/metadata_uuid unchanged and will only have CHANGING_FSID_V2 flag. This is handled by introducing code in the scan path which: a) Handles the case when a device with CHANGING_FSID_V2 flag is scanned and as a result btrfs_fs_devices is created with matching fsid/metdata_uuid. Subsequently, when a device with completed fsid change is scanned it will detect this via the new code in find_fsid i.e that such an fs_devices exist that fsid_change flag is set to true, it's metadata_uuid/fsid match and the metadata_uuid of the scanned device matches that of the fs_devices. In this case, it's important to note that the devices which has its fsid change completed will have a higher generation number than the device with FSID_CHANGING_V2 flag set, so its superblock block will be used during mount. To prevent an assertion triggering because the sb used for mounting will have differing fsid/metadata_uuid than the ones in the fs_devices struct also add code in device_list_add which overwrites the values in fs_devices. b) Alternatively we can end up with a device that completed its fsid change be scanned first which will create the respective btrfs_fs_devices struct with differing fsid/metadata_uuid. In this case when a device with FSID_CHANGING_V2 flag set is scanned it will call the newly added find_fsid_inprogress function which will return the correct fs_devices. Signed-off-by:
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Nikolay Borisov authored
In order to gracefully handle split-brain scenario during fsid change (which are very unlikely, yet possible), two more pieces of information will be necessary: 1. The highest generation number among all devices registered to a particular btrfs_fs_devices 2. A boolean flag whether a given btrfs_fs_devices was created by a device which had the FSID_CHANGING_V2 flag set. This is a preparatory patch and just introduces the variables as well as code which sets them, their actual use is going to happen in a later patch. Signed-off-by:
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Nikolay Borisov authored
Even though fsid change without rewrite is a very quick operation it's still possible to experience a split-brain scenario if power loss occurs at the most inconvenient time. This patch handles the case where power failure occurs while the first transaction (the one setting CHANGING_FSID_V2) flag is being persisted on disk. This can cause the btrfs_fs_devices of this filesystem to be created by a device which: a) has the CHANGING_FSID_V2 flag set but its fsid value is intact b) or a device which doesn't have CHANGING_FSID_V2 flag set and its fsid value is intact This situation is trivially handled by the current find_fsid code since in both cases the devices are going to be treated like ordinary devices. Since btrfs is always mounted using the superblock of the latest device (the one with highest generation number), meaning it will have the CHANGING_FSID_V2 flag set, ensure it's being cleared on mount. On the first transaction commit following mount all disks will have it cleared. Signed-off-by: -
Nikolay Borisov authored
Currently btrfs_fs_info structure contains a copy of the fsid/metadata_uuid fields. Same values are also contained in the btrfs_fs_devices structure which fs_info has a reference to. Let's reduce duplication by removing the fields from fs_info and always refer to the ones in fs_devices. No functional changes. Signed-off-by:
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Nikolay Borisov authored
Since the metadata_uuid is a new incompat feature it requires the respective sysfs hooks. This patch adds the 'metdata_uuid' feature to be shown if it supported by the kernel. Additionally it adds /sys/fs/btrfs/UUID/metadata_uuid attribute which allows one to read the current metadata_uuid. Signed-off-by:
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Nikolay Borisov authored
This field is going to be used when the user wants to change the UUID of the filesystem without having to rewrite all metadata blocks. This field adds another level of indirection such that when the FSID is changed what really happens is the current UUID (the one with which the fs was created) is copied to the 'metadata_uuid' field in the superblock as well as a new incompat flag is set METADATA_UUID. When the kernel detects this flag is set it knows that the superblock in fact has 2 UUIDs: 1. Is the UUID which is user-visible, currently known as FSID. 2. Metadata UUID - this is the UUID which is stamped into all on-disk datastructures belonging to this file system. When the new incompat flag is present device scanning checks whether both fsid/metadata_uuid of the scanned device match any of the registered filesystems. When the flag is not set then both UUIDs are equal and only the FSID is retained on disk, metadata_uuid is set only in-memory during mount. Additionally a new metadata_uuid field is also added to the fs_info struct. It's initialised either with the FSID in case METADATA_UUID incompat flag is not set or with the metdata_uuid of the superblock otherwise. This commit introduces the new fields as well as the new incompat flag and switches all users of the fsid to the new logic. Signed-off-by:
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Johannes Thumshirn authored
Several functions in BTRFS are only used inside the source file they are declared if CONFIG_BTRFS_FS_RUN_SANITY_TESTS is not defined. However if CONFIG_BTRFS_FS_RUN_SANITY_TESTS is defined these functions are shared with the unit tests code. Before the introduction of the EXPORT_FOR_TESTS macro, these functions could not be declared as static and the compiler had a harder task when optimizing and inlining them. As we have EXPORT_FOR_TESTS now, use it where appropriate to support the compiler. Reviewed-by:
Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by:
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Johannes Thumshirn authored
Depending on whether CONFIG_BTRFS_FS_RUN_SANITY_TESTS is set, some BTRFS functions are either local to the file they are implemented in and thus should be declared static or are called from within the test implementation defined in a different file. Introduce an EXPORT_FOR_TESTS macro which depending on CONFIG_BTRFS_FS_RUN_SANITY_TESTS either adds the 'static' keyword to a function or not. Reviewed-by:
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Johannes Thumshirn authored
Up to commit 32955c54 ("btrfs: switch to discard_new_inode()") the drop_on_err variable in btrfs_mkdir() was used to check whether the inode had to be dropped via iput(). After commit 32955c54 ("btrfs: switch to discard_new_inode()") discard_new_inode() is called when err is set and inode is non NULL. Therefore drop_on_err is not used anymore and thus causes a warning when building with -Wunused-but-set-variable. Reviewed-by:
Omar Sandoval <osandov@fb.com> Reviewed-by:
Qu Wenruo <wqu@suse.com> Signed-off-by:
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Nikolay Borisov authored
lock_delalloc_pages should only return 2 values - 0 in case of success and -EAGAIN if the range of pages to be locked should be shrunk due to some of gone. Manual inspections confirms that this is indeed the case since __process_pages_contig is where lock_delalloc_pages gets its return value. The latter always returns 0 or -EAGAIN so the invariant holds. No functional changes. Reviewed-by:
Anand Jain <anand.jain@oracle.com> Signed-off-by:
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Nikolay Borisov authored
All callers of this function pass BTRFS_MAX_EXTENT_SIZE (128M) so let's reduce the argument count and make that a local variable. No functional changes. Reviewed-by:
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Nikolay Borisov authored
It's unnecessary to check map->stripes[i].dev for NULL given its value is already set and dereferenced above the the check. No functional changes. Reviewed-by:
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Anand Jain authored
As of now only user requested replace cancel can cancel the replace-scrub so no need to log the error. Signed-off-by:
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Anand Jain authored
When we successfully cancel the device replace, its scrub worker returns -ECANCELED, which is then passed to btrfs_dev_replace_finishing. It cleans up based on the returned status and propagates the same -ECANCELED back the parent function. As of now only user can cancel the replace-scrub, so its ok to silence the warning here. Signed-off-by:
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Anand Jain authored
We recast the replace return status BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS to 0, to indicate no error. And since BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR should also return 0, which is also declared as 0, so we just return. Instead add it to the if statement so that there is enough clarity while reading the code. Signed-off-by:
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Anand Jain authored
When the replace state is in the suspended state, btrfs_scrub_cancel() should fail with -ENOTCONN as there is no scrub running. As a safety catch check if btrfs_scrub_cancel() returns -ENOTCONN and assert if it doesn't. Signed-off-by:
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Anand Jain authored
The device-replace needs to check the result code of the scrub workers in btrfs_dev_replace_cancel and distinguish if successful cancel operation and when the there was no operation running. If btrfs_scrub_cancel() fails, return BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED so that user can try to cancel the replace again. Signed-off-by:
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Anand Jain authored
The device replace cancel thread can race with the replace start thread and if fs_info::scrubs_running is not yet set, btrfs_scrub_cancel() will fail to stop the scrub thread. The scrub thread continues with the scrub for replace which then will try to write to the target device and which is already freed by the cancel thread. scrub_setup_ctx() warns as tgtdev is NULL. struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev, int is_dev_replace) { ... if (is_dev_replace) { WARN_ON(!fs_info->dev_replace.tgtdev); <=== sctx->pages_per_wr_bio = SCRUB_PAGES_PER_WR_BIO; sctx->wr_tgtdev = fs_info->dev_replace.tgtdev; sctx->flush_all_writes = false; } [ 6724.497655] BTRFS info (device sdb): dev_replace from /dev/sdb (devid 1) to /dev/sdc started [ 6753.945017] BTRFS info (device sdb): dev_replace from /dev/sdb (devid 1) to /dev/sdc canceled [ 6852.426700] WARNING: CPU: 0 PID: 4494 at fs/btrfs/scrub.c:622 scrub_setup_ctx.isra.19+0x220/0x230 [btrfs] ... [ 6852.428928] RIP: 0010:scrub_setup_ctx.isra.19+0x220/0x230 [btrfs] ... [ 6852.432970] Call Trace: [ 6852.433202] btrfs_scrub_dev+0x19b/0x5c0 [btrfs] [ 6852.433471] btrfs_dev_replace_start+0x48c/0x6a0 [btrfs] [ 6852.433800] btrfs_dev_replace_by_ioctl+0x3a/0x60 [btrfs] [ 6852.434097] btrfs_ioctl+0x2476/0x2d20 [btrfs] [ 6852.434365] ? do_sigaction+0x7d/0x1e0 [ 6852.434623] do_vfs_ioctl+0xa9/0x6c0 [ 6852.434865] ? syscall_trace_enter+0x1c8/0x310 [ 6852.435124] ? syscall_trace_enter+0x1c8/0x310 [ 6852.435387] ksys_ioctl+0x60/0x90 [ 6852.435663] __x64_sys_ioctl+0x16/0x20 [ 6852.435907] do_syscall_64+0x50/0x180 [ 6852.436150] entry_SYSCALL_64_after_hwframe+0x49/0xbe Further, as the replace thread enters scrub_write_page_to_dev_replace() without the target device it panics: static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx, struct scrub_page *spage) { ... bio_set_dev(bio, sbio->dev->bdev); <====== [ 6929.715145] BUG: unable to handle kernel NULL pointer dereference at 00000000000000a0 .. [ 6929.717106] Workqueue: btrfs-scrub btrfs_scrub_helper [btrfs] [ 6929.717420] RIP: 0010:scrub_write_page_to_dev_replace+0xb4/0x260 [btrfs] .. [ 6929.721430] Call Trace: [ 6929.721663] scrub_write_block_to_dev_replace+0x3f/0x60 [btrfs] [ 6929.721975] scrub_bio_end_io_worker+0x1af/0x490 [btrfs] [ 6929.722277] normal_work_helper+0xf0/0x4c0 [btrfs] [ 6929.722552] process_one_work+0x1f4/0x520 [ 6929.722805] ? process_one_work+0x16e/0x520 [ 6929.723063] worker_thread+0x46/0x3d0 [ 6929.723313] kthread+0xf8/0x130 [ 6929.723544] ? process_one_work+0x520/0x520 [ 6929.723800] ? kthread_delayed_work_timer_fn+0x80/0x80 [ 6929.724081] ret_from_fork+0x3a/0x50 Fix this by letting the btrfs_dev_replace_finishing() to do the job of cleaning after the cancel, including freeing of the target device. btrfs_dev_replace_finishing() is called when btrfs_scub_dev() returns along with the scrub return status. Signed-off-by: -
Anand Jain authored
In a secnario where balance and replace co-exists as below, - start balance - pause balance - start replace - reboot and when system restarts, balance resumes first. Then the replace is attempted to restart but will fail as the EXCL_OP lock is already held by the balance. If so place the replace state back to BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED state. Fixes: 010a47bd ("btrfs: add proper safety check before resuming dev-replace") CC: stable@vger.kernel.org # 4.18+ Signed-off-by:
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Anand Jain authored
At the time of forced unmount we place the running replace to BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED state, so when the system comes back and expect the target device is missing. Then let the replace state continue to be in BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED state instead of BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED as there isn't any matching scrub running as part of replace. Fixes: e93c89c1 ("Btrfs: add new sources for device replace code") CC: stable@vger.kernel.org # 4.4+ Signed-off-by:
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Anand Jain authored
There isn't any other consumer other than in its own file dev-replace.c. Signed-off-by:
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Anand Jain authored
It's not that impossible to imagine that a device OR a btrfs image is copied just by using the dd or the cp command. Which in case both the copies of the btrfs will have the same fsid. If on the system with automount enabled, the copied FS gets scanned. We have a known bug in btrfs, that we let the device path be changed after the device has been mounted. So using this loop hole the new copied device would appears as if its mounted immediately after it's been copied. For example: Initially.. /dev/mmcblk0p4 is mounted as / $ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT mmcblk0 179:0 0 29.2G 0 disk |-mmcblk0p4 179:4 0 4G 0 part / |-mmcblk0p2 179:2 0 500M 0 part /boot |-mmcblk0p3 179:3 0 256M 0 part [SWAP] `-mmcblk0p1 179:1 0 256M 0 part /boot/efi $ btrfs fi show Label: none uuid: 07892354-ddaa-4443-90ea-f76a06accaba Total devices 1 FS bytes used 1.40GiB devid 1 size 4.00GiB used 3.00GiB path /dev/mmcblk0p4 Copy mmcblk0 to sda $ dd if=/dev/mmcblk0 of=/dev/sda And immediately after the copy completes the change in the device superblock is notified which the automount scans using btrfs device scan and the new device sda becomes the mounted root device. $ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 1 14.9G 0 disk |-sda4 8:4 1 4G 0 part / |-sda2 8:2 1 500M 0 part |-sda3 8:3 1 256M 0 part `-sda1 8:1 1 256M 0 part mmcblk0 179:0 0 29.2G 0 disk |-mmcblk0p4 179:4 0 4G 0 part |-mmcblk0p2 179:2 0 500M 0 part /boot |-mmcblk0p3 179:3 0 256M 0 part [SWAP] `-mmcblk0p1 179:1 0 256M 0 part /boot/efi $ btrfs fi show / Label: none uuid: 07892354-ddaa-4443-90ea-f76a06accaba Total devices 1 FS bytes used 1.40GiB devid 1 size 4.00GiB used 3.00GiB path /dev/sda4 The bug is quite nasty that you can't either unmount /dev/sda4 or /dev/mmcblk0p4. And the problem does not get solved until you take sda out of the system on to another system to change its fsid using the 'btrfstune -u' command. Signed-off-by: -
Hans van Kranenburg authored
Instead of hardcoding exceptions for RAID5 and RAID6 in the code, use an nparity field in raid_attr. Signed-off-by:
Hans van Kranenburg <hans.van.kranenburg@mendix.com> Signed-off-by:
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Hans van Kranenburg authored
RAID5 and RAID6 profile store one copy of the data, not 2 or 3. These values are not yet used anywhere so there's no change. Reviewed-by:
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Hans van Kranenburg authored
Commit 92e222df "btrfs: alloc_chunk: fix DUP stripe size handling" fixed calculating the stripe_size for a new DUP chunk. However, the same calculation reappears a bit later, and that one was not changed yet. The resulting bug that is exposed is that the newly allocated device extents ('stripes') can have a few MiB overlap with the next thing stored after them, which is another device extent or the end of the disk. The scenario in which this can happen is: * The block device for the filesystem is less than 10GiB in size. * The amount of contiguous free unallocated disk space chosen to use for chunk allocation is 20% of the total device size, or a few MiB more or less. An example: - The filesystem device is 7880MiB (max_chunk_size gets set to 788MiB) - There's 1578MiB unallocated raw disk space left in one contiguous piece. In this case stripe_size is first calculated as 789MiB, (half of 1578MiB). Since 789MiB (stripe_size * data_stripes) > 788MiB (max_chunk_size), we enter the if block. Now stripe_size value is immediately overwritten while calculating an adjusted value based on max_chunk_size, which ends up as 788MiB. Next, the value is rounded up to a 16MiB boundary, 800MiB, which is actually more than the value we had before. However, the last comparison fails to detect this, because it's comparing the value with the total amount of free space, which is about twice the size of stripe_size. In the example above, this means that the resulting raw disk space being allocated is 1600MiB, while only a gap of 1578MiB has been found. The second device extent object for this DUP chunk will overlap for 22MiB with whatever comes next. The underlying problem here is that the stripe_size is reused all the time for different things. So, when entering the code in the if block, stripe_size is immediately overwritten with something else. If later we decide we want to have the previous value back, then the logic to compute it was copy pasted in again. With this change, the value in stripe_size is not unnecessarily destroyed, so the duplicated calculation is not needed any more. Signed-off-by:
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Hans van Kranenburg authored
The variable num_bytes is really a way too generic name for a variable in this function. There are a dozen other variables that hold a number of bytes as value. Give it a name that actually describes what it does, which is holding the size of the chunk that we're allocating. Reviewed-by:
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Hans van Kranenburg authored
The variable num_bytes is used to store the chunk length of the chunk that we're allocating. Do not reuse it for something really different in the same function. Reviewed-by:
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Ethan Lien authored
Snapshot is expected to be fast. But if there are writers steadily creating dirty pages in our subvolume, the snapshot may take a very long time to complete. To fix the problem, we use tagged writepage for snapshot flusher as we do in the generic write_cache_pages(), so we can omit pages dirtied after the snapshot command. This does not change the semantics regarding which data get to the snapshot, if there are pages being dirtied during the snapshotting operation. There's a sync called before snapshot is taken in old/new case, any IO in flight just after that may be in the snapshot but this depends on other system effects that might still sync the IO. We do a simple snapshot speed test on a Intel D-1531 box: fio --ioengine=libaio --iodepth=32 --bs=4k --rw=write --size=64G --direct=0 --thread=1 --numjobs=1 --time_based --runtime=120 --filename=/mnt/sub/testfile --name=job1 --group_reporting & sleep 5; time btrfs sub snap -r /mnt/sub /mnt/snap; killall fio original: 1m58sec patched: 6.54sec This is the best case for this patch since for a sequential write case, we omit nearly all pages dirtied after the snapshot command. For a multi writers, random write test: fio --ioengine=libaio --iodepth=32 --bs=4k --rw=randwrite --size=64G --direct=0 --thread=1 --numjobs=4 --time_based --runtime=120 --filename=/mnt/sub/testfile --name=job1 --group_reporting & sleep 5; time btrfs sub snap -r /mnt/sub /mnt/snap; killall fio original: 15.83sec patched: 10.35sec The improvement is smaller compared to the sequential write case, since we omit only half of the pages dirtied after snapshot command. Reviewed-by:
Ethan Lien <ethanlien@synology.com> Reviewed-by:
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Nikolay Borisov authored
This parameter was never used, yet was part of the interface of the function ever since its introduction as extent_io_ops::writepage_end_io_hook in e6dcd2dc ("Btrfs: New data=ordered implementation"). Now that NULL is passed everywhere as a value for this parameter let's remove it for good. No functional changes. Signed-off-by:
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Nikolay Borisov authored
The only remaining use of the 'epd' argument in writepage_delalloc is to reference the extent_io_tree which was set in extent_writepages. Since it is guaranteed that page->mapping of any page passed to writepage_delalloc (and __extent_writepage as the sole caller) to be equal to that passed in extent_writepages we can directly get the io_tree via the already passed inode (which is also taken from page->mapping->host). No functional changes. Signed-off-by:
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Nikolay Borisov authored
If epd::extent_locked is set then writepage_delalloc terminates. Make this a bit more apparent in the caller by simply bubbling the check up. This enables to remove epd as an argument to writepage_delalloc in a future patch. No functional change. Signed-off-by:
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Nikolay Borisov authored
Before btrfs_map_bio submits all stripe bios it does a number of checks to ensure the device for every stripe is present. However, it doesn't do a DEV_STATE_MISSING check, instead this is relegated to the lower level btrfs_schedule_bio (in the async submission case, sync submission doesn't check DEV_STATE_MISSING at all). Additionally btrfs_schedule_bios does the duplicate device->bdev check which has already been performed in btrfs_map_bio. This patch moves the DEV_STATE_MISSING check in btrfs_map_bio and removes the duplicate device->bdev check. Doing so ensures that no bio cloning/submission happens for both async/sync requests in the face of missing device. This makes the async io submission path slightly shorter in terms of instruction count. No functional changes. Reviewed-by:
Josef Bacik <josef@toxicpanda.com> Reviewed-by:
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Anand Jain authored
dev_replace::replace_state has been set to BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED (0) in the same function, So delete the line which sets replace_state = 0; Reviewed-by:
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Filipe Manana authored
The io_err field of struct btrfs_log_ctx is no longer used after the recent simplification of the fast fsync path, where we now wait for ordered extents to complete before logging the inode. We did this in commit b5e6c3e1 ("btrfs: always wait on ordered extents at fsync time") and commit a2120a47 ("btrfs: clean up the left over logged_list usage") removed its last use. Reviewed-by:
Filipe Manana <fdmanana@suse.com> Signed-off-by:
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Filipe Manana authored
We currently are in a loop finding each range (corresponding to a btree node/leaf) in a log root's extent io tree and then clean it up. This is a waste of time since we are traversing the extent io tree's rb_tree more times then needed (one for a range lookup and another for cleaning it up) without any good reason. We free the log trees when we are in the critical section of a transaction commit (the transaction state is set to TRANS_STATE_COMMIT_DOING), so it's of great convenience to do everything as fast as possible in order to reduce the time we block other tasks from starting a new transaction. So fix this by traversing the extent io tree once and cleaning up all its records in one go while traversing it. Reviewed-by:
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Nikolay Borisov authored
The loop construct in free_extent_buffer was added in 242e18c7 ("Btrfs: reduce lock contention on extent buffer locks") as means of reducing the times the eb lock is taken, the non-last ref count is decremented and lock is released. As the special handling of UNMAPPED extent buffers was removed now there is only one decrement op which is happening for EXTENT_BUFFER_UNMAPPED case. This commit modifies the loop condition so that in case of UNMAPPED buffers the eb's lock is taken only if we are 100% sure the eb is going to be freed by the current executor of the code. Additionally, remove superfluous ref count ops in btrfs test. Signed-off-by:
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Nikolay Borisov authored
Now that the whole of btrfs code has been audited for eb reference count management it's time to remove the hunk in free_extent_buffer that essentially considered the condition "eb->ref == 2 && EXTENT_BUFFER_DUMMY" to equal "eb->ref = 1". Also remove the last location which takes an extra reference count in alloc_test_extent_buffer. Signed-off-by:
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Nikolay Borisov authored
In qgroup_rescan_leaf a copy is made of the target leaf by calling btrfs_clone_extent_buffer. The latter allocates a new buffer and attaches a new set of pages and copies the content of the source buffer. The new scratch buffer is only used to iterate it's items, it's not published anywhere and cannot be accessed by a third party. Hence, it's not necessary to perform any locking on it whatsoever. Furthermore, remove the extra extent_buffer_get call since the new buffer is always allocated with a reference count of 1 which is sufficient here. No functional changes. Signed-off-by:
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Nikolay Borisov authored
When the 2 comparison trees roots are initialised they are private to the function and already have reference counts of 1 each. There is no need to further increment the reference count since the cloned buffers are already accessed via struct btrfs_path. Eventually the 2 paths used for comparison are going to be released, effectively disposing of the cloned buffers. Signed-off-by:
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