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* btrfs: qgroup: mark qgroup inconsistent if we're inherting snapshot to a new ↵Qu Wenruo2020-05-251-0/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | qgroup [BUG] For the following operation, qgroup is guaranteed to be screwed up due to snapshot adding to a new qgroup: # mkfs.btrfs -f $dev # mount $dev $mnt # btrfs qgroup en $mnt # btrfs subv create $mnt/src # xfs_io -f -c "pwrite 0 1m" $mnt/src/file # sync # btrfs qgroup create 1/0 $mnt/src # btrfs subv snapshot -i 1/0 $mnt/src $mnt/snapshot # btrfs qgroup show -prce $mnt/src qgroupid rfer excl max_rfer max_excl parent child -------- ---- ---- -------- -------- ------ ----- 0/5 16.00KiB 16.00KiB none none --- --- 0/257 1.02MiB 16.00KiB none none --- --- 0/258 1.02MiB 16.00KiB none none 1/0 --- 1/0 0.00B 0.00B none none --- 0/258 ^^^^^^^^^^^^^^^^^^^^ [CAUSE] The problem is in btrfs_qgroup_inherit(), we don't have good enough check to determine if the new relation would break the existing accounting. Unlike btrfs_add_qgroup_relation(), which has proper check to determine if we can do quick update without a rescan, in btrfs_qgroup_inherit() we can even assign a snapshot to multiple qgroups. [FIX] Fix it by manually marking qgroup inconsistent for snapshot inheritance. For subvolume creation, since all its extents are exclusively owned, we don't need to rescan. In theory, we should call relation check like quick_update_accounting() when doing qgroup inheritance and inform user about qgroup accounting inconsistency. But we don't have good mechanism to relay that back to the user in the snapshot creation context, thus we can only silently mark the qgroup inconsistent. Anyway, user shouldn't use qgroup inheritance during snapshot creation, and should add qgroup relationship after snapshot creation by 'btrfs qgroup assign', which has a much better UI to inform user about qgroup inconsistent and kick in rescan automatically. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: move the root freeing stuff into btrfs_put_rootJosef Bacik2020-03-231-6/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | There are a few different ways to free roots, either you allocated them yourself and you just do free_extent_buffer(root->node); free_extent_buffer(root->commit_node); btrfs_put_root(root); Which is the pattern for log roots. Or for snapshots/subvolumes that are being dropped you simply call btrfs_free_fs_root() which does all the cleanup for you. Unify this all into btrfs_put_root(), so that we don't free up things associated with the root until the last reference is dropped. This makes the root freeing code much more significant. The only caveat is at close_ctree() time we have to free the extent buffers for all of our main roots (extent_root, chunk_root, etc) because we have to drop the btree_inode and we'll run into issues if we hold onto those nodes until ->kill_sb() time. This will be addressed in the future when we kill the btree_inode. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Remove the unnecesaary spin lock for qgroup_rescan_runningQu Wenruo2020-03-231-6/+0
| | | | | | | | | | After the previous patch, qgroup_rescan_running is protected by btrfs_fs_info::qgroup_rescan_lock, thus no need for the extra spinlock. Suggested-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: ensure qgroup_rescan_running is only set when the worker is ↵Qu Wenruo2020-03-231-2/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | at least queued [BUG] There are some reports about btrfs wait forever to unmount itself, with the following call trace: INFO: task umount:4631 blocked for more than 491 seconds. Tainted: G X 5.3.8-2-default #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. umount D 0 4631 3337 0x00000000 Call Trace: ([<00000000174adf7a>] __schedule+0x342/0x748) [<00000000174ae3ca>] schedule+0x4a/0xd8 [<00000000174b1f08>] schedule_timeout+0x218/0x420 [<00000000174af10c>] wait_for_common+0x104/0x1d8 [<000003ff804d6994>] btrfs_qgroup_wait_for_completion+0x84/0xb0 [btrfs] [<000003ff8044a616>] close_ctree+0x4e/0x380 [btrfs] [<0000000016fa3136>] generic_shutdown_super+0x8e/0x158 [<0000000016fa34d6>] kill_anon_super+0x26/0x40 [<000003ff8041ba88>] btrfs_kill_super+0x28/0xc8 [btrfs] [<0000000016fa39f8>] deactivate_locked_super+0x68/0x98 [<0000000016fcb198>] cleanup_mnt+0xc0/0x140 [<0000000016d6a846>] task_work_run+0xc6/0x110 [<0000000016d04f76>] do_notify_resume+0xae/0xb8 [<00000000174b30ae>] system_call+0xe2/0x2c8 [CAUSE] The problem happens when we have called qgroup_rescan_init(), but not queued the worker. It can be caused mostly by error handling. Qgroup ioctl thread | Unmount thread ----------------------------------------+----------------------------------- | btrfs_qgroup_rescan() | |- qgroup_rescan_init() | | |- qgroup_rescan_running = true; | | | |- trans = btrfs_join_transaction() | | Some error happened | | | |- btrfs_qgroup_rescan() returns error | But qgroup_rescan_running == true; | | close_ctree() | |- btrfs_qgroup_wait_for_completion() | |- running == true; | |- wait_for_completion(); btrfs_qgroup_rescan_worker is never queued, thus no one is going to wake up close_ctree() and we get a deadlock. All involved qgroup_rescan_init() callers are: - btrfs_qgroup_rescan() The example above. It's possible to trigger the deadlock when error happened. - btrfs_quota_enable() Not possible. Just after qgroup_rescan_init() we queue the work. - btrfs_read_qgroup_config() It's possible to trigger the deadlock. It only init the work, the work queueing happens in btrfs_qgroup_rescan_resume(). Thus if error happened in between, deadlock is possible. We shouldn't set fs_info->qgroup_rescan_running just in qgroup_rescan_init(), as at that stage we haven't yet queued qgroup rescan worker to run. [FIX] Set qgroup_rescan_running before queueing the work, so that we ensure the rescan work is queued when we wait for it. Fixes: 8d9eddad1946 ("Btrfs: fix qgroup rescan worker initialization") Signed-off-by: Jeff Mahoney <jeffm@suse.com> [ Change subject and cause analyse, use a smaller fix ] Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: rename btrfs_put_fs_root and btrfs_grab_fs_rootJosef Bacik2020-03-231-2/+2
| | | | | | | | | | We are now using these for all roots, rename them to btrfs_put_root() and btrfs_grab_root(); Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: use btrfs_put_fs_root to free roots alwaysJosef Bacik2020-03-231-2/+2
| | | | | | | | | | If we are going to track leaked roots we need to free them all the same way, so don't kfree() roots directly, use btrfs_put_fs_root. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: destroy qgroup extent records on transaction abortJeff Mahoney2020-02-191-0/+13
| | | | | | | | | | | | | | | | | | We clean up the delayed references when we abort a transaction but we leave the pending qgroup extent records behind, leaking memory. This patch destroys the extent records when we destroy the delayed refs and makes sure ensure they're gone before releasing the transaction. Fixes: 3368d001ba5d ("btrfs: qgroup: Record possible quota-related extent for qgroup.") CC: stable@vger.kernel.org # 4.4+ Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jeff Mahoney <jeffm@suse.com> [ Rebased to latest upstream, remove to_qgroup() helper, use rbtree_postorder_for_each_entry_safe() wrapper ] Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: return ENOTCONN instead of EINVAL when quotas are not enabledMarcos Paulo de Souza2020-01-201-5/+5
| | | | | | | | | | | | | | | | | | | | [PROBLEM] qgroup create/remove code is currently returning EINVAL when the user tries to create a qgroup on a subvolume without quota enabled. EINVAL is already being used for too many error scenarios so that is hard to depict what is the problem. [FIX] Currently scrub and balance code return -ENOTCONN when the user tries to cancel/pause and no scrub or balance is currently running for the desired subvolume. Do the same here by returning -ENOTCONN when a user tries to create/delete/assing/list a qgroup on a subvolume without quota enabled. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: remove one-time use variables for quota_root checksMarcos Paulo de Souza2020-01-201-24/+10
| | | | | | | | | | Remove some variables that are set only to be checked later, and never used. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: fix memory leak in qgroup accountingJohannes Thumshirn2020-01-081-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When running xfstests on the current btrfs I get the following splat from kmemleak: unreferenced object 0xffff88821b2404e0 (size 32): comm "kworker/u4:7", pid 26663, jiffies 4295283698 (age 8.776s) hex dump (first 32 bytes): 01 00 00 00 00 00 00 00 10 ff fd 26 82 88 ff ff ...........&.... 10 ff fd 26 82 88 ff ff 20 ff fd 26 82 88 ff ff ...&.... ..&.... backtrace: [<00000000f94fd43f>] ulist_alloc+0x25/0x60 [btrfs] [<00000000fd023d99>] btrfs_find_all_roots_safe+0x41/0x100 [btrfs] [<000000008f17bd32>] btrfs_find_all_roots+0x52/0x70 [btrfs] [<00000000b7660afb>] btrfs_qgroup_rescan_worker+0x343/0x680 [btrfs] [<0000000058e66778>] btrfs_work_helper+0xac/0x1e0 [btrfs] [<00000000f0188930>] process_one_work+0x1cf/0x350 [<00000000af5f2f8e>] worker_thread+0x28/0x3c0 [<00000000b55a1add>] kthread+0x109/0x120 [<00000000f88cbd17>] ret_from_fork+0x35/0x40 This corresponds to: (gdb) l *(btrfs_find_all_roots_safe+0x41) 0x8d7e1 is in btrfs_find_all_roots_safe (fs/btrfs/backref.c:1413). 1408 1409 tmp = ulist_alloc(GFP_NOFS); 1410 if (!tmp) 1411 return -ENOMEM; 1412 *roots = ulist_alloc(GFP_NOFS); 1413 if (!*roots) { 1414 ulist_free(tmp); 1415 return -ENOMEM; 1416 } 1417 Following the lifetime of the allocated 'roots' ulist, it gets freed again in btrfs_qgroup_account_extent(). But this does not happen if the function is called with the 'BTRFS_FS_QUOTA_ENABLED' flag cleared, then btrfs_qgroup_account_extent() does a short leave and directly returns. Instead of directly returning we should jump to the 'out_free' in order to free all resources as expected. CC: stable@vger.kernel.org # 4.14+ Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> [ add comment ] Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: Fix error messages in qgroup_rescan_initNikolay Borisov2019-12-131-2/+2
| | | | | | | | | | | The branch of qgroup_rescan_init which is executed from the mount path prints wrong errors messages. The textual print out in case BTRFS_QGROUP_STATUS_FLAG_RESCAN/BTRFS_QGROUP_STATUS_FLAG_ON are not set are transposed. Fix it by exchanging their place. Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: rename btrfs_block_group_cacheDavid Sterba2019-11-181-1/+1
| | | | | | | | | | The type name is misleading, a single entry is named 'cache' while this normally means a collection of objects. Rename that everywhere. Also the identifier was quite long, making function prototypes harder to format. Suggested-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: opencode extent_buffer_getDavid Sterba2019-11-181-3/+3
| | | | | | | | | The helper is trivial and we can understand what the atomic_inc on something named refs does. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: get rid of unique workqueue helper functionsOmar Sandoval2019-11-181-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | Commit 9e0af2376434 ("Btrfs: fix task hang under heavy compressed write") worked around the issue that a recycled work item could get a false dependency on the original work item due to how the workqueue code guarantees non-reentrancy. It did so by giving different work functions to different types of work. However, the fixes in the previous few patches are more complete, as they prevent a work item from being recycled at all (except for a tiny window that the kernel workqueue code handles for us). This obsoletes the previous fix, so we don't need the unique helpers for correctness. The only other reason to keep them would be so they show up in stack traces, but they always seem to be optimized to a tail call, so they don't show up anyways. So, let's just get rid of the extra indirection. While we're here, rename normal_work_helper() to the more informative btrfs_work_helper(). Reviewed-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Omar Sandoval <osandov@fb.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: get rid of unnecessary memset() of work itemOmar Sandoval2019-11-181-2/+0
| | | | | | | | | | | | Commit fc97fab0ea59 ("btrfs: Replace fs_info->qgroup_rescan_worker workqueue with btrfs_workqueue.") converted qgroup_rescan_work to be initialized with btrfs_init_work(), but it left behind an unnecessary memset(). Get rid of the memset(). Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Omar Sandoval <osandov@fb.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: tracepoints: Fix wrong parameter order for qgroup eventsQu Wenruo2019-10-171-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | [BUG] For btrfs:qgroup_meta_reserve event, the trace event can output garbage: qgroup_meta_reserve: 9c7f6acc-b342-4037-bc47-7f6e4d2232d7: refroot=5(FS_TREE) type=DATA diff=2 The diff should always be alinged to sector size (4k), so there is definitely something wrong. [CAUSE] For the wrong @diff, it's caused by wrong parameter order. The correct parameters are: struct btrfs_root, s64 diff, int type. However the parameters used are: struct btrfs_root, int type, s64 diff. Fixes: 4ee0d8832c2e ("btrfs: qgroup: Update trace events for metadata reservation") CC: stable@vger.kernel.org # 4.19+ Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Fix reserved data space leak if we have multiple reserve callsQu Wenruo2019-09-271-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [BUG] The following script can cause btrfs qgroup data space leak: mkfs.btrfs -f $dev mount $dev -o nospace_cache $mnt btrfs subv create $mnt/subv btrfs quota en $mnt btrfs quota rescan -w $mnt btrfs qgroup limit 128m $mnt/subv for (( i = 0; i < 3; i++)); do # Create 3 64M holes for latter fallocate to fail truncate -s 192m $mnt/subv/file xfs_io -c "pwrite 64m 4k" $mnt/subv/file > /dev/null xfs_io -c "pwrite 128m 4k" $mnt/subv/file > /dev/null sync # it's supposed to fail, and each failure will leak at least 64M # data space xfs_io -f -c "falloc 0 192m" $mnt/subv/file &> /dev/null rm $mnt/subv/file sync done # Shouldn't fail after we removed the file xfs_io -f -c "falloc 0 64m" $mnt/subv/file [CAUSE] Btrfs qgroup data reserve code allow multiple reservations to happen on a single extent_changeset: E.g: btrfs_qgroup_reserve_data(inode, &data_reserved, 0, SZ_1M); btrfs_qgroup_reserve_data(inode, &data_reserved, SZ_1M, SZ_2M); btrfs_qgroup_reserve_data(inode, &data_reserved, 0, SZ_4M); Btrfs qgroup code has its internal tracking to make sure we don't double-reserve in above example. The only pattern utilizing this feature is in the main while loop of btrfs_fallocate() function. However btrfs_qgroup_reserve_data()'s error handling has a bug in that on error it clears all ranges in the io_tree with EXTENT_QGROUP_RESERVED flag but doesn't free previously reserved bytes. This bug has a two fold effect: - Clearing EXTENT_QGROUP_RESERVED ranges This is the correct behavior, but it prevents btrfs_qgroup_check_reserved_leak() to catch the leakage as the detector is purely EXTENT_QGROUP_RESERVED flag based. - Leak the previously reserved data bytes. The bug manifests when N calls to btrfs_qgroup_reserve_data are made and the last one fails, leaking space reserved in the previous ones. [FIX] Also free previously reserved data bytes when btrfs_qgroup_reserve_data fails. Fixes: 524725537023 ("btrfs: qgroup: Introduce btrfs_qgroup_reserve_data function") CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Fix the wrong target io_tree when freeing reserved data spaceQu Wenruo2019-09-271-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [BUG] Under the following case with qgroup enabled, if some error happened after we have reserved delalloc space, then in error handling path, we could cause qgroup data space leakage: From btrfs_truncate_block() in inode.c: ret = btrfs_delalloc_reserve_space(inode, &data_reserved, block_start, blocksize); if (ret) goto out; again: page = find_or_create_page(mapping, index, mask); if (!page) { btrfs_delalloc_release_space(inode, data_reserved, block_start, blocksize, true); btrfs_delalloc_release_extents(BTRFS_I(inode), blocksize, true); ret = -ENOMEM; goto out; } [CAUSE] In the above case, btrfs_delalloc_reserve_space() will call btrfs_qgroup_reserve_data() and mark the io_tree range with EXTENT_QGROUP_RESERVED flag. In the error handling path, we have the following call stack: btrfs_delalloc_release_space() |- btrfs_free_reserved_data_space() |- btrsf_qgroup_free_data() |- __btrfs_qgroup_release_data(reserved=@reserved, free=1) |- qgroup_free_reserved_data(reserved=@reserved) |- clear_record_extent_bits(); |- freed += changeset.bytes_changed; However due to a completion bug, qgroup_free_reserved_data() will clear EXTENT_QGROUP_RESERVED flag in BTRFS_I(inode)->io_failure_tree, other than the correct BTRFS_I(inode)->io_tree. Since io_failure_tree is never marked with that flag, btrfs_qgroup_free_data() will not free any data reserved space at all, causing a leakage. This type of error handling can only be triggered by errors outside of qgroup code. So EDQUOT error from qgroup can't trigger it. [FIX] Fix the wrong target io_tree. Reported-by: Josef Bacik <josef@toxicpanda.com> Fixes: bc42bda22345 ("btrfs: qgroup: Fix qgroup reserved space underflow by only freeing reserved ranges") CC: stable@vger.kernel.org # 4.14+ Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* Btrfs: fix race setting up and completing qgroup rescan workersFilipe Manana2019-09-241-14/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is a race between setting up a qgroup rescan worker and completing a qgroup rescan worker that can lead to callers of the qgroup rescan wait ioctl to either not wait for the rescan worker to complete or to hang forever due to missing wake ups. The following diagram shows a sequence of steps that illustrates the race. CPU 1 CPU 2 CPU 3 btrfs_ioctl_quota_rescan() btrfs_qgroup_rescan() qgroup_rescan_init() mutex_lock(&fs_info->qgroup_rescan_lock) spin_lock(&fs_info->qgroup_lock) fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_RESCAN init_completion( &fs_info->qgroup_rescan_completion) fs_info->qgroup_rescan_running = true mutex_unlock(&fs_info->qgroup_rescan_lock) spin_unlock(&fs_info->qgroup_lock) btrfs_init_work() --> starts the worker btrfs_qgroup_rescan_worker() mutex_lock(&fs_info->qgroup_rescan_lock) fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN mutex_unlock(&fs_info->qgroup_rescan_lock) starts transaction, updates qgroup status item, etc btrfs_ioctl_quota_rescan() btrfs_qgroup_rescan() qgroup_rescan_init() mutex_lock(&fs_info->qgroup_rescan_lock) spin_lock(&fs_info->qgroup_lock) fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_RESCAN init_completion( &fs_info->qgroup_rescan_completion) fs_info->qgroup_rescan_running = true mutex_unlock(&fs_info->qgroup_rescan_lock) spin_unlock(&fs_info->qgroup_lock) btrfs_init_work() --> starts another worker mutex_lock(&fs_info->qgroup_rescan_lock) fs_info->qgroup_rescan_running = false mutex_unlock(&fs_info->qgroup_rescan_lock) complete_all(&fs_info->qgroup_rescan_completion) Before the rescan worker started by the task at CPU 3 completes, if another task calls btrfs_ioctl_quota_rescan(), it will get -EINPROGRESS because the flag BTRFS_QGROUP_STATUS_FLAG_RESCAN is set at fs_info->qgroup_flags, which is expected and correct behaviour. However if other task calls btrfs_ioctl_quota_rescan_wait() before the rescan worker started by the task at CPU 3 completes, it will return immediately without waiting for the new rescan worker to complete, because fs_info->qgroup_rescan_running is set to false by CPU 2. This race is making test case btrfs/171 (from fstests) to fail often: btrfs/171 9s ... - output mismatch (see /home/fdmanana/git/hub/xfstests/results//btrfs/171.out.bad) --- tests/btrfs/171.out 2018-09-16 21:30:48.505104287 +0100 +++ /home/fdmanana/git/hub/xfstests/results//btrfs/171.out.bad 2019-09-19 02:01:36.938486039 +0100 @@ -1,2 +1,3 @@ QA output created by 171 +ERROR: quota rescan failed: Operation now in progress Silence is golden ... (Run 'diff -u /home/fdmanana/git/hub/xfstests/tests/btrfs/171.out /home/fdmanana/git/hub/xfstests/results//btrfs/171.out.bad' to see the entire diff) That is because the test calls the btrfs-progs commands "qgroup quota rescan -w", "qgroup assign" and "qgroup remove" in a sequence that makes calls to the rescan start ioctl fail with -EINPROGRESS (note the "btrfs" commands 'qgroup assign' and 'qgroup remove' often call the rescan start ioctl after calling the qgroup assign ioctl, btrfs_ioctl_qgroup_assign()), since previous waits didn't actually wait for a rescan worker to complete. Another problem the race can cause is missing wake ups for waiters, since the call to complete_all() happens outside a critical section and after clearing the flag BTRFS_QGROUP_STATUS_FLAG_RESCAN. In the sequence diagram above, if we have a waiter for the first rescan task (executed by CPU 2), then fs_info->qgroup_rescan_completion.wait is not empty, and if after the rescan worker clears BTRFS_QGROUP_STATUS_FLAG_RESCAN and before it calls complete_all() against fs_info->qgroup_rescan_completion, the task at CPU 3 calls init_completion() against fs_info->qgroup_rescan_completion which re-initilizes its wait queue to an empty queue, therefore causing the rescan worker at CPU 2 to call complete_all() against an empty queue, never waking up the task waiting for that rescan worker. Fix this by clearing BTRFS_QGROUP_STATUS_FLAG_RESCAN and setting fs_info->qgroup_rescan_running to false in the same critical section, delimited by the mutex fs_info->qgroup_rescan_lock, as well as doing the call to complete_all() in that same critical section. This gives the protection needed to avoid rescan wait ioctl callers not waiting for a running rescan worker and the lost wake ups problem, since setting that rescan flag and boolean as well as initializing the wait queue is done already in a critical section delimited by that mutex (at qgroup_rescan_init()). Fixes: 57254b6ebce4ce ("Btrfs: add ioctl to wait for qgroup rescan completion") Fixes: d2c609b834d62f ("btrfs: properly track when rescan worker is running") CC: stable@vger.kernel.org # 4.4+ Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Try our best to delete qgroup relationsQu Wenruo2019-09-091-17/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When we try to delete qgroups, we're pretty cautious, we make sure both qgroups exist and there is a relationship between them, then try to delete the relation. This behavior is OK, but the problem is we need to two relation items, and if we failed the first item deletion, we error out, leaving the other relation item in qgroup tree. Sometimes the error from del_qgroup_relation_item() could just be -ENOENT, thus we can ignore that error and continue without any problem. Further more, such cautious behavior makes qgroup relation deletion impossible for orphan relation items. This patch will enhance __del_qgroup_relation(): - If both qgroups and their relation items exist Go the regular deletion routine and update their accounting if needed. - If any qgroup or relation item doesn't exist Then we still try to delete the orphan items anyway, but don't trigger the accounting update. By this, we try our best to remove relation items, and can handle orphan relation items properly, while still keep the existing behavior for good qgroup tree. Reported-by: Andrei Borzenkov <arvidjaar@gmail.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: move basic block_group definitions to their own headerJosef Bacik2019-09-091-1/+1
| | | | | | | | | | This is prep work for moving all of the block group cache code into its own file. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> [ minor comment updates ] Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Don't hold qgroup_ioctl_lock in btrfs_qgroup_inherit()Qu Wenruo2019-07-021-2/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [BUG] Lockdep will report the following circular locking dependency: WARNING: possible circular locking dependency detected 5.2.0-rc2-custom #24 Tainted: G O ------------------------------------------------------ btrfs/8631 is trying to acquire lock: 000000002536438c (&fs_info->qgroup_ioctl_lock#2){+.+.}, at: btrfs_qgroup_inherit+0x40/0x620 [btrfs] but task is already holding lock: 000000003d52cc23 (&fs_info->tree_log_mutex){+.+.}, at: create_pending_snapshot+0x8b6/0xe60 [btrfs] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&fs_info->tree_log_mutex){+.+.}: __mutex_lock+0x76/0x940 mutex_lock_nested+0x1b/0x20 btrfs_commit_transaction+0x475/0xa00 [btrfs] btrfs_commit_super+0x71/0x80 [btrfs] close_ctree+0x2bd/0x320 [btrfs] btrfs_put_super+0x15/0x20 [btrfs] generic_shutdown_super+0x72/0x110 kill_anon_super+0x18/0x30 btrfs_kill_super+0x16/0xa0 [btrfs] deactivate_locked_super+0x3a/0x80 deactivate_super+0x51/0x60 cleanup_mnt+0x3f/0x80 __cleanup_mnt+0x12/0x20 task_work_run+0x94/0xb0 exit_to_usermode_loop+0xd8/0xe0 do_syscall_64+0x210/0x240 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&fs_info->reloc_mutex){+.+.}: __mutex_lock+0x76/0x940 mutex_lock_nested+0x1b/0x20 btrfs_commit_transaction+0x40d/0xa00 [btrfs] btrfs_quota_enable+0x2da/0x730 [btrfs] btrfs_ioctl+0x2691/0x2b40 [btrfs] do_vfs_ioctl+0xa9/0x6d0 ksys_ioctl+0x67/0x90 __x64_sys_ioctl+0x1a/0x20 do_syscall_64+0x65/0x240 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&fs_info->qgroup_ioctl_lock#2){+.+.}: lock_acquire+0xa7/0x190 __mutex_lock+0x76/0x940 mutex_lock_nested+0x1b/0x20 btrfs_qgroup_inherit+0x40/0x620 [btrfs] create_pending_snapshot+0x9d7/0xe60 [btrfs] create_pending_snapshots+0x94/0xb0 [btrfs] btrfs_commit_transaction+0x415/0xa00 [btrfs] btrfs_mksubvol+0x496/0x4e0 [btrfs] btrfs_ioctl_snap_create_transid+0x174/0x180 [btrfs] btrfs_ioctl_snap_create_v2+0x11c/0x180 [btrfs] btrfs_ioctl+0xa90/0x2b40 [btrfs] do_vfs_ioctl+0xa9/0x6d0 ksys_ioctl+0x67/0x90 __x64_sys_ioctl+0x1a/0x20 do_syscall_64+0x65/0x240 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: &fs_info->qgroup_ioctl_lock#2 --> &fs_info->reloc_mutex --> &fs_info->tree_log_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&fs_info->tree_log_mutex); lock(&fs_info->reloc_mutex); lock(&fs_info->tree_log_mutex); lock(&fs_info->qgroup_ioctl_lock#2); *** DEADLOCK *** 6 locks held by btrfs/8631: #0: 00000000ed8f23f6 (sb_writers#12){.+.+}, at: mnt_want_write_file+0x28/0x60 #1: 000000009fb1597a (&type->i_mutex_dir_key#10/1){+.+.}, at: btrfs_mksubvol+0x70/0x4e0 [btrfs] #2: 0000000088c5ad88 (&fs_info->subvol_sem){++++}, at: btrfs_mksubvol+0x128/0x4e0 [btrfs] #3: 000000009606fc3e (sb_internal#2){.+.+}, at: start_transaction+0x37a/0x520 [btrfs] #4: 00000000f82bbdf5 (&fs_info->reloc_mutex){+.+.}, at: btrfs_commit_transaction+0x40d/0xa00 [btrfs] #5: 000000003d52cc23 (&fs_info->tree_log_mutex){+.+.}, at: create_pending_snapshot+0x8b6/0xe60 [btrfs] [CAUSE] Due to the delayed subvolume creation, we need to call btrfs_qgroup_inherit() inside commit transaction code, with a lot of other mutex hold. This hell of lock chain can lead to above problem. [FIX] On the other hand, we don't really need to hold qgroup_ioctl_lock if we're in the context of create_pending_snapshot(). As in that context, we're the only one being able to modify qgroup. All other qgroup functions which needs qgroup_ioctl_lock are either holding a transaction handle, or will start a new transaction: Functions will start a new transaction(): * btrfs_quota_enable() * btrfs_quota_disable() Functions hold a transaction handler: * btrfs_add_qgroup_relation() * btrfs_del_qgroup_relation() * btrfs_create_qgroup() * btrfs_remove_qgroup() * btrfs_limit_qgroup() * btrfs_qgroup_inherit() call inside create_subvol() So we have a higher level protection provided by transaction, thus we don't need to always hold qgroup_ioctl_lock in btrfs_qgroup_inherit(). Only the btrfs_qgroup_inherit() call in create_subvol() needs to hold qgroup_ioctl_lock, while the btrfs_qgroup_inherit() call in create_pending_snapshot() is already protected by transaction. So the fix is to detect the context by checking trans->transaction->state. If we're at TRANS_STATE_COMMIT_DOING, then we're in commit transaction context and no need to get the mutex. Reported-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Check bg while resuming relocation to avoid NULL pointer ↵Qu Wenruo2019-05-281-1/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | dereference [BUG] When mounting a fs with reloc tree and has qgroup enabled, it can cause NULL pointer dereference at mount time: BUG: kernel NULL pointer dereference, address: 00000000000000a8 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI RIP: 0010:btrfs_qgroup_add_swapped_blocks+0x186/0x300 [btrfs] Call Trace: replace_path.isra.23+0x685/0x900 [btrfs] merge_reloc_root+0x26e/0x5f0 [btrfs] merge_reloc_roots+0x10a/0x1a0 [btrfs] btrfs_recover_relocation+0x3cd/0x420 [btrfs] open_ctree+0x1bc8/0x1ed0 [btrfs] btrfs_mount_root+0x544/0x680 [btrfs] legacy_get_tree+0x34/0x60 vfs_get_tree+0x2d/0xf0 fc_mount+0x12/0x40 vfs_kern_mount.part.12+0x61/0xa0 vfs_kern_mount+0x13/0x20 btrfs_mount+0x16f/0x860 [btrfs] legacy_get_tree+0x34/0x60 vfs_get_tree+0x2d/0xf0 do_mount+0x81f/0xac0 ksys_mount+0xbf/0xe0 __x64_sys_mount+0x25/0x30 do_syscall_64+0x65/0x240 entry_SYSCALL_64_after_hwframe+0x49/0xbe [CAUSE] In btrfs_recover_relocation(), we don't have enough info to determine which block group we're relocating, but only to merge existing reloc trees. Thus in btrfs_recover_relocation(), rc->block_group is NULL. btrfs_qgroup_add_swapped_blocks() hasn't taken this into consideration, and causes a NULL pointer dereference. The bug is introduced by commit 3d0174f78e72 ("btrfs: qgroup: Only trace data extents in leaves if we're relocating data block group"), and later qgroup refactoring still keeps this optimization. [FIX] Thankfully in the context of btrfs_recover_relocation(), there is no other progress can modify tree blocks, thus those swapped tree blocks pair will never affect qgroup numbers, no matter whatever we set for block->trace_leaf. So we only need to check if @bg is NULL before accessing @bg->flags. Reported-by: Juan Erbes <jerbes@gmail.com> Link: https://bugzilla.opensuse.org/show_bug.cgi?id=1134806 Fixes: 3d0174f78e72 ("btrfs: qgroup: Only trace data extents in leaves if we're relocating data block group") CC: stable@vger.kernel.org # 4.20+ Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: get fs_info from trans in btrfs_create_treeDavid Sterba2019-04-291-2/+1
| | | | | | | We can read fs_info from the transaction and can drop it from the parameters. Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: get fs_info from eb in clean_tree_blockDavid Sterba2019-04-291-1/+1
| | | | | | | We can read fs_info from extent buffer and can drop it from the parameters. Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: Fix bound checking in qgroup_trace_new_subtree_blocksNikolay Borisov2019-03-191-2/+2
| | | | | | | | | | | | | | | | | If 'cur_level' is 7 then the bound checking at the top of the function will actually pass. Later on, it's possible to dereference ds_path->nodes[cur_level+1] which will be an out of bounds. The correct check will be cur_level >= BTRFS_MAX_LEVEL - 1 . Fixes-coverty-id: 1440918 Fixes-coverty-id: 1440911 Fixes: ea49f3e73c4b ("btrfs: qgroup: Introduce function to find all new tree blocks of reloc tree") CC: stable@vger.kernel.org # 4.20+ Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: move ulist allocation out of transaction in quota enableDavid Sterba2019-02-271-7/+6
| | | | | | | | | | | | | | The allocation happens with GFP_KERNEL after a transaction has been started, this can potentially cause deadlock if reclaim tries to get the memory by flushing filesystem data. The fs_info::qgroup_ulist is not used during transaction start when quotas are not enabled. The status bit BTRFS_FS_QUOTA_ENABLED is set later in btrfs_quota_enable so it's safe to move it before the transaction start. Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Make qgroup async transaction commit more aggressiveQu Wenruo2019-02-251-14/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [BUG] Btrfs qgroup will still hit EDQUOT under the following case: $ dev=/dev/test/test $ mnt=/mnt/btrfs $ umount $mnt &> /dev/null $ umount $dev &> /dev/null $ mkfs.btrfs -f $dev $ mount $dev $mnt -o nospace_cache $ btrfs subv create $mnt/subv $ btrfs quota enable $mnt $ btrfs quota rescan -w $mnt $ btrfs qgroup limit -e 1G $mnt/subv $ fallocate -l 900M $mnt/subv/padding $ sync $ rm $mnt/subv/padding # Hit EDQUOT $ xfs_io -f -c "pwrite 0 512M" $mnt/subv/real_file [CAUSE] Since commit a514d63882c3 ("btrfs: qgroup: Commit transaction in advance to reduce early EDQUOT"), btrfs is not forced to commit transaction to reclaim more quota space. Instead, we just check pertrans metadata reservation against some threshold and try to do asynchronously transaction commit. However in above case, the pertrans metadata reservation is pretty small thus it will never trigger asynchronous transaction commit. [FIX] Instead of only accounting pertrans metadata reservation, we calculate how much free space we have, and if there isn't much free space left, commit transaction asynchronously to try to free some space. This may slow down the fs when we have less than 32M free qgroup space, but should reduce a lot of false EDQUOT, so the cost should be acceptable. Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Move reserved data accounting from btrfs_delayed_ref_head to ↵Qu Wenruo2019-02-251-4/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | btrfs_qgroup_extent_record [BUG] Btrfs/139 will fail with a high probability if the testing machine (VM) has only 2G RAM. Resulting the final write success while it should fail due to EDQUOT, and the fs will have quota exceeding the limit by 16K. The simplified reproducer will be: (needs a 2G ram VM) $ mkfs.btrfs -f $dev $ mount $dev $mnt $ btrfs subv create $mnt/subv $ btrfs quota enable $mnt $ btrfs quota rescan -w $mnt $ btrfs qgroup limit -e 1G $mnt/subv $ for i in $(seq -w 1 8); do xfs_io -f -c "pwrite 0 128M" $mnt/subv/file_$i > /dev/null echo "file $i written" > /dev/kmsg done $ sync $ btrfs qgroup show -pcre --raw $mnt The last pwrite will not trigger EDQUOT and final 'qgroup show' will show something like: qgroupid rfer excl max_rfer max_excl parent child -------- ---- ---- -------- -------- ------ ----- 0/5 16384 16384 none none --- --- 0/256 1073758208 1073758208 none 1073741824 --- --- And 1073758208 is larger than > 1073741824. [CAUSE] It's a bug in btrfs qgroup data reserved space management. For quota limit, we must ensure that: reserved (data + metadata) + rfer/excl <= limit Since rfer/excl is only updated at transaction commmit time, reserved space needs to be taken special care. One important part of reserved space is data, and for a new data extent written to disk, we still need to take the reserved space until rfer/excl numbers get updated. Originally when an ordered extent finishes, we migrate the reserved qgroup data space from extent_io tree to delayed ref head of the data extent, expecting delayed ref will only be cleaned up at commit transaction time. However for small RAM machine, due to memory pressure dirty pages can be flushed back to disk without committing a transaction. The related events will be something like: file 1 written btrfs_finish_ordered_io: ino=258 ordered offset=0 len=54947840 btrfs_finish_ordered_io: ino=258 ordered offset=54947840 len=5636096 btrfs_finish_ordered_io: ino=258 ordered offset=61153280 len=57344 btrfs_finish_ordered_io: ino=258 ordered offset=61210624 len=8192 btrfs_finish_ordered_io: ino=258 ordered offset=60583936 len=569344 cleanup_ref_head: num_bytes=54947840 cleanup_ref_head: num_bytes=5636096 cleanup_ref_head: num_bytes=569344 cleanup_ref_head: num_bytes=57344 cleanup_ref_head: num_bytes=8192 ^^^^^^^^^^^^^^^^ This will free qgroup data reserved space file 2 written ... file 8 written cleanup_ref_head: num_bytes=8192 ... btrfs_commit_transaction <<< the only transaction committed during the test When file 2 is written, we have already freed 128M reserved qgroup data space for ino 258. Thus later write won't trigger EDQUOT. This allows us to write more data beyond qgroup limit. In my 2G ram VM, it could reach about 1.2G before hitting EDQUOT. [FIX] By moving reserved qgroup data space from btrfs_delayed_ref_head to btrfs_qgroup_extent_record, we can ensure that reserved qgroup data space won't be freed half way before commit transaction, thus fix the problem. Fixes: f64d5ca86821 ("btrfs: delayed_ref: Add new function to record reserved space into delayed ref") Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Remove duplicated trace points for qgroup_rsv_add/releaseQu Wenruo2019-02-251-2/+0
| | | | | | | | | | | | | Inside qgroup_rsv_add/release(), we have trace events trace_qgroup_update_reserve() to catch reserved space update. However we still have two manual trace_qgroup_update_reserve() calls just outside these functions. Remove these duplicated calls. Fixes: 64ee4e751a1c ("btrfs: qgroup: Update trace events to use new separate rsv types") Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: replace btrfs_set_lock_blocking_rw with appropriate helpersDavid Sterba2019-02-251-3/+3
| | | | | | | We can use the right helper where the lock type is a fixed parameter. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Cleanup old subtree swap codeQu Wenruo2019-02-251-94/+0
| | | | | | | | | | | Since it's replaced by new delayed subtree swap code, remove the original code. The cleanup is small since most of its core function is still used by delayed subtree swap trace. Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Use delayed subtree rescan for balanceQu Wenruo2019-02-251-0/+88
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Before this patch, qgroup code traces the whole subtree of subvolume and reloc trees unconditionally. This makes qgroup numbers consistent, but it could cause tons of unnecessary extent tracing, which causes a lot of overhead. However for subtree swap of balance, just swap both subtrees because they contain the same contents and tree structure, so qgroup numbers won't change. It's the race window between subtree swap and transaction commit could cause qgroup number change. This patch will delay the qgroup subtree scan until COW happens for the subtree root. So if there is no other operations for the fs, balance won't cause extra qgroup overhead. (best case scenario) Depending on the workload, most of the subtree scan can still be avoided. Only for worst case scenario, it will fall back to old subtree swap overhead. (scan all swapped subtrees) [[Benchmark]] Hardware: VM 4G vRAM, 8 vCPUs, disk is using 'unsafe' cache mode, backing device is SAMSUNG 850 evo SSD. Host has 16G ram. Mkfs parameter: --nodesize 4K (To bump up tree size) Initial subvolume contents: 4G data copied from /usr and /lib. (With enough regular small files) Snapshots: 16 snapshots of the original subvolume. each snapshot has 3 random files modified. balance parameter: -m So the content should be pretty similar to a real world root fs layout. And after file system population, there is no other activity, so it should be the best case scenario. | v4.20-rc1 | w/ patchset | diff ----------------------------------------------------------------------- relocated extents | 22615 | 22457 | -0.1% qgroup dirty extents | 163457 | 121606 | -25.6% time (sys) | 22.884s | 18.842s | -17.6% time (real) | 27.724s | 22.884s | -17.5% Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Introduce per-root swapped blocks infrastructureQu Wenruo2019-02-251-0/+150
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To allow delayed subtree swap rescan, btrfs needs to record per-root information about which tree blocks get swapped. This patch introduces the required infrastructure. The designed workflow will be: 1) Record the subtree root block that gets swapped. During subtree swap: O = Old tree blocks N = New tree blocks reloc tree subvolume tree X Root Root / \ / \ NA OB OA OB / | | \ / | | \ NC ND OE OF OC OD OE OF In this case, NA and OA are going to be swapped, record (NA, OA) into subvolume tree X. 2) After subtree swap. reloc tree subvolume tree X Root Root / \ / \ OA OB NA OB / | | \ / | | \ OC OD OE OF NC ND OE OF 3a) COW happens for OB If we are going to COW tree block OB, we check OB's bytenr against tree X's swapped_blocks structure. If it doesn't fit any, nothing will happen. 3b) COW happens for NA Check NA's bytenr against tree X's swapped_blocks, and get a hit. Then we do subtree scan on both subtrees OA and NA. Resulting 6 tree blocks to be scanned (OA, OC, OD, NA, NC, ND). Then no matter what we do to subvolume tree X, qgroup numbers will still be correct. Then NA's record gets removed from X's swapped_blocks. 4) Transaction commit Any record in X's swapped_blocks gets removed, since there is no modification to swapped subtrees, no need to trigger heavy qgroup subtree rescan for them. This will introduce 128 bytes overhead for each btrfs_root even qgroup is not enabled. This is to reduce memory allocations and potential failures. Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Refactor btrfs_qgroup_trace_subtree_swapQu Wenruo2019-02-251-21/+56
| | | | | | | | | | | Refactor btrfs_qgroup_trace_subtree_swap() into qgroup_trace_subtree_swap(), which only needs two extent buffer and some other bool to control the behavior. This provides the basis for later delayed subtree scan work. Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: Fix typos in comments and stringsAndrea Gelmini2018-12-171-7/+7
| | | | | | | | | The typos accumulate over time so once in a while time they get fixed in a large patch. Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* Btrfs: fix deadlock when enabling quotas due to concurrent snapshot creationFilipe Manana2018-12-171-4/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If the quota enable and snapshot creation ioctls are called concurrently we can get into a deadlock where the task enabling quotas will deadlock on the fs_info->qgroup_ioctl_lock mutex because it attempts to lock it twice, or the task creating a snapshot tries to commit the transaction while the task enabling quota waits for the former task to commit the transaction while holding the mutex. The following time diagrams show how both cases happen. First scenario: CPU 0 CPU 1 btrfs_ioctl() btrfs_ioctl_quota_ctl() btrfs_quota_enable() mutex_lock(fs_info->qgroup_ioctl_lock) btrfs_start_transaction() btrfs_ioctl() btrfs_ioctl_snap_create_v2 create_snapshot() --> adds snapshot to the list pending_snapshots of the current transaction btrfs_commit_transaction() create_pending_snapshots() create_pending_snapshot() qgroup_account_snapshot() btrfs_qgroup_inherit() mutex_lock(fs_info->qgroup_ioctl_lock) --> deadlock, mutex already locked by this task at btrfs_quota_enable() Second scenario: CPU 0 CPU 1 btrfs_ioctl() btrfs_ioctl_quota_ctl() btrfs_quota_enable() mutex_lock(fs_info->qgroup_ioctl_lock) btrfs_start_transaction() btrfs_ioctl() btrfs_ioctl_snap_create_v2 create_snapshot() --> adds snapshot to the list pending_snapshots of the current transaction btrfs_commit_transaction() --> waits for task at CPU 0 to release its transaction handle btrfs_commit_transaction() --> sees another task started the transaction commit first --> releases its transaction handle --> waits for the transaction commit to be completed by the task at CPU 1 create_pending_snapshot() qgroup_account_snapshot() btrfs_qgroup_inherit() mutex_lock(fs_info->qgroup_ioctl_lock) --> deadlock, task at CPU 0 has the mutex locked but it is waiting for us to finish the transaction commit So fix this by setting the quota enabled flag in fs_info after committing the transaction at btrfs_quota_enable(). This ends up serializing quota enable and snapshot creation as if the snapshot creation happened just before the quota enable request. The quota rescan task, scheduled after committing the transaction in btrfs_quote_enable(), will do the accounting. Fixes: 6426c7ad697d ("btrfs: qgroup: Fix qgroup accounting when creating snapshot") Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: Remove unnecessary tree locking code in qgroup_rescan_leafNikolay Borisov2018-12-171-6/+1
| | | | | | | | | | | | | | | | | 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: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* Btrfs: fix race between enabling quotas and subvolume creationFilipe Manana2018-11-221-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We have a race between enabling quotas end subvolume creation that cause subvolume creation to fail with -EINVAL, and the following diagram shows how it happens: CPU 0 CPU 1 btrfs_ioctl() btrfs_ioctl_quota_ctl() btrfs_quota_enable() mutex_lock(fs_info->qgroup_ioctl_lock) btrfs_ioctl() create_subvol() btrfs_qgroup_inherit() -> save fs_info->quota_root into quota_root -> stores a NULL value -> tries to lock the mutex qgroup_ioctl_lock -> blocks waiting for the task at CPU0 -> sets BTRFS_FS_QUOTA_ENABLED in fs_info -> sets quota_root in fs_info->quota_root (non-NULL value) mutex_unlock(fs_info->qgroup_ioctl_lock) -> checks quota enabled flag is set -> returns -EINVAL because fs_info->quota_root was NULL before it acquired the mutex qgroup_ioctl_lock -> ioctl returns -EINVAL Returning -EINVAL to user space will be confusing if all the arguments passed to the subvolume creation ioctl were valid. Fix it by grabbing the value from fs_info->quota_root after acquiring the mutex. CC: stable@vger.kernel.org # 4.4+ Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: move the qgroup->members check out from (!qgroup)'s else branchLu Fengqi2018-10-151-6/+7
| | | | | | | | | | | There is no reason to put this check in (!qgroup)'s else branch because if qgroup is null, it will goto out directly. So move it out to reduce indentation level. No functional change. Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Avoid calling qgroup functions if qgroup is not enabledQu Wenruo2018-10-151-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Some qgroup trace events like btrfs_qgroup_release_data() and btrfs_qgroup_free_delayed_ref() can still be triggered even if qgroup is not enabled. This is caused by the lack of qgroup status check before calling some qgroup functions. Thankfully the functions can handle quota disabled case well and just do nothing for qgroup disabled case. This patch will do earlier check before triggering related trace events. And for enabled <-> disabled race case: 1) For enabled->disabled case Disable will wipe out all qgroups data including reservation and excl/rfer. Even if we leak some reservation or numbers, it will still be cleared, so nothing will go wrong. 2) For disabled -> enabled case Current btrfs_qgroup_release_data() will use extent_io tree to ensure we won't underflow reservation. And for delayed_ref we use head->qgroup_reserved to record the reserved space, so in that case head->qgroup_reserved should be 0 and we won't underflow. CC: stable@vger.kernel.org # 4.14+ Reported-by: Chris Murphy <lists@colorremedies.com> Link: https://lore.kernel.org/linux-btrfs/CAJCQCtQau7DtuUUeycCkZ36qjbKuxNzsgqJ7+sJ6W0dK_NLE3w@mail.gmail.com/ Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Only trace data extents in leaves if we're relocating data ↵Qu Wenruo2018-10-151-6/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | block group For qgroup_trace_extent_swap(), if we find one leaf that needs to be traced, we will also iterate all file extents and trace them. This is OK if we're relocating data block groups, but if we're relocating metadata block groups, balance code itself has ensured that both subtree of file tree and reloc tree contain the same contents. That's to say, if we're relocating metadata block groups, all file extents in reloc and file tree should match, thus no need to trace them. This should reduce the total number of dirty extents processed in metadata block group balance. [[Benchmark]] (with all previous enhancement) Hardware: VM 4G vRAM, 8 vCPUs, disk is using 'unsafe' cache mode, backing device is SAMSUNG 850 evo SSD. Host has 16G ram. Mkfs parameter: --nodesize 4K (To bump up tree size) Initial subvolume contents: 4G data copied from /usr and /lib. (With enough regular small files) Snapshots: 16 snapshots of the original subvolume. each snapshot has 3 random files modified. balance parameter: -m So the content should be pretty similar to a real world root fs layout. | v4.19-rc1 | w/ patchset | diff (*) --------------------------------------------------------------- relocated extents | 22929 | 22851 | -0.3% qgroup dirty extents | 227757 | 140886 | -38.1% time (sys) | 65.253s | 37.464s | -42.6% time (real) | 74.032s | 44.722s | -39.6% Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Use generation-aware subtree swap to mark dirty extentsQu Wenruo2018-10-151-0/+104
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Before this patch, with quota enabled during balance, we need to mark the whole subtree dirty for quota. E.g. OO = Old tree blocks (from file tree) NN = New tree blocks (from reloc tree) File tree (src) Reloc tree (dst) OO (a) NN (a) / \ / \ (b) OO OO (c) (b) NN NN (c) / \ / \ / \ / \ OO OO OO OO (d) OO OO OO NN (d) For old balance + quota case, quota will mark the whole src and dst tree dirty, including all the 3 old tree blocks in reloc tree. It's doable for small file tree or new tree blocks are all located at lower level. But for large file tree or new tree blocks are all located at higher level, this will lead to mark the whole tree dirty, and be unbelievably slow. This patch will change how we handle such balance with quota enabled case. Now we will search from (b) and (c) for any new tree blocks whose generation is equal to @last_snapshot, and only mark them dirty. In above case, we only need to trace tree blocks NN(b), NN(c) and NN(d). (NN(a) will be traced when COW happens for nodeptr modification). And also for tree blocks OO(b), OO(c), OO(d). (OO(a) will be traced when COW happens for nodeptr modification.) For above case, we could skip 3 tree blocks, but for larger tree, we can skip tons of unmodified tree blocks, and hugely speed up balance. This patch will introduce a new function, btrfs_qgroup_trace_subtree_swap(), which will do the following main work: 1) Read out real root eb And setup basic dst_path for later calls 2) Call qgroup_trace_new_subtree_blocks() To trace all new tree blocks in reloc tree and their counter parts in the file tree. Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Introduce function to find all new tree blocks of reloc treeQu Wenruo2018-10-151-0/+135
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Introduce new function, qgroup_trace_new_subtree_blocks(), to iterate all new tree blocks in a reloc tree. So that qgroup could skip unrelated tree blocks during balance, which should hugely speedup balance speed when quota is enabled. The function qgroup_trace_new_subtree_blocks() itself only cares about new tree blocks in reloc tree. All its main works are: 1) Read out tree blocks according to parent pointers 2) Do recursive depth-first search Will call the same function on all its children tree blocks, with search level set to current level -1. And will also skip all children whose generation is smaller than @last_snapshot. 3) Call qgroup_trace_extent_swap() to trace tree blocks So although we have parameter list related to source file tree, it's not used at all, but only passed to qgroup_trace_extent_swap(). Thus despite the tree read code, the core should be pretty short and all about recursive depth-first search. Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Introduce function to trace two swaped extentsQu Wenruo2018-10-151-0/+162
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Introduce a new function, qgroup_trace_extent_swap(), which will be used later for balance qgroup speedup. The basis idea of balance is swapping tree blocks between reloc tree and the real file tree. The swap will happen in highest tree block, but there may be a lot of tree blocks involved. For example: OO = Old tree blocks NN = New tree blocks allocated during balance File tree (257) Reloc tree for 257 L2 OO NN / \ / \ L1 OO OO (a) OO NN (a) / \ / \ / \ / \ L0 OO OO OO OO OO OO NN NN (b) (c) (b) (c) When calling qgroup_trace_extent_swap(), we will pass: @src_eb = OO(a) @dst_path = [ nodes[1] = NN(a), nodes[0] = NN(c) ] @dst_level = 0 @root_level = 1 In that case, qgroup_trace_extent_swap() will search from OO(a) to reach OO(c), then mark both OO(c) and NN(c) as qgroup dirty. The main work of qgroup_trace_extent_swap() can be split into 3 parts: 1) Tree search from @src_eb It should acts as a simplified btrfs_search_slot(). The key for search can be extracted from @dst_path->nodes[dst_level] (first key). 2) Mark the final tree blocks in @src_path and @dst_path qgroup dirty NOTE: In above case, OO(a) and NN(a) won't be marked qgroup dirty. They should be marked during preivous (@dst_level = 1) iteration. 3) Mark file extents in leaves dirty We don't have good way to pick out new file extents only. So we still follow the old method by scanning all file extents in the leave. This function can free us from keeping two pathes, thus later we only need to care about how to iterate all new tree blocks in reloc tree. Signed-off-by: Qu Wenruo <wqu@suse.com> [ copy changelog to function comment ] Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Introduce trace event to analyse the number of dirty extents ↵Qu Wenruo2018-10-151-0/+4
| | | | | | | | | | | | | | | | accounted Number of qgroup dirty extents is directly linked to the performance overhead, so add a new trace event, trace_qgroup_num_dirty_extents(), to record how many dirty extents is processed in btrfs_qgroup_account_extents(). This will be pretty handy to analyze later balance performance improvement. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: qgroup: Dirty all qgroups before rescanQu Wenruo2018-10-151-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [BUG] In the following case, rescan won't zero out the number of qgroup 1/0: $ mkfs.btrfs -fq $DEV $ mount $DEV /mnt $ btrfs quota enable /mnt $ btrfs qgroup create 1/0 /mnt $ btrfs sub create /mnt/sub $ btrfs qgroup assign 0/257 1/0 /mnt $ dd if=/dev/urandom of=/mnt/sub/file bs=1k count=1000 $ btrfs sub snap /mnt/sub /mnt/snap $ btrfs quota rescan -w /mnt $ btrfs qgroup show -pcre /mnt qgroupid rfer excl max_rfer max_excl parent child -------- ---- ---- -------- -------- ------ ----- 0/5 16.00KiB 16.00KiB none none --- --- 0/257 1016.00KiB 16.00KiB none none 1/0 --- 0/258 1016.00KiB 16.00KiB none none --- --- 1/0 1016.00KiB 16.00KiB none none --- 0/257 So far so good, but: $ btrfs qgroup remove 0/257 1/0 /mnt WARNING: quotas may be inconsistent, rescan needed $ btrfs quota rescan -w /mnt $ btrfs qgroup show -pcre /mnt qgoupid rfer excl max_rfer max_excl parent child -------- ---- ---- -------- -------- ------ ----- 0/5 16.00KiB 16.00KiB none none --- --- 0/257 1016.00KiB 16.00KiB none none --- --- 0/258 1016.00KiB 16.00KiB none none --- --- 1/0 1016.00KiB 16.00KiB none none --- --- ^^^^^^^^^^ ^^^^^^^^ not cleared [CAUSE] Before rescan we call qgroup_rescan_zero_tracking() to zero out all qgroups' accounting numbers. However we don't mark all qgroups dirty, but rely on rescan to do so. If we have any high level qgroup without children, it won't be marked dirty during rescan, since we cannot reach that qgroup. This will cause QGROUP_INFO items of childless qgroups never get updated in the quota tree, thus their numbers will stay the same in "btrfs qgroup show" output. [FIX] Just mark all qgroups dirty in qgroup_rescan_zero_tracking(), so even if we have childless qgroups, their QGROUP_INFO items will still get updated during rescan. Reported-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com> CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com> Tested-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: Remove 'objectid' member from struct btrfs_rootMisono Tomohiro2018-10-151-11/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are two members in struct btrfs_root which indicate root's objectid: objectid and root_key.objectid. They are both set to the same value in __setup_root(): static void __setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info, u64 objectid) { ... root->objectid = objectid; ... root->root_key.objectid = objecitd; ... } and not changed to other value after initialization. grep in btrfs directory shows both are used in many places: $ grep -rI "root->root_key.objectid" | wc -l 133 $ grep -rI "root->objectid" | wc -l 55 (4.17, inc. some noise) It is confusing to have two similar variable names and it seems that there is no rule about which should be used in a certain case. Since ->root_key itself is needed for tree reloc tree, let's remove 'objecitd' member and unify code to use ->root_key.objectid in all places. Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: use after free in btrfs_quota_enableDan Carpenter2018-08-231-3/+2
| | | | | | | | | | | | | | The issue here is that btrfs_commit_transaction() frees "trans" on both the error and the success path. So the problem would be if btrfs_commit_transaction() succeeds, and then qgroup_rescan_init() fails. That means that "ret" is non-zero and "trans" is non-NULL and it leads to a use after free inside the btrfs_end_transaction() macro. Fixes: 340f1aa27f36 ("btrfs: qgroups: Move transaction management inside btrfs_quota_enable/disable") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: Remove fs_info from btrfs_del_rootLu Fengqi2018-08-061-1/+1
| | | | | | | It can be referenced from the passed transaction handle. Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com> Signed-off-by: David Sterba <dsterba@suse.com>
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