summaryrefslogtreecommitdiffstats
path: root/fs/btrfs/transaction.c
AgeCommit message (Collapse)AuthorFilesLines
2022-05-16btrfs: turn fs_roots_radix in btrfs_fs_info into an XArrayGabriel Niebler1-63/+49
… rename it to simply fs_roots and adjust all usages of this object to use the XArray API, because it is notionally easier to use and understand, as it provides array semantics, and also takes care of locking for us, further simplifying the code. Also do some refactoring, esp. where the API change requires largely rewriting some functions, anyway. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Gabriel Niebler <gniebler@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-05-16btrfs: use a read/write lock for protecting the block groups treeFilipe Manana1-2/+2
Currently we use a spin lock to protect the red black tree that we use to track block groups. Most accesses to that tree are actually read only and for large filesystems, with thousands of block groups, it actually has a bad impact on performance, as concurrent read only searches on the tree are serialized. Read only searches on the tree are very frequent and done when: 1) Pinning and unpinning extents, as we need to lookup the respective block group from the tree; 2) Freeing the last reference of a tree block, regardless if we pin the underlying extent or add it back to free space cache/tree; 3) During NOCOW writes, both buffered IO and direct IO, we need to check if the block group that contains an extent is read only or not and to increment the number of NOCOW writers in the block group. For those operations we need to search for the block group in the tree. Similarly, after creating the ordered extent for the NOCOW write, we need to decrement the number of NOCOW writers from the same block group, which requires searching for it in the tree; 4) Decreasing the number of extent reservations in a block group; 5) When allocating extents and freeing reserved extents; 6) Adding and removing free space to the free space tree; 7) When releasing delalloc bytes during ordered extent completion; 8) When relocating a block group; 9) During fitrim, to iterate over the block groups; 10) etc; Write accesses to the tree, to add or remove block groups, are much less frequent as they happen only when allocating a new block group or when deleting a block group. We also use the same spin lock to protect the list of currently caching block groups. Additions to this list are made when we need to cache a block group, because we don't have a free space cache for it (or we have but it's invalid), and removals from this list are done when caching of the block group's free space finishes. These cases are also not very common, but when they happen, they happen only once when the filesystem is mounted. So switch the lock that protects the tree of block groups from a spinning lock to a read/write lock. Reviewed-by: Nikolay Borisov <nborisov@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>
2022-03-14btrfs: pass btrfs_fs_info for deleting snapshots and cleanerJosef Bacik1-2/+2
We're passing a root around here, but we only really need the fs_info, so fix up btrfs_clean_one_deleted_snapshot() to take an fs_info instead, and then fix up all the callers appropriately. Reviewed-by: Filipe Manana <fdmanana@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>
2022-03-14btrfs: add support for multiple global rootsJosef Bacik1-0/+15
With extent tree v2 you will be able to create multiple csum, extent, and free space trees. They will be used based on the block group, which will now use the block_group_item->chunk_objectid to point to the set of global roots that it will use. When allocating new block groups we'll simply mod the gigabyte offset of the block group against the number of global roots we have and that will be the block groups global id. >From there we can take the bytenr that we're modifying in the respective tree, look up the block group and get that block groups corresponding global root id. From there we can get to the appropriate global root for that bytenr. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-03-02btrfs: fix relocation crash due to premature return from ↵Omar Sandoval1-1/+31
btrfs_commit_transaction() We are seeing crashes similar to the following trace: [38.969182] WARNING: CPU: 20 PID: 2105 at fs/btrfs/relocation.c:4070 btrfs_relocate_block_group+0x2dc/0x340 [btrfs] [38.973556] CPU: 20 PID: 2105 Comm: btrfs Not tainted 5.17.0-rc4 #54 [38.974580] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 [38.976539] RIP: 0010:btrfs_relocate_block_group+0x2dc/0x340 [btrfs] [38.980336] RSP: 0000:ffffb0dd42e03c20 EFLAGS: 00010206 [38.981218] RAX: ffff96cfc4ede800 RBX: ffff96cfc3ce0000 RCX: 000000000002ca14 [38.982560] RDX: 0000000000000000 RSI: 4cfd109a0bcb5d7f RDI: ffff96cfc3ce0360 [38.983619] RBP: ffff96cfc309c000 R08: 0000000000000000 R09: 0000000000000000 [38.984678] R10: ffff96cec0000001 R11: ffffe84c80000000 R12: ffff96cfc4ede800 [38.985735] R13: 0000000000000000 R14: 0000000000000000 R15: ffff96cfc3ce0360 [38.987146] FS: 00007f11c15218c0(0000) GS:ffff96d6dfb00000(0000) knlGS:0000000000000000 [38.988662] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [38.989398] CR2: 00007ffc922c8e60 CR3: 00000001147a6001 CR4: 0000000000370ee0 [38.990279] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [38.991219] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [38.992528] Call Trace: [38.992854] <TASK> [38.993148] btrfs_relocate_chunk+0x27/0xe0 [btrfs] [38.993941] btrfs_balance+0x78e/0xea0 [btrfs] [38.994801] ? vsnprintf+0x33c/0x520 [38.995368] ? __kmalloc_track_caller+0x351/0x440 [38.996198] btrfs_ioctl_balance+0x2b9/0x3a0 [btrfs] [38.997084] btrfs_ioctl+0x11b0/0x2da0 [btrfs] [38.997867] ? mod_objcg_state+0xee/0x340 [38.998552] ? seq_release+0x24/0x30 [38.999184] ? proc_nr_files+0x30/0x30 [38.999654] ? call_rcu+0xc8/0x2f0 [39.000228] ? __x64_sys_ioctl+0x84/0xc0 [39.000872] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs] [39.001973] __x64_sys_ioctl+0x84/0xc0 [39.002566] do_syscall_64+0x3a/0x80 [39.003011] entry_SYSCALL_64_after_hwframe+0x44/0xae [39.003735] RIP: 0033:0x7f11c166959b [39.007324] RSP: 002b:00007fff2543e998 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [39.008521] RAX: ffffffffffffffda RBX: 00007f11c1521698 RCX: 00007f11c166959b [39.009833] RDX: 00007fff2543ea40 RSI: 00000000c4009420 RDI: 0000000000000003 [39.011270] RBP: 0000000000000003 R08: 0000000000000013 R09: 00007f11c16f94e0 [39.012581] R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff25440df3 [39.014046] R13: 0000000000000000 R14: 00007fff2543ea40 R15: 0000000000000001 [39.015040] </TASK> [39.015418] ---[ end trace 0000000000000000 ]--- [43.131559] ------------[ cut here ]------------ [43.132234] kernel BUG at fs/btrfs/extent-tree.c:2717! [43.133031] invalid opcode: 0000 [#1] PREEMPT SMP PTI [43.133702] CPU: 1 PID: 1839 Comm: btrfs Tainted: G W 5.17.0-rc4 #54 [43.134863] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 [43.136426] RIP: 0010:unpin_extent_range+0x37a/0x4f0 [btrfs] [43.139913] RSP: 0000:ffffb0dd4216bc70 EFLAGS: 00010246 [43.140629] RAX: 0000000000000000 RBX: ffff96cfc34490f8 RCX: 0000000000000001 [43.141604] RDX: 0000000080000001 RSI: 0000000051d00000 RDI: 00000000ffffffff [43.142645] RBP: 0000000000000000 R08: 0000000000000000 R09: ffff96cfd07dca50 [43.143669] R10: ffff96cfc46e8a00 R11: fffffffffffec000 R12: 0000000041d00000 [43.144657] R13: ffff96cfc3ce0000 R14: ffffb0dd4216bd08 R15: 0000000000000000 [43.145686] FS: 00007f7657dd68c0(0000) GS:ffff96d6df640000(0000) knlGS:0000000000000000 [43.146808] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [43.147584] CR2: 00007f7fe81bf5b0 CR3: 00000001093ee004 CR4: 0000000000370ee0 [43.148589] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [43.149581] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [43.150559] Call Trace: [43.150904] <TASK> [43.151253] btrfs_finish_extent_commit+0x88/0x290 [btrfs] [43.152127] btrfs_commit_transaction+0x74f/0xaa0 [btrfs] [43.152932] ? btrfs_attach_transaction_barrier+0x1e/0x50 [btrfs] [43.153786] btrfs_ioctl+0x1edc/0x2da0 [btrfs] [43.154475] ? __check_object_size+0x150/0x170 [43.155170] ? preempt_count_add+0x49/0xa0 [43.155753] ? __x64_sys_ioctl+0x84/0xc0 [43.156437] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs] [43.157456] __x64_sys_ioctl+0x84/0xc0 [43.157980] do_syscall_64+0x3a/0x80 [43.158543] entry_SYSCALL_64_after_hwframe+0x44/0xae [43.159231] RIP: 0033:0x7f7657f1e59b [43.161819] RSP: 002b:00007ffda5cd1658 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [43.162702] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f7657f1e59b [43.163526] RDX: 0000000000000000 RSI: 0000000000009408 RDI: 0000000000000003 [43.164358] RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000 [43.165208] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 [43.166029] R13: 00005621b91c3232 R14: 00005621b91ba580 R15: 00007ffda5cd1800 [43.166863] </TASK> [43.167125] Modules linked in: btrfs blake2b_generic xor pata_acpi ata_piix libata raid6_pq scsi_mod libcrc32c virtio_net virtio_rng net_failover rng_core failover scsi_common [43.169552] ---[ end trace 0000000000000000 ]--- [43.171226] RIP: 0010:unpin_extent_range+0x37a/0x4f0 [btrfs] [43.174767] RSP: 0000:ffffb0dd4216bc70 EFLAGS: 00010246 [43.175600] RAX: 0000000000000000 RBX: ffff96cfc34490f8 RCX: 0000000000000001 [43.176468] RDX: 0000000080000001 RSI: 0000000051d00000 RDI: 00000000ffffffff [43.177357] RBP: 0000000000000000 R08: 0000000000000000 R09: ffff96cfd07dca50 [43.178271] R10: ffff96cfc46e8a00 R11: fffffffffffec000 R12: 0000000041d00000 [43.179178] R13: ffff96cfc3ce0000 R14: ffffb0dd4216bd08 R15: 0000000000000000 [43.180071] FS: 00007f7657dd68c0(0000) GS:ffff96d6df800000(0000) knlGS:0000000000000000 [43.181073] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [43.181808] CR2: 00007fe09905f010 CR3: 00000001093ee004 CR4: 0000000000370ee0 [43.182706] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [43.183591] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 We first hit the WARN_ON(rc->block_group->pinned > 0) in btrfs_relocate_block_group() and then the BUG_ON(!cache) in unpin_extent_range(). This tells us that we are exiting relocation and removing the block group with bytes still pinned for that block group. This is supposed to be impossible: the last thing relocate_block_group() does is commit the transaction to get rid of pinned extents. Commit d0c2f4fa555e ("btrfs: make concurrent fsyncs wait less when waiting for a transaction commit") introduced an optimization so that commits from fsync don't have to wait for the previous commit to unpin extents. This was only intended to affect fsync, but it inadvertently made it possible for any commit to skip waiting for the previous commit to unpin. This is because if a call to btrfs_commit_transaction() finds that another thread is already committing the transaction, it waits for the other thread to complete the commit and then returns. If that other thread was in fsync, then it completes the commit without completing the previous commit. This makes the following sequence of events possible: Thread 1____________________|Thread 2 (fsync)_____________________|Thread 3 (balance)___________________ btrfs_commit_transaction(N) | | btrfs_run_delayed_refs | | pin extents | | ... | | state = UNBLOCKED |btrfs_sync_file | | btrfs_start_transaction(N + 1) |relocate_block_group | | btrfs_join_transaction(N + 1) | btrfs_commit_transaction(N + 1) | ... | trans->state = COMMIT_START | | | btrfs_commit_transaction(N + 1) | | wait_for_commit(N + 1, COMPLETED) | wait_for_commit(N, SUPER_COMMITTED)| state = SUPER_COMMITTED | ... | btrfs_finish_extent_commit| | unpin_extent_range() | trans->state = COMPLETED | | | return | | ... | |Thread 1 isn't done, so pinned > 0 | |and we WARN | | | |btrfs_remove_block_group unpin_extent_range() | | Thread 3 removed the | | block group, so we BUG| | There are other sequences involving SUPER_COMMITTED transactions that can cause a similar outcome. We could fix this by making relocation explicitly wait for unpinning, but there may be other cases that need it. Josef mentioned ENOSPC flushing and the free space cache inode as other potential victims. Rather than playing whack-a-mole, this fix is conservative and makes all commits not in fsync wait for all previous transactions, which is what the optimization intended. Fixes: d0c2f4fa555e ("btrfs: make concurrent fsyncs wait less when waiting for a transaction commit") CC: stable@vger.kernel.org # 5.15+ Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-03-02btrfs: do not start relocation until in progress drops are doneJosef Bacik1-1/+32
We hit a bug with a recovering relocation on mount for one of our file systems in production. I reproduced this locally by injecting errors into snapshot delete with balance running at the same time. This presented as an error while looking up an extent item WARNING: CPU: 5 PID: 1501 at fs/btrfs/extent-tree.c:866 lookup_inline_extent_backref+0x647/0x680 CPU: 5 PID: 1501 Comm: btrfs-balance Not tainted 5.16.0-rc8+ #8 RIP: 0010:lookup_inline_extent_backref+0x647/0x680 RSP: 0018:ffffae0a023ab960 EFLAGS: 00010202 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 000000000000000c RDI: 0000000000000000 RBP: ffff943fd2a39b60 R08: 0000000000000000 R09: 0000000000000001 R10: 0001434088152de0 R11: 0000000000000000 R12: 0000000001d05000 R13: ffff943fd2a39b60 R14: ffff943fdb96f2a0 R15: ffff9442fc923000 FS: 0000000000000000(0000) GS:ffff944e9eb40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1157b1fca8 CR3: 000000010f092000 CR4: 0000000000350ee0 Call Trace: <TASK> insert_inline_extent_backref+0x46/0xd0 __btrfs_inc_extent_ref.isra.0+0x5f/0x200 ? btrfs_merge_delayed_refs+0x164/0x190 __btrfs_run_delayed_refs+0x561/0xfa0 ? btrfs_search_slot+0x7b4/0xb30 ? btrfs_update_root+0x1a9/0x2c0 btrfs_run_delayed_refs+0x73/0x1f0 ? btrfs_update_root+0x1a9/0x2c0 btrfs_commit_transaction+0x50/0xa50 ? btrfs_update_reloc_root+0x122/0x220 prepare_to_merge+0x29f/0x320 relocate_block_group+0x2b8/0x550 btrfs_relocate_block_group+0x1a6/0x350 btrfs_relocate_chunk+0x27/0xe0 btrfs_balance+0x777/0xe60 balance_kthread+0x35/0x50 ? btrfs_balance+0xe60/0xe60 kthread+0x16b/0x190 ? set_kthread_struct+0x40/0x40 ret_from_fork+0x22/0x30 </TASK> Normally snapshot deletion and relocation are excluded from running at the same time by the fs_info->cleaner_mutex. However if we had a pending balance waiting to get the ->cleaner_mutex, and a snapshot deletion was running, and then the box crashed, we would come up in a state where we have a half deleted snapshot. Again, in the normal case the snapshot deletion needs to complete before relocation can start, but in this case relocation could very well start before the snapshot deletion completes, as we simply add the root to the dead roots list and wait for the next time the cleaner runs to clean up the snapshot. Fix this by setting a bit on the fs_info if we have any DEAD_ROOT's that had a pending drop_progress key. If they do then we know we were in the middle of the drop operation and set a flag on the fs_info. Then balance can wait until this flag is cleared to start up again. If there are DEAD_ROOT's that don't have a drop_progress set then we're safe to start balance right away as we'll be properly protected by the cleaner_mutex. CC: stable@vger.kernel.org # 5.10+ Reviewed-by: Filipe Manana <fdmanana@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>
2022-02-09btrfs: get rid of warning on transaction commit when using flushoncommitFilipe Manana1-2/+10
When using the flushoncommit mount option, during almost every transaction commit we trigger a warning from __writeback_inodes_sb_nr(): $ cat fs/fs-writeback.c: (...) static void __writeback_inodes_sb_nr(struct super_block *sb, ... { (...) WARN_ON(!rwsem_is_locked(&sb->s_umount)); (...) } (...) The trace produced in dmesg looks like the following: [947.473890] WARNING: CPU: 5 PID: 930 at fs/fs-writeback.c:2610 __writeback_inodes_sb_nr+0x7e/0xb3 [947.481623] Modules linked in: nfsd nls_cp437 cifs asn1_decoder cifs_arc4 fscache cifs_md4 ipmi_ssif [947.489571] CPU: 5 PID: 930 Comm: btrfs-transacti Not tainted 95.16.3-srb-asrock-00001-g36437ad63879 #186 [947.497969] RIP: 0010:__writeback_inodes_sb_nr+0x7e/0xb3 [947.502097] Code: 24 10 4c 89 44 24 18 c6 (...) [947.519760] RSP: 0018:ffffc90000777e10 EFLAGS: 00010246 [947.523818] RAX: 0000000000000000 RBX: 0000000000963300 RCX: 0000000000000000 [947.529765] RDX: 0000000000000000 RSI: 000000000000fa51 RDI: ffffc90000777e50 [947.535740] RBP: ffff888101628a90 R08: ffff888100955800 R09: ffff888100956000 [947.541701] R10: 0000000000000002 R11: 0000000000000001 R12: ffff888100963488 [947.547645] R13: ffff888100963000 R14: ffff888112fb7200 R15: ffff888100963460 [947.553621] FS: 0000000000000000(0000) GS:ffff88841fd40000(0000) knlGS:0000000000000000 [947.560537] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [947.565122] CR2: 0000000008be50c4 CR3: 000000000220c000 CR4: 00000000001006e0 [947.571072] Call Trace: [947.572354] <TASK> [947.573266] btrfs_commit_transaction+0x1f1/0x998 [947.576785] ? start_transaction+0x3ab/0x44e [947.579867] ? schedule_timeout+0x8a/0xdd [947.582716] transaction_kthread+0xe9/0x156 [947.585721] ? btrfs_cleanup_transaction.isra.0+0x407/0x407 [947.590104] kthread+0x131/0x139 [947.592168] ? set_kthread_struct+0x32/0x32 [947.595174] ret_from_fork+0x22/0x30 [947.597561] </TASK> [947.598553] ---[ end trace 644721052755541c ]--- This is because we started using writeback_inodes_sb() to flush delalloc when committing a transaction (when using -o flushoncommit), in order to avoid deadlocks with filesystem freeze operations. This change was made by commit ce8ea7cc6eb313 ("btrfs: don't call btrfs_start_delalloc_roots in flushoncommit"). After that change we started producing that warning, and every now and then a user reports this since the warning happens too often, it spams dmesg/syslog, and a user is unsure if this reflects any problem that might compromise the filesystem's reliability. We can not just lock the sb->s_umount semaphore before calling writeback_inodes_sb(), because that would at least deadlock with filesystem freezing, since at fs/super.c:freeze_super() sync_filesystem() is called while we are holding that semaphore in write mode, and that can trigger a transaction commit, resulting in a deadlock. It would also trigger the same type of deadlock in the unmount path. Possibly, it could also introduce some other locking dependencies that lockdep would report. To fix this call try_to_writeback_inodes_sb() instead of writeback_inodes_sb(), because that will try to read lock sb->s_umount and then will only call writeback_inodes_sb() if it was able to lock it. This is fine because the cases where it can't read lock sb->s_umount are during a filesystem unmount or during a filesystem freeze - in those cases sb->s_umount is write locked and sync_filesystem() is called, which calls writeback_inodes_sb(). In other words, in all cases where we can't take a read lock on sb->s_umount, writeback is already being triggered elsewhere. An alternative would be to call btrfs_start_delalloc_roots() with a number of pages different from LONG_MAX, for example matching the number of delalloc bytes we currently have, in which case we would end up starting all delalloc with filemap_fdatawrite_wbc() and not with an async flush via filemap_flush() - that is only possible after the rather recent commit e076ab2a2ca70a ("btrfs: shrink delalloc pages instead of full inodes"). However that creates a whole new can of worms due to new lock dependencies, which lockdep complains, like for example: [ 8948.247280] ====================================================== [ 8948.247823] WARNING: possible circular locking dependency detected [ 8948.248353] 5.17.0-rc1-btrfs-next-111 #1 Not tainted [ 8948.248786] ------------------------------------------------------ [ 8948.249320] kworker/u16:18/933570 is trying to acquire lock: [ 8948.249812] ffff9b3de1591690 (sb_internal#2){.+.+}-{0:0}, at: find_free_extent+0x141e/0x1590 [btrfs] [ 8948.250638] but task is already holding lock: [ 8948.251140] ffff9b3e09c717d8 (&root->delalloc_mutex){+.+.}-{3:3}, at: start_delalloc_inodes+0x78/0x400 [btrfs] [ 8948.252018] which lock already depends on the new lock. [ 8948.252710] the existing dependency chain (in reverse order) is: [ 8948.253343] -> #2 (&root->delalloc_mutex){+.+.}-{3:3}: [ 8948.253950] __mutex_lock+0x90/0x900 [ 8948.254354] start_delalloc_inodes+0x78/0x400 [btrfs] [ 8948.254859] btrfs_start_delalloc_roots+0x194/0x2a0 [btrfs] [ 8948.255408] btrfs_commit_transaction+0x32f/0xc00 [btrfs] [ 8948.255942] btrfs_mksubvol+0x380/0x570 [btrfs] [ 8948.256406] btrfs_mksnapshot+0x81/0xb0 [btrfs] [ 8948.256870] __btrfs_ioctl_snap_create+0x17f/0x190 [btrfs] [ 8948.257413] btrfs_ioctl_snap_create_v2+0xbb/0x140 [btrfs] [ 8948.257961] btrfs_ioctl+0x1196/0x3630 [btrfs] [ 8948.258418] __x64_sys_ioctl+0x83/0xb0 [ 8948.258793] do_syscall_64+0x3b/0xc0 [ 8948.259146] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 8948.259709] -> #1 (&fs_info->delalloc_root_mutex){+.+.}-{3:3}: [ 8948.260330] __mutex_lock+0x90/0x900 [ 8948.260692] btrfs_start_delalloc_roots+0x97/0x2a0 [btrfs] [ 8948.261234] btrfs_commit_transaction+0x32f/0xc00 [btrfs] [ 8948.261766] btrfs_set_free_space_cache_v1_active+0x38/0x60 [btrfs] [ 8948.262379] btrfs_start_pre_rw_mount+0x119/0x180 [btrfs] [ 8948.262909] open_ctree+0x1511/0x171e [btrfs] [ 8948.263359] btrfs_mount_root.cold+0x12/0xde [btrfs] [ 8948.263863] legacy_get_tree+0x30/0x50 [ 8948.264242] vfs_get_tree+0x28/0xc0 [ 8948.264594] vfs_kern_mount.part.0+0x71/0xb0 [ 8948.265017] btrfs_mount+0x11d/0x3a0 [btrfs] [ 8948.265462] legacy_get_tree+0x30/0x50 [ 8948.265851] vfs_get_tree+0x28/0xc0 [ 8948.266203] path_mount+0x2d4/0xbe0 [ 8948.266554] __x64_sys_mount+0x103/0x140 [ 8948.266940] do_syscall_64+0x3b/0xc0 [ 8948.267300] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 8948.267790] -> #0 (sb_internal#2){.+.+}-{0:0}: [ 8948.268322] __lock_acquire+0x12e8/0x2260 [ 8948.268733] lock_acquire+0xd7/0x310 [ 8948.269092] start_transaction+0x44c/0x6e0 [btrfs] [ 8948.269591] find_free_extent+0x141e/0x1590 [btrfs] [ 8948.270087] btrfs_reserve_extent+0x14b/0x280 [btrfs] [ 8948.270588] cow_file_range+0x17e/0x490 [btrfs] [ 8948.271051] btrfs_run_delalloc_range+0x345/0x7a0 [btrfs] [ 8948.271586] writepage_delalloc+0xb5/0x170 [btrfs] [ 8948.272071] __extent_writepage+0x156/0x3c0 [btrfs] [ 8948.272579] extent_write_cache_pages+0x263/0x460 [btrfs] [ 8948.273113] extent_writepages+0x76/0x130 [btrfs] [ 8948.273573] do_writepages+0xd2/0x1c0 [ 8948.273942] filemap_fdatawrite_wbc+0x68/0x90 [ 8948.274371] start_delalloc_inodes+0x17f/0x400 [btrfs] [ 8948.274876] btrfs_start_delalloc_roots+0x194/0x2a0 [btrfs] [ 8948.275417] flush_space+0x1f2/0x630 [btrfs] [ 8948.275863] btrfs_async_reclaim_data_space+0x108/0x1b0 [btrfs] [ 8948.276438] process_one_work+0x252/0x5a0 [ 8948.276829] worker_thread+0x55/0x3b0 [ 8948.277189] kthread+0xf2/0x120 [ 8948.277506] ret_from_fork+0x22/0x30 [ 8948.277868] other info that might help us debug this: [ 8948.278548] Chain exists of: sb_internal#2 --> &fs_info->delalloc_root_mutex --> &root->delalloc_mutex [ 8948.279601] Possible unsafe locking scenario: [ 8948.280102] CPU0 CPU1 [ 8948.280508] ---- ---- [ 8948.280915] lock(&root->delalloc_mutex); [ 8948.281271] lock(&fs_info->delalloc_root_mutex); [ 8948.281915] lock(&root->delalloc_mutex); [ 8948.282487] lock(sb_internal#2); [ 8948.282800] *** DEADLOCK *** [ 8948.283333] 4 locks held by kworker/u16:18/933570: [ 8948.283750] #0: ffff9b3dc00a9d48 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1d2/0x5a0 [ 8948.284609] #1: ffffa90349dafe70 ((work_completion)(&fs_info->async_data_reclaim_work)){+.+.}-{0:0}, at: process_one_work+0x1d2/0x5a0 [ 8948.285637] #2: ffff9b3e14db5040 (&fs_info->delalloc_root_mutex){+.+.}-{3:3}, at: btrfs_start_delalloc_roots+0x97/0x2a0 [btrfs] [ 8948.286674] #3: ffff9b3e09c717d8 (&root->delalloc_mutex){+.+.}-{3:3}, at: start_delalloc_inodes+0x78/0x400 [btrfs] [ 8948.287596] stack backtrace: [ 8948.287975] CPU: 3 PID: 933570 Comm: kworker/u16:18 Not tainted 5.17.0-rc1-btrfs-next-111 #1 [ 8948.288677] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [ 8948.289649] Workqueue: events_unbound btrfs_async_reclaim_data_space [btrfs] [ 8948.290298] Call Trace: [ 8948.290517] <TASK> [ 8948.290700] dump_stack_lvl+0x59/0x73 [ 8948.291026] check_noncircular+0xf3/0x110 [ 8948.291375] ? start_transaction+0x228/0x6e0 [btrfs] [ 8948.291826] __lock_acquire+0x12e8/0x2260 [ 8948.292241] lock_acquire+0xd7/0x310 [ 8948.292714] ? find_free_extent+0x141e/0x1590 [btrfs] [ 8948.293241] ? lock_is_held_type+0xea/0x140 [ 8948.293601] start_transaction+0x44c/0x6e0 [btrfs] [ 8948.294055] ? find_free_extent+0x141e/0x1590 [btrfs] [ 8948.294518] find_free_extent+0x141e/0x1590 [btrfs] [ 8948.294957] ? _raw_spin_unlock+0x29/0x40 [ 8948.295312] ? btrfs_get_alloc_profile+0x124/0x290 [btrfs] [ 8948.295813] btrfs_reserve_extent+0x14b/0x280 [btrfs] [ 8948.296270] cow_file_range+0x17e/0x490 [btrfs] [ 8948.296691] btrfs_run_delalloc_range+0x345/0x7a0 [btrfs] [ 8948.297175] ? find_lock_delalloc_range+0x247/0x270 [btrfs] [ 8948.297678] writepage_delalloc+0xb5/0x170 [btrfs] [ 8948.298123] __extent_writepage+0x156/0x3c0 [btrfs] [ 8948.298570] extent_write_cache_pages+0x263/0x460 [btrfs] [ 8948.299061] extent_writepages+0x76/0x130 [btrfs] [ 8948.299495] do_writepages+0xd2/0x1c0 [ 8948.299817] ? sched_clock_cpu+0xd/0x110 [ 8948.300160] ? lock_release+0x155/0x4a0 [ 8948.300494] filemap_fdatawrite_wbc+0x68/0x90 [ 8948.300874] ? do_raw_spin_unlock+0x4b/0xa0 [ 8948.301243] start_delalloc_inodes+0x17f/0x400 [btrfs] [ 8948.301706] ? lock_release+0x155/0x4a0 [ 8948.302055] btrfs_start_delalloc_roots+0x194/0x2a0 [btrfs] [ 8948.302564] flush_space+0x1f2/0x630 [btrfs] [ 8948.302970] btrfs_async_reclaim_data_space+0x108/0x1b0 [btrfs] [ 8948.303510] process_one_work+0x252/0x5a0 [ 8948.303860] ? process_one_work+0x5a0/0x5a0 [ 8948.304221] worker_thread+0x55/0x3b0 [ 8948.304543] ? process_one_work+0x5a0/0x5a0 [ 8948.304904] kthread+0xf2/0x120 [ 8948.305184] ? kthread_complete_and_exit+0x20/0x20 [ 8948.305598] ret_from_fork+0x22/0x30 [ 8948.305921] </TASK> It all comes from the fact that btrfs_start_delalloc_roots() takes the delalloc_root_mutex, in the transaction commit path we are holding a read lock on one of the superblock's freeze semaphores (via sb_start_intwrite()), the async reclaim task can also do a call to btrfs_start_delalloc_roots(), which ends up triggering writeback with calls to filemap_fdatawrite_wbc(), resulting in extent allocation which in turn can call btrfs_start_transaction(), which will result in taking the freeze semaphore via sb_start_intwrite(), forming a nasty dependency on all those locks which can be taken in different orders by different code paths. So just adopt the simple approach of calling try_to_writeback_inodes_sb() at btrfs_start_delalloc_flush(). Link: https://lore.kernel.org/linux-btrfs/20220130005258.GA7465@cuci.nl/ Link: https://lore.kernel.org/linux-btrfs/43acc426-d683-d1b6-729d-c6bc4a2fff4d@gmail.com/ Link: https://lore.kernel.org/linux-btrfs/6833930a-08d7-6fbc-0141-eb9cdfd6bb4d@gmail.com/ Link: https://lore.kernel.org/linux-btrfs/20190322041731.GF16651@hungrycats.org/ Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> [ add more link reports ] Signed-off-by: David Sterba <dsterba@suse.com>
2022-01-31btrfs: fix use-after-free after failure to create a snapshotFilipe Manana1-0/+24
At ioctl.c:create_snapshot(), we allocate a pending snapshot structure and then attach it to the transaction's list of pending snapshots. After that we call btrfs_commit_transaction(), and if that returns an error we jump to 'fail' label, where we kfree() the pending snapshot structure. This can result in a later use-after-free of the pending snapshot: 1) We allocated the pending snapshot and added it to the transaction's list of pending snapshots; 2) We call btrfs_commit_transaction(), and it fails either at the first call to btrfs_run_delayed_refs() or btrfs_start_dirty_block_groups(). In both cases, we don't abort the transaction and we release our transaction handle. We jump to the 'fail' label and free the pending snapshot structure. We return with the pending snapshot still in the transaction's list; 3) Another task commits the transaction. This time there's no error at all, and then during the transaction commit it accesses a pointer to the pending snapshot structure that the snapshot creation task has already freed, resulting in a user-after-free. This issue could actually be detected by smatch, which produced the following warning: fs/btrfs/ioctl.c:843 create_snapshot() warn: '&pending_snapshot->list' not removed from list So fix this by not having the snapshot creation ioctl directly add the pending snapshot to the transaction's list. Instead add the pending snapshot to the transaction handle, and then at btrfs_commit_transaction() we add the snapshot to the list only when we can guarantee that any error returned after that point will result in a transaction abort, in which case the ioctl code can safely free the pending snapshot and no one can access it anymore. CC: stable@vger.kernel.org # 5.10+ Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-01-07btrfs: make send work with concurrent block group relocationFilipe Manana1-0/+4
We don't allow send and balance/relocation to run in parallel in order to prevent send failing or silently producing some bad stream. This is because while send is using an extent (specially metadata) or about to read a metadata extent and expecting it belongs to a specific parent node, relocation can run, the transaction used for the relocation is committed and the extent gets reallocated while send is still using the extent, so it ends up with a different content than expected. This can result in just failing to read a metadata extent due to failure of the validation checks (parent transid, level, etc), failure to find a backreference for a data extent, and other unexpected failures. Besides reallocation, there's also a similar problem of an extent getting discarded when it's unpinned after the transaction used for block group relocation is committed. The restriction between balance and send was added in commit 9e967495e0e0 ("Btrfs: prevent send failures and crashes due to concurrent relocation"), kernel 5.3, while the more general restriction between send and relocation was added in commit 1cea5cf0e664 ("btrfs: ensure relocation never runs while we have send operations running"), kernel 5.14. Both send and relocation can be very long running operations. Relocation because it has to do a lot of IO and expensive backreference lookups in case there are many snapshots, and send due to read IO when operating on very large trees. This makes it inconvenient for users and tools to deal with scheduling both operations. For zoned filesystem we also have automatic block group relocation, so send can fail with -EAGAIN when users least expect it or send can end up delaying the block group relocation for too long. In the future we might also get the automatic block group relocation for non zoned filesystems. This change makes it possible for send and relocation to run in parallel. This is achieved the following way: 1) For all tree searches, send acquires a read lock on the commit root semaphore; 2) After each tree search, and before releasing the commit root semaphore, the leaf is cloned and placed in the search path (struct btrfs_path); 3) After releasing the commit root semaphore, the changed_cb() callback is invoked, which operates on the leaf and writes commands to the pipe (or file in case send/receive is not used with a pipe). It's important here to not hold a lock on the commit root semaphore, because if we did we could deadlock when sending and receiving to the same filesystem using a pipe - the send task blocks on the pipe because it's full, the receive task, which is the only consumer of the pipe, triggers a transaction commit when attempting to create a subvolume or reserve space for a write operation for example, but the transaction commit blocks trying to write lock the commit root semaphore, resulting in a deadlock; 4) Before moving to the next key, or advancing to the next change in case of an incremental send, check if a transaction used for relocation was committed (or is about to finish its commit). If so, release the search path(s) and restart the search, to where we were before, so that we don't operate on stale extent buffers. The search restarts are always possible because both the send and parent roots are RO, and no one can add, remove of update keys (change their offset) in RO trees - the only exception is deduplication, but that is still not allowed to run in parallel with send; 5) Periodically check if there is contention on the commit root semaphore, which means there is a transaction commit trying to write lock it, and release the semaphore and reschedule if there is contention, so as to avoid causing any significant delays to transaction commits. This leaves some room for optimizations for send to have less path releases and re searching the trees when there's relocation running, but for now it's kept simple as it performs quite well (on very large trees with resulting send streams in the order of a few hundred gigabytes). Test case btrfs/187, from fstests, stresses relocation, send and deduplication attempting to run in parallel, but without verifying if send succeeds and if it produces correct streams. A new test case will be added that exercises relocation happening in parallel with send and then checks that send succeeds and the resulting streams are correct. A final note is that for now this still leaves the mutual exclusion between send operations and deduplication on files belonging to a root used by send operations. A solution for that will be slightly more complex but it will eventually be built on top of this change. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-01-03btrfs: remove useless WARN_ON in record_root_in_transJosef Bacik1-1/+0
We don't set SHAREABLE on the extent root, we don't need to have this safety check here. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-01-03btrfs: stop accessing ->extent_root directlyJosef Bacik1-1/+1
When we start having multiple extent roots we'll need to use a helper to get to the correct extent_root. Rename fs_info->extent_root to _extent_root and convert all of the users of the extent root to using the btrfs_extent_root() helper. This will allow us to easily clean up the remaining direct accesses in the future. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-01-03btrfs: do not special case the extent root for switch commit rootsJosef Bacik1-6/+2
This is a leftover from when we used to independently swap the extent root's commit root and the fs tree commit roots. At the time I simply changed the helper to a list_add. There's actually no reason to not add the extent root to the switch commit root at this point, we don't care about the order we do the switching since it's all done under the commit_root_sem. If we re-mark the extent root dirty after adding it to the switch_commits list we'll see that BTRFS_ROOT_DIRTY isn't set and then list_move it back onto the dirty list, and then we'll redo the tree update and everything will be ok. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-01-03btrfs: remove trans_handle->rootJosef Bacik1-1/+0
Nobody is using this anymore, remove it. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-01-03btrfs: pass fs_info to trace_btrfs_transaction_commitJosef Bacik1-2/+2
The root on the trans->root can be anything, and generally we're committing from the transaction kthread so it's usually the tree_root. Change this to just take an fs_info, and to maintain compatibility simply put the ROOT_TREE_OBJECTID as the root objectid for the tracepoint. This will allow use to remove trans->root. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-01-03btrfs: rework async transaction committingJosef Bacik1-53/+11
Currently we do this awful thing where we get another ref on a trans handle, async off that handle and commit the transaction from that work. Because we do this we have to mess with current->journal_info and the freeze counting stuff. We already have an async thing to kick for the transaction commit, the transaction kthread. Replace this work struct with a flag on the fs_info to tell the kthread to go ahead and commit even if it's before our timeout. Then we can drastically simplify the async transaction commit path. Note: this can be simplified and functionality based on the pending operation COMMIT. Signed-off-by: Josef Bacik <josef@toxicpanda.com> [ add note ] Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-01-03btrfs: change root to fs_info for btrfs_reserve_metadata_bytesJosef Bacik1-2/+2
We used to need the root for btrfs_reserve_metadata_bytes to check the orphan cleanup state, but we no longer need that, we simply need the fs_info. Change btrfs_reserve_metadata_bytes() to use the fs_info, and change both btrfs_block_rsv_refill() and btrfs_block_rsv_add() to do the same as they simply call btrfs_reserve_metadata_bytes() and then manipulate the block_rsv that is being used. 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>
2022-01-03btrfs: reduce the scope of the tree log mutex during transaction commitFilipe Manana1-34/+42
In the transaction commit path we are acquiring the tree log mutex too early and we have a stale comment because: 1) It mentions a function named btrfs_commit_tree_roots(), which does not exists anymore, it was the old name of commit_cowonly_roots(), renamed a very long time ago by commit 5d4f98a28c7d33 ("Btrfs: Mixed back reference (FORWARD ROLLING FORMAT CHANGE)")); 2) It mentions that we need to acquire the tree log mutex at that point to ensure we have no running log writers. That is not correct anymore, for many years at least, since we are guaranteed that we do not have any log writers at that point simply because we have set the state of the transaction to TRANS_STATE_COMMIT_DOING and have waited for all writers to complete - meaning no one can log until we change the state of the transaction to TRANS_STATE_UNBLOCKED. Any attempts to join the transaction or start a new one will block until we do that state transition; 3) The comment mentions a "trans mutex" which doesn't exists since 2011, commit a4abeea41adf ("Btrfs: kill trans_mutex") removed it; 4) The current use of the tree log mutex is to ensure proper serialization of super block writes - if someone started a new transaction and uses it for logging, it will wait for the previous transaction to write its super block before writing the super block when attempting to sync the log. So acquire the tree log mutex only when it's absolutely needed, before setting the transaction state to TRANS_STATE_UNBLOCKED, fix and move the stale comment, add some assertions and new comments where appropriate. Also, this has no effect on concurrency or performance, since the new start of the critical section is still when the transaction is in the state TRANS_STATE_COMMIT_DOING. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-10-26btrfs: add a BTRFS_FS_ERROR helperJosef Bacik1-6/+5
We have a few flags that are inconsistently used to describe the fs in different states of failure. As of 5963ffcaf383 ("btrfs: always abort the transaction if we abort a trans handle") we will always set BTRFS_FS_STATE_ERROR if we abort, so we don't have to check both ABORTED and ERROR to see if things have gone wrong. Add a helper to check BTRFS_FS_STATE_ERROR and then convert all checkers of FS_STATE_ERROR to use the helper. The TRANS_ABORTED bit check was added in af7227338135 ("Btrfs: clean up resources during umount after trans is aborted") but is not actually specific. Reviewed-by: Anand Jain <anand.jain@oracle.com> 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>
2021-07-07btrfs: rework chunk allocation to avoid exhaustion of the system chunk arrayFilipe Manana1-5/+5
Commit eafa4fd0ad0607 ("btrfs: fix exhaustion of the system chunk array due to concurrent allocations") fixed a problem that resulted in exhausting the system chunk array in the superblock when there are many tasks allocating chunks in parallel. Basically too many tasks enter the first phase of chunk allocation without previous tasks having finished their second phase of allocation, resulting in too many system chunks being allocated. That was originally observed when running the fallocate tests of stress-ng on a PowerPC machine, using a node size of 64K. However that commit also introduced a deadlock where a task in phase 1 of the chunk allocation waited for another task that had allocated a system chunk to finish its phase 2, but that other task was waiting on an extent buffer lock held by the first task, therefore resulting in both tasks not making any progress. That change was later reverted by a patch with the subject "btrfs: fix deadlock with concurrent chunk allocations involving system chunks", since there is no simple and short solution to address it and the deadlock is relatively easy to trigger on zoned filesystems, while the system chunk array exhaustion is not so common. This change reworks the chunk allocation to avoid the system chunk array exhaustion. It accomplishes that by making the first phase of chunk allocation do the updates of the device items in the chunk btree and the insertion of the new chunk item in the chunk btree. This is done while under the protection of the chunk mutex (fs_info->chunk_mutex), in the same critical section that checks for available system space, allocates a new system chunk if needed and reserves system chunk space. This way we do not have chunk space reserved until the second phase completes. The same logic is applied to chunk removal as well, since it keeps reserved system space long after it is done updating the chunk btree. For direct allocation of system chunks, the previous behaviour remains, because otherwise we would deadlock on extent buffers of the chunk btree. Changes to the chunk btree are by large done by chunk allocation and chunk removal, which first reserve chunk system space and then later do changes to the chunk btree. The other remaining cases are uncommon and correspond to adding a device, removing a device and resizing a device. All these other cases do not pre-reserve system space, they modify the chunk btree right away, so they don't hold reserved space for a long period like chunk allocation and chunk removal do. The diff of this change is huge, but more than half of it is just addition of comments describing both how things work regarding chunk allocation and removal, including both the new behavior and the parts of the old behavior that did not change. CC: stable@vger.kernel.org # 5.12+ Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com> Tested-by: Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Tested-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-07-07btrfs: fix deadlock with concurrent chunk allocations involving system chunksFilipe Manana1-5/+0
When a task attempting to allocate a new chunk verifies that there is not currently enough free space in the system space_info and there is another task that allocated a new system chunk but it did not finish yet the creation of the respective block group, it waits for that other task to finish creating the block group. This is to avoid exhaustion of the system chunk array in the superblock, which is limited, when we have a thundering herd of tasks allocating new chunks. This problem was described and fixed by commit eafa4fd0ad0607 ("btrfs: fix exhaustion of the system chunk array due to concurrent allocations"). However there are two very similar scenarios where this can lead to a deadlock: 1) Task B allocated a new system chunk and task A is waiting on task B to finish creation of the respective system block group. However before task B ends its transaction handle and finishes the creation of the system block group, it attempts to allocate another chunk (like a data chunk for an fallocate operation for a very large range). Task B will be unable to progress and allocate the new chunk, because task A set space_info->chunk_alloc to 1 and therefore it loops at btrfs_chunk_alloc() waiting for task A to finish its chunk allocation and set space_info->chunk_alloc to 0, but task A is waiting on task B to finish creation of the new system block group, therefore resulting in a deadlock; 2) Task B allocated a new system chunk and task A is waiting on task B to finish creation of the respective system block group. By the time that task B enter the final phase of block group allocation, which happens at btrfs_create_pending_block_groups(), when it modifies the extent tree, the device tree or the chunk tree to insert the items for some new block group, it needs to allocate a new chunk, so it ends up at btrfs_chunk_alloc() and keeps looping there because task A has set space_info->chunk_alloc to 1, but task A is waiting for task B to finish creation of the new system block group and release the reserved system space, therefore resulting in a deadlock. In short, the problem is if a task B needs to allocate a new chunk after it previously allocated a new system chunk and if another task A is currently waiting for task B to complete the allocation of the new system chunk. Unfortunately this deadlock scenario introduced by the previous fix for the system chunk array exhaustion problem does not have a simple and short fix, and requires a big change to rework the chunk allocation code so that chunk btree updates are all made in the first phase of chunk allocation. And since this deadlock regression is being frequently hit on zoned filesystems and the system chunk array exhaustion problem is triggered in more extreme cases (originally observed on PowerPC with a node size of 64K when running the fallocate tests from stress-ng), revert the changes from that commit. The next patch in the series, with a subject of "btrfs: rework chunk allocation to avoid exhaustion of the system chunk array" does the necessary changes to fix the system chunk array exhaustion problem. Reported-by: Naohiro Aota <naohiro.aota@wdc.com> Link: https://lore.kernel.org/linux-btrfs/20210621015922.ewgbffxuawia7liz@naota-xeon/ Fixes: eafa4fd0ad0607 ("btrfs: fix exhaustion of the system chunk array due to concurrent allocations") CC: stable@vger.kernel.org # 5.12+ Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com> Tested-by: Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Tested-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-06-22btrfs: send: fix crash when memory allocations trigger reclaimFilipe Manana1-3/+0
When doing a send we don't expect the task to ever start a transaction after the initial check that verifies if commit roots match the regular roots. This is because after that we set current->journal_info with a stub (special value) that signals we are in send context, so that we take a read lock on an extent buffer when reading it from disk and verifying it is valid (its generation matches the generation stored in the parent). This stub was introduced in 2014 by commit a26e8c9f75b0bf ("Btrfs: don't clear uptodate if the eb is under IO") in order to fix a concurrency issue between send and balance. However there is one particular exception where we end up needing to start a transaction and when this happens it results in a crash with a stack trace like the following: [60015.902283] kernel: WARNING: CPU: 3 PID: 58159 at arch/x86/include/asm/kfence.h:44 kfence_protect_page+0x21/0x80 [60015.902292] kernel: Modules linked in: uinput rfcomm snd_seq_dummy (...) [60015.902384] kernel: CPU: 3 PID: 58159 Comm: btrfs Not tainted 5.12.9-300.fc34.x86_64 #1 [60015.902387] kernel: Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./F2A88XN-WIFI, BIOS F6 12/24/2015 [60015.902389] kernel: RIP: 0010:kfence_protect_page+0x21/0x80 [60015.902393] kernel: Code: ff 0f 1f 84 00 00 00 00 00 55 48 89 fd (...) [60015.902396] kernel: RSP: 0018:ffff9fb583453220 EFLAGS: 00010246 [60015.902399] kernel: RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff9fb583453224 [60015.902401] kernel: RDX: ffff9fb583453224 RSI: 0000000000000000 RDI: 0000000000000000 [60015.902402] kernel: RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 [60015.902404] kernel: R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002 [60015.902406] kernel: R13: ffff9fb583453348 R14: 0000000000000000 R15: 0000000000000001 [60015.902408] kernel: FS: 00007f158e62d8c0(0000) GS:ffff93bd37580000(0000) knlGS:0000000000000000 [60015.902410] kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [60015.902412] kernel: CR2: 0000000000000039 CR3: 00000001256d2000 CR4: 00000000000506e0 [60015.902414] kernel: Call Trace: [60015.902419] kernel: kfence_unprotect+0x13/0x30 [60015.902423] kernel: page_fault_oops+0x89/0x270 [60015.902427] kernel: ? search_module_extables+0xf/0x40 [60015.902431] kernel: ? search_bpf_extables+0x57/0x70 [60015.902435] kernel: kernelmode_fixup_or_oops+0xd6/0xf0 [60015.902437] kernel: __bad_area_nosemaphore+0x142/0x180 [60015.902440] kernel: exc_page_fault+0x67/0x150 [60015.902445] kernel: asm_exc_page_fault+0x1e/0x30 [60015.902450] kernel: RIP: 0010:start_transaction+0x71/0x580 [60015.902454] kernel: Code: d3 0f 84 92 00 00 00 80 e7 06 0f 85 63 (...) [60015.902456] kernel: RSP: 0018:ffff9fb5834533f8 EFLAGS: 00010246 [60015.902458] kernel: RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000000 [60015.902460] kernel: RDX: 0000000000000801 RSI: 0000000000000000 RDI: 0000000000000039 [60015.902462] kernel: RBP: ffff93bc0a7eb800 R08: 0000000000000001 R09: 0000000000000000 [60015.902463] kernel: R10: 0000000000098a00 R11: 0000000000000001 R12: 0000000000000001 [60015.902464] kernel: R13: 0000000000000000 R14: ffff93bc0c92b000 R15: ffff93bc0c92b000 [60015.902468] kernel: btrfs_commit_inode_delayed_inode+0x5d/0x120 [60015.902473] kernel: btrfs_evict_inode+0x2c5/0x3f0 [60015.902476] kernel: evict+0xd1/0x180 [60015.902480] kernel: inode_lru_isolate+0xe7/0x180 [60015.902483] kernel: __list_lru_walk_one+0x77/0x150 [60015.902487] kernel: ? iput+0x1a0/0x1a0 [60015.902489] kernel: ? iput+0x1a0/0x1a0 [60015.902491] kernel: list_lru_walk_one+0x47/0x70 [60015.902495] kernel: prune_icache_sb+0x39/0x50 [60015.902497] kernel: super_cache_scan+0x161/0x1f0 [60015.902501] kernel: do_shrink_slab+0x142/0x240 [60015.902505] kernel: shrink_slab+0x164/0x280 [60015.902509] kernel: shrink_node+0x2c8/0x6e0 [60015.902512] kernel: do_try_to_free_pages+0xcb/0x4b0 [60015.902514] kernel: try_to_free_pages+0xda/0x190 [60015.902516] kernel: __alloc_pages_slowpath.constprop.0+0x373/0xcc0 [60015.902521] kernel: ? __memcg_kmem_charge_page+0xc2/0x1e0 [60015.902525] kernel: __alloc_pages_nodemask+0x30a/0x340 [60015.902528] kernel: pipe_write+0x30b/0x5c0 [60015.902531] kernel: ? set_next_entity+0xad/0x1e0 [60015.902534] kernel: ? switch_mm_irqs_off+0x58/0x440 [60015.902538] kernel: __kernel_write+0x13a/0x2b0 [60015.902541] kernel: kernel_write+0x73/0x150 [60015.902543] kernel: send_cmd+0x7b/0xd0 [60015.902545] kernel: send_extent_data+0x5a3/0x6b0 [60015.902549] kernel: process_extent+0x19b/0xed0 [60015.902551] kernel: btrfs_ioctl_send+0x1434/0x17e0 [60015.902554] kernel: ? _btrfs_ioctl_send+0xe1/0x100 [60015.902557] kernel: _btrfs_ioctl_send+0xbf/0x100 [60015.902559] kernel: ? enqueue_entity+0x18c/0x7b0 [60015.902562] kernel: btrfs_ioctl+0x185f/0x2f80 [60015.902564] kernel: ? psi_task_change+0x84/0xc0 [60015.902569] kernel: ? _flat_send_IPI_mask+0x21/0x40 [60015.902572] kernel: ? check_preempt_curr+0x2f/0x70 [60015.902576] kernel: ? selinux_file_ioctl+0x137/0x1e0 [60015.902579] kernel: ? expand_files+0x1cb/0x1d0 [60015.902582] kernel: ? __x64_sys_ioctl+0x82/0xb0 [60015.902585] kernel: __x64_sys_ioctl+0x82/0xb0 [60015.902588] kernel: do_syscall_64+0x33/0x40 [60015.902591] kernel: entry_SYSCALL_64_after_hwframe+0x44/0xae [60015.902595] kernel: RIP: 0033:0x7f158e38f0ab [60015.902599] kernel: Code: ff ff ff 85 c0 79 9b (...) [60015.902602] kernel: RSP: 002b:00007ffcb2519bf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [60015.902605] kernel: RAX: ffffffffffffffda RBX: 00007ffcb251ae00 RCX: 00007f158e38f0ab [60015.902607] kernel: RDX: 00007ffcb2519cf0 RSI: 0000000040489426 RDI: 0000000000000004 [60015.902608] kernel: RBP: 0000000000000004 R08: 00007f158e297640 R09: 00007f158e297640 [60015.902610] kernel: R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000000 [60015.902612] kernel: R13: 0000000000000002 R14: 00007ffcb251aee0 R15: 0000558c1a83e2a0 [60015.902615] kernel: ---[ end trace 7bbc33e23bb887ae ]--- This happens because when writing to the pipe, by calling kernel_write(), we end up doing page allocations using GFP_HIGHUSER | __GFP_ACCOUNT as the gfp flags, which allow reclaim to happen if there is memory pressure. This allocation happens at fs/pipe.c:pipe_write(). If the reclaim is triggered, inode eviction can be triggered and that in turn can result in starting a transaction if the inode has a link count of 0. The transaction start happens early on during eviction, when we call btrfs_commit_inode_delayed_inode() at btrfs_evict_inode(). This happens if there is currently an open file descriptor for an inode with a link count of 0 and the reclaim task gets a reference on the inode before that descriptor is closed, in which case the reclaim task ends up doing the final iput that triggers the inode eviction. When we have assertions enabled (CONFIG_BTRFS_ASSERT=y), this triggers the following assertion at transaction.c:start_transaction(): /* Send isn't supposed to start transactions. */ ASSERT(current->journal_info != BTRFS_SEND_TRANS_STUB); And when assertions are not enabled, it triggers a crash since after that assertion we cast current->journal_info into a transaction handle pointer and then dereference it: if (current->journal_info) { WARN_ON(type & TRANS_EXTWRITERS); h = current->journal_info; refcount_inc(&h->use_count); (...) Which obviously results in a crash due to an invalid memory access. The same type of issue can happen during other memory allocations we do directly in the send code with kmalloc (and friends) as they use GFP_KERNEL and therefore may trigger reclaim too, which started to happen since 2016 after commit e780b0d1c1523e ("btrfs: send: use GFP_KERNEL everywhere"). The issue could be solved by setting up a NOFS context for the entire send operation so that reclaim could not be triggered when allocating memory or pages through kernel_write(). However that is not very friendly and we can in fact get rid of the send stub because: 1) The stub was introduced way back in 2014 by commit a26e8c9f75b0bf ("Btrfs: don't clear uptodate if the eb is under IO") to solve an issue exclusive to when send and balance are running in parallel, however there were other problems between balance and send and we do not allow anymore to have balance and send run concurrently since commit 9e967495e0e0ae ("Btrfs: prevent send failures and crashes due to concurrent relocation"). More generically the issues are between send and relocation, and that last commit eliminated only the possibility of having send and balance run concurrently, but shrinking a device also can trigger relocation, and on zoned filesystems we have relocation of partially used block groups triggered automatically as well. The previous patch that has a subject of: "btrfs: ensure relocation never runs while we have send operations running" Addresses all the remaining cases that can trigger relocation. 2) We can actually allow starting and even committing transactions while in a send context if needed because send is not holding any locks that would block the start or the commit of a transaction. So get rid of all the logic added by commit a26e8c9f75b0bf ("Btrfs: don't clear uptodate if the eb is under IO"). We can now always call clear_extent_buffer_uptodate() at verify_parent_transid() since send is the only case that uses commit roots without having a transaction open or without holding the commit_root_sem. Reported-by: Chris Murphy <lists@colorremedies.com> Link: https://lore.kernel.org/linux-btrfs/CAJCQCtRQ57=qXo3kygwpwEBOU_CA_eKvdmjP52sU=eFvuVOEGw@mail.gmail.com/ Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-06-22btrfs: fix unbalanced unlock in qgroup_account_snapshot()Naohiro Aota1-1/+1
qgroup_account_snapshot() is trying to unlock the not taken tree_log_mutex in a error path. Since ret != 0 in this case, we can just return from here. Fixes: 2a4d84c11a87 ("btrfs: move delayed ref flushing for qgroup into qgroup helper") CC: stable@vger.kernel.org # 5.12+ Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-06-21btrfs: inline wait_current_trans_commit_start in its callerDavid Sterba1-13/+7
Function wait_current_trans_commit_start is now fairly trivial so it can be inlined in its only caller. Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-06-21btrfs: sink wait_for_unblock parameter to async commitDavid Sterba1-22/+2
There's only one caller left btrfs_ioctl_start_sync that passes 0, so we can remove the switch in btrfs_commit_transaction_async. A cleanup 9babda9f33fd ("btrfs: Remove async_transid from btrfs_mksubvol/create_subvol/create_snapshot") removed calls that passed 1, so this is a followup. As this removes last call of wait_current_trans_commit_start_and_unblock, remove the function as well. Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-06-21btrfs: clear defrag status of a root if starting transaction failsDavid Sterba1-2/+4
The defrag loop processes leaves in batches and starting transaction for each. The whole defragmentation on a given root is protected by a bit but in case the transaction fails, the bit is not cleared In case the transaction fails the bit would prevent starting defragmentation again, so make sure it's cleared. CC: stable@vger.kernel.org # 4.4+ Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-06-21btrfs: always abort the transaction if we abort a trans handleJosef Bacik1-8/+0
While stress testing our error handling I noticed that sometimes we would still commit the transaction even though we had aborted the transaction. Currently we track if a trans handle has dirtied any metadata, and if it hasn't we mark the filesystem as having an error (so no new transactions can be started), but we will allow the current transaction to complete as we do not mark the transaction itself as having been aborted. This sounds good in theory, but we were not properly tracking IO errors in btrfs_finish_ordered_io, and thus committing the transaction with bogus free space data. This isn't necessarily a problem per-se with the free space cache, as the other guards in place would have kept us from accepting the free space cache as valid, but highlights a real world case where we had a bug and could have corrupted the filesystem because of it. This "skip abort on empty trans handle" is nice in theory, but assumes we have perfect error handling everywhere, which we clearly do not. Also we do not allow further transactions to be started, so all this does is save the last transaction that was happening, which doesn't necessarily gain us anything other than the potential for real corruption. Remove this particular bit of code, if we decide we need to abort the transaction then abort the current one and keep us from doing real harm to the file system, regardless of whether this specific trans handle dirtied anything or not. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-04-19btrfs: fix race between transaction aborts and fsyncs leading to use-after-freeFilipe Manana1-1/+11
There is a race between a task aborting a transaction during a commit, a task doing an fsync and the transaction kthread, which leads to an use-after-free of the log root tree. When this happens, it results in a stack trace like the following: BTRFS info (device dm-0): forced readonly BTRFS warning (device dm-0): Skipping commit of aborted transaction. BTRFS: error (device dm-0) in cleanup_transaction:1958: errno=-5 IO failure BTRFS warning (device dm-0): lost page write due to IO error on /dev/mapper/error-test (-5) BTRFS warning (device dm-0): Skipping commit of aborted transaction. BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0xa4e8 len 4096 err no 10 BTRFS error (device dm-0): error writing primary super block to device 1 BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e000 len 4096 err no 10 BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e008 len 4096 err no 10 BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e010 len 4096 err no 10 BTRFS: error (device dm-0) in write_all_supers:4110: errno=-5 IO failure (1 errors while writing supers) BTRFS: error (device dm-0) in btrfs_sync_log:3308: errno=-5 IO failure general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b68: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI CPU: 2 PID: 2458471 Comm: fsstress Not tainted 5.12.0-rc5-btrfs-next-84 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 RIP: 0010:__mutex_lock+0x139/0xa40 Code: c0 74 19 (...) RSP: 0018:ffff9f18830d7b00 EFLAGS: 00010202 RAX: 6b6b6b6b6b6b6b68 RBX: 0000000000000001 RCX: 0000000000000002 RDX: ffffffffb9c54d13 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff9f18830d7bc0 R08: 0000000000000000 R09: 0000000000000000 R10: ffff9f18830d7be0 R11: 0000000000000001 R12: ffff8c6cd199c040 R13: ffff8c6c95821358 R14: 00000000fffffffb R15: ffff8c6cbcf01358 FS: 00007fa9140c2b80(0000) GS:ffff8c6fac600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa913d52000 CR3: 000000013d2b4003 CR4: 0000000000370ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ? __btrfs_handle_fs_error+0xde/0x146 [btrfs] ? btrfs_sync_log+0x7c1/0xf20 [btrfs] ? btrfs_sync_log+0x7c1/0xf20 [btrfs] btrfs_sync_log+0x7c1/0xf20 [btrfs] btrfs_sync_file+0x40c/0x580 [btrfs] do_fsync+0x38/0x70 __x64_sys_fsync+0x10/0x20 do_syscall_64+0x33/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fa9142a55c3 Code: 8b 15 09 (...) RSP: 002b:00007fff26278d48 EFLAGS: 00000246 ORIG_RAX: 000000000000004a RAX: ffffffffffffffda RBX: 0000563c83cb4560 RCX: 00007fa9142a55c3 RDX: 00007fff26278cb0 RSI: 00007fff26278cb0 RDI: 0000000000000005 RBP: 0000000000000005 R08: 0000000000000001 R09: 00007fff26278d5c R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000340 R13: 00007fff26278de0 R14: 00007fff26278d96 R15: 0000563c83ca57c0 Modules linked in: btrfs dm_zero dm_snapshot dm_thin_pool (...) ---[ end trace ee2f1b19327d791d ]--- The steps that lead to this crash are the following: 1) We are at transaction N; 2) We have two tasks with a transaction handle attached to transaction N. Task A and Task B. Task B is doing an fsync; 3) Task B is at btrfs_sync_log(), and has saved fs_info->log_root_tree into a local variable named 'log_root_tree' at the top of btrfs_sync_log(). Task B is about to call write_all_supers(), but before that... 4) Task A calls btrfs_commit_transaction(), and after it sets the transaction state to TRANS_STATE_COMMIT_START, an error happens before it waits for the transaction's 'num_writers' counter to reach a value of 1 (no one else attached to the transaction), so it jumps to the label "cleanup_transaction"; 5) Task A then calls cleanup_transaction(), where it aborts the transaction, setting BTRFS_FS_STATE_TRANS_ABORTED on fs_info->fs_state, setting the ->aborted field of the transaction and the handle to an errno value and also setting BTRFS_FS_STATE_ERROR on fs_info->fs_state. After that, at cleanup_transaction(), it deletes the transaction from the list of transactions (fs_info->trans_list), sets the transaction to the state TRANS_STATE_COMMIT_DOING and then waits for the number of writers to go down to 1, as it's currently 2 (1 for task A and 1 for task B); 6) The transaction kthread is running and sees that BTRFS_FS_STATE_ERROR is set in fs_info->fs_state, so it calls btrfs_cleanup_transaction(). There it sees the list fs_info->trans_list is empty, and then proceeds into calling btrfs_drop_all_logs(), which frees the log root tree with a call to btrfs_free_log_root_tree(); 7) Task B calls write_all_supers() and, shortly after, under the label 'out_wake_log_root', it deferences the pointer stored in 'log_root_tree', which was already freed in the previous step by the transaction kthread. This results in a use-after-free leading to a crash. Fix this by deleting the transaction from the list of transactions at cleanup_transaction() only after setting the transaction state to TRANS_STATE_COMMIT_DOING and waiting for all existing tasks that are attached to the transaction to release their transaction handles. This makes the transaction kthread wait for all the tasks attached to the transaction to be done with the transaction before dropping the log roots and doing other cleanups. Fixes: ef67963dac255b ("btrfs: drop logs when we've aborted a transaction") CC: stable@vger.kernel.org # 5.10+ Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-04-19btrfs: handle btrfs_update_reloc_root failure in commit_fs_rootsJosef Bacik1-1/+3
btrfs_update_reloc_root will will return errors in the future, so handle the error properly in commit_fs_roots. Reviewed-by: Qu Wenruo <wqu@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>
2021-04-19btrfs: return an error from btrfs_record_root_in_transJosef Bacik1-2/+3
We can create a reloc root when we record the root in the trans, which can fail for all sorts of different reasons. Propagate this error up the chain of callers. Future patches will fix the callers of btrfs_record_root_in_trans() to handle the error. Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-04-19btrfs: handle record_root_in_trans failure in create_pending_snapshotJosef Bacik1-3/+8
record_root_in_trans can currently fail, so handle this failure properly. Reviewed-by: Qu Wenruo <wqu@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>
2021-04-19btrfs: handle record_root_in_trans failure in btrfs_record_root_in_transJosef Bacik1-2/+3
record_root_in_trans can fail currently, handle this failure properly. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-04-19btrfs: handle record_root_in_trans failure in qgroup_account_snapshotJosef Bacik1-2/+4
record_root_in_trans can fail currently, so handle this failure properly. Reviewed-by: Qu Wenruo <wqu@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>
2021-04-19btrfs: handle btrfs_record_root_in_trans failure in start_transactionJosef Bacik1-1/+10
btrfs_record_root_in_trans will return errors in the future, so handle the error properly in start_transaction. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> [ add comment ] Signed-off-by: David Sterba <dsterba@suse.com>
2021-04-19btrfs: fix exhaustion of the system chunk array due to concurrent allocationsFilipe Manana1-0/+5
When we are running out of space for updating the chunk tree, that is, when we are low on available space in the system space info, if we have many task concurrently allocating block groups, via fallocate for example, many of them can end up all allocating new system chunks when only one is needed. In extreme cases this can lead to exhaustion of the system chunk array, which has a size limit of 2048 bytes, and results in a transaction abort with errno EFBIG, producing a trace in dmesg like the following, which was triggered on a PowerPC machine with a node/leaf size of 64K: [1359.518899] ------------[ cut here ]------------ [1359.518980] BTRFS: Transaction aborted (error -27) [1359.519135] WARNING: CPU: 3 PID: 16463 at ../fs/btrfs/block-group.c:1968 btrfs_create_pending_block_groups+0x340/0x3c0 [btrfs] [1359.519152] Modules linked in: (...) [1359.519239] Supported: Yes, External [1359.519252] CPU: 3 PID: 16463 Comm: stress-ng Tainted: G X 5.3.18-47-default #1 SLE15-SP3 [1359.519274] NIP: c008000000e36fe8 LR: c008000000e36fe4 CTR: 00000000006de8e8 [1359.519293] REGS: c00000056890b700 TRAP: 0700 Tainted: G X (5.3.18-47-default) [1359.519317] MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 48008222 XER: 00000007 [1359.519356] CFAR: c00000000013e170 IRQMASK: 0 [1359.519356] GPR00: c008000000e36fe4 c00000056890b990 c008000000e83200 0000000000000026 [1359.519356] GPR04: 0000000000000000 0000000000000000 0000d52a3b027651 0000000000000007 [1359.519356] GPR08: 0000000000000003 0000000000000001 0000000000000007 0000000000000000 [1359.519356] GPR12: 0000000000008000 c00000063fe44600 000000001015e028 000000001015dfd0 [1359.519356] GPR16: 000000000000404f 0000000000000001 0000000000010000 0000dd1e287affff [1359.519356] GPR20: 0000000000000001 c000000637c9a000 ffffffffffffffe5 0000000000000000 [1359.519356] GPR24: 0000000000000004 0000000000000000 0000000000000100 ffffffffffffffc0 [1359.519356] GPR28: c000000637c9a000 c000000630e09230 c000000630e091d8 c000000562188b08 [1359.519561] NIP [c008000000e36fe8] btrfs_create_pending_block_groups+0x340/0x3c0 [btrfs] [1359.519613] LR [c008000000e36fe4] btrfs_create_pending_block_groups+0x33c/0x3c0 [btrfs] [1359.519626] Call Trace: [1359.519671] [c00000056890b990] [c008000000e36fe4] btrfs_create_pending_block_groups+0x33c/0x3c0 [btrfs] (unreliable) [1359.519729] [c00000056890ba90] [c008000000d68d44] __btrfs_end_transaction+0xbc/0x2f0 [btrfs] [1359.519782] [c00000056890bae0] [c008000000e309ac] btrfs_alloc_data_chunk_ondemand+0x154/0x610 [btrfs] [1359.519844] [c00000056890bba0] [c008000000d8a0fc] btrfs_fallocate+0xe4/0x10e0 [btrfs] [1359.519891] [c00000056890bd00] [c0000000004a23b4] vfs_fallocate+0x174/0x350 [1359.519929] [c00000056890bd50] [c0000000004a3cf8] ksys_fallocate+0x68/0xf0 [1359.519957] [c00000056890bda0] [c0000000004a3da8] sys_fallocate+0x28/0x40 [1359.519988] [c00000056890bdc0] [c000000000038968] system_call_exception+0xe8/0x170 [1359.520021] [c00000056890be20] [c00000000000cb70] system_call_common+0xf0/0x278 [1359.520037] Instruction dump: [1359.520049] 7d0049ad 40c2fff4 7c0004ac 71490004 40820024 2f83fffb 419e0048 3c620000 [1359.520082] e863bcb8 7ec4b378 48010d91 e8410018 <0fe00000> 3c820000 e884bcc8 7ec6b378 [1359.520122] ---[ end trace d6c186e151022e20 ]--- The following steps explain how we can end up in this situation: 1) Task A is at check_system_chunk(), either because it is allocating a new data or metadata block group, at btrfs_chunk_alloc(), or because it is removing a block group or turning a block group RO. It does not matter why; 2) Task A sees that there is not enough free space in the system space_info object, that is 'left' is < 'thresh'. And at this point the system space_info has a value of 0 for its 'bytes_may_use' counter; 3) As a consequence task A calls btrfs_alloc_chunk() in order to allocate a new system block group (chunk) and then reserves 'thresh' bytes in the chunk block reserve with the call to btrfs_block_rsv_add(). This changes the chunk block reserve's 'reserved' and 'size' counters by an amount of 'thresh', and changes the 'bytes_may_use' counter of the system space_info object from 0 to 'thresh'. Also during its call to btrfs_alloc_chunk(), we end up increasing the value of the 'total_bytes' counter of the system space_info object by 8MiB (the size of a system chunk stripe). This happens through the call chain: btrfs_alloc_chunk() create_chunk() btrfs_make_block_group() btrfs_update_space_info() 4) After it finishes the first phase of the block group allocation, at btrfs_chunk_alloc(), task A unlocks the chunk mutex; 5) At this point the new system block group was added to the transaction handle's list of new block groups, but its block group item, device items and chunk item were not yet inserted in the extent, device and chunk trees, respectively. That only happens later when we call btrfs_finish_chunk_alloc() through a call to btrfs_create_pending_block_groups(); Note that only when we update the chunk tree, through the call to btrfs_finish_chunk_alloc(), we decrement the 'reserved' counter of the chunk block reserve as we COW/allocate extent buffers, through: btrfs_alloc_tree_block() btrfs_use_block_rsv() btrfs_block_rsv_use_bytes() And the system space_info's 'bytes_may_use' is decremented everytime we allocate an extent buffer for COW operations on the chunk tree, through: btrfs_alloc_tree_block() btrfs_reserve_extent() find_free_extent() btrfs_add_reserved_bytes() If we end up COWing less chunk btree nodes/leaves than expected, which is the typical case since the amount of space we reserve is always pessimistic to account for the worst possible case, we release the unused space through: btrfs_create_pending_block_groups() btrfs_trans_release_chunk_metadata() btrfs_block_rsv_release() block_rsv_release_bytes() btrfs_space_info_free_bytes_may_use() But before task A gets into btrfs_create_pending_block_groups()... 6) Many other tasks start allocating new block groups through fallocate, each one does the first phase of block group allocation in a serialized way, since btrfs_chunk_alloc() takes the chunk mutex before calling check_system_chunk() and btrfs_alloc_chunk(). However before everyone enters the final phase of the block group allocation, that is, before calling btrfs_create_pending_block_groups(), new tasks keep coming to allocate new block groups and while at check_system_chunk(), the system space_info's 'bytes_may_use' keeps increasing each time a task reserves space in the chunk block reserve. This means that eventually some other task can end up not seeing enough free space in the system space_info and decide to allocate yet another system chunk. This may repeat several times if yet more new tasks keep allocating new block groups before task A, and all the other tasks, finish the creation of the pending block groups, which is when reserved space in excess is released. Eventually this can result in exhaustion of system chunk array in the superblock, with btrfs_add_system_chunk() returning EFBIG, resulting later in a transaction abort. Even when we don't reach the extreme case of exhausting the system array, most, if not all, unnecessarily created system block groups end up being unused since when finishing creation of the first pending system block group, the creation of the following ones end up not needing to COW nodes/leaves of the chunk tree, so we never allocate and deallocate from them, resulting in them never being added to the list of unused block groups - as a consequence they don't get deleted by the cleaner kthread - the only exceptions are if we unmount and mount the filesystem again, which adds any unused block groups to the list of unused block groups, if a scrub is run, which also adds unused block groups to the unused list, and under some circumstances when using a zoned filesystem or async discard, which may also add unused block groups to the unused list. So fix this by: *) Tracking the number of reserved bytes for the chunk tree per transaction, which is the sum of reserved chunk bytes by each transaction handle currently being used; *) When there is not enough free space in the system space_info, if there are other transaction handles which reserved chunk space, wait for some of them to complete in order to have enough excess reserved space released, and then try again. Otherwise proceed with the creation of a new system chunk. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-02-09btrfs: zoned: redirty released extent buffersNaohiro Aota1-0/+10
Tree manipulating operations like merging nodes often release once-allocated tree nodes. Such nodes are cleaned so that pages in the node are not uselessly written out. On zoned volumes, however, such optimization blocks the following IOs as the cancellation of the write out of the freed blocks breaks the sequential write sequence expected by the device. Introduce a list of clean and unwritten extent buffers that have been released in a transaction. Redirty the buffers so that btree_write_cache_pages() can send proper bios to the devices. Besides it clears the entire content of the extent buffer not to confuse raw block scanners e.g. 'btrfs check'. By clearing the content, csum_dirty_buffer() complains about bytenr mismatch, so avoid the checking and checksum using newly introduced buffer flag EXTENT_BUFFER_NO_CHECK. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-02-08btrfs: make concurrent fsyncs wait less when waiting for a transaction commitFilipe Manana1-8/+31
Often an fsync needs to fallback to a transaction commit for several reasons (to ensure consistency after a power failure, a new block group was allocated or a temporary error such as ENOMEM or ENOSPC happened). In that case the log is marked as needing a full commit and any concurrent tasks attempting to log inodes or commit the log will also fallback to the transaction commit. When this happens they all wait for the task that first started the transaction commit to finish the transaction commit - however they wait until the full transaction commit happens, which is not needed, as they only need to wait for the superblocks to be persisted and not for unpinning all the extents pinned during the transaction's lifetime, which even for short lived transactions can be a few thousand and take some significant amount of time to complete - for dbench workloads I have observed up to 4~5 milliseconds of time spent unpinning extents in the worst cases, and the number of pinned extents was between 2 to 3 thousand. So allow fsync tasks to skip waiting for the unpinning of extents when they call btrfs_commit_transaction() and they were not the task that started the transaction commit (that one has to do it, the alternative would be to offload the transaction commit to another task so that it could avoid waiting for the extent unpinning or offload the extent unpinning to another task). This patch is part of a patchset comprised of the following patches: btrfs: remove unnecessary directory inode item update when deleting dir entry btrfs: stop setting nbytes when filling inode item for logging btrfs: avoid logging new ancestor inodes when logging new inode btrfs: skip logging directories already logged when logging all parents btrfs: skip logging inodes already logged when logging new entries btrfs: remove unnecessary check_parent_dirs_for_sync() btrfs: make concurrent fsyncs wait less when waiting for a transaction commit After applying the entire patchset, dbench shows improvements in respect to throughput and latency. The script used to measure it is the following: $ cat dbench-test.sh #!/bin/bash DEV=/dev/sdk MNT=/mnt/sdk MOUNT_OPTIONS="-o ssd" MKFS_OPTIONS="-m single -d single" echo "performance" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor umount $DEV &> /dev/null mkfs.btrfs -f $MKFS_OPTIONS $DEV mount $MOUNT_OPTIONS $DEV $MNT dbench -D $MNT -t 300 64 umount $MNT The test was run on a physical machine with 12 cores (Intel corei7), 64G of ram, using a NVMe device and a non-debug kernel configuration (Debian's default configuration). Before applying patchset, 32 clients: Operation Count AvgLat MaxLat ---------------------------------------- NTCreateX 9627107 0.153 61.938 Close 7072076 0.001 3.175 Rename 407633 1.222 44.439 Unlink 1943895 0.658 44.440 Deltree 256 17.339 110.891 Mkdir 128 0.003 0.009 Qpathinfo 8725406 0.064 17.850 Qfileinfo 1529516 0.001 2.188 Qfsinfo 1599884 0.002 1.457 Sfileinfo 784200 0.005 3.562 Find 3373513 0.411 30.312 WriteX 4802132 0.053 29.054 ReadX 15089959 0.002 5.801 LockX 31344 0.002 0.425 UnlockX 31344 0.001 0.173 Flush 674724 5.952 341.830 Throughput 1008.02 MB/sec 32 clients 32 procs max_latency=341.833 ms After applying patchset, 32 clients: After patchset, with 32 clients: Operation Count AvgLat MaxLat ---------------------------------------- NTCreateX 9931568 0.111 25.597 Close 7295730 0.001 2.171 Rename 420549 0.982 49.714 Unlink 2005366 0.497 39.015 Deltree 256 11.149 89.242 Mkdir 128 0.002 0.014 Qpathinfo 9001863 0.049 20.761 Qfileinfo 1577730 0.001 2.546 Qfsinfo 1650508 0.002 3.531 Sfileinfo 809031 0.005 5.846 Find 3480259 0.309 23.977 WriteX 4952505 0.043 41.283 ReadX 15568127 0.002 5.476 LockX 32338 0.002 0.978 UnlockX 32338 0.001 2.032 Flush 696017 7.485 228.835 Throughput 1049.91 MB/sec 32 clients 32 procs max_latency=228.847 ms --> +4.1% throughput, -39.6% max latency Before applying patchset, 64 clients: Operation Count AvgLat MaxLat ---------------------------------------- NTCreateX 8956748 0.342 108.312 Close 6579660 0.001 3.823 Rename 379209 2.396 81.897 Unlink 1808625 1.108 131.148 Deltree 256 25.632 172.176 Mkdir 128 0.003 0.018 Qpathinfo 8117615 0.131 55.916 Qfileinfo 1423495 0.001 2.635 Qfsinfo 1488496 0.002 5.412 Sfileinfo 729472 0.007 8.643 Find 3138598 0.855 78.321 WriteX 4470783 0.102 79.442 ReadX 14038139 0.002 7.578 LockX 29158 0.002 0.844 UnlockX 29158 0.001 0.567 Flush 627746 14.168 506.151 Throughput 924.738 MB/sec 64 clients 64 procs max_latency=506.154 ms After applying patchset, 64 clients: Operation Count AvgLat MaxLat ---------------------------------------- NTCreateX 9069003 0.303 43.193 Close 6662328 0.001 3.888 Rename 383976 2.194 46.418 Unlink 1831080 1.022 43.873 Deltree 256 24.037 155.763 Mkdir 128 0.002 0.005 Qpathinfo 8219173 0.137 30.233 Qfileinfo 1441203 0.001 3.204 Qfsinfo 1507092 0.002 4.055 Sfileinfo 738775 0.006 5.431 Find 3177874 0.936 38.170 WriteX 4526152 0.084 39.518 ReadX 14213562 0.002 24.760 LockX 29522 0.002 1.221 UnlockX 29522 0.001 0.694 Flush 635652 14.358 422.039 Throughput 990.13 MB/sec 64 clients 64 procs max_latency=422.043 ms --> +6.8% throughput, -18.1% max latency Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-02-08btrfs: run delayed refs less often in commit_cowonly_rootsJosef Bacik1-11/+12
We love running delayed refs in commit_cowonly_roots, but it is a bit excessive. I was seeing cases of running 3 or 4 refs a few times in a row during this time. Instead simply: - update all of the roots first - then run delayed refs - then handle the empty block groups case - and then if we have any more dirty roots do the whole thing again This allows us to be much more efficient with our delayed ref running, as we can batch a few more operations at once. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-02-08btrfs: stop running all delayed refs during snapshotJosef Bacik1-6/+0
This was added in commit 361048f586f5 ("Btrfs: fix full backref problem when inserting shared block reference") to address a problem where we hit the following BUG_ON() in alloc_reserved_tree_block if (node->type == BTRFS_SHARED_BLOCK_REF_KEY) { BUG_ON(!(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)); However this BUG_ON() is bogus, and was removed by previous commit: btrfs: remove bogus BUG_ON in alloc_reserved_tree_block We no longer need to run delayed refs because of this, and can remove this flushing here. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-02-08btrfs: move delayed ref flushing for qgroup into qgroup helperJosef Bacik1-6/+17
The commit d67263354541 ("btrfs: qgroup: Make snapshot accounting work with new extent-oriented qgroup.") added a flush of the delayed refs during snapshot creation in order to get the qgroup accounting properly. However this code has changed and been moved to it's own helper that is skipped if qgroups are turned off. Move the flushing to the helper, as we do not need it when qgroups are turned off. Also add a comment explaining why it exists, and why it doesn't actually save us. This will be helpful later when we try to fix qgroup accounting properly. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-02-08btrfs: only run delayed refs once before committingJosef Bacik1-6/+0
We try to pre-flush the delayed refs when committing, because we want to do as little work as possible in the critical section of the transaction commit. However doing this twice can lead to very long transaction commit delays as other threads are allowed to continue to generate more delayed refs, which potentially delays the commit by multiple minutes in very extreme cases. So simply stick to one pre-flush, and then continue the rest of the transaction commit. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-02-08btrfs: only let one thread pre-flush delayed refs in commitJosef Bacik1-17/+15
I've been running a stress test that runs 20 workers in their own subvolume, which are running an fsstress instance with 4 threads per worker, which is 80 total fsstress threads. In addition to this I'm running balance in the background as well as creating and deleting snapshots. This test takes around 12 hours to run normally, going slower and slower as the test goes on. The reason for this is because fsstress is running fsync sometimes, and because we're messing with block groups we often fall through to btrfs_commit_transaction, so will often have 20-30 threads all calling btrfs_commit_transaction at the same time. These all get stuck contending on the extent tree while they try to run delayed refs during the initial part of the commit. This is suboptimal, really because the extent tree is a single point of failure we only want one thread acting on that tree at once to reduce lock contention. Fix this by making the flushing mechanism a bit operation, to make it easy to use test_and_set_bit() in order to make sure only one task does this initial flush. Once we're into the transaction commit we only have one thread doing delayed ref running, it's just this initial pre-flush that is problematic. With this patch my stress test takes around 90 minutes to run, instead of 12 hours. The memory barrier is not necessary for the flushing bit as it's ordered, unlike plain int. The transaction state accessed in btrfs_should_end_transaction could be affected by that too as it's not always used under transaction lock. Upon Nikolay's analysis in [1] it's not necessary: In should_end_transaction it's read without holding any locks. (U) It's modified in btrfs_cleanup_transaction without holding the fs_info->trans_lock (U), but the STATE_ERROR flag is going to be set. set in cleanup_transaction under fs_info->trans_lock (L) set in btrfs_commit_trans to COMMIT_START under fs_info->trans_lock.(L) set in btrfs_commit_trans to COMMIT_DOING under fs_info->trans_lock.(L) set in btrfs_commit_trans to COMMIT_UNBLOCK under fs_info->trans_lock.(L) set in btrfs_commit_trans to COMMIT_COMPLETED without locks but at this point the transaction is finished and fs_info->running_trans is NULL (U but irrelevant). So by the looks of it we can have a concurrent READ race with a WRITE, due to reads not taking a lock. In this case what we want to ensure is we either see new or old state. I consulted with Will Deacon and he said that in such a case we'd want to annotate the accesses to ->state with (READ|WRITE)_ONCE so as to avoid a theoretical tear, in this case I don't think this could happen but I imagine at some point KCSAN would flag such an access as racy (which it is). [1] https://lore.kernel.org/linux-btrfs/e1fd5cc1-0f28-f670-69f4-e9958b4964e6@suse.com Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> [ add comments regarding memory barrier ] Signed-off-by: David Sterba <dsterba@suse.com>
2021-02-08btrfs: rename btrfs_find_free_objectid to btrfs_get_free_objectidNikolay Borisov1-1/+1
This better reflects the semantics of the function i.e no search is performed whatsoever. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-02-08btrfs: fix error handling in commit_fs_rootsJosef Bacik1-5/+6
While doing error injection I would sometimes get a corrupt file system. This is because I was injecting errors at btrfs_search_slot, but would only do it one time per stack. This uncovered a problem in commit_fs_roots, where if we get an error we would just break. However we're in a nested loop, the first loop being a loop to find all the dirty fs roots, and then subsequent root updates would succeed clearing the error value. This isn't likely to happen in real scenarios, however we could potentially get a random ENOMEM once and then not again, and we'd end up with a corrupted file system. Fix this by moving the error checking around a bit to the main loop, as this is the only place where something will fail, and return the error as soon as it occurs. With this patch my reproducer no longer corrupts the file system. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2021-01-12btrfs: no need to run delayed refs after commit_fs_roots during commitDavid Sterba1-8/+0
The inode number cache has been removed in this dev cycle, there's one more leftover. We don't need to run the delayed refs again after commit_fs_roots as stated in the comment, because btrfs_save_ino_cache is no more since 5297199a8bca ("btrfs: remove inode number cache feature"). Nothing else between commit_fs_roots and btrfs_qgroup_account_extents could create new delayed refs so the qgroup consistency should be safe. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2020-12-09btrfs: keep sb cache_generation consistent with space_cacheBoris Burkov1-0/+2
When mounting, btrfs uses the cache_generation in the super block to determine if space cache v1 is in use. However, by mounting with nospace_cache or space_cache=v2, it is possible to disable space cache v1, which does not result in un-setting cache_generation back to 0. In order to base some logic, like mount option printing in /proc/mounts, on the current state of the space cache rather than just the values of the mount option, keep the value of cache_generation consistent with the status of space cache v1. We ensure that cache_generation > 0 iff the file system is using space_cache v1. This requires committing a transaction on any mount which changes whether we are using v1. (v1->nospace_cache, v1->v2, nospace_cache->v1, v2->v1). Since the mechanism for writing out the cache generation is transaction commit, but we want some finer grained control over when we un-set it, we can't just rely on the SPACE_CACHE mount option, and introduce an fs_info flag that mount can use when it wants to unset the generation. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
2020-12-09btrfs: remove inode number cache featureNikolay Borisov1-19/+0
It's been deprecated since commit b547a88ea577 ("btrfs: start deprecation of mount option inode_cache") which enumerates the reasons. A filesystem that uses the feature (mount -o inode_cache) tracks the inode numbers in bitmaps, that data stay on the filesystem after this patch. The size is roughly 5MiB for 1M inodes [1], which is considered small enough to be left there. Removal of the change can be implemented in btrfs-progs if needed. [1] https://lore.kernel.org/linux-btrfs/20201127145836.GZ6430@twin.jikos.cz/ Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> [ update changelog ] Signed-off-by: David Sterba <dsterba@suse.com>
2020-12-08btrfs: return bool from btrfs_should_end_transactionNikolay Borisov1-2/+2
Results in slightly smaller code. add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-11 (-11) Function old new delta btrfs_should_end_transaction 96 85 -11 Total: Before=20070, After=20059, chg -0.05% Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2020-12-08btrfs: return bool from should_end_transactionNikolay Borisov1-2/+2
Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2020-12-08btrfs: make btrfs_update_inode_fallback take btrfs_inodeNikolay Borisov1-1/+1
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2020-12-08btrfs: protect fs_info->caching_block_groups by block_group_cache_lockJosef Bacik1-0/+2
I got the following lockdep splat ====================================================== WARNING: possible circular locking dependency detected 5.9.0+ #101 Not tainted ------------------------------------------------------ btrfs-cleaner/3445 is trying to acquire lock: ffff89dbec39ab48 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x170 but task is already holding lock: ffff89dbeaf28a88 (&fs_info->commit_root_sem){++++}-{3:3}, at: btrfs_find_all_roots+0x41/0x80 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&fs_info->commit_root_sem){++++}-{3:3}: down_write+0x3d/0x70 btrfs_cache_block_group+0x2d5/0x510 find_free_extent+0xb6e/0x12f0 btrfs_reserve_extent+0xb3/0x1b0 btrfs_alloc_tree_block+0xb1/0x330 alloc_tree_block_no_bg_flush+0x4f/0x60 __btrfs_cow_block+0x11d/0x580 btrfs_cow_block+0x10c/0x220 commit_cowonly_roots+0x47/0x2e0 btrfs_commit_transaction+0x595/0xbd0 sync_filesystem+0x74/0x90 generic_shutdown_super+0x22/0x100 kill_anon_super+0x14/0x30 btrfs_kill_super+0x12/0x20 deactivate_locked_super+0x36/0xa0 cleanup_mnt+0x12d/0x190 task_work_run+0x5c/0xa0 exit_to_user_mode_prepare+0x1df/0x200 syscall_exit_to_user_mode+0x54/0x280 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #1 (&space_info->groups_sem){++++}-{3:3}: down_read+0x40/0x130 find_free_extent+0x2ed/0x12f0 btrfs_reserve_extent+0xb3/0x1b0 btrfs_alloc_tree_block+0xb1/0x330 alloc_tree_block_no_bg_flush+0x4f/0x60 __btrfs_cow_block+0x11d/0x580 btrfs_cow_block+0x10c/0x220 commit_cowonly_roots+0x47/0x2e0 btrfs_commit_transaction+0x595/0xbd0 sync_filesystem+0x74/0x90 generic_shutdown_super+0x22/0x100 kill_anon_super+0x14/0x30 btrfs_kill_super+0x12/0x20 deactivate_locked_super+0x36/0xa0 cleanup_mnt+0x12d/0x190 task_work_run+0x5c/0xa0 exit_to_user_mode_prepare+0x1df/0x200 syscall_exit_to_user_mode+0x54/0x280 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #0 (btrfs-root-00){++++}-{3:3}: __lock_acquire+0x1167/0x2150 lock_acquire+0xb9/0x3d0 down_read_nested+0x43/0x130 __btrfs_tree_read_lock+0x32/0x170 __btrfs_read_lock_root_node+0x3a/0x50 btrfs_search_slot+0x614/0x9d0 btrfs_find_root+0x35/0x1b0 btrfs_read_tree_root+0x61/0x120 btrfs_get_root_ref+0x14b/0x600 find_parent_nodes+0x3e6/0x1b30 btrfs_find_all_roots_safe+0xb4/0x130 btrfs_find_all_roots+0x60/0x80 btrfs_qgroup_trace_extent_post+0x27/0x40 btrfs_add_delayed_data_ref+0x3fd/0x460 btrfs_free_extent+0x42/0x100 __btrfs_mod_ref+0x1d7/0x2f0 walk_up_proc+0x11c/0x400 walk_up_tree+0xf0/0x180 btrfs_drop_snapshot+0x1c7/0x780 btrfs_clean_one_deleted_snapshot+0xfb/0x110 cleaner_kthread+0xd4/0x140 kthread+0x13a/0x150 ret_from_fork+0x1f/0x30 other info that might help us debug this: Chain exists of: btrfs-root-00 --> &space_info->groups_sem --> &fs_info->commit_root_sem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&fs_info->commit_root_sem); lock(&space_info->groups_sem); lock(&fs_info->commit_root_sem); lock(btrfs-root-00); *** DEADLOCK *** 3 locks held by btrfs-cleaner/3445: #0: ffff89dbeaf28838 (&fs_info->cleaner_mutex){+.+.}-{3:3}, at: cleaner_kthread+0x6e/0x140 #1: ffff89dbeb6c7640 (sb_internal){.+.+}-{0:0}, at: start_transaction+0x40b/0x5c0 #2: ffff89dbeaf28a88 (&fs_info->commit_root_sem){++++}-{3:3}, at: btrfs_find_all_roots+0x41/0x80 stack backtrace: CPU: 0 PID: 3445 Comm: btrfs-cleaner Not tainted 5.9.0+ #101 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-2.fc32 04/01/2014 Call Trace: dump_stack+0x8b/0xb0 check_noncircular+0xcf/0xf0 __lock_acquire+0x1167/0x2150 ? __bfs+0x42/0x210 lock_acquire+0xb9/0x3d0 ? __btrfs_tree_read_lock+0x32/0x170 down_read_nested+0x43/0x130 ? __btrfs_tree_read_lock+0x32/0x170 __btrfs_tree_read_lock+0x32/0x170 __btrfs_read_lock_root_node+0x3a/0x50 btrfs_search_slot+0x614/0x9d0 ? find_held_lock+0x2b/0x80 btrfs_find_root+0x35/0x1b0 ? do_raw_spin_unlock+0x4b/0xa0 btrfs_read_tree_root+0x61/0x120 btrfs_get_root_ref+0x14b/0x600 find_parent_nodes+0x3e6/0x1b30 btrfs_find_all_roots_safe+0xb4/0x130 btrfs_find_all_roots+0x60/0x80 btrfs_qgroup_trace_extent_post+0x27/0x40 btrfs_add_delayed_data_ref+0x3fd/0x460 btrfs_free_extent+0x42/0x100 __btrfs_mod_ref+0x1d7/0x2f0 walk_up_proc+0x11c/0x400 walk_up_tree+0xf0/0x180 btrfs_drop_snapshot+0x1c7/0x780 ? btrfs_clean_one_deleted_snapshot+0x73/0x110 btrfs_clean_one_deleted_snapshot+0xfb/0x110 cleaner_kthread+0xd4/0x140 ? btrfs_alloc_root+0x50/0x50 kthread+0x13a/0x150 ? kthread_create_worker_on_cpu+0x40/0x40 ret_from_fork+0x1f/0x30 while testing another lockdep fix. This happens because we're using the commit_root_sem to protect fs_info->caching_block_groups, which creates a dependency on the groups_sem -> commit_root_sem, which is problematic because we will allocate blocks while holding tree roots. Fix this by making the list itself protected by the fs_info->block_group_cache_lock. Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>