- 18 Jan, 2019 4 commits
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Josef Bacik authored
Delayed iputs means we can have final iputs of deleted inodes in the queue, which could potentially generate a lot of pinned space that could be free'd. So before we decide to commit the transaction for ENOPSC reasons, run the delayed iputs so that any potential space is free'd up. If there is and we freed enough we can then commit the transaction and potentially be able to make our reservation. Reviewed-by:
Omar Sandoval <osandov@fb.com> Signed-off-by:
Josef Bacik <josef@toxicpanda.com> Signed-off-by:
David Sterba <dsterba@suse.com>
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Josef Bacik authored
If we flip read-only before we initiate writeback on all dirty pages for ordered extents we've created then we'll have ordered extents left over on umount, which results in all sorts of bad things happening. Fix this by making sure we wait on ordered extents if we have to do the aborted transaction cleanup stuff. generic/475 can produce this warning: [ 8531.177332] WARNING: CPU: 2 PID: 11997 at fs/btrfs/disk-io.c:3856 btrfs_free_fs_root+0x95/0xa0 [btrfs] [ 8531.183282] CPU: 2 PID: 11997 Comm: umount Tainted: G W 5.0.0-rc1-default+ #394 [ 8531.185164] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),BIOS rel-1.11.2-0-gf9626cc-prebuilt.qemu-project.org 04/01/2014 [ 8531.187851] RIP: 0010:btrfs_free_fs_root+0x95/0xa0 [btrfs] [ 8531.193082] RSP: 0018:ffffb1ab86163d98 EFLAGS: 00010286 [ 8531.194198] RAX: ffff9f3449494d18 RBX: ffff9f34a2695000 RCX:0000000000000000 [ 8531.195629] RDX: 0000000000000002 RSI: 0000000000000001 RDI:0000000000000000 [ 8531.197315] RBP: ffff9f344e930000 R08: 0000000000000001 R09:0000000000000000 [ 8531.199095] R10: 0000000000000000 R11: ffff9f34494d4ff8 R12:ffffb1ab86163dc0 [ 8531.200870] R13: ffff9f344e9300b0 R14: ffffb1ab86163db8 R15:0000000000000000 [ 8531.202707] FS: 00007fc68e949fc0(0000) GS:ffff9f34bd800000(0000)knlGS:0000000000000000 [ 8531.204851] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 8531.205942] CR2: 00007ffde8114dd8 CR3: 000000002dfbd000 CR4:00000000000006e0 [ 8531.207516] Call Trace: [ 8531.208175] btrfs_free_fs_roots+0xdb/0x170 [btrfs] [ 8531.210209] ? wait_for_completion+0x5b/0x190 [ 8531.211303] close_ctree+0x157/0x350 [btrfs] [ 8531.212412] generic_shutdown_super+0x64/0x100 [ 8531.213485] kill_anon_super+0x14/0x30 [ 8531.214430] btrfs_kill_super+0x12/0xa0 [btrfs] [ 8531.215539] deactivate_locked_super+0x29/0x60 [ 8531.216633] cleanup_mnt+0x3b/0x70 [ 8531.217497] task_work_run+0x98/0xc0 [ 8531.218397] exit_to_usermode_loop+0x83/0x90 [ 8531.219324] do_syscall_64+0x15b/0x180 [ 8531.220192] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 8531.221286] RIP: 0033:0x7fc68e5e4d07 [ 8531.225621] RSP: 002b:00007ffde8116608 EFLAGS: 00000246 ORIG_RAX:00000000000000a6 [ 8531.227512] RAX: 0000000000000000 RBX: 00005580c2175970 RCX:00007fc68e5e4d07 [ 8531.229098] RDX: 0000000000000001 RSI: 0000000000000000 RDI:00005580c2175b80 [ 8531.230730] RBP: 0000000000000000 R08: 00005580c2175ba0 R09:00007ffde8114e80 [ 8531.232269] R10: 0000000000000000 R11: 0000000000000246 R12:00005580c2175b80 [ 8531.233839] R13: 00007fc68eac61c4 R14: 00005580c2175a68 R15:0000000000000000 Leaving a tree in the rb-tree: 3853 void btrfs_free_fs_root(struct btrfs_root *root) 3854 { 3855 iput(root->ino_cache_inode); 3856 WARN_ON(!RB_EMPTY_ROOT(&root->inode_tree)); CC: stable@vger.kernel.org Reviewed-by:Nikolay Borisov <nborisov@suse.com> Signed-off-by:
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Josef Bacik authored
We weren't doing any of the accounting cleanup when we aborted transactions. Fix this by making cleanup_ref_head_accounting global and calling it from the abort code, this fixes the issue where our accounting was all wrong after the fs aborts. The test generic/475 on a 2G VM can trigger the problems eg.: [ 8502.136957] WARNING: CPU: 0 PID: 11064 at fs/btrfs/extent-tree.c:5986 btrfs_free_block_grou +ps+0x3dc/0x410 [btrfs] [ 8502.148372] CPU: 0 PID: 11064 Comm: umount Not tainted 5.0.0-rc1-default+ #394 [ 8502.150807] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626 +cc-prebuilt.qemu-project.org 04/01/2014 [ 8502.154317] RIP: 0010:btrfs_free_block_groups+0x3dc/0x410 [btrfs] [ 8502.160623] RSP: 0018:ffffb1ab84b93de8 EFLAGS: 00010206 [ 8502.161906] RAX: 0000000001000000 RBX: ffff9f34b1756400 RCX: 0000000000000000 [ 8502.163448] RDX: 0000000000000002 RSI: 0000000000000001 RDI: ffff9f34b1755400 [ 8502.164906] RBP: ffff9f34b7e8c000 R08: 0000000000000001 R09: 0000000000000000 [ 8502.166716] R10: 0000000000000000 R11: 0000000000000001 R12: ffff9f34b7e8c108 [ 8502.168498] R13: ffff9f34b7e8c158 R14: 0000000000000000 R15: dead000000000100 [ 8502.170296] FS: 00007fb1cf15ffc0(0000) GS:ffff9f34bd400000(0000) knlGS:0000000000000000 [ 8502.172439] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 8502.173669] CR2: 00007fb1ced507b0 CR3: 000000002f7a6000 CR4: 00000000000006f0 [ 8502.175094] Call Trace: [ 8502.175759] close_ctree+0x17f/0x350 [btrfs] [ 8502.176721] generic_shutdown_super+0x64/0x100 [ 8502.177702] kill_anon_super+0x14/0x30 [ 8502.178607] btrfs_kill_super+0x12/0xa0 [btrfs] [ 8502.179602] deactivate_locked_super+0x29/0x60 [ 8502.180595] cleanup_mnt+0x3b/0x70 [ 8502.181406] task_work_run+0x98/0xc0 [ 8502.182255] exit_to_usermode_loop+0x83/0x90 [ 8502.183113] do_syscall_64+0x15b/0x180 [ 8502.183919] entry_SYSCALL_64_after_hwframe+0x49/0xbe Corresponding to release_global_block_rsv() { ... WARN_ON(fs_info->delayed_refs_rsv.reserved > 0); CC: stable@vger.kernel.org Signed-off-by: -
David Sterba authored
This reverts commit e73e81b6. This patch causes a few problems: - adds latency to btrfs_finish_ordered_io - as btrfs_finish_ordered_io is used for free space cache, generating more work from btrfs_btree_balance_dirty_nodelay could end up in the same workque, effectively deadlocking 12260 kworker/u96:16+btrfs-freespace-write D [<0>] balance_dirty_pages+0x6e6/0x7ad [<0>] balance_dirty_pages_ratelimited+0x6bb/0xa90 [<0>] btrfs_finish_ordered_io+0x3da/0x770 [<0>] normal_work_helper+0x1c5/0x5a0 [<0>] process_one_work+0x1ee/0x5a0 [<0>] worker_thread+0x46/0x3d0 [<0>] kthread+0xf5/0x130 [<0>] ret_from_fork+0x24/0x30 [<0>] 0xffffffffffffffff Transaction commit will wait on the freespace cache: 838 btrfs-transacti D [<0>] btrfs_start_ordered_extent+0x154/0x1e0 [<0>] btrfs_wait_ordered_range+0xbd/0x110 [<0>] __btrfs_wait_cache_io+0x49/0x1a0 [<0>] btrfs_write_dirty_block_groups+0x10b/0x3b0 [<0>] commit_cowonly_roots+0x215/0x2b0 [<0>] btrfs_commit_transaction+0x37e/0x910 [<0>] transaction_kthread+0x14d/0x180 [<0>] kthread+0xf5/0x130 [<0>] ret_from_fork+0x24/0x30 [<0>] 0xffffffffffffffff And then writepages ends up waiting on transaction commit: 9520 kworker/u96:13+flush-btrfs-1 D [<0>] wait_current_trans+0xac/0xe0 [<0>] start_transaction+0x21b/0x4b0 [<0>] cow_file_range_inline+0x10b/0x6b0 [<0>] cow_file_range.isra.69+0x329/0x4a0 [<0>] run_delalloc_range+0x105/0x3c0 [<0>] writepage_delalloc+0x119/0x180 [<0>] __extent_writepage+0x10c/0x390 [<0>] extent_write_cache_pages+0x26f/0x3d0 [<0>] extent_writepages+0x4f/0x80 [<0>] do_writepages+0x17/0x60 [<0>] __writeback_single_inode+0x59/0x690 [<0>] writeback_sb_inodes+0x291/0x4e0 [<0>] __writeback_inodes_wb+0x87/0xb0 [<0>] wb_writeback+0x3bb/0x500 [<0>] wb_workfn+0x40d/0x610 [<0>] process_one_work+0x1ee/0x5a0 [<0>] worker_thread+0x1e0/0x3d0 [<0>] kthread+0xf5/0x130 [<0>] ret_from_fork+0x24/0x30 [<0>] 0xffffffffffffffff Eventually, we have every process in the system waiting on balance_dirty_pages(), and nobody is able to make progress on page writeback. The original patch tried to fix an OOM condition, that happened on 4.4 but no success reproducing that on later kernels (4.19 and 4.20). This is more likely a problem in OOM itself. Link: https://lore.kernel.org/linux-btrfs/20180528054821.9092-1-ethanlien@synology.com/Reported-by:
Chris Mason <clm@fb.com> CC: stable@vger.kernel.org # 4.18+ CC: ethanlien <ethanlien@synology.com> Signed-off-by:
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- 10 Jan, 2019 1 commit
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Qu Wenruo authored
[BUG] Linux v5.0-rc1 will fail fstests/btrfs/163 with the following kernel message: BTRFS error (device dm-6): dev extent devid 1 physical offset 13631488 len 8388608 is beyond device boundary 0 BTRFS error (device dm-6): failed to verify dev extents against chunks: -117 BTRFS error (device dm-6): open_ctree failed [CAUSE] Commit cf90d884 ("btrfs: Introduce mount time chunk <-> dev extent mapping check") introduced strict check on dev extents. We use btrfs_find_device() with dev uuid and fs uuid set to NULL, and only dependent on @devid to find the real device. For seed devices, we call clone_fs_devices() in open_seed_devices() to allow us search seed devices directly. However clone_fs_devices() just populates devices with devid and dev uuid, without populating other essential members, like disk_total_bytes. This makes any device returned by btrfs_find_device(fs_info, devid, NULL, NULL) is just a dummy, with 0 disk_total_bytes, and any dev extents on the seed device will not pass the device boundary check. [FIX] This patch will try to verify the device returned by btrfs_find_device() and if it's a dummy then re-search in seed devices. Fixes: cf90d884 ("btrfs: Introduce mount time chunk <-> dev extent mapping check") CC: stable@vger.kernel.org # 4.19+ Reported-by:
Filipe Manana <fdmanana@suse.com> Signed-off-by:
Qu Wenruo <wqu@suse.com> Signed-off-by:
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- 09 Jan, 2019 3 commits
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Filipe Manana authored
When modifying the free space tree we can end up COWing one of its extent buffers which in turn might result in allocating a new chunk, which in turn can result in flushing (finish creation) of pending block groups. If that happens we can deadlock because creating a pending block group needs to update the free space tree, and if any of the updates tries to modify the same extent buffer that we are COWing, we end up in a deadlock since we try to write lock twice the same extent buffer. So fix this by skipping pending block group creation if we are COWing an extent buffer from the free space tree. This is a case missed by commit 5ce55557 ("Btrfs: fix deadlock when writing out free space caches"). Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202173 Fixes: 5ce55557 ("Btrfs: fix deadlock when writing out free space caches") CC: stable@vger.kernel.org # 4.18+ Signed-off-by:
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Filipe Manana authored
The recent rework that makes btrfs' remap_file_range operation use the generic helper generic_remap_file_range_prep() introduced a race between relocation and reflinking (for both cloning and deduplication) the file extents between the source and destination inodes. This happens because we no longer lock the source range anymore, and we do not lock it anymore because we wait for direct IO writes and writeback to complete early on the code path right after locking the inodes, which guarantees no other file operations interfere with the reflinking. However there is one exception which is relocation, since it replaces the byte number of file extents items in the fs tree after locking the range the file extent items represent. This is a problem because after finding each file extent to clone in the fs tree, the reflink process copies the file extent item into a local buffer, releases the search path, inserts new file extent items in the destination range and then increments the reference count for the extent mentioned in the file extent item that it previously copied to the buffer. If right after copying the file extent item into the buffer and releasing the path the relocation process updates the file extent item to point to the new extent, the reflink process ends up creating a delayed reference to increment the reference count of the old extent, for which the relocation process already created a delayed reference to drop it. This results in failure to run delayed references because we will attempt to increment the count of a reference that was already dropped. This is illustrated by the following diagram: CPU 1 CPU 2 relocation is running btrfs_clone_files() btrfs_clone() --> finds extent item in source range point to extent at bytenr X --> copies it into a local buffer --> releases path replace_file_extents() --> successfully locks the range represented by the file extent item --> replaces disk_bytenr field in the file extent item with some other value Y --> creates delayed reference to increment reference count for extent at bytenr Y --> creates delayed reference to drop the extent at bytenr X --> starts transaction --> creates delayed reference to increment extent at bytenr X <delayed references are run, due to a transaction commit for example, and the transaction is aborted with -EIO because we attempt to increment reference count for the extent at bytenr X after we freed it> When this race is hit the running transaction ends up getting aborted with an -EIO error and a trace like the following is produced: [ 4382.553858] WARNING: CPU: 2 PID: 3648 at fs/btrfs/extent-tree.c:1552 lookup_inline_extent_backref+0x4f4/0x650 [btrfs] (...) [ 4382.556293] CPU: 2 PID: 3648 Comm: btrfs Tainted: G W 4.20.0-rc6-btrfs-next-41 #1 [ 4382.556294] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626ccb91-prebuilt.qemu-project.org 04/01/2014 [ 4382.556308] RIP: 0010:lookup_inline_extent_backref+0x4f4/0x650 [btrfs] (...) [ 4382.556310] RSP: 0018:ffffac784408f738 EFLAGS: 00010202 [ 4382.556311] RAX: 0000000000000001 RBX: ffff8980673c3a48 RCX: 0000000000000001 [ 4382.556312] RDX: 0000000000000008 RSI: 0000000000000000 RDI: 0000000000000000 [ 4382.556312] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001 [ 4382.556313] R10: 0000000000000001 R11: ffff897f40000000 R12: 0000000000001000 [ 4382.556313] R13: 00000000c224f000 R14: ffff89805de9bd40 R15: ffff8980453f4548 [ 4382.556315] FS: 00007f5e759178c0(0000) GS:ffff89807b300000(0000) knlGS:0000000000000000 [ 4382.563130] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 4382.563562] CR2: 00007f2e9789fcbc CR3: 0000000120512001 CR4: 00000000003606e0 [ 4382.564005] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 4382.564451] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 4382.564887] Call Trace: [ 4382.565343] insert_inline_extent_backref+0x55/0xe0 [btrfs] [ 4382.565796] __btrfs_inc_extent_ref.isra.60+0x88/0x260 [btrfs] [ 4382.566249] ? __btrfs_run_delayed_refs+0x93/0x1650 [btrfs] [ 4382.566702] __btrfs_run_delayed_refs+0xa22/0x1650 [btrfs] [ 4382.567162] btrfs_run_delayed_refs+0x7e/0x1d0 [btrfs] [ 4382.567623] btrfs_commit_transaction+0x50/0x9c0 [btrfs] [ 4382.568112] ? _raw_spin_unlock+0x24/0x30 [ 4382.568557] ? block_rsv_release_bytes+0x14e/0x410 [btrfs] [ 4382.569006] create_subvol+0x3c8/0x830 [btrfs] [ 4382.569461] ? btrfs_mksubvol+0x317/0x600 [btrfs] [ 4382.569906] btrfs_mksubvol+0x317/0x600 [btrfs] [ 4382.570383] ? rcu_sync_lockdep_assert+0xe/0x60 [ 4382.570822] ? __sb_start_write+0xd4/0x1c0 [ 4382.571262] ? mnt_want_write_file+0x24/0x50 [ 4382.571712] btrfs_ioctl_snap_create_transid+0x117/0x1a0 [btrfs] [ 4382.572155] ? _copy_from_user+0x66/0x90 [ 4382.572602] btrfs_ioctl_snap_create+0x66/0x80 [btrfs] [ 4382.573052] btrfs_ioctl+0x7c1/0x30e0 [btrfs] [ 4382.573502] ? mem_cgroup_commit_charge+0x8b/0x570 [ 4382.573946] ? do_raw_spin_unlock+0x49/0xc0 [ 4382.574379] ? _raw_spin_unlock+0x24/0x30 [ 4382.574803] ? __handle_mm_fault+0xf29/0x12d0 [ 4382.575215] ? do_vfs_ioctl+0xa2/0x6f0 [ 4382.575622] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs] [ 4382.576020] do_vfs_ioctl+0xa2/0x6f0 [ 4382.576405] ksys_ioctl+0x70/0x80 [ 4382.576776] __x64_sys_ioctl+0x16/0x20 [ 4382.577137] do_syscall_64+0x60/0x1b0 [ 4382.577488] entry_SYSCALL_64_after_hwframe+0x49/0xbe (...) [ 4382.578837] RSP: 002b:00007ffe04bf64c8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010 [ 4382.579174] RAX: ffffffffffffffda RBX: 00005564136f3050 RCX: 00007f5e74724dd7 [ 4382.579505] RDX: 00007ffe04bf64d0 RSI: 000000005000940e RDI: 0000000000000003 [ 4382.579848] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000044 [ 4382.580164] R10: 0000000000000541 R11: 0000000000000202 R12: 00005564136f3010 [ 4382.580477] R13: 0000000000000003 R14: 00005564136f3035 R15: 00005564136f3050 [ 4382.580792] irq event stamp: 0 [ 4382.581106] hardirqs last enabled at (0): [<0000000000000000>] (null) [ 4382.581441] hardirqs last disabled at (0): [<ffffffff8d085842>] copy_process.part.32+0x6e2/0x2320 [ 4382.581772] softirqs last enabled at (0): [<ffffffff8d085842>] copy_process.part.32+0x6e2/0x2320 [ 4382.582095] softirqs last disabled at (0): [<0000000000000000>] (null) [ 4382.582413] ---[ end trace d3c188e3e9367382 ]--- [ 4382.623855] BTRFS: error (device sdc) in btrfs_run_delayed_refs:2981: errno=-5 IO failure [ 4382.624295] BTRFS info (device sdc): forced readonly Fix this by locking the source range before searching for the file extent items in the fs tree, since the relocation process will try to lock the range a file extent item represents before updating it with the new extent location. Fixes: 34a28e3d ("Btrfs: use generic_remap_file_range_prep() for cloning and deduplication") Signed-off-by: -
Filipe Manana authored
The recent rework that makes btrfs' remap_file_range operation use the generic helper generic_remap_file_range_prep() introduced a race between writeback and cloning a range that covers the eof extent of the source file into a destination offset that is greater then the same file's size. This happens because we now wait for writeback to complete before doing the truncation of the eof block, while previously we did the truncation and then waited for writeback to complete. This leads to a race between writeback of the truncated block and cloning the file extents in the source range, because we copy each file extent item we find in the fs root into a buffer, then release the path and then increment the reference count for the extent referred in that file extent item we copied, which can no longer exist if writeback of the truncated eof block completes after we copied the file extent item into the buffer and before we incremented the reference count. This is illustrated by the following diagram: CPU 1 CPU 2 btrfs_clone_files() btrfs_cont_expand() btrfs_truncate_block() --> zeroes part of the page containg eof, marking it for delalloc btrfs_clone() --> finds extent item covering eof, points to extent at bytenr X --> copies it into a local buffer --> releases path writeback starts btrfs_finish_ordered_io() insert_reserved_file_extent() __btrfs_drop_extents() --> creates delayed reference to drop the extent at bytenr X --> starts transaction --> creates delayed reference to increment extent at bytenr X <delayed references are run, due to a transaction commit for example, and the transaction is aborted with -EIO because we attempt to increment reference count for the extent at bytenr X after we freed it> When this race is hit the running transaction ends up getting aborted with an -EIO error and a trace like the following is produced: [ 4382.553858] WARNING: CPU: 2 PID: 3648 at fs/btrfs/extent-tree.c:1552 lookup_inline_extent_backref+0x4f4/0x650 [btrfs] (...) [ 4382.556293] CPU: 2 PID: 3648 Comm: btrfs Tainted: G W 4.20.0-rc6-btrfs-next-41 #1 [ 4382.556294] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626ccb91-prebuilt.qemu-project.org 04/01/2014 [ 4382.556308] RIP: 0010:lookup_inline_extent_backref+0x4f4/0x650 [btrfs] (...) [ 4382.556310] RSP: 0018:ffffac784408f738 EFLAGS: 00010202 [ 4382.556311] RAX: 0000000000000001 RBX: ffff8980673c3a48 RCX: 0000000000000001 [ 4382.556312] RDX: 0000000000000008 RSI: 0000000000000000 RDI: 0000000000000000 [ 4382.556312] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001 [ 4382.556313] R10: 0000000000000001 R11: ffff897f40000000 R12: 0000000000001000 [ 4382.556313] R13: 00000000c224f000 R14: ffff89805de9bd40 R15: ffff8980453f4548 [ 4382.556315] FS: 00007f5e759178c0(0000) GS:ffff89807b300000(0000) knlGS:0000000000000000 [ 4382.563130] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 4382.563562] CR2: 00007f2e9789fcbc CR3: 0000000120512001 CR4: 00000000003606e0 [ 4382.564005] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 4382.564451] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 4382.564887] Call Trace: [ 4382.565343] insert_inline_extent_backref+0x55/0xe0 [btrfs] [ 4382.565796] __btrfs_inc_extent_ref.isra.60+0x88/0x260 [btrfs] [ 4382.566249] ? __btrfs_run_delayed_refs+0x93/0x1650 [btrfs] [ 4382.566702] __btrfs_run_delayed_refs+0xa22/0x1650 [btrfs] [ 4382.567162] btrfs_run_delayed_refs+0x7e/0x1d0 [btrfs] [ 4382.567623] btrfs_commit_transaction+0x50/0x9c0 [btrfs] [ 4382.568112] ? _raw_spin_unlock+0x24/0x30 [ 4382.568557] ? block_rsv_release_bytes+0x14e/0x410 [btrfs] [ 4382.569006] create_subvol+0x3c8/0x830 [btrfs] [ 4382.569461] ? btrfs_mksubvol+0x317/0x600 [btrfs] [ 4382.569906] btrfs_mksubvol+0x317/0x600 [btrfs] [ 4382.570383] ? rcu_sync_lockdep_assert+0xe/0x60 [ 4382.570822] ? __sb_start_write+0xd4/0x1c0 [ 4382.571262] ? mnt_want_write_file+0x24/0x50 [ 4382.571712] btrfs_ioctl_snap_create_transid+0x117/0x1a0 [btrfs] [ 4382.572155] ? _copy_from_user+0x66/0x90 [ 4382.572602] btrfs_ioctl_snap_create+0x66/0x80 [btrfs] [ 4382.573052] btrfs_ioctl+0x7c1/0x30e0 [btrfs] [ 4382.573502] ? mem_cgroup_commit_charge+0x8b/0x570 [ 4382.573946] ? do_raw_spin_unlock+0x49/0xc0 [ 4382.574379] ? _raw_spin_unlock+0x24/0x30 [ 4382.574803] ? __handle_mm_fault+0xf29/0x12d0 [ 4382.575215] ? do_vfs_ioctl+0xa2/0x6f0 [ 4382.575622] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs] [ 4382.576020] do_vfs_ioctl+0xa2/0x6f0 [ 4382.576405] ksys_ioctl+0x70/0x80 [ 4382.576776] __x64_sys_ioctl+0x16/0x20 [ 4382.577137] do_syscall_64+0x60/0x1b0 [ 4382.577488] entry_SYSCALL_64_after_hwframe+0x49/0xbe (...) [ 4382.578837] RSP: 002b:00007ffe04bf64c8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010 [ 4382.579174] RAX: ffffffffffffffda RBX: 00005564136f3050 RCX: 00007f5e74724dd7 [ 4382.579505] RDX: 00007ffe04bf64d0 RSI: 000000005000940e RDI: 0000000000000003 [ 4382.579848] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000044 [ 4382.580164] R10: 0000000000000541 R11: 0000000000000202 R12: 00005564136f3010 [ 4382.580477] R13: 0000000000000003 R14: 00005564136f3035 R15: 00005564136f3050 [ 4382.580792] irq event stamp: 0 [ 4382.581106] hardirqs last enabled at (0): [<0000000000000000>] (null) [ 4382.581441] hardirqs last disabled at (0): [<ffffffff8d085842>] copy_process.part.32+0x6e2/0x2320 [ 4382.581772] softirqs last enabled at (0): [<ffffffff8d085842>] copy_process.part.32+0x6e2/0x2320 [ 4382.582095] softirqs last disabled at (0): [<0000000000000000>] (null) [ 4382.582413] ---[ end trace d3c188e3e9367382 ]--- [ 4382.623855] BTRFS: error (device sdc) in btrfs_run_delayed_refs:2981: errno=-5 IO failure [ 4382.624295] BTRFS info (device sdc): forced readonly Fix this by waiting for writeback to complete after truncating the eof block. Fixes: 34a28e3d ("Btrfs: use generic_remap_file_range_prep() for cloning and deduplication") Signed-off-by:
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- 17 Dec, 2018 32 commits
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Andrea Gelmini authored
The typos accumulate over time so once in a while time they get fixed in a large patch. Signed-off-by:
Andrea Gelmini <andrea.gelmini@gelma.net> Reviewed-by:
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Johannes Thumshirn authored
In the error handling block, err holds the return value of either btrfs_del_root_ref() or btrfs_del_inode_ref() but it hasn't been checked since it's introduction with commit fe66a05a (Btrfs: improve error handling for btrfs_insert_dir_item callers) in 2012. If the error handling in the error handling fails, there's not much left to do and the abort either happened earlier in the callees or is necessary here. So if one of btrfs_del_root_ref() or btrfs_del_inode_ref() failed, abort the transaction, but still return the original code of the failure stored in 'ret' as this will be reported to the user. Signed-off-by:
Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by:
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Filipe Manana authored
Since cloning and deduplication are no longer Btrfs specific operations, we now have generic code to handle parameter validation, compare file ranges used for deduplication, clear capabilities when cloning, etc. This change makes Btrfs use it, eliminating a lot of code in Btrfs and also fixing a few bugs, such as: 1) When cloning, the destination file's capabilities were not dropped (the fstest generic/513 tests this); 2) We were not checking if the destination file is immutable; 3) Not checking if either the source or destination files are swap files (swap file support is coming soon for Btrfs); 4) System limits were not checked (resource limits and O_LARGEFILE). Note that the generic helper generic_remap_file_range_prep() does start and waits for writeback by calling filemap_write_and_wait_range(), however that is not enough for Btrfs for two reasons: 1) With compression, we need to start writeback twice in order to get the pages marked for writeback and ordered extents created; 2) filemap_write_and_wait_range() (and all its other variants) only waits for the IO to complete, but we need to wait for the ordered extents to finish, so that when we do the actual reflinking operations the file extent items are in the fs tree. This is also important due to the fact that the generic helper, for the deduplication case, compares the contents of the pages in the requested range, which might require reading extents from disk in the very unlikely case that pages get invalidated after writeback finishes (so the file extent items must be up to date in the fs tree). Since these reasons are specific to Btrfs we have to do it in the Btrfs code before calling generic_remap_file_range_prep(). This also results in a simpler way of dealing with existing delalloc in the source/target ranges, specially for the deduplication case where we used to lock all the pages first and then if we found any dealloc for the range, or ordered extent, we would unlock the pages trigger writeback and wait for ordered extents to complete, then lock all the pages again and check if deduplication can be done. So now we get a simpler approach: lock the inodes, then trigger writeback and then wait for ordered extents to complete. So make btrfs use generic_remap_file_range_prep() (XFS and OCFS2 use it) to eliminate duplicated code, fix a few bugs and benefit from future bug fixes done there - for example the recent clone and dedupe bugs involving reflinking a partial EOF block got a counterpart fix in the generic helper, since it affected all filesystems supporting these operations, so we no longer need special checks in Btrfs for them. Reviewed-by:
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Nikolay Borisov authored
extent_readpages processes all pages in the readlist in batches of 16, this is implemented by a single for loop but thanks to an if condition the loop does 2 things based on whether we've filled the batch or not. Additionally due to the structure of the code there is an additional check which deals with partial batches. Streamline all of this by explicitly using two loops. The outter one is used to process all pages while the inner one just fills in the batch of 16 (currently). Due to this new structure the code guarantees that all pages are processed in the loop hence the code to deal with any leftovers is eliminated. This also enable the compiler to inline __extent_readpages: ./scripts/bloat-o-meter fs/btrfs/extent_io.o extent_io.for add/remove: 0/1 grow/shrink: 1/0 up/down: 660/-820 (-160) Function old new delta extent_readpages 476 1136 +660 __extent_readpages 820 - -820 Total: Before=44315, After=44155, chg -0.36% Signed-off-by:
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Nikolay Borisov authored
The first step of the rebalance process ensures there is 1MiB free on each device. This number seems rather small. And in fact when talking to the original authors their opinions were: "man that's a little bonkers" "i don't think we even need that code anymore" "I think it was there to make sure we had room for the blank 1M at the beginning. I bet it goes all the way back to v0" "we just don't need any of that tho, i say we just delete it" Clearly, this piece of code has lost its original intent throughout the years. It doesn't really bring any real practical benefits to the relocation process. Additionally, this patch makes the balance process more lightweight by removing a pair of shrink/grow operations which are rather expensive for heavily populated filesystems. This is mainly due to shrink requiring relocating block groups, involving heavy use of the btree. The intermediate shrink/grow can fail and leave the filesystem in a middle state that would need to be changed back by the user. Suggested-by:
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Filipe Manana authored
If we create a snapshot of a snapshot currently being used by a send operation, we can end up with send failing unexpectedly (returning -ENOENT error to user space for example). The following diagram shows how this happens. CPU 1 CPU2 CPU3 btrfs_ioctl_send() (...) create_snapshot() -> creates snapshot of a root used by the send task btrfs_commit_transaction() create_pending_snapshot() __get_inode_info() btrfs_search_slot() btrfs_search_slot_get_root() down_read commit_root_sem get reference on eb of the commit root -> eb with bytenr == X up_read commit_root_sem btrfs_cow_block(root node) btrfs_free_tree_block() -> creates delayed ref to free the extent btrfs_run_delayed_refs() -> runs the delayed ref, adds extent to fs_info->pinned_extents btrfs_finish_extent_commit() unpin_extent_range() -> marks extent as free in the free space cache transaction commit finishes btrfs_start_transaction() (...) btrfs_cow_block() btrfs_alloc_tree_block() btrfs_reserve_extent() -> allocates extent at bytenr == X btrfs_init_new_buffer(bytenr X) btrfs_find_create_tree_block() alloc_extent_buffer(bytenr X) find_extent_buffer(bytenr X) -> returns existing eb, which the send task got (...) -> modifies content of the eb with bytenr == X -> uses an eb that now belongs to some other tree and no more matches the commit root of the snapshot, resuts will be unpredictable The consequences of this race can be various, and can lead to searches in the commit root performed by the send task failing unexpectedly (unable to find inode items, returning -ENOENT to user space, for example) or not failing because an inode item with the same number was added to the tree that reused the metadata extent, in which case send can behave incorrectly in the worst case or just fail later for some reason. Fix this by performing a copy of the commit root's extent buffer when doing a search in the context of a send operation. CC: stable@vger.kernel.org # 4.4.x: 1fc28d8e: Btrfs: move get root out of btrfs_search_slot to a helper CC: stable@vger.kernel.org # 4.4.x: f9ddfd05: Btrfs: remove unused check of skip_locking CC: stable@vger.kernel.org # 4.4.x Signed-off-by: -
Filipe Manana authored
When initializing the security xattrs, we are holding a transaction handle therefore we need to use a GFP_NOFS context in order to avoid a deadlock with reclaim in case it's triggered. Fixes: 39a27ec1 ("btrfs: use GFP_KERNEL for xattr and acl allocations") Reviewed-by:
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Josef Bacik authored
With my delayed refs patches in place we started seeing a large amount of aborts in __btrfs_free_extent: BTRFS error (device sdb1): unable to find ref byte nr 91947008 parent 0 root 35964 owner 1 offset 0 Call Trace: ? btrfs_merge_delayed_refs+0xaf/0x340 __btrfs_run_delayed_refs+0x6ea/0xfc0 ? btrfs_set_path_blocking+0x31/0x60 btrfs_run_delayed_refs+0xeb/0x180 btrfs_commit_transaction+0x179/0x7f0 ? btrfs_check_space_for_delayed_refs+0x30/0x50 ? should_end_transaction.isra.19+0xe/0x40 btrfs_drop_snapshot+0x41c/0x7c0 btrfs_clean_one_deleted_snapshot+0xb5/0xd0 cleaner_kthread+0xf6/0x120 kthread+0xf8/0x130 ? btree_invalidatepage+0x90/0x90 ? kthread_bind+0x10/0x10 ret_from_fork+0x35/0x40 This was because btrfs_drop_snapshot depends on the root not being modified while it's dropping the snapshot. It will unlock the root node (and really every node) as it walks down the tree, only to re-lock it when it needs to do something. This is a problem because if we modify the tree we could cow a block in our path, which frees our reference to that block. Then once we get back to that shared block we'll free our reference to it again, and get ENOENT when trying to lookup our extent reference to that block in __btrfs_free_extent. This is ultimately happening because we have delayed items left to be processed for our deleted snapshot _after_ all of the inodes are closed for the snapshot. We only run the delayed inode item if we're deleting the inode, and even then we do not run the delayed insertions or delayed removals. These can be run at any point after our final inode does its last iput, which is what triggers the snapshot deletion. We can end up with the snapshot deletion happening and then have the delayed items run on that file system, resulting in the above problem. This problem has existed forever, however my patches made it much easier to hit as I wake up the cleaner much more often to deal with delayed iputs, which made us more likely to start the snapshot dropping work before the transaction commits, which is when the delayed items would generally be run. Before, generally speaking, we would run the delayed items, commit the transaction, and wakeup the cleaner thread to start deleting snapshots, which means we were less likely to hit this problem. You could still hit it if you had multiple snapshots to be deleted and ended up with lots of delayed items, but it was definitely harder. Fix for now by simply running all the delayed items before starting to drop the snapshot. We could make this smarter in the future by making the delayed items per-root, and then simply drop any delayed items for roots that we are going to delete. But for now just a quick and easy solution is the safest. CC: stable@vger.kernel.org # 4.4+ Reviewed-by:
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Josef Bacik authored
When debugging some weird extent reference bug I suspected that we were changing a snapshot while we were deleting it, which could explain my bug. This was indeed what was happening, and this patch helped me verify my theory. It is never correct to modify the snapshot once it's being deleted, so mark the root when we are deleting it and make sure we complain about it when it happens. Reviewed-by:
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Qu Wenruo authored
@blocksize variable in do_walk_down() is only used once, really no need to declare it. Reviewed-by:
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Filipe Manana authored
Since scrub workers only do memory allocation with GFP_KERNEL when they need to perform repair, we can move the recent setup of the nofs context up to scrub_handle_errored_block() instead of setting it up down the call chain at insert_full_stripe_lock() and scrub_add_page_to_wr_bio(), removing some duplicate code and comment. So the only paths for which a scrub worker can do memory allocations using GFP_KERNEL are the following: scrub_bio_end_io_worker() scrub_block_complete() scrub_handle_errored_block() lock_full_stripe() insert_full_stripe_lock() -> kmalloc with GFP_KERNEL scrub_bio_end_io_worker() scrub_block_complete() scrub_handle_errored_block() scrub_write_page_to_dev_replace() scrub_add_page_to_wr_bio() -> kzalloc with GFP_KERNEL Signed-off-by: -
David Sterba authored
The scrub context is allocated with GFP_KERNEL and called from btrfs_scrub_dev under the fs_info::device_list_mutex. This is not safe regarding reclaim that could try to flush filesystem data in order to get the memory. And the device_list_mutex is held during superblock commit, so this would cause a lockup. Move the alocation and initialization before any changes that require the mutex. Signed-off-by: -
David Sterba authored
We can pass fs_info directly as this is the only member of btrfs_device that's bing used inside scrub_setup_ctx. Reviewed-by:
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Josef Bacik authored
We have a bunch of magic to make sure we're throttling delayed refs when truncating a file. Now that we have a delayed refs rsv and a mechanism for refilling that reserve simply use that instead of all of this magic. Reviewed-by:
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Josef Bacik authored
Over the years we have built up a lot of infrastructure to keep delayed refs in check, mostly by running them at btrfs_end_transaction() time. We have a lot of different maths we do to figure out how much, if we should do it inline or async, etc. This existed because we had no feedback mechanism to force the flushing of delayed refs when they became a problem. However with the enospc flushing infrastructure in place for flushing delayed refs when they put too much pressure on the enospc system we have this problem solved. Rip out all of this code as it is no longer needed. Signed-off-by:
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Josef Bacik authored
Now with the delayed_refs_rsv we can now know exactly how much pending delayed refs space we need. This means we can drastically simplify btrfs_check_space_for_delayed_refs by simply checking how much space we have reserved for the global rsv (which acts as a spill over buffer) and the delayed refs rsv. If our total size is beyond that amount then we know it's time to commit the transaction and stop any more delayed refs from being generated. With the introduction of dealyed_refs_rsv infrastructure, namely btrfs_update_delayed_refs_rsv we now know exactly how much pending delayed refs space is required. Reviewed-by:
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Josef Bacik authored
A nice thing we gain with the delayed refs rsv is the ability to flush the delayed refs on demand to deal with enospc pressure. Add states to flush delayed refs on demand, and this will allow us to remove a lot of ad-hoc work around checking to see if we should commit the transaction to run our delayed refs. Signed-off-by:
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Josef Bacik authored
Any space used in the delayed_refs_rsv will be freed up by a transaction commit, so instead of just counting the pinned space we also need to account for any space in the delayed_refs_rsv when deciding if it will make a different to commit the transaction to satisfy our space reservation. If we have enough bytes to satisfy our reservation ticket then we are good to go, otherwise subtract out what space we would gain back by committing the transaction and compare that against the pinned space to make our decision. Reviewed-by:
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Josef Bacik authored
Traditionally we've had voodoo in btrfs to account for the space that delayed refs may take up by having a global_block_rsv. This works most of the time, except when it doesn't. We've had issues reported and seen in production where sometimes the global reserve is exhausted during transaction commit before we can run all of our delayed refs, resulting in an aborted transaction. Because of this voodoo we have equally dubious flushing semantics around throttling delayed refs which we often get wrong. So instead give them their own block_rsv. This way we can always know exactly how much outstanding space we need for delayed refs. This allows us to make sure we are constantly filling that reservation up with space, and allows us to put more precise pressure on the enospc system. Instead of doing math to see if its a good time to throttle, the normal enospc code will be invoked if we have a lot of delayed refs pending, and they will be run via the normal flushing mechanism. For now the delayed_refs_rsv will hold the reservations for the delayed refs, the block group updates, and deleting csums. We could have a separate rsv for the block group updates, but the csum deletion stuff is still handled via the delayed_refs so that will stay there. Historical background: The global reserve has grown to cover everything we don't reserve space explicitly for, and we've grown a lot of weird ad-hoc heuristics to know if we're running short on space and when it's time to force a commit. A failure rate of 20-40 file systems when we run hundreds of thousands of them isn't super high, but cleaning up this code will make things less ugly and more predictible. Thus the delayed refs rsv. We always know how many delayed refs we have outstanding, and although running them generates more we can use the global reserve for that spill over, which fits better into it's desired use than a full blown reservation. This first approach is to simply take how many times we're reserving space for and multiply that by 2 in order to save enough space for the delayed refs that could be generated. This is a niave approach and will probably evolve, but for now it works. Signed-off-by:
Josef Bacik <jbacik@fb.com> Reviewed-by: David Sterba <dsterba@suse.com> # high-level review [ added background notes from the cover letter ] Signed-off-by:
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Josef Bacik authored
We use this number to figure out how many delayed refs to run, but __btrfs_run_delayed_refs really only checks every time we need a new delayed ref head, so we always run at least one ref head completely no matter what the number of items on it. Fix the accounting to only be adjusted when we add/remove a ref head. In addition to using this number to limit the number of delayed refs run, a future patch is also going to use it to calculate the amount of space required for delayed refs space reservation. Reviewed-by:
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Josef Bacik authored
The cleanup_extent_op function actually would run the extent_op if it needed running, which made the name sort of a misnomer. Change it to run_and_cleanup_extent_op, and move the actual cleanup work to cleanup_extent_op so it can be used by check_ref_cleanup() in order to unify the extent op handling. Reviewed-by:
Lu Fengqi <lufq.fnst@cn.fujitsu.com> Signed-off-by:
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Josef Bacik authored
We were missing some quota cleanups in check_ref_cleanup, so break the ref head accounting cleanup into a helper and call that from both check_ref_cleanup and cleanup_ref_head. This will hopefully ensure that we don't screw up accounting in the future for other things that we add. Reviewed-by:
Liu Bo <bo.liu@linux.alibaba.com> Reviewed-by:
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Josef Bacik authored
We do this dance in cleanup_ref_head and check_ref_cleanup, unify it into a helper and cleanup the calling functions. Reviewed-by:
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Johannes Thumshirn authored
When using a 'var & (PAGE_SIZE - 1)' construct one is checking for a page alignment and thus should use the PAGE_ALIGNED() macro instead of open-coding it. Convert all open-coded occurrences of PAGE_ALIGNED(). Reviewed-by:
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Johannes Thumshirn authored
Constructs like 'var & (PAGE_SIZE - 1)' or 'var & ~PAGE_MASK' can denote an offset into a page. So replace them by the offset_in_page() macro instead of open-coding it if they're not used as an alignment check. Reviewed-by:
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David Sterba authored
The dev-replace locking functions are now trivial wrappers around rw semaphore that can be used directly everywhere. No functional change. Signed-off-by: -
David Sterba authored
After the rw semaphore has been added, the custom blocking using ::blocking_readers and ::read_lock_wq is redundant. The blocking logic in __btrfs_map_block is replaced by extending the time the semaphore is held, that has the same blocking effect on writes as the previous custom scheme that waited until ::blocking_readers was zero. Signed-off-by: -
David Sterba authored
This is the first part of removing the custom locking and waiting scheme used for device replace. It was probably copied from extent buffer locking, but there's nothing that would require more than is provided by the common locking primitives. The rw spinlock protects waiting tasks counter in case of incompatible locks and the waitqueue. Same as rw semaphore. This patch only switches the locking primitive, for better bisectability. There should be no functional change other than the overhead of the locking and potential sleeping instead of spinning when the lock is contended. Signed-off-by: -
David Sterba authored
The device-replace read lock is going to use rw semaphore in followup commits. The semaphore might sleep which is not possible in the radix tree preload section. The lock nesting is now: * device replace * radix tree preload * readahead spinlock Signed-off-by: -
Nikolay Borisov authored
Running btrfs/124 in a loop hung up on me sporadically with the following call trace: btrfs D 0 5760 5324 0x00000000 Call Trace: ? __schedule+0x243/0x800 schedule+0x33/0x90 btrfs_start_ordered_extent+0x10c/0x1b0 [btrfs] ? wait_woken+0xa0/0xa0 btrfs_wait_ordered_range+0xbb/0x100 [btrfs] btrfs_relocate_block_group+0x1ff/0x230 [btrfs] btrfs_relocate_chunk+0x49/0x100 [btrfs] btrfs_balance+0xbeb/0x1740 [btrfs] btrfs_ioctl_balance+0x2ee/0x380 [btrfs] btrfs_ioctl+0x1691/0x3110 [btrfs] ? lockdep_hardirqs_on+0xed/0x180 ? __handle_mm_fault+0x8e7/0xfb0 ? _raw_spin_unlock+0x24/0x30 ? __handle_mm_fault+0x8e7/0xfb0 ? do_vfs_ioctl+0xa5/0x6e0 ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs] do_vfs_ioctl+0xa5/0x6e0 ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe ksys_ioctl+0x3a/0x70 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x60/0x1b0 entry_SYSCALL_64_after_hwframe+0x49/0xbe This happens because during page writeback it's valid for writepage_delalloc to instantiate a delalloc range which doesn't belong to the page currently being written back. The reason this case is valid is due to find_lock_delalloc_range returning any available range after the passed delalloc_start and ignoring whether the page under writeback is within that range. In turn ordered extents (OE) are always created for the returned range from find_lock_delalloc_range. If, however, a failure occurs while OE are being created then the clean up code in btrfs_cleanup_ordered_extents will be called. Unfortunately the code in btrfs_cleanup_ordered_extents doesn't consider the case of such 'foreign' range being processed and instead it always assumes that the range OE are created for belongs to the page. This leads to the first page of such foregin range to not be cleaned up since it's deliberately missed and skipped by the current cleaning up code. Fix this by correctly checking whether the current page belongs to the range being instantiated and if so adjsut the range parameters passed for cleaning up. If it doesn't, then just clean the whole OE range directly. Fixes: 52427260 ("btrfs: Handle delalloc error correctly to avoid ordered extent hang") CC: stable@vger.kernel.org # 4.14+ Reviewed-by:
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Lu Fengqi authored
The @found is always false when it comes to the if branch. Besides, the bool type is more suitable for @found. Change the return value of the function and its caller to bool as well. Reviewed-by:
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Lu Fengqi authored
The test case btrfs/001 with inode_cache mount option will encounter the following warning: WARNING: CPU: 1 PID: 23700 at fs/btrfs/inode.c:956 cow_file_range.isra.19+0x32b/0x430 [btrfs] CPU: 1 PID: 23700 Comm: btrfs Kdump: loaded Tainted: G W O 4.20.0-rc4-custom+ #30 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:cow_file_range.isra.19+0x32b/0x430 [btrfs] Call Trace: ? free_extent_buffer+0x46/0x90 [btrfs] run_delalloc_nocow+0x455/0x900 [btrfs] btrfs_run_delalloc_range+0x1a7/0x360 [btrfs] writepage_delalloc+0xf9/0x150 [btrfs] __extent_writepage+0x125/0x3e0 [btrfs] extent_write_cache_pages+0x1b6/0x3e0 [btrfs] ? __wake_up_common_lock+0x63/0xc0 extent_writepages+0x50/0x80 [btrfs] do_writepages+0x41/0xd0 ? __filemap_fdatawrite_range+0x9e/0xf0 __filemap_fdatawrite_range+0xbe/0xf0 btrfs_fdatawrite_range+0x1b/0x50 [btrfs] __btrfs_write_out_cache+0x42c/0x480 [btrfs] btrfs_write_out_ino_cache+0x84/0xd0 [btrfs] btrfs_save_ino_cache+0x551/0x660 [btrfs] commit_fs_roots+0xc5/0x190 [btrfs] btrfs_commit_transaction+0x2bf/0x8d0 [btrfs] btrfs_mksubvol+0x48d/0x4d0 [btrfs] btrfs_ioctl_snap_create_transid+0x170/0x180 [btrfs] btrfs_ioctl_snap_create_v2+0x124/0x180 [btrfs] btrfs_ioctl+0x123f/0x3030 [btrfs] The file extent generation of the free space inode is equal to the last snapshot of the file root, so the inode will be passed to cow_file_rage. But the inode was created and its extents were preallocated in btrfs_save_ino_cache, there are no cow copies on disk. The preallocated extent is not yet in the extent tree, and btrfs_cross_ref_exist will ignore the -ENOENT returned by check_committed_ref, so we can directly write the inode to the disk. Fixes: 78d4295b ("btrfs: lift some btrfs_cross_ref_exist checks in nocow path") CC: stable@vger.kernel.org # 4.18+ Reviewed-by:
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