- 08 Apr, 2020 3 commits
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Filipe Manana authored
This is a revert of commit 0a8068a3 ("btrfs: make ranged full fsyncs more efficient"), with updated comment in btrfs_sync_file. Commit 0a8068a3 ("btrfs: make ranged full fsyncs more efficient") made full fsyncs operate on the given range only as it assumed it was safe when using the NO_HOLES feature, since the hole detection was simplified some time ago and no longer was a source for races with ordered extent completion of adjacent file ranges. However it's still not safe to have a full fsync only operate on the given range, because extent maps for new extents might not be present in memory due to inode eviction or extent cloning. Consider the following example: 1) We are currently at transaction N; 2) We write to the file range [0, 1MiB); 3) Writeback finishes for the whole range and ordered extents complete, while we are still at transaction N; 4) The inode is evicted; 5) We open the file for writing, causing the inode to be loaded to memory again, which sets the 'full sync' bit on its flags. At this point the inode's list of modified extent maps is empty (figuring out which extents were created in the current transaction and were not yet logged by an fsync is expensive, that's why we set the 'full sync' bit when loading an inode); 6) We write to the file range [512KiB, 768KiB); 7) We do a ranged fsync (such as msync()) for file range [512KiB, 768KiB). This correctly flushes this range and logs its extent into the log tree. When the writeback started an extent map for range [512KiB, 768KiB) was added to the inode's list of modified extents, and when the fsync() finishes logging it removes that extent map from the list of modified extent maps. This fsync also clears the 'full sync' bit; 8) We do a regular fsync() (full ranged). This fsync() ends up doing nothing because the inode's list of modified extents is empty and no other changes happened since the previous ranged fsync(), so it just returns success (0) and we end up never logging extents for the file ranges [0, 512KiB) and [768KiB, 1MiB). Another scenario where this can happen is if we replace steps 2 to 4 with cloning from another file into our test file, as that sets the 'full sync' bit in our inode's flags and does not populate its list of modified extent maps. This was causing test case generic/457 to fail sporadically when using the NO_HOLES feature, as it exercised this later case where the inode has the 'full sync' bit set and has no extent maps in memory to represent the new extents due to extent cloning. Fix this by reverting commit 0a8068a3 ("btrfs: make ranged full fsyncs more efficient") since there is no easy way to work around it. Fixes: 0a8068a3 ("btrfs: make ranged full fsyncs more efficient") Signed-off-by:
Filipe Manana <fdmanana@suse.com> Signed-off-by:
David Sterba <dsterba@suse.com>
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Filipe Manana authored
When not using the NO_HOLES feature we were not marking the destination's file range as written after cloning an inline extent into it. This can lead to a data loss if the current destination file size is smaller than the source file's size. Example: $ mkfs.btrfs -f -O ^no-holes /dev/sdc $ mount /mnt/sdc /mnt $ echo "hello world" > /mnt/foo $ cp --reflink=always /mnt/foo /mnt/bar $ rm -f /mnt/foo $ umount /mnt $ mount /mnt/sdc /mnt $ cat /mnt/bar $ $ stat -c %s /mnt/bar 0 # -> the file is empty, since we deleted foo, the data lost is forever Fix that by calling btrfs_inode_set_file_extent_range() after cloning an inline extent. A test case for fstests will follow soon. Link: https://lore.kernel.org/linux-btrfs/20200404193846.GA432065@latitude/Reported-by:
Johannes Hirte <johannes.hirte@datenkhaos.de> Fixes: 9ddc959e ("btrfs: use the file extent tree infrastructure") Tested-by:
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Josef Bacik authored
Previously we would set the reloc root's last snapshot to transid - 1. However there was a problem with doing this, and we changed it to setting the last snapshot to the generation of the commit node of the fs root. This however broke should_ignore_root(). The assumption is that if we are in a generation newer than when the reloc root was created, then we would find the reloc root through normal backref lookups, and thus can ignore any fs roots we find with an old enough reloc root. Now that the last snapshot could be considerably further in the past than before, we'd end up incorrectly ignoring an fs root. Thus we'd find no nodes for the bytenr we were searching for, and we'd fail to relocate anything. We'd loop through the relocate code again and see that there were still used space in that block group, attempt to relocate those bytenr's again, fail in the same way, and just loop like this forever. This is tricky in that we have to not modify the fs root at all during this time, so we need to have a block group that has data in this fs root that is not shared by any other root, which is why this has been difficult to reproduce. Fixes: 054570a1 ("Btrfs: fix relocation incorrectly dropping data references") CC: stable@vger.kernel.org # 4.9+ Reviewed-by:
Josef Bacik <josef@toxicpanda.com> Signed-off-by:
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- 25 Mar, 2020 2 commits
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Robbie Ko authored
Ordered ops are started twice in sync file, once outside of inode mutex and once inside, taking the dio semaphore. There was one error path missing the semaphore unlock. Fixes: aab15e8e ("Btrfs: fix rare chances for data loss when doing a fast fsync") CC: stable@vger.kernel.org # 4.19+ Signed-off-by:
Robbie Ko <robbieko@synology.com> Reviewed-by:
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Josef Bacik authored
Zygo reported the following lockdep splat while testing the balance patches ====================================================== WARNING: possible circular locking dependency detected 5.6.0-c6f0579d496a+ #53 Not tainted ------------------------------------------------------ kswapd0/1133 is trying to acquire lock: ffff888092f622c0 (&delayed_node->mutex){+.+.}, at: __btrfs_release_delayed_node+0x7c/0x5b0 but task is already holding lock: ffffffff8fc5f860 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (fs_reclaim){+.+.}: fs_reclaim_acquire.part.91+0x29/0x30 fs_reclaim_acquire+0x19/0x20 kmem_cache_alloc_trace+0x32/0x740 add_block_entry+0x45/0x260 btrfs_ref_tree_mod+0x6e2/0x8b0 btrfs_alloc_tree_block+0x789/0x880 alloc_tree_block_no_bg_flush+0xc6/0xf0 __btrfs_cow_block+0x270/0x940 btrfs_cow_block+0x1ba/0x3a0 btrfs_search_slot+0x999/0x1030 btrfs_insert_empty_items+0x81/0xe0 btrfs_insert_delayed_items+0x128/0x7d0 __btrfs_run_delayed_items+0xf4/0x2a0 btrfs_run_delayed_items+0x13/0x20 btrfs_commit_transaction+0x5cc/0x1390 insert_balance_item.isra.39+0x6b2/0x6e0 btrfs_balance+0x72d/0x18d0 btrfs_ioctl_balance+0x3de/0x4c0 btrfs_ioctl+0x30ab/0x44a0 ksys_ioctl+0xa1/0xe0 __x64_sys_ioctl+0x43/0x50 do_syscall_64+0x77/0x2c0 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&delayed_node->mutex){+.+.}: __lock_acquire+0x197e/0x2550 lock_acquire+0x103/0x220 __mutex_lock+0x13d/0xce0 mutex_lock_nested+0x1b/0x20 __btrfs_release_delayed_node+0x7c/0x5b0 btrfs_remove_delayed_node+0x49/0x50 btrfs_evict_inode+0x6fc/0x900 evict+0x19a/0x2c0 dispose_list+0xa0/0xe0 prune_icache_sb+0xbd/0xf0 super_cache_scan+0x1b5/0x250 do_shrink_slab+0x1f6/0x530 shrink_slab+0x32e/0x410 shrink_node+0x2a5/0xba0 balance_pgdat+0x4bd/0x8a0 kswapd+0x35a/0x800 kthread+0x1e9/0x210 ret_from_fork+0x3a/0x50 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(&delayed_node->mutex); lock(fs_reclaim); lock(&delayed_node->mutex); *** DEADLOCK *** 3 locks held by kswapd0/1133: #0: ffffffff8fc5f860 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30 #1: ffffffff8fc380d8 (shrinker_rwsem){++++}, at: shrink_slab+0x1e8/0x410 #2: ffff8881e0e6c0e8 (&type->s_umount_key#42){++++}, at: trylock_super+0x1b/0x70 stack backtrace: CPU: 2 PID: 1133 Comm: kswapd0 Not tainted 5.6.0-c6f0579d496a+ #53 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: dump_stack+0xc1/0x11a print_circular_bug.isra.38.cold.57+0x145/0x14a check_noncircular+0x2a9/0x2f0 ? print_circular_bug.isra.38+0x130/0x130 ? stack_trace_consume_entry+0x90/0x90 ? save_trace+0x3cc/0x420 __lock_acquire+0x197e/0x2550 ? btrfs_inode_clear_file_extent_range+0x9b/0xb0 ? register_lock_class+0x960/0x960 lock_acquire+0x103/0x220 ? __btrfs_release_delayed_node+0x7c/0x5b0 __mutex_lock+0x13d/0xce0 ? __btrfs_release_delayed_node+0x7c/0x5b0 ? __asan_loadN+0xf/0x20 ? pvclock_clocksource_read+0xeb/0x190 ? __btrfs_release_delayed_node+0x7c/0x5b0 ? mutex_lock_io_nested+0xc20/0xc20 ? __kasan_check_read+0x11/0x20 ? check_chain_key+0x1e6/0x2e0 mutex_lock_nested+0x1b/0x20 ? mutex_lock_nested+0x1b/0x20 __btrfs_release_delayed_node+0x7c/0x5b0 btrfs_remove_delayed_node+0x49/0x50 btrfs_evict_inode+0x6fc/0x900 ? btrfs_setattr+0x840/0x840 ? do_raw_spin_unlock+0xa8/0x140 evict+0x19a/0x2c0 dispose_list+0xa0/0xe0 prune_icache_sb+0xbd/0xf0 ? invalidate_inodes+0x310/0x310 super_cache_scan+0x1b5/0x250 do_shrink_slab+0x1f6/0x530 shrink_slab+0x32e/0x410 ? do_shrink_slab+0x530/0x530 ? do_shrink_slab+0x530/0x530 ? __kasan_check_read+0x11/0x20 ? mem_cgroup_protected+0x13d/0x260 shrink_node+0x2a5/0xba0 balance_pgdat+0x4bd/0x8a0 ? mem_cgroup_shrink_node+0x490/0x490 ? _raw_spin_unlock_irq+0x27/0x40 ? finish_task_switch+0xce/0x390 ? rcu_read_lock_bh_held+0xb0/0xb0 kswapd+0x35a/0x800 ? _raw_spin_unlock_irqrestore+0x4c/0x60 ? balance_pgdat+0x8a0/0x8a0 ? finish_wait+0x110/0x110 ? __kasan_check_read+0x11/0x20 ? __kthread_parkme+0xc6/0xe0 ? balance_pgdat+0x8a0/0x8a0 kthread+0x1e9/0x210 ? kthread_create_worker_on_cpu+0xc0/0xc0 ret_from_fork+0x3a/0x50 This is because we hold that delayed node's mutex while doing tree operations. Fix this by just wrapping the searches in nofs. CC: stable@vger.kernel.org # 4.4+ Signed-off-by:
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- 23 Mar, 2020 35 commits
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Takashi Iwai authored
snprintf() is a hard-to-use function, and it's especially difficult to use it properly for concatenating substrings in a buffer with a limited size. Since snprintf() returns the would-be-output size, not the actual size, the subsequent use of snprintf() may point to the incorrect position easily. Also, returning the value from snprintf() directly to sysfs show function would pass a bogus value that is higher than the actually truncated string. That said, although the current code doesn't actually overflow the buffer with PAGE_SIZE, it's a usage that shouldn't be done. Or it's worse; this gives a wrong confidence as if it were doing safe operations. This patch replaces such snprintf() calls with a safer version, scnprintf(). It returns the actual output size, hence it's more intuitive and the code does what's expected. Signed-off-by:
Takashi Iwai <tiwai@suse.de> Reviewed-by:
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Josef Bacik authored
Zygo reported a deadlock where a task was stuck in the inode logical resolve code. The deadlock looks like this Task 1 btrfs_ioctl_logical_to_ino ->iterate_inodes_from_logical ->iterate_extent_inodes ->path->search_commit_root isn't set, so a transaction is started ->resolve_indirect_ref for a root that's being deleted ->search for our key, attempt to lock a node, DEADLOCK Task 2 btrfs_drop_snapshot ->walk down to a leaf, lock it, walk up, lock node ->end transaction ->start transaction -> wait_cur_trans Task 3 btrfs_commit_transaction ->wait_event(cur_trans->write_wait, num_writers == 1) DEADLOCK We are holding a transaction open in btrfs_ioctl_logical_to_ino while we try to resolve our references. btrfs_drop_snapshot() holds onto its locks while it stops and starts transaction handles, because it assumes nobody is going to touch the root now. Commit just does what commit does, waiting for the writers to finish, blocking any new trans handles from starting. Fix this by making the backref code not try to resolve backrefs of roots that are currently being deleted. This will keep us from walking into a snapshot that's currently being deleted. This problem was harder to hit before because we rarely broke out of the snapshot delete halfway through, but with my delayed ref throttling code it happened much more often. However we've always been able to do this, so it's not a new problem. Fixes: 8da6d581 ("Btrfs: added btrfs_find_all_roots()") Signed-off-by: -
Josef Bacik authored
We always search the commit root of the extent tree for looking up back references, however we track the reloc roots based on their current bytenr. This is wrong, if we commit the transaction between relocating tree blocks we could end up in this code in build_backref_tree if (key.objectid == key.offset) { /* * Only root blocks of reloc trees use backref * pointing to itself. */ root = find_reloc_root(rc, cur->bytenr); ASSERT(root); cur->root = root; break; } find_reloc_root() is looking based on the bytenr we had in the commit root, but if we've COWed this reloc root we will not find that bytenr, and we will trip over the ASSERT(root). Fix this by using the commit_root->start bytenr for indexing the commit root. Then we change the __update_reloc_root() caller to be used when we switch the commit root for the reloc root during commit. This fixes the panic I was seeing when we started throttling relocation for delayed refs. Signed-off-by: -
Josef Bacik authored
There are two bugs here, but fixing them independently would just result in pain if you happened to bisect between the two patches. First is how we handle the -EAGAIN from relocate_tree_block(). We don't set error, unless we happen to be the first node, which makes no sense, I have no idea what the code was trying to accomplish here. We in fact _do_ want err set here so that we know we need to restart in relocate_block_group(). Also we need finish_pending_nodes() to not actually call link_to_upper(), because we didn't actually relocate the block. And then if we do get -EAGAIN we do not want to set our backref cache last_trans to the one before ours. This would force us to update our backref cache if we didn't cross transaction ids, which would mean we'd have some nodes updated to their new_bytenr, but still able to find their old bytenr because we're searching the same commit root as the last time we went through relocate_tree_blocks. Fixing these two things keeps us from panicing when we start breaking out of relocate_tree_blocks() either for delayed ref flushing or enospc. Signed-off-by:
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Josef Bacik authored
Since we're not only checking for metadata reservations but also if we need to throttle our delayed ref generation, reorder reserve_metadata_space() above the select_one_root() call in relocate_tree_block(). The reason we want this is because select_reloc_root() will mess with the backref cache, and if we're going to bail we want to be able to cleanly remove this node from the backref cache and come back along to regenerate it. Move it up so this is the first thing we do to make restarting cleaner. Signed-off-by:
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Josef Bacik authored
Here we are just searching down to the bytenr we're building the backref tree for, and all of it's paths to the roots. These bytenrs are not guaranteed to be anywhere near each other, so readahead just generates extra latency. Reviewed-by:
Qu Wenruo <wqu@suse.com> Signed-off-by:
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Josef Bacik authored
Readahead will generate a lot of extra reads for adjacent nodes, but when running delayed refs we have no idea if the next ref is going to be adjacent or not, so this potentially just generates a lot of extra IO. To make matters worse each ref is truly just looking for one item, it doesn't generally search forward, so we simply don't need it here. Reviewed-by:
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Nikolay Borisov authored
With BTRFS_SUBVOL_CREATE_ASYNC support remove it's no longer required to pass the async_transid parameter so remove it and any code using it. Signed-off-by:
Nikolay Borisov <nborisov@suse.com> Reviewed-by:
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Nikolay Borisov authored
btrfs_ioctl_snap_create_transid no longer takes a transid argument, so remove it and rename the function to __btrfs_ioctl_snap_create to reflect it's an internal, worker function. Signed-off-by:
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Nikolay Borisov authored
This functionality was deprecated in kernel 5.4. Since no one has complained of the impending removal it's time we did so. Signed-off-by:
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Josef Bacik authored
Now that we have proper root ref counting everywhere we can kill the subvol_srcu. * removal of fs_info::subvol_srcu reduces size of fs_info by 1176 bytes * the refcount_t used for the references checks for accidental 0->1 in cases where the root lifetime would not be properly protected * there's a leak detector for roots to catch unfreed roots at umount time * SRCU served us well over the years but is was not a proper synchronization mechanism for some cases Signed-off-by:
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Josef Bacik authored
The radix root is primarily protected by the fs_roots_radix_lock, so use that to lookup and get a ref on all of our fs roots in btrfs_cleanup_fs_roots. The tree reference is taken in the protected section as before. Signed-off-by:
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Josef Bacik authored
Now that all the users of roots take references for them we can drop the extra root ref we've been taking. Before we had roots at 2 refs for the life of the file system, one for the radix tree, and one simply for existing. Now that we have proper ref accounting in all places that use roots we can drop this extra ref simply for existing as we no longer need it. Signed-off-by:
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Josef Bacik authored
At the point we add a root to the dead roots list we have no open inodes for that root, so we need to hold a ref on that root to keep it from disappearing. Signed-off-by:
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Josef Bacik authored
If we make sure all the inodes have refs on their root we don't have to worry about the root disappearing while we have open inodes. Signed-off-by:
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Josef Bacik authored
There are a few different ways to free roots, either you allocated them yourself and you just do free_extent_buffer(root->node); free_extent_buffer(root->commit_node); btrfs_put_root(root); Which is the pattern for log roots. Or for snapshots/subvolumes that are being dropped you simply call btrfs_free_fs_root() which does all the cleanup for you. Unify this all into btrfs_put_root(), so that we don't free up things associated with the root until the last reference is dropped. This makes the root freeing code much more significant. The only caveat is at close_ctree() time we have to free the extent buffers for all of our main roots (extent_root, chunk_root, etc) because we have to drop the btree_inode and we'll run into issues if we hold onto those nodes until ->kill_sb() time. This will be addressed in the future when we kill the btree_inode. Signed-off-by:
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Josef Bacik authored
We are going to make root life be controlled soley by refcounting, and inodes will be one of the things that hold a ref on the root. This means we need to handle dropping the ino_cache_inode outside of the root freeing logic, so move it into btrfs_drop_and_free_fs_root() so it is cleaned up properly on unmount. Signed-off-by:
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Josef Bacik authored
I'm going to make the entire destruction of btrfs_root's controlled by their refcount, so it will be helpful to notice if we're leaking their eb's on umount. Signed-off-by:
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Josef Bacik authored
This was pretty subtle, we default to reloc roots having 0 root refs, so if we crash in the middle of the relocation they can just be deleted. If we successfully complete the relocation operations we'll set our root refs to 1 in prepare_to_merge() and then go on to merge_reloc_roots(). At prepare_to_merge() time if any of the reloc roots have a 0 reference still, we will remove that reloc root from our reloc root rb tree, and then clean it up later. However this only happens if we successfully start a transaction. If we've aborted previously we will skip this step completely, and only have reloc roots with a reference count of 0, but were never properly removed from the reloc control's rb tree. This isn't a problem per-se, our references are held by the list the reloc roots are on, and by the original root the reloc root belongs to. If we end up in this situation all the reloc roots will be added to the dirty_reloc_list, and then properly dropped at that point. The reloc control will be free'd and the rb tree is no longer used. There were two options when fixing this, one was to remove the BUG_ON(), the other was to make prepare_to_merge() handle the case where we couldn't start a trans handle. IMO this is the cleaner solution. I started with handling the error in prepare_to_merge(), but it turned out super ugly. And in the end this BUG_ON() simply doesn't matter, the cleanup was happening properly, we were just panicing because this BUG_ON() only matters in the success case. So I've opted to just remove it and add a comment where it was. Reviewed-by:
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Josef Bacik authored
We previously were relying on root->reloc_root to be cleaned up by the drop snapshot, or the error handling. However if btrfs_drop_snapshot() failed it wouldn't drop the ref for the root. Also we sort of depend on the right thing to happen with moving reloc roots between lists and the fs root they belong to, which makes it hard to figure out who owns the reference. Fix this by explicitly holding a reference on the reloc root for roo->reloc_root. This means that we hold two references on reloc roots, one for whichever reloc_roots list it's attached to, and the root->reloc_root we're on. This makes it easier to reason out who owns a reference on the root, and when it needs to be dropped. Reviewed-by:
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Josef Bacik authored
The DEAD_RELOC_TREE flag is in place in order to avoid a use after free in init_reloc_root, tracking the presence of reloc_root. However adding the explicit tree references in previous patches makes the use after free impossible because at this point we no longer have a reloc_control set on the fs_info and thus cannot enter the function. So move this to be coupled with clearing the root->reloc_root so we're consistent with all other operations of the reloc root. Signed-off-by:
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Josef Bacik authored
If we have an error while processing the reloc roots we could leak roots that were added to rc->reloc_roots before we hit the error. We could have also not removed the reloc tree mapping from our rb_tree, so clean up any remaining nodes in the reloc root rb_tree. Signed-off-by:
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Josef Bacik authored
We previously were checking if the root had a dead root before accessing root->reloc_root in order to avoid a use-after-free type bug. However this scenario happens after we've unset the reloc control, so we would have been saved if we'd simply checked for fs_info->reloc_control. At this point during relocation we no longer need to be creating new reloc roots, so simply move this check above the reloc_root checks to avoid any future races and confusion. Reviewed-by:
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Josef Bacik authored
If we do merge_reloc_roots() we could insert a few roots onto the dirty subvol roots list, where we hold a ref on them. If we fail to start the transaction we need to run clean_dirty_subvols() in order to cleanup the refs. CC: stable@vger.kernel.org # 5.4+ Signed-off-by:
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Josef Bacik authored
If we fail to load an fs root, or fail to start a transaction we can bail without unsetting the reloc control, which leads to problems later when we free the reloc control but still have it attached to the file system. In the normal path we'll end up calling unset_reloc_control() twice, but all it does is set fs_info->reloc_control = NULL, and we can only have one balance at a time so it's not racey. CC: stable@vger.kernel.org # 5.4+ Reviewed-by:
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Josef Bacik authored
If we have an error while building the backref tree in relocation we'll process all the pending edges and then free the node. However if we integrated some edges into the cache we'll lose our link to those edges by simply freeing this node, which means we'll leak memory and references to any roots that we've found. Instead we need to use remove_backref_node(), which walks through all of the edges that are still linked to this node and free's them up and drops any root references we may be holding. CC: stable@vger.kernel.org # 4.9+ Reviewed-by:
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Qu Wenruo authored
In relocation, we need to locate all parent tree leaves referring to one data extent, thus we have a complex mechanism to iterate throught extent tree and subvolume trees to locate the related leaves. However this is already done in backref.c, we have btrfs_find_all_leafs(), which can return a ulist containing all leaves referring to that data extent. Use btrfs_find_all_leafs() to replace find_data_references(). There is a special handling for v1 space cache data extents, where we need to delete the v1 space cache data extents, to avoid those data extents to hang the data relocation. In this patch, the special handling is done by re-iterating the root tree leaf. Although it's a little less efficient than the old handling, considering we can reuse a lot of code, it should be acceptable. Signed-off-by:
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Josef Bacik authored
While debugging I noticed I wasn't getting ref verify errors before everything blew up. Turns out it's because we don't warn when we try to add a normal ref via btrfs_inc_ref() if the block entry exists but has 0 references. This is incorrect, we should never be doing anything other than adding a new extent once a block entry drops to 0 references. Signed-off-by:
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Filipe Manana authored
Commit 0c713cba ("Btrfs: fix race between ranged fsync and writeback of adjacent ranges") fixed a bug where we could end up with file extent items in a log tree that represent file ranges that overlap due to a race between the hole detection of a ranged full fsync and writeback for a different file range. The problem was solved by forcing any ranged full fsync to become a non-ranged full fsync - setting the range start to 0 and the end offset to LLONG_MAX. This was a simple solution because the code that detected and marked holes was very complex, it used to be done at copy_items() and implied several searches on the fs/subvolume tree. The drawback of that solution was that we started to flush delalloc for the entire file and wait for all the ordered extents to complete for ranged full fsyncs (including ordered extents covering ranges completely outside the given range). Fortunatelly ranged full fsyncs are not the most common case (hopefully for most workloads). However a later fix for detecting and marking holes was made by commit 0e56315c ("Btrfs: fix missing hole after hole punching and fsync when using NO_HOLES") and it simplified a lot the detection of holes, and now copy_items() no longer does it and we do it in a much more simple way at btrfs_log_holes(). This makes it now possible to simply make the code that detects holes to operate only on the initial range and no longer need to operate on the whole file, while also avoiding the need to flush delalloc for the entire file and wait for ordered extents that cover ranges that don't overlap the given range. Another special care is that we must skip file extent items that fall entirely outside the fsync range when copying inode items from the fs/subvolume tree into the log tree - this is to avoid races with ordered extent completion for extents falling outside the fsync range, which could cause us to end up with file extent items in the log tree that have overlapping ranges - for example if the fsync range is [1Mb, 2Mb], when we copy inode items we could copy an extent item for the range [0, 512K], then release the search path and before moving to the next leaf, an ordered extent for a range of [256Kb, 512Kb] completes - this would cause us to copy the new extent item for range [256Kb, 512Kb] into the log tree after we have copied one for the range [0, 512Kb] - the extents overlap, resulting in a corruption. So this change just does these steps: 1) When the NO_HOLES feature is enabled it leaves the initial range intact - no longer sets it to [0, LLONG_MAX] when the full sync bit is set in the inode. If NO_HOLES is not enabled, always set the range to a full, just like before this change, to avoid missing file extent items representing holes after replaying the log (for both full and fast fsyncs); 2) Make the hole detection code to operate only on the fsync range; 3) Make the code that copies items from the fs/subvolume tree to skip copying file extent items that cover a range completely outside the range of the fsync. Reviewed-by:
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Filipe Manana authored
The function btrfs_log_inode() is quite large and so is its loop which iterates the inode items from the fs/subvolume tree and copies them into a log tree. Because this is a large loop inside a very large function and because an upcoming patch in this series needs to add some more logic inside that loop, move the loop into a helper function to make it a bit more manageable. Reviewed-by:
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Filipe Manana authored
Getting the end offset for a file extent item requires a bit of code since the extent can be either inline or regular/prealloc. There are some places all over the code base that open code this logic and in another patch later in this series it will be needed again. Therefore encapsulate this logic in a helper function and use it. Reviewed-by:
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Filipe Manana authored
When doing a fast fsync for a range that starts at an offset greater than zero, we can end up with a log that when replayed causes the respective inode miss a file extent item representing a hole if we are not using the NO_HOLES feature. This is because for fast fsyncs we don't log any extents that cover a range different from the one requested in the fsync. Example scenario to trigger it: $ mkfs.btrfs -O ^no-holes -f /dev/sdd $ mount /dev/sdd /mnt # Create a file with a single 256K and fsync it to clear to full sync # bit in the inode - we want the msync below to trigger a fast fsync. $ xfs_io -f -c "pwrite -S 0xab 0 256K" -c "fsync" /mnt/foo # Force a transaction commit and wipe out the log tree. $ sync # Dirty 768K of data, increasing the file size to 1Mb, and flush only # the range from 256K to 512K without updating the log tree # (sync_file_range() does not trigger fsync, it only starts writeback # and waits for it to finish). $ xfs_io -c "pwrite -S 0xcd 256K 768K" /mnt/foo $ xfs_io -c "sync_range -abw 256K 256K" /mnt/foo # Now dirty the range from 768K to 1M again and sync that range. $ xfs_io -c "mmap -w 768K 256K" \ -c "mwrite -S 0xef 768K 256K" \ -c "msync -s 768K 256K" \ -c "munmap" \ /mnt/foo <power fail> # Mount to replay the log. $ mount /dev/sdd /mnt $ umount /mnt $ btrfs check /dev/sdd Opening filesystem to check... Checking filesystem on /dev/sdd UUID: 482fb574-b288-478e-a190-a9c44a78fca6 [1/7] checking root items [2/7] checking extents [3/7] checking free space cache [4/7] checking fs roots root 5 inode 257 errors 100, file extent discount Found file extent holes: start: 262144, len: 524288 ERROR: errors found in fs roots found 720896 bytes used, error(s) found total csum bytes: 512 total tree bytes: 131072 total fs tree bytes: 32768 total extent tree bytes: 16384 btree space waste bytes: 123514 file data blocks allocated: 589824 referenced 589824 Fix this issue by setting the range to full (0 to LLONG_MAX) when the NO_HOLES feature is not enabled. This results in extra work being done but it gives the guarantee we don't end up with missing holes after replaying the log. CC: stable@vger.kernel.org # 4.19+ Reviewed-by: -
Nikolay Borisov authored
Instead of iterating all pending tickets on the normal/priority list to sum their total size the cost can be amortized across ticket addition/ removal. This turns O(n) + O(m) (where n is the size of the normal list and m of the priority list) into O(1). This will mostly have effect in workloads that experience heavy flushing. Signed-off-by:
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Roman Gushchin authored
Currently btrfs doesn't provide a migratepage callback for data pages. It means that fallback_migrate_page() is used to migrate btrfs pages. fallback_migrate_page() cannot move dirty pages, instead it tries to flush them (in sync mode) or just fails (in async mode). In the sync mode pages which are scheduled to be processed by btrfs_writepage_fixup_worker() can't be effectively flushed by the migration code, because there is no established way to wait for the completion of the delayed work. It all leads to page migration failures. To fix it the patch implements a btrs-specific migratepage callback, which is similar to iomap_migrate_page() used by some other fs, except it does take care of the PagePrivate2 flag which is used for data ordering purposes. Reviewed-by:
Chris Mason <clm@fb.com> Signed-off-by:
Roman Gushchin <guro@fb.com> Signed-off-by:
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Nikolay Borisov authored
It's no longer used following 30d40577 ("btrfs: reloc: Also queue orphan reloc tree for cleanup to avoid BUG_ON()"), so just remove it. Signed-off-by:
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