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path: root/fs/btrfs/delayed-ref.c
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2025-01-13btrfs: update tree_insert() to use rb helpersRoger L. Beckermeyer III
Update tree_insert() to use rb_find_add_cached(). add cmp_refs_node in rb_find_add_cached() to compare. Since we're here, also make comp_data_refs() and comp_refs() accept both parameters as const. Signed-off-by: Roger L. Beckermeyer III <beckerlee3@gmail.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-01-13btrfs: drop fs_info argument from btrfs_update_space_info_*()Naohiro Aota
Since commit e1e577aafe41 ("btrfs: store fs_info in space_info"), we have the fs_info in a space_info. So, we can drop fs_info argument from btrfs_update_space_info_*. There is no behavior change. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.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>
2025-01-13btrfs: selftests: add delayed ref self test casesJosef Bacik
The recent fix for a stupid mistake I made uncovered the fact that we don't have adequate testing in the delayed refs code, as it took a pretty extensive and long running stress test to uncover something that a unit test would have uncovered right away. Fix this by adding a delayed refs self test suite. This will validate that the btrfs_ref transformation does the correct thing, that we do the correct thing when merging delayed refs, and that we get the delayed refs in the order that we expect. These are all crucial to how the delayed refs operate. I introduced various bugs (including the original bug) into the delayed refs code to validate that these tests caught all of the shenanigans that I could think of. Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-01-13btrfs: move select_delayed_ref() and export itJosef Bacik
This helper is how we select the delayed ref to run once we've selected the delayed ref head. I need this exported to add a unit test for delayed refs, and it's more natural home is in delayed-ref.c. Rename it to btrfs_select_delayed_ref and move it into delayed-ref.c. Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-18Merge tag 'for-6.13-tag' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux Pull btrfs updates from David Sterba: "Changes outside of btrfs: add io_uring command flag to track a dying task (the rest will go via the block git tree). User visible changes: - wire encoded read (ioctl) to io_uring commands, this can be used on itself, in the future this will allow 'send' to be asynchronous. As a consequence, the encoded read ioctl can also work in non-blocking mode - new ioctl to wait for cleaned subvolumes, no need to use the generic and root-only SEARCH_TREE ioctl, will be used by "btrfs subvol sync" - recognize different paths/symlinks for the same devices and don't report them during rescanning, this can be observed with LVM or DM - seeding device use case change, the sprout device (the one capturing new writes) will not clear the read-only status of the super block; this prevents accumulating space from deleted snapshots Performance improvements: - reduce lock contention when traversing extent buffers - reduce extent tree lock contention when searching for inline backref - switch from rb-trees to xarray for delayed ref tracking, improvements due to better cache locality, branching factors and more compact data structures - enable extent map shrinker again (prevent memory exhaustion under some types of IO load), reworked to run in a single worker thread (there used to be problems causing long stalls under memory pressure) Core changes: - raid-stripe-tree feature updates: - make device replace and scrub work - implement partial deletion of stripe extents - new selftests - split the config option BTRFS_DEBUG and add EXPERIMENTAL for features that are experimental or with known problems so we don't misuse debugging config for that - subpage mode updates (sector < page): - update compression implementations - update writepage, writeback - continued folio API conversions: - buffered writes - make buffered write copy one page at a time, preparatory work for future integration with large folios, may cause performance drop - proper locking of root item regarding starting send - error handling improvements - code cleanups and refactoring: - dead code removal - unused parameter reduction - lockdep assertions" * tag 'for-6.13-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (119 commits) btrfs: send: check for read-only send root under critical section btrfs: send: check for dead send root under critical section btrfs: remove check for NULL fs_info at btrfs_folio_end_lock_bitmap() btrfs: fix warning on PTR_ERR() against NULL device at btrfs_control_ioctl() btrfs: fix a typo in btrfs_use_zone_append btrfs: avoid superfluous calls to free_extent_map() in btrfs_encoded_read() btrfs: simplify logic to decrement snapshot counter at btrfs_mksnapshot() btrfs: remove hole from struct btrfs_delayed_node btrfs: update stale comment for struct btrfs_delayed_ref_node::add_list btrfs: add new ioctl to wait for cleaned subvolumes btrfs: simplify range tracking in cow_file_range() btrfs: remove conditional path allocation in btrfs_read_locked_inode() btrfs: push cleanup into btrfs_read_locked_inode() io_uring/cmd: let cmds to know about dying task btrfs: add struct io_btrfs_cmd as type for io_uring_cmd_to_pdu() btrfs: add io_uring command for encoded reads (ENCODED_READ ioctl) btrfs: move priv off stack in btrfs_encoded_read_regular_fill_pages() btrfs: don't sleep in btrfs_encoded_read() if IOCB_NOWAIT is set btrfs: change btrfs_encoded_read() so that reading of extent is done by caller btrfs: remove pointless iocb::ki_pos addition in btrfs_encoded_read() ...
2024-11-14btrfs: fix incorrect comparison for delayed refsJosef Bacik
When I reworked delayed ref comparison in cf4f04325b2b ("btrfs: move ->parent and ->ref_root into btrfs_delayed_ref_node"), I made a mistake and returned -1 for the case where ref1->ref_root was > than ref2->ref_root. This is a subtle bug that can result in improper delayed ref running order, which can result in transaction aborts. Fixes: cf4f04325b2b ("btrfs: move ->parent and ->ref_root into btrfs_delayed_ref_node") CC: stable@vger.kernel.org # 6.10+ Reviewed-by: Filipe Manana <fdmanana@suse.com> 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>
2024-11-11btrfs: remove no longer used delayed ref head search functionalityFilipe Manana
After the previous patch, which converted the rb-tree used to track delayed ref heads into an xarray, the find_ref_head() function is now used only by one caller which always passes false to the 'return_bigger' argument. So remove the 'return_bigger' logic, simplifying the function, and move all the function code to the single caller. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11btrfs: track delayed ref heads in an xarrayFilipe Manana
Currently we use a red black tree (rb-tree) to track the delayed ref heads (in struct btrfs_delayed_ref_root::href_root). This however is not very efficient when the number of delayed ref heads is large (and it's very common to be at least in the order of thousands) since rb-trees are binary trees. For example for 10K delayed ref heads, the tree has a depth of 13. Besides that, inserting into the tree requires navigating through it and pulling useless cache lines in the process since the red black tree nodes are embedded within the delayed ref head structure - on the other hand, by being embedded, it requires no extra memory allocations. We can improve this by using an xarray instead which has a much higher branching factor than a red black tree (binary balanced tree) and is more cache friendly and behaves like a resizable array, with a much better search and insertion complexity than a red black tree. This only has one small disadvantage which is that insertion will sometimes require allocating memory for the xarray - which may fail (not that often since it uses a kmem_cache) - but on the other hand we can reduce the delayed ref head structure size by 24 bytes (from 152 down to 128 bytes) after removing the embedded red black tree node, meaning than we can now fit 32 delayed ref heads per 4K page instead of 26, and that gain compensates for the occasional memory allocations needed for the xarray nodes. We also end up using only 2 cache lines instead of 3 per delayed ref head. Running the following fs_mark test showed some improvements: $ cat test.sh #!/bin/bash DEV=/dev/nullb0 MNT=/mnt/nullb0 MOUNT_OPTIONS="-o ssd" FILES=100000 THREADS=$(nproc --all) echo "performance" | \ tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor mkfs.btrfs -f $DEV mount $MOUNT_OPTIONS $DEV $MNT OPTS="-S 0 -L 5 -n $FILES -s 0 -t $THREADS -k" for ((i = 1; i <= $THREADS; i++)); do OPTS="$OPTS -d $MNT/d$i" done fs_mark $OPTS umount $MNT Before this patch: FSUse% Count Size Files/sec App Overhead 10 1200000 0 171845.7 12253839 16 2400000 0 230898.7 12308254 23 3600000 0 212292.9 12467768 30 4800000 0 195737.8 12627554 46 6000000 0 171055.2 12783329 After this patch: FSUse% Count Size Files/sec App Overhead 10 1200000 0 173835.0 12246131 16 2400000 0 233537.8 12271746 23 3600000 0 220398.7 12307737 30 4800000 0 204483.6 12392318 40 6000000 0 182923.3 12771843 Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11btrfs: assert delayed refs lock is held at add_delayed_ref_head()Filipe Manana
The delayed refs lock must be held when calling add_delayed_ref_head(), so assert that it's being held. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11btrfs: assert delayed refs lock is held at find_first_ref_head()Filipe Manana
The delayed refs lock must be held when calling find_first_ref_head(), so assert that it's being held. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11btrfs: assert delayed refs lock is held at find_ref_head()Filipe Manana
We have 3 callers for find_ref_head() so assert at find_ref_head() that we have the delayed refs lock held, removing the assertion from one of its callers (btrfs_find_delayed_ref_head()). Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11btrfs: pass fs_info to btrfs_delete_ref_head()Filipe Manana
One of the following patches in the series will need to access fs_info at btrfs_delete_ref_head(), so pass a fs_info argument to it. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11btrfs: pass fs_info to functions that search for delayed ref headsFilipe Manana
One of the following patches in the series will need to access fs_info in the function find_ref_head(), so pass a fs_info argument to it as well as to the functions btrfs_select_ref_head() and btrfs_find_delayed_ref_head() which call find_ref_head(). Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11btrfs: move delayed ref head unselection to delayed-ref.cFilipe Manana
The unselect_delayed_ref_head() at extent-tree.c doesn't really belong in that file as it's a delayed refs specific detail and therefore should be at delayed-ref.c. Further its inverse, btrfs_select_ref_head(), is at delayed-ref.c, so it only makes sense to have it there too. So move unselect_delayed_ref_head() into delayed-ref.c and rename it to btrfs_unselect_ref_head() so that its name closely matches its inverse (btrfs_select_ref_head()). Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11btrfs: simplify obtaining a delayed ref headFilipe Manana
Instead of doing it in two steps outside of delayed-ref.c, leaking low level details such as locking, move the logic entirely to delayed-ref.c under btrfs_select_ref_head(), reducing code and making things simpler for the caller. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11btrfs: change return type of btrfs_delayed_ref_lock() to booleanFilipe Manana
The function only returns 0, meaning it was able to lock the delayed ref head, or -EAGAIN in case it wasn't able to lock it. So simplify this and use a boolean return type instead, returning true if it was able to lock and false otherwise. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11btrfs: remove num_entries atomic counter from delayed ref rootFilipe Manana
The atomic counter 'num_entries' is not used anymore, we increment it and decrement it but then we don't ever read it to use for any logic. Its last use was removed with commit 61a56a992fcf ("btrfs: delayed refs pre-flushing should only run the heads we have"). So remove it. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11btrfs: use helper to find first ref head at btrfs_destroy_delayed_refs()Filipe Manana
Instead of open coding it, use the find_first_ref_head() helper at btrfs_destroy_delayed_refs(). This avoids duplicating the logic, specially with the upcoming changes in subsequent patches. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11btrfs: remove duplicated code to drop delayed ref during transaction abortFilipe Manana
When destroying delayed refs during a transaction abort, we have open coded the removal of a delayed ref, which is also done by the static helper function drop_delayed_ref(). So remove that duplicated code and use drop_delayed_ref() instead. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11btrfs: remove fs_info parameter from btrfs_destroy_delayed_refs()Filipe Manana
The fs_info parameter is redundant because it can be extracted from the transaction given as another parameter. So remove it and use the fs_info accessible from the transaction. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11btrfs: move btrfs_destroy_delayed_refs() to delayed-ref.cFilipe Manana
It's better suited at delayed-ref.c since it's about delayed refs and contains logic to iterate over them (using the red black tree, doing all the locking, freeing, etc), so move it from disk-io.c, which is pretty big, into delayed-ref.c, hiding implementation details of how delayed refs are tracked and managed. This also facilitates the next patches in the series. This change moves the code between files but also does the following simple cleanups: 1) Rename the 'cache' variable to 'bg', since it's a block group (the 'cache' logic comes from old days where the block group structure was named 'btrfs_block_group_cache'); 2) Move the 'ref' variable declaration to the scope of the inner while loop, since it's not used outside that loop. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11btrfs: qgroups: remove bytenr field from struct btrfs_qgroup_extent_recordFilipe Manana
Now that we track qgroup extent records in a xarray we don't need to have a "bytenr" field in struct btrfs_qgroup_extent_record, since we can get it from the index of the record in the xarray. So remove the field and grab the bytenr from either the index key or any other place where it's available (delayed refs). This reduces the size of struct btrfs_qgroup_extent_record from 40 bytes down to 32 bytes, meaning that we now can store 128 instances of this structure instead of 102 per 4K page. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-07btrfs: reinitialize delayed ref list after deleting it from the listFilipe Manana
At insert_delayed_ref() if we need to update the action of an existing ref to BTRFS_DROP_DELAYED_REF, we delete the ref from its ref head's ref_add_list using list_del(), which leaves the ref's add_list member not reinitialized, as list_del() sets the next and prev members of the list to LIST_POISON1 and LIST_POISON2, respectively. If later we end up calling drop_delayed_ref() against the ref, which can happen during merging or when destroying delayed refs due to a transaction abort, we can trigger a crash since at drop_delayed_ref() we call list_empty() against the ref's add_list, which returns false since the list was not reinitialized after the list_del() and as a consequence we call list_del() again at drop_delayed_ref(). This results in an invalid list access since the next and prev members are set to poison pointers, resulting in a splat if CONFIG_LIST_HARDENED and CONFIG_DEBUG_LIST are set or invalid poison pointer dereferences otherwise. So fix this by deleting from the list with list_del_init() instead. Fixes: 1d57ee941692 ("btrfs: improve delayed refs iterations") CC: stable@vger.kernel.org # 4.19+ Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-10-11btrfs: use sector numbers as keys for the dirty extents xarrayFilipe Manana
We are using the logical address ("bytenr") of an extent as the key for qgroup records in the dirty extents xarray. This is a problem because the xarrays use "unsigned long" for keys/indices, meaning that on a 32 bits platform any extent starting at or beyond 4G is truncated, which is a too low limitation as virtually everyone is using storage with more than 4G of space. This means a "bytenr" of 4G gets truncated to 0, and so does 8G and 16G for example, resulting in incorrect qgroup accounting. Fix this by using sector numbers as keys instead, that is, using keys that match the logical address right shifted by fs_info->sectorsize_bits, which is what we do for the fs_info->buffer_radix that tracks extent buffers (radix trees also use an "unsigned long" type for keys). This also makes the index space more dense which helps optimize the xarray (as mentioned at Documentation/core-api/xarray.rst). Fixes: 3cce39a8ca4e ("btrfs: qgroup: use xarray to track dirty extents in transaction") Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-10-07btrfs: fix missing error handling when adding delayed ref with qgroups enabledFilipe Manana
When adding a delayed ref head, at delayed-ref.c:add_delayed_ref_head(), if we fail to insert the qgroup record we don't error out, we ignore it. In fact we treat it as if there was no error and there was already an existing record - we don't distinguish between the cases where btrfs_qgroup_trace_extent_nolock() returns 1, meaning a record already existed and we can free the given record, and the case where it returns a negative error value, meaning the insertion into the xarray that is used to track records failed. Effectively we end up ignoring that we are lacking qgroup record in the dirty extents xarray, resulting in incorrect qgroup accounting. Fix this by checking for errors and return them to the callers. Fixes: 3cce39a8ca4e ("btrfs: qgroup: use xarray to track dirty extents in transaction") Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-09-10btrfs: qgroup: use xarray to track dirty extents in transactionJunchao Sun
Use xarray to track dirty extents to reduce the size of the struct btrfs_qgroup_extent_record from 64 bytes to 40 bytes. The xarray is more cache line friendly, it also reduces the complexity of insertion and search code compared to rb tree. Another change introduced is about error handling. Before this patch, the result of btrfs_qgroup_trace_extent_nolock() is always a success. In this patch, because of this function calls the function xa_store() which has the possibility to fail, so mark qgroup as inconsistent if error happened and then free preallocated memory. Also we preallocate memory before spin_lock(), if memory preallcation failed, error handling is the same the existing code. Suggested-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Junchao Sun <sunjunchao2870@gmail.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-09-10btrfs: qgroup: use goto style to handle errors in add_delayed_ref()Junchao Sun
Clean up resources using goto to get rid of repeated code. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Junchao Sun <sunjunchao2870@gmail.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-08-13btrfs: check delayed refs when we're checking if a ref existsJosef Bacik
In the patch 78c52d9eb6b7 ("btrfs: check for refs on snapshot delete resume") I added some code to handle file systems that had been corrupted by a bug that incorrectly skipped updating the drop progress key while dropping a snapshot. This code would check to see if we had already deleted our reference for a child block, and skip the deletion if we had already. Unfortunately there is a bug, as the check would only check the on-disk references. I made an incorrect assumption that blocks in an already deleted snapshot that was having the deletion resume on mount wouldn't be modified. If we have 2 pending deleted snapshots that share blocks, we can easily modify the rules for a block. Take the following example subvolume a exists, and subvolume b is a snapshot of subvolume a. They share references to block 1. Block 1 will have 2 full references, one for subvolume a and one for subvolume b, and it belongs to subvolume a (btrfs_header_owner(block 1) == subvolume a). When deleting subvolume a, we will drop our full reference for block 1, and because we are the owner we will drop our full reference for all of block 1's children, convert block 1 to FULL BACKREF, and add a shared reference to all of block 1's children. Then we will start the snapshot deletion of subvolume b. We look up the extent info for block 1, which checks delayed refs and tells us that FULL BACKREF is set, so sets parent to the bytenr of block 1. However because this is a resumed snapshot deletion, we call into check_ref_exists(). Because check_ref_exists() only looks at the disk, it doesn't find the shared backref for the child of block 1, and thus returns 0 and we skip deleting the reference for the child of block 1 and continue. This orphans the child of block 1. The fix is to lookup the delayed refs, similar to what we do in btrfs_lookup_extent_info(). However we only care about whether the reference exists or not. If we fail to find our reference on disk, go look up the bytenr in the delayed refs, and if it exists look for an existing ref in the delayed ref head. If that exists then we know we can delete the reference safely and carry on. If it doesn't exist we know we have to skip over this block. This bug has existed since I introduced this fix, however requires having multiple deleted snapshots pending when we unmount. We noticed this in production because our shutdown path stops the container on the system, which deletes a bunch of subvolumes, and then reboots the box. This gives us plenty of opportunities to hit this issue. Looking at the history we've seen this occasionally in production, but we had a big spike recently thanks to faster machines getting jobs with multiple subvolumes in the job. Chris Mason wrote a reproducer which does the following mount /dev/nvme4n1 /btrfs btrfs subvol create /btrfs/s1 simoop -E -f 4k -n 200000 -z /btrfs/s1 while(true) ; do btrfs subvol snap /btrfs/s1 /btrfs/s2 simoop -f 4k -n 200000 -r 10 -z /btrfs/s2 btrfs subvol snap /btrfs/s2 /btrfs/s3 btrfs balance start -dusage=80 /btrfs btrfs subvol del /btrfs/s2 /btrfs/s3 umount /btrfs btrfsck /dev/nvme4n1 || exit 1 mount /dev/nvme4n1 /btrfs done On the second loop this would fail consistently, with my patch it has been running for hours and hasn't failed. I also used dm-log-writes to capture the state of the failure so I could debug the problem. Using the existing failure case to test my patch validated that it fixes the problem. Fixes: 78c52d9eb6b7 ("btrfs: check for refs on snapshot delete resume") CC: stable@vger.kernel.org # 5.4+ Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-11btrfs: avoid allocating and running pointless delayed extent operationsFilipe Manana
We always allocate a delayed extent op structure when allocating a tree block (except for log trees), but most of the time we don't need it as we only need to set the BTRFS_BLOCK_FLAG_FULL_BACKREF if we're dealing with a relocation tree and we only need to set the key of a tree block in a btrfs_tree_block_info structure if we are not using skinny metadata (feature enabled by default since btrfs-progs 3.18 and available as of kernel 3.10). In these cases, where we don't need neither to update flags nor to set the key, we only use the delayed extent op structure to set the tree block's level. This is a waste of memory and besides that, the memory allocation can fail and can add additional latency. Instead of using a delayed extent op structure to store the level of the tree block, use the delayed ref head to store it. This doesn't change the size of neither structure and helps us avoid allocating delayed extent ops structures when using the skinny metadata feature and there's no relocation going on. This also gets rid of a BUG_ON(). For example, for a fs_mark run, with 5 iterations, 8 threads and 100K files per iteration, before this patch there were 118109 allocations of delayed extent op structures and after it there were none. Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-11btrfs: remove no longer used btrfs_migrate_to_delayed_refs_rsv()Filipe Manana
The function btrfs_migrate_to_delayed_refs_rsv() is no longer used. Its last use was removed in commit 2f6397e448e6 ("btrfs: don't refill whole delayed refs block reserve when starting transaction"). So remove the function. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-05-07btrfs: replace btrfs_delayed_*_ref with btrfs_*_refJosef Bacik
Now that these two structs are the same, move the btrfs_data_ref and btrfs_tree_ref up and use these in the btrfs_delayed_ref_node. Then remove the btrfs_delayed_*_ref structs. 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>
2024-05-07btrfs: rename btrfs_data_ref->ino to ->objectidJosef Bacik
This is how we refer to it in the rest of the extent reference related code, make it consistent. 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>
2024-05-07btrfs: move ->parent and ->ref_root into btrfs_delayed_ref_nodeJosef Bacik
These two members are shared by both the tree refs and data refs, so move them into btrfs_delayed_ref_node proper. This allows us to greatly simplify the comparison code, as the shared refs always only sort on parent, and the non shared refs always sort first on ref_root, and then only data refs sort on their specific fields. 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>
2024-05-07btrfs: rename ->len to ->num_bytes in btrfs_refJosef Bacik
We consistently use ->num_bytes everywhere through the delayed ref code, except in btrfs_ref. Rename btrfs_ref to match all the other code. 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>
2024-05-07btrfs: unify the btrfs_add_delayed_*_ref helpers into one helperJosef Bacik
Now that these helpers are identical, create a helper function that handles everything properly and strip the individual helpers down to use just the common helper. This cleans up a significant amount of duplicated code. 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>
2024-05-07btrfs: simplify delayed ref tracepointsJosef Bacik
Now that all of the delayed ref information is in the delayed ref node, drastically simplify the delayed ref tracepoints by simply passing in the btrfs_delayed_ref_node and populating the tracepoints with the values from the structure itself. 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>
2024-05-07btrfs: move ref specific initialization into init_delayed_ref_commonJosef Bacik
Now that the btrfs_delayed_ref_node contains a union of the data and metadata specific information we can move the initialization into init_delayed_ref_common and just use the btrfs_ref to initialize the correct fields of the reference. 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>
2024-05-07btrfs: initialize btrfs_delayed_ref_head with btrfs_refJosef Bacik
We are calling init_delayed_ref_head with all of the elements from btrfs_ref, clean this up to simply pass in the btrfs_ref and initialize the btrfs_delayed_ref_head with the values from the btrfs_ref directly. 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>
2024-05-07btrfs: pass btrfs_ref to init_delayed_ref_commonJosef Bacik
We're extracting all of these values from the btrfs_ref we passed in already, just pass the btrfs_ref through to init_delayed_ref_common and get the values directly from the struct. 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>
2024-05-07btrfs: move ref_root into btrfs_refJosef Bacik
We have this in both btrfs_tree_ref and btrfs_data_ref, which is just wasting space and making the code more complicated. Move this into btrfs_ref proper and update all the call sites to do the assignment in btrfs_ref. 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>
2024-05-07btrfs: do not use a function to initialize btrfs_refJosef Bacik
btrfs_ref currently has ->owning_root, and ->ref_root is shared between the tree ref and data ref, so in order to move that into btrfs_ref proper I would need to add another root parameter to the initialization function. This function has too many arguments, and adding another root will make it easy to make mistakes about which root goes where. Drop the generic ref init function and statically initialize the btrfs_ref in every usage. This makes the code easier to read because we can see what elements we're assigning, and will make the upcoming change moving the ref_root into the btrfs_ref more clear and less error prone than adding a new element to the initialization function. 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>
2024-05-07btrfs: embed data_ref and tree_ref in btrfs_delayed_ref_nodeJosef Bacik
We have been embedding btrfs_delayed_ref_node in the btrfs_delayed_data_ref and btrfs_delayed_tree_ref, and then we have two sets of cachep's and a variety of handling that is awkward because of this separation. Instead union these two members inside of btrfs_delayed_ref_node and make that the first class object. This allows us to go down to one cachep for our delayed ref nodes instead of two. 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>
2024-05-07btrfs: add a helper to get the delayed ref node from the data/tree refJosef Bacik
We have several different ways we refer to references throughout the code and it's not consistent and there's a bit of duplication. In order to clean this up I want to have one structure we use to define reference information, and one structure we use for the delayed reference information. Start this process by adding a helper to get from the btrfs_delayed_data_ref/btrfs_delayed_tree_ref to the btrfs_delayed_ref_node so that it'll make moving these structures around simpler. 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>
2024-03-05btrfs: remove SLAB_MEM_SPREAD flag useChengming Zhou
The SLAB_MEM_SPREAD flag used to be implemented in SLAB, which was removed as of v6.8-rc1, so it became a dead flag since the commit 16a1d968358a ("mm/slab: remove mm/slab.c and slab_def.h"). And the series[1] went on to mark it obsolete to avoid confusion for users. Here we can just remove all its users, which has no functional change. [1] https://lore.kernel.org/all/20240223-slab-cleanup-flags-v2-1-02f1753e8303@suse.cz/ Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-03-04btrfs: use KMEM_CACHE() to create delayed ref cachesKunwu Chan
Use the KMEM_CACHE() macro instead of kmem_cache_create() to simplify the creation of SLAB caches related to delayed refs when the default values are used. Signed-off-by: Kunwu Chan <chentao@kylinos.cn> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2024-03-04btrfs: uninline some static inline helpers from delayed-ref.hDavid Sterba
The helpers are doing an initialization or release work, none of which is performance critical that it would require a static inline, so move them to the .c file. Signed-off-by: David Sterba <dsterba@suse.com>
2023-11-09btrfs: fix qgroup record leaks when using simple quotasFilipe Manana
When using simple quotas we are not supposed to allocate qgroup records when adding delayed references. However we allocate them if either mode of quotas is enabled (the new simple one or the old one), but then we never free them because running the accounting, which frees the records, is only run when using the old quotas (at btrfs_qgroup_account_extents()), resulting in a memory leak of the records allocated when adding delayed references. Fix this by allocating the records only if the old quotas mode is enabled. Also fix btrfs_qgroup_trace_extent_nolock() to return 1 if the old quotas mode is not enabled - meaning the caller has to free the record. Fixes: 182940f4f4db ("btrfs: qgroup: add new quota mode for simple quotas") Reported-by: syzbot+d3ddc6dcc6386dea398b@syzkaller.appspotmail.com Link: https://lore.kernel.org/linux-btrfs/00000000000004769106097f9a34@google.com/ Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12btrfs: stop reserving excessive space for block group item insertionsFilipe Manana
Space for block group item insertions, necessary after allocating a new block group, is reserved in the delayed refs block reserve. Currently we do this by incrementing the transaction handle's delayed_ref_updates counter and then calling btrfs_update_delayed_refs_rsv(), which will increase the size of the delayed refs block reserve by an amount that corresponds to the same amount we use for delayed refs, given by btrfs_calc_delayed_ref_bytes(). That is an excessive amount because it corresponds to the amount of space needed to insert one item in a btree (btrfs_calc_insert_metadata_size()) times 2 when the free space tree feature is enabled. All we need is an amount as given by btrfs_calc_insert_metadata_size(), since we only need to insert a block group item in the extent tree (or block group tree if this feature is enabled). By using btrfs_calc_insert_metadata_size() we will need to reserve 2 times less space when using the free space tree, putting less pressure on space reservation. So use helpers to reserve and release space for block group item insertions that use btrfs_calc_insert_metadata_size() for calculation of the space. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12btrfs: stop reserving excessive space for block group item updatesFilipe Manana
Space for block group item updates, necessary after allocating or deallocating an extent from a block group, is reserved in the delayed refs block reserve. Currently we do this by incrementing the transaction handle's delayed_ref_updates counter and then calling btrfs_update_delayed_refs_rsv(), which will increase the size of the delayed refs block reserve by an amount that corresponds to the same amount we use for delayed refs, given by btrfs_calc_delayed_ref_bytes(). That is an excessive amount because it corresponds to the amount of space needed to insert one item in a btree (btrfs_calc_insert_metadata_size()) times 2 when the free space tree feature is enabled. All we need is an amount as given by btrfs_calc_metadata_size(), since we only need to update an existing block group item in the extent tree (or block group tree if this feature is enabled). By using btrfs_calc_metadata_size() we will need to reserve 4 times less space when using the free space tree and 2 times less space when not using it, putting less pressure on space reservation. So use helpers to reserve and release space for block group item updates that use btrfs_calc_metadata_size() for calculation of the space. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12btrfs: record simple quota deltas in delayed refsBoris Burkov
At the moment that we run delayed refs, we make the final ref-count based decision on creating/removing extent (and metadata) items. Therefore, it is exactly the spot to hook up simple quotas. There are a few important subtleties to the fields we must collect to accurately track simple quotas, particularly when removing an extent. When removing a data extent, the ref could be in any tree (due to reflink, for example) and so we need to recover the owning root id from the owner ref item. When removing a metadata extent, we know the owning root from the owner field in the header when we create the delayed ref, so we can recover it from there. We must also be careful to handle reservations properly to not leaked reserved space. The happy path is freeing the reservation when the simple quota delta runs on a data extent. If that doesn't happen, due to refs canceling out or some error, the ref head already has the must_insert_reserved machinery to handle this, so we piggy back on that and use it to clean up the reserved data. Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>