kernel/git/stable/linux.git/fs/btrfs/space-info.h, branch master

btrfs: zoned: fix deadlock waiting for ticket during data relocation

2026-06-09T16:22:44+00:00

When performing data relocation on a zoned filesystem, BTRFS can deadlock in handle_reserve_tickets(). The relocation process is waiting on a space reservation ticket that can never be fulfilled, because the relocation itself is the operation responsible for freeing up that space. Fix this by introducing a new flush state, BTRFS_RESERVE_FLUSH_ZONED_RELOCATION, specifically for data chunk allocation during zoned relocation. Like BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE, this state uses priority_reclaim_data_space() instead of the normal flushing path, which avoids re-entering the relocation code and breaking the deadlock cycle. In btrfs_alloc_data_chunk_ondemand(), select this new flush state when the inode belongs to a data relocation root on a zoned filesystem. Fixes: e2a7fd22378f ("btrfs: zoned: add zone reclaim flush state for DATA space_info") Reviewed-by: Boris Burkov Reviewed-by: Naohiro Aota Signed-off-by: Johannes Thumshirn Signed-off-by: David Sterba

btrfs: constify arguments of some functions

2026-04-07T16:55:58+00:00

There are several functions that take pointer arguments but don't need to modify the objects they point to, so add the const qualifiers. Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: zoned: add zone reclaim flush state for DATA space_info

2026-04-07T16:55:55+00:00

On zoned block devices, DATA block groups can accumulate large amounts of zone_unusable space (space between the write pointer and zone end). When zone_unusable reaches high levels (e.g., 98% of total space), new allocations fail with ENOSPC even though space could be reclaimed by relocating data and resetting zones. The existing flush states don't handle this scenario effectively - they either try to free cached space (which doesn't exist for zone_unusable) or reset empty zones (which doesn't help when zones contain valid data mixed with zone_unusable space). Add a new RECLAIM_ZONES flush state that triggers the block group reclaim machinery. This state: - Calls btrfs_reclaim_sweep() to identify reclaimable block groups - Calls btrfs_reclaim_bgs() to queue reclaim work - Waits for reclaim_bgs_work to complete via flush_work() - Commits the transaction to finalize changes The reclaim work (btrfs_reclaim_bgs_work) safely relocates valid data from fragmented block groups to other locations before resetting zones, converting zone_unusable space back into usable space. Insert RECLAIM_ZONES before RESET_ZONES in data_flush_states so that we attempt to reclaim partially-used block groups before falling back to resetting completely empty ones. Reviewed-by: Filipe Manana Signed-off-by: Johannes Thumshirn Signed-off-by: David Sterba

btrfs: update comment for BTRFS_RESERVE_NO_FLUSH

2026-04-07T16:55:53+00:00

The comment is incomplete as BTRFS_RESERVE_NO_FLUSH is used for more reasons than currently holding a transaction handle open. Update the comment with all the other reasons and give some details. Signed-off-by: Filipe Manana Signed-off-by: David Sterba

btrfs: move space_info_flag_to_str() to space-info.h

2026-02-03T06:49:12+00:00

Move space_info_flag_to_str() to space-info.h and as it now isn't static to space-info.c any more prefix it with 'btrfs_'. This way it can be re-used in other places. Reviewed-by: Filipe Manana Reviewed-by: Naohiro Aota Signed-off-by: Johannes Thumshirn Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: move struct reserve_ticket definition to space-info.c

2025-11-24T21:42:23+00:00

It's not used anywhere outside space-info.c so move it from space-info.h into space-info.c. Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: avoid space_info locking when checking if tickets are served

2025-11-24T21:18:21+00:00

When checking if a ticket was served, we take the space_info's spinlock. If the ticket was served (its ->bytes is 0) or had an error (its ->error it not 0) then we just unlock the space_info and return. This however causes contention on the space_info's spinlock, which is heavily used (space reservation, space flushing, allocating and deallocating an extent from a block group (btrfs_update_block_group()), etc). Instead of using the space_info's spinlock to check if a ticket was served, use a per ticket spinlock which isn't used by anyone other than the task that created the ticket (stack allocated) and the task that serves the ticket (a reclaim task or any task deallocating space that ends up at btrfs_try_granting_tickets()). After applying this patch and all previous patches from the same patchset (many attempt to reduce space_info critical sections), lockstat showed some improvements for a fs_mark test regarding the space_info's spinlock 'lock'. The lockstat results: Before patchset: con-bounces: 13733858 contentions: 15902322 waittime-total: 264902529.72 acq-bounces: 28161791 acquisitions: 38679282 After patchset: con-bounces: 12032220 contentions: 13598034 waittime-total: 221806127.28 acq-bounces: 24717947 acquisitions: 34103281 Reviewed-by: Johannes Thumshirn Signed-off-by: Filipe Manana Signed-off-by: David Sterba

btrfs: inline btrfs_space_info_used()

2025-11-24T21:08:14+00:00

The function is simple enough to be inlined and in fact doing it even reduces the object code. In x86_64 with gcc 14.2.0-19 from Debian the results were the following: Before this change $ size fs/btrfs/btrfs.ko text data bss dec hex filename 1919410 161703 15592 2096705 1ffe41 fs/btrfs/btrfs.ko After this change $ size fs/btrfs/btrfs.ko text data bss dec hex filename 1918991 161675 15592 2096258 1ffc82 fs/btrfs/btrfs.ko Also remove the ASSERT() that checks the space_info argument is not NULL, as it's odd to be there since it can never be NULL and in case that ever happens during development, a stack trace from a NULL pointer dereference will be obvious. It was originally added when btrfs_space_info_used() was introduced in commit 4136135b080f ("Btrfs: use helper to get used bytes of space_info"). Also add a lockdep assertion to check the space_info's lock is being held by the calling task. Reviewed-by: Johannes Thumshirn Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: make btrfs_can_overcommit() return bool instead of int

2025-11-24T21:06:26+00:00

It's a boolean function, so switch its return type to bool. Reviewed-by: Johannes Thumshirn Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: remove fs_info argument from btrfs_reserve_metadata_bytes()

2025-11-24T20:59:11+00:00

We don't need it since we can grab fs_info from the given space_info. So remove the fs_info argument. Reviewed-by: Qu Wenruo Reviewed-by: Johannes Thumshirn Reviewed-by: Anand Jain Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba