- 21 Aug, 2023 40 commits
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Naohiro Aota authored
We currently advance the meta_write_pointer in btrfs_check_meta_write_pointer(). That makes it necessary to revert it when locking the buffer failed. Instead, we can advance it just before sending the buffer. Also, this is necessary for the following commit. In the commit, it needs to release the zoned_meta_io_lock to allow IOs to come in and wait for them to fill the currently active block group. If we advance the meta_write_pointer before locking the extent buffer, the following extent buffer can pass the meta_write_pointer check, resulting in an unaligned write failure. Advancing the pointer is still thread-safe as the extent buffer is locked. Reviewed-by:
Christoph Hellwig <hch@lst.de> 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:
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Naohiro Aota authored
Now that we have writeback_control passed to btrfs_check_meta_write_pointer(), we can move the wbc condition in submit_eb_page() to btrfs_check_meta_write_pointer() and return int. Reviewed-by:
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Naohiro Aota authored
For metadata write out on the zoned mode, we call btrfs_check_meta_write_pointer() to check if an extent buffer to be written is aligned to the write pointer. We look up a block group containing the extent buffer for every extent buffer, which takes unnecessary effort as the writing extent buffers are mostly contiguous. Introduce "zoned_bg" to cache the block group working on. Also, while at it, rename "cache" to "block_group". Reviewed-by:
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Naohiro Aota authored
Introduce btrfs_eb_write_context to consolidate writeback_control and the exntent buffer context. This will help adding a block group context as well. While at it, move the eb context setting before btrfs_check_meta_write_pointer(). We can set it here because we anyway need to skip pages in the same eb if that eb is rejected by btrfs_check_meta_write_pointer(). Suggested-by:
Christoph Hellwig <hch@infradead.org> Reviewed-by:
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Filipe Manana authored
When flushing qgroups, we try to join a running transaction, with btrfs_join_transaction(), and then commit the transaction. However using btrfs_join_transaction() will result in creating a new transaction in case there isn't any running or if there's an existing one already committing. This is pointless as we only need to attach to an existing one that is not committing and in case there's an existing one committing, wait for its commit to complete. Creating and committing an empty transaction is wasteful, pointless IO and unnecessary rotation of the backup roots. So use btrfs_attach_transaction_barrier() instead, to avoid creating and committing empty transactions. Signed-off-by:
Filipe Manana <fdmanana@suse.com> Signed-off-by:
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Filipe Manana authored
When starting a qgroup rescan, we try to join a running transaction, with btrfs_join_transaction(), and then commit the transaction. However using btrfs_join_transaction() will result in creating a new transaction in case there isn't any running or if there's an existing one already committing. This is pointless as we only need to attach to an existing one that is not committing and in case there's an existing one committing, wait for its commit to complete. Creating and committing an empty transaction is wasteful, pointless IO and unnecessary rotation of the backup roots. So use btrfs_attach_transaction_barrier() instead, to avoid creating and committing empty transactions. Signed-off-by:
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Filipe Manana authored
When flushing space and we are in the COMMIT_TRANS state, we join a transaction with btrfs_join_transaction() and then commit the returned transaction. However btrfs_join_transaction() starts a new transaction if there is none currently open, which is pointless since comitting a new, empty transaction, doesn't achieve anything, it only wastes time, IO and creates an unnecessary rotation of the backup roots. So use btrfs_attach_transaction_barrier() to avoid starting a new transaction. This also waits for any ongoing transaction that is committing (state >= TRANS_STATE_COMMIT_DOING) to fully complete, and therefore wait for all the extents that were pinned during the transaction's lifetime to be unpinned. Signed-off-by:
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Filipe Manana authored
When flushing space we join a transaction to flush delayed items and delayed references, in order to try to release space. However using btrfs_join_transaction() not only joins an existing transaction as well as it starts a new transaction if there is none open. If there is no transaction open, we don't have neither delayed items nor delayed references, so creating a new transaction is a waste of time, IO and creates an unnecessary rotation of the backup roots without gaining any benefits (including releasing space). So use btrfs_join_transaction_nostart() when attempting to flush delayed items and references. Signed-off-by:
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Filipe Manana authored
There is no point in having find_free_dev_extent() because it's just a simple wrapper around find_free_dev_extent_start() which always passes a value of 0 for the search_start argument. Since there are no other callers of find_free_dev_extent_start(), remove find_free_dev_extent() and rename find_free_dev_extent_start() to find_free_dev_extent(), removing its search_start argument because it's always 0. Signed-off-by:
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Filipe Manana authored
The function find_free_dev_extent() is only used within volumes.c, so make it static and remove its prototype from volumes.h. Signed-off-by:
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Filipe Manana authored
btrfs_cleanup_fs_roots() is not used outside disk-io.c, so make it static, remove its prototype from disk-io.h and move its definition above the where it's used in disk-io.c Signed-off-by:
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Filipe Manana authored
At priority_reclaim_metadata_space(), if we were not able to satisfy the the ticket after going through the various flushing states and we notice the fs went into an error state, likely due to a transaction abort during the flushing, set the ticket's error to the error that caused the transaction abort instead of an unconditional -EROFS. Signed-off-by:
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Filipe Manana authored
During mount we will call btrfs_orphan_cleanup() to remove any inodes that were previously deleted (have a link count of 0) but for which we were not able before to remove their items from the subvolume tree. The removal of the items will happen by triggering eviction, when we do the final iput() on them at btrfs_orphan_cleanup(), which will end in the loop at btrfs_evict_inode() that truncates inode items. In a dire situation we may have a transaction abort due to -ENOSPC when attempting to truncate the inode items, and in that case the orphan item (key type BTRFS_ORPHAN_ITEM_KEY) will remain in the subvolume tree and when we hit the next iteration of the while loop at btrfs_orphan_cleanup() we will find the same orphan item as before, and then we will return -EINVAL from btrfs_orphan_cleanup() through the following if statement: if (found_key.offset == last_objectid) { btrfs_err(fs_info, "Error removing orphan entry, stopping orphan cleanup"); ret = -EINVAL; goto out; } This makes the mount operation fail with -EINVAL, when it should have been -ENOSPC. This is confusing because -EINVAL might lead a user into thinking it provided invalid mount options for example. An example where this happens: $ mount test.img /mnt mount: /mnt: wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error. $ dmesg [ 2542.356934] BTRFS: device fsid 977fff75-1181-4d2b-a739-384fa710d16e devid 1 transid 47409973 /dev/loop0 scanned by mount (4459) [ 2542.357451] BTRFS info (device loop0): using crc32c (crc32c-intel) checksum algorithm [ 2542.357461] BTRFS info (device loop0): disk space caching is enabled [ 2542.742287] BTRFS info (device loop0): auto enabling async discard [ 2542.764554] BTRFS info (device loop0): checking UUID tree [ 2551.743065] ------------[ cut here ]------------ [ 2551.743068] BTRFS: Transaction aborted (error -28) [ 2551.743149] WARNING: CPU: 7 PID: 215 at fs/btrfs/block-group.c:3494 btrfs_write_dirty_block_groups+0x397/0x3d0 [btrfs] [ 2551.743311] Modules linked in: btrfs blake2b_generic (...) [ 2551.743353] CPU: 7 PID: 215 Comm: kworker/u24:5 Not tainted 6.4.0-rc6-btrfs-next-134+ #1 [ 2551.743356] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014 [ 2551.743357] Workqueue: events_unbound btrfs_async_reclaim_metadata_space [btrfs] [ 2551.743405] RIP: 0010:btrfs_write_dirty_block_groups+0x397/0x3d0 [btrfs] [ 2551.743449] Code: 8b 43 0c (...) [ 2551.743451] RSP: 0018:ffff982c005a7c40 EFLAGS: 00010286 [ 2551.743452] RAX: 0000000000000000 RBX: ffff88fc6e44b400 RCX: 0000000000000000 [ 2551.743453] RDX: 0000000000000002 RSI: ffffffff8dff0878 RDI: 00000000ffffffff [ 2551.743454] RBP: ffff88fc51817208 R08: 0000000000000000 R09: ffff982c005a7ae0 [ 2551.743455] R10: 0000000000000001 R11: 0000000000000001 R12: ffff88fc43d2e570 [ 2551.743456] R13: ffff88fc43d2e400 R14: ffff88fc8fb08ee0 R15: ffff88fc6e44b530 [ 2551.743457] FS: 0000000000000000(0000) GS:ffff89035fbc0000(0000) knlGS:0000000000000000 [ 2551.743458] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 2551.743459] CR2: 00007fa8cdf2f6f4 CR3: 0000000124850003 CR4: 0000000000370ee0 [ 2551.743462] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 2551.743463] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 2551.743464] Call Trace: [ 2551.743472] <TASK> [ 2551.743474] ? __warn+0x80/0x130 [ 2551.743478] ? btrfs_write_dirty_block_groups+0x397/0x3d0 [btrfs] [ 2551.743520] ? report_bug+0x1f4/0x200 [ 2551.743523] ? handle_bug+0x42/0x70 [ 2551.743526] ? exc_invalid_op+0x14/0x70 [ 2551.743528] ? asm_exc_invalid_op+0x16/0x20 [ 2551.743532] ? btrfs_write_dirty_block_groups+0x397/0x3d0 [btrfs] [ 2551.743574] ? _raw_spin_unlock+0x15/0x30 [ 2551.743576] ? btrfs_run_delayed_refs+0x1bd/0x200 [btrfs] [ 2551.743609] commit_cowonly_roots+0x1e9/0x260 [btrfs] [ 2551.743652] btrfs_commit_transaction+0x42e/0xfa0 [btrfs] [ 2551.743693] ? __pfx_autoremove_wake_function+0x10/0x10 [ 2551.743697] flush_space+0xf1/0x5d0 [btrfs] [ 2551.743743] ? _raw_spin_unlock+0x15/0x30 [ 2551.743745] ? finish_task_switch+0x91/0x2a0 [ 2551.743748] ? _raw_spin_unlock+0x15/0x30 [ 2551.743750] ? btrfs_get_alloc_profile+0xc9/0x1f0 [btrfs] [ 2551.743793] btrfs_async_reclaim_metadata_space+0xe1/0x230 [btrfs] [ 2551.743837] process_one_work+0x1d9/0x3e0 [ 2551.743844] worker_thread+0x4a/0x3b0 [ 2551.743847] ? __pfx_worker_thread+0x10/0x10 [ 2551.743849] kthread+0xee/0x120 [ 2551.743852] ? __pfx_kthread+0x10/0x10 [ 2551.743854] ret_from_fork+0x29/0x50 [ 2551.743860] </TASK> [ 2551.743861] ---[ end trace 0000000000000000 ]--- [ 2551.743863] BTRFS info (device loop0: state A): dumping space info: [ 2551.743866] BTRFS info (device loop0: state A): space_info DATA has 126976 free, is full [ 2551.743868] BTRFS info (device loop0: state A): space_info total=13458472960, used=13458137088, pinned=143360, reserved=0, may_use=0, readonly=65536 zone_unusable=0 [ 2551.743870] BTRFS info (device loop0: state A): space_info METADATA has -51625984 free, is full [ 2551.743872] BTRFS info (device loop0: state A): space_info total=771751936, used=770146304, pinned=1605632, reserved=0, may_use=51625984, readonly=0 zone_unusable=0 [ 2551.743874] BTRFS info (device loop0: state A): space_info SYSTEM has 14663680 free, is not full [ 2551.743875] BTRFS info (device loop0: state A): space_info total=14680064, used=16384, pinned=0, reserved=0, may_use=0, readonly=0 zone_unusable=0 [ 2551.743877] BTRFS info (device loop0: state A): global_block_rsv: size 53231616 reserved 51544064 [ 2551.743878] BTRFS info (device loop0: state A): trans_block_rsv: size 0 reserved 0 [ 2551.743879] BTRFS info (device loop0: state A): chunk_block_rsv: size 0 reserved 0 [ 2551.743880] BTRFS info (device loop0: state A): delayed_block_rsv: size 0 reserved 0 [ 2551.743881] BTRFS info (device loop0: state A): delayed_refs_rsv: size 786432 reserved 0 [ 2551.743886] BTRFS: error (device loop0: state A) in btrfs_write_dirty_block_groups:3494: errno=-28 No space left [ 2551.743911] BTRFS info (device loop0: state EA): forced readonly [ 2551.743951] BTRFS warning (device loop0: state EA): could not allocate space for delete; will truncate on mount [ 2551.743962] BTRFS error (device loop0: state EA): Error removing orphan entry, stopping orphan cleanup [ 2551.743973] BTRFS warning (device loop0: state EA): Skipping commit of aborted transaction. [ 2551.743989] BTRFS error (device loop0: state EA): could not do orphan cleanup -22 So make the btrfs_orphan_cleanup() return the value of BTRFS_FS_ERROR(), if it's set, and -EINVAL otherwise. For that same example, after this change, the mount operation fails with -ENOSPC: $ mount test.img /mnt mount: /mnt: mount(2) system call failed: No space left on device. Signed-off-by: -
Filipe Manana authored
Currently when we turn the fs into an error state, typically after a transaction abort, we don't store the error anywhere, we just set a bit (BTRFS_FS_STATE_ERROR) at struct btrfs_fs_info::fs_state to signal the error state. There are cases where it would be useful to have access to the specific error in order to provide a more meaningful error to users/applications. This change adds a member to struct btrfs_fs_info to store the error and removes the BTRFS_FS_STATE_ERROR bit. When there's no error, the new member (fs_error) has a value of 0, otherwise its value is a negative errno value. Followup changes will make use of this new member. Signed-off-by:
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Filipe Manana authored
When doing a priority metadata space reclaim, while we are going through the flush states and running their respective operations, it's possible that a transaction abort happened, for example when running delayed refs we hit -ENOSPC or in the critical section of transaction commit we failed with -ENOSPC or some other error. In these cases a transaction was aborted and the fs turned into error state. If that happened, then it makes no sense to steal from the global block reserve and return success to the caller if the stealing was successful - the caller will later get an error when attempting to modify the fs. Instead make the ticket fail if we have the fs in error state and don't attempt to steal from the global rsv, as it's not only it's pointless, it also simplifies debugging some -ENOSPC problems. Signed-off-by:
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Filipe Manana authored
When dumping a space info also sum the available space for all block groups and then print it. This often useful for debugging -ENOSPC related problems. Signed-off-by:
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Filipe Manana authored
When dumping a space info, we iterate over all its block groups and then print their size and the amounts of bytes used, reserved, pinned, etc. When debugging -ENOSPC problems it's also useful to know how much space is available (free), so calculate that and print it as well. Signed-off-by:
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Filipe Manana authored
When dumping a space info's block groups, also print the number of bytes used for super blocks and delalloc. This is often useful for debugging -ENOSPC problems. Signed-off-by:
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Filipe Manana authored
When dumping free space, with btrfs_dump_free_space(), we pass a bytes argument in order to count how many free space entries in the block group have a size greater than or equal to that number of bytes. We then print how many suitable entries we found, but we don't print the target number of bytes, we just say "bytes". Change the message to actually print the number of bytes, which makes debugging -ENOSPC issues a bit easier. Also sligthly change the odd grammar and terminology: the sentence is ending with 'is', which doesn't make sense, and the term 'blocks' is confusing as we are referring to free space entries within the block group's free space cache. Signed-off-by:
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Filipe Manana authored
Update the comment for btrfs_join_transaction_nostart() to be more clear about how it works and how it's different from btrfs_attach_transaction(). Signed-off-by:
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Filipe Manana authored
When joining a transaction with TRANS_JOIN_NOSTART, if we don't find a running transaction we end up creating one. This goes against the purpose of TRANS_JOIN_NOSTART which is to join a running transaction if its state is at or below the state TRANS_STATE_COMMIT_START, otherwise return an -ENOENT error and don't start a new transaction. So fix this to not create a new transaction if there's no running transaction at or below that state. CC: stable@vger.kernel.org # 4.14+ Fixes: a6d155d2 ("Btrfs: fix deadlock between fiemap and transaction commits") Signed-off-by:
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Qu Wenruo authored
[BACKGROUND] Currently memove_extent_buffer() does a loop where it strop at any page boundary inside [dst_offset, dst_offset + len) or [src_offset, src_offset + len). This is mostly allowing us to do copy_pages(), but if we're going to use folios we will need to handle multi-page (the old behavior) or single folio (the new optimization). The current code would be a burden for future changes. [ENHANCEMENT] Instead of sticking with copy_pages(), here we utilize the new __write_extent_buffer() helper to handle the writes. Unlike the refactoring in memcpy_extent_buffer(), we can not just rely on the write_extent_buffer() and only handle page boundaries inside src range. The function write_extent_buffer() itself is still doing forward writing, thus it cannot handle the following case: (already in the extent buffer memory operation tests, cross page overlapping run 2) Src Page boundary |///////| |///|////| Dst In the above case, if we just follow page boundary in the src range, we have no need to do any split, just one __write_extent_buffer() with use_memmove = true. But __write_extent_buffer() would split the dst range into two, so it first copies the beginning part of the src range into the first half of the dst range. After this operation, the beginning of the dst range is already updated, causing corruption. So we have to follow the old behavior of handling both page boundaries. And since we're the last caller of copy_pages(), we can remove it completely. Signed-off-by:
Qu Wenruo <wqu@suse.com> Signed-off-by:
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Qu Wenruo authored
[BACKGROUND] Currently memcpy_extent_buffer() does a loop where it would stop at any page boundary inside [dst_offset, dst_offset + len) or [src_offset, src_offset + len). This is mostly allowing us to do copy_pages(), but if we're going to use folios we will need to handle multi-page (the old behavior) or single folio (the new optimization). The current code would be a burden for future changes. [ENHANCEMENT] There is a hidden pitfall of the naming memcpy_extent_buffer(), unlike regular memcpy(), this function can handle overlapping ranges. So here we extract write_extent_buffer() into a new internal helper, __write_extent_buffer(), and add a new parameter @use_memmove, to indicate whether we should use memmove() or regular memcpy(). Now we can go __write_extent_buffer() to handle writing into the dst range, with proper overlapping detection. This has a tiny change to the chance of calling memmove(). As the split only happens at the source range page boundaries, the memcpy/memmove() range would be slightly larger than the old code, thus slightly increase the chance we call memmove() other than memcopy(). Signed-off-by:
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Qu Wenruo authored
btrfs_clone_extent_buffer() calls copy_page() at each iteration but we can copy all pages at the end in one go if there were no errors. This would make later conversion to folios easier. Reviewed-by:
Sweet Tea Dorminy <sweettea-kernel@dorminy.me> Signed-off-by:
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Qu Wenruo authored
[BACKGROUND] copy_extent_buffer_full() currently does different handling for regular and subpage cases, for regular cases it does a page by page copying. For subpage cases, it just copies the content. This is fine for the page based extent buffer code, but for the incoming folio conversion, it can be a burden to add a new branch just to handle all the different combinations (subpage vs regular, one single folio vs multi pages). [ENHANCE] Instead of handling the different combinations, just go one single handling for all cases, utilizing write_extent_buffer() to do the copying. Reviewed-by:
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Qu Wenruo authored
Helpers write_extent_buffer_chunk_tree_uuid() and write_extent_buffer_fsid(), they can be implemented by write_extent_buffer(). These two helpers are not that frequently used, they only get called during initialization of a new tree block. There is not much need for those slightly optimized versions. And since they can be easily converted to one write_extent_buffer() call, define them as inline helpers. This would make later page/folio switch much easier, as all change only need to happen in write_extent_buffer(). Reviewed-by:
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Qu Wenruo authored
[BACKGROUND] Currently we handle extent bitmaps manually in extent_buffer_bitmap_set() and extent_buffer_bitmap_clear(). Although with various helpers like eb_bitmap_offset() it's still a little messy to read. The code seems to be a copy of bitmap_set(), but with all the cross-page handling embedded into the code. [ENHANCEMENT] This patch would enhance the readability by introducing two helpers: - memset_extent_buffer() To handle the byte aligned range, thus all the cross-page handling is done there. - extent_buffer_get_byte() This for the first and the last byte operations, which only need to grab one byte, thus no need for any cross-page handling. So we can split both extent_buffer_bitmap_set() and extent_buffer_bitmap_clear() into 3 parts: - Handle the first byte If the range fits inside the first byte, we can exit early. - Handle the byte aligned part This is the part which can have cross-page operations, and it would be handled by memset_extent_buffer(). - Handle the last byte This refactoring does not only make the code a little easier to read, but also makes later folio/page switch much easier, as the switch only needs to be done inside memset_extent_buffer() and extent_buffer_get_byte(). Reviewed-by:
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Qu Wenruo authored
The new self tests would populate a memory range with random bytes, then copy it to the extent buffer, so that we can verify if the extent buffer memory operation and memmove()/memcopy() are resulting the same contents. Signed-off-by:
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Qu Wenruo authored
Enhance extent bitmap tests for the following aspects: - Remove unnecessary @len from __test_eb_bitmaps() We can fetch the length from extent buffer - Explicitly distinguish bit and byte length Now every start/len inside bitmap tests would have either "byte_" or "bit_" prefix to make it more explicit. - Better error reporting If we have mismatch bits, the error report would dump the following contents: * start bytenr * bit number * the full byte from bitmap * the full byte from the extent This is to save developers time so obvious problem can be found immediately - Extract bitmap set/clear and check operation into two helpers This is to save some code lines, as we will have more tests to do. - Add new tests The following tests are added, mostly for the incoming extent bitmap accessor refactoring: * Set bits inside the same byte * Clear bits inside the same byte * Cross byte boundary set * Cross byte boundary clear * Cross multi-byte boundary set * Cross multi-byte boundary clear Those new tests have already saved my backend for the incoming extent buffer bitmap refactoring. Reviewed-by:
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Josef Bacik authored
Some of these loop types aren't described, and they should be with the definitions to make it easier to tell what each of them do. Reviewed-by:
Boris Burkov <boris@bur.io> Signed-off-by:
Josef Bacik <josef@toxicpanda.com> Reviewed-by:
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Anand Jain authored
There is a race between systemd and mount, as both of them try to register the device in the kernel. When systemd loses the race, it prints the following message: BTRFS error: device /dev/sdb7 belongs to fsid 1b3bacbf-14db-49c9-a3ef-547998aacc4e, and the fs is already mounted. The 'btrfs dev scan' registers one device at a time, so there is no way for the mount thread to wait in the kernel for all the devices to have registered as it won't know if all the devices are discovered. For now, improve the error log by printing the command name and process ID along with the error message. Signed-off-by:
Anand Jain <anand.jain@oracle.com> Reviewed-by:
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Christoph Hellwig authored
Fold folio_account_redirty into folio_redirty_for_writepage now that all other users except for the also unused account_page_redirty wrapper are gone. Reviewed-by:
Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by:
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Christoph Hellwig authored
For zoned file systems we need to use run_delalloc_zoned to submit writeback, as we need to write out partial allocations when running into zone active limits. submit_uncompressed_range currently always calls cow_file_range to allocate blocks and thus misses the active zone limits handling. Fix this by passing the pages_dirty argument to run_delalloc_zoned and always using it from submit_uncompressed_range as it does the right thing for zoned and non-zoned file systems. To account for the fact that run_delalloc_zoned is now also used for non-zoned file systems rename it to run_delalloc_cow, and add comment describing it. Fixes: 42c01100 ("btrfs: zoned: introduce dedicated data write path for zoned filesystems") Reviewed-by:
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Christoph Hellwig authored
extent_write_locked_range currently expects that either all or no pages are dirty when it is called. Bur run_delalloc_zoned is called directly in the writepages path, and has the dirty bit cleared only for locked_page and which the extent_write_cache_pages currently operates. It currently works around this by redirtying locked_page, but that is a bit inefficient and cumbersome. Pass a locked_page argument to run_delalloc_zoned so that clearing the dirty bit can be skipped on just that page. Reviewed-by:
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Christoph Hellwig authored
Handling of the done_offset to cow_file_range is a bit confusing, as it is not updated at all when the function succeeds, and the -EAGAIN status is used bother for the case where we need to wait for a zone finish and the one where the allocation was partially successful. Change the calling convention so that done_offset is always updated, and 0 is returned if some allocation was successful (partial allocation can still only happen for zoned devices), and waiting for a zone finish is done internally in cow_file_range instead of the caller. Also write a comment explaining the logic. Reviewed-by:
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Christoph Hellwig authored
compress_file_range needs to clear the dirty bit before handing off work to the compression worker threads to prevent processes coming in through mmap and changing the file contents while the compression is accessing the data (See commit 4adaa611 ("Btrfs: fix race between mmap writes and compression"). But when compress_file_range decides to not compress the data, it falls back to submit_uncompressed_range which uses extent_write_locked_range to write the uncompressed data. extent_write_locked_range currently expects all pages to be marked dirty so that it can clear the dirty bit itself, and thus compress_file_range has to redirty the page range. Redirtying the page range is rather inefficient and also pointless, so instead pass a pages_dirty parameter to extent_write_locked_range and skip the redirty game entirely. Note that compress_file_range was even redirtying the locked_page twice given that extent_range_clear_dirty_for_io already redirties all pages in the range, which must include locked_page if there is one. Reviewed-by:
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Christoph Hellwig authored
compress_file_range has two code blocks to free the page array for the compressed data. Share the code using a goto label. Reviewed-by:
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Christoph Hellwig authored
compress_file_range can fail to compress either because of resource or alignment constraints or because the data is incompressible. In the latter case the inode is marked so that compression isn't tried again. Currently that check is based on the condition that the pages array has been allocated which is rather cryptic. Use a separate label to clearly distinguish this case. Reviewed-by:
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Christoph Hellwig authored
Currently the logic whether to compress or not in compress_file_range is a bit convoluted because it tries to share code for creating inline extents for the compressible [1] path and the bail to uncompressed path. But the latter isn't needed at all, because cow_file_range as called by submit_uncompressed_range will already create inline extents as needed, so there is no need to have special handling for it if we can live with the fact that it will be called a bit later in the ->ordered_func of the workqueue instead of right now. [1] there is undocumented logic that creates an uncompressed inline extent outside of the shall not compress logic if total_in is too small. This logic isn't explained in comments or any commit log I could find, so I've preserved it. Documentation explaining it would be appreciated if anyone understands this code. Reviewed-by:
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Christoph Hellwig authored
Reorder compress_file_range so that the main compression flow happens straight line and not in branches. To do this ensure that pages is always zeroed before a page allocation happens, which allows the cleanup_and_bail_uncompressed label to clean up the page allocations as needed. Reviewed-by:
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