- 26 Oct, 2021 40 commits
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Kai Song authored
Fix memdup.cocci warning: fs/btrfs/zoned.c:1198:23-30: WARNING opportunity for kmemdup Reviewed-by:
Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by:
Kai Song <songkai01@inspur.com> Reviewed-by:
David Sterba <dsterba@suse.com> Signed-off-by:
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Qu Wenruo authored
For compressed write, we use a mechanism called async COW, which unlike regular run_delalloc_cow() or cow_file_range() will also unlock the first page. This mechanism allows us to continue handling next ranges, without waiting for the time consuming compression. But this has a problem for subpage case, as we could have the following delalloc range for a page: 0 32K 64K | |///////| |///////| \- A \- B In the above case, if we pass both ranges to cow_file_range_async(), both range A and range B will try to unlock the full page [0, 64K). And which one finishes later than the other one will try to do other page operations like end_page_writeback() on a unlocked page, triggering VM layer BUG_ON(). To make subpage compression work at least partially, here we add another restriction for it, only allow compression if the delalloc range is fully page aligned. By that, async extent is always ensured to unlock the first page exclusively, just like it used to be for regular sectorsize. In theory, we only need to make sure the delalloc range fully covers its first page, but the tail page will be locked anyway, blocking later writeback until the compression finishes. Thus here we choose to make sure the range is fully page aligned before doing the compression. In the future, we could optimize the situation by properly increasing subpage::writers number for the locked page, but that also means we need to change how we run delalloc range of page. (Instead of running each delalloc range we hit, we need to find and lock all delalloc ranges covering the page, then run each of them). Reviewed-by:
Nikolay Borisov <nborisov@suse.com> Signed-off-by:
Qu Wenruo <wqu@suse.com> Signed-off-by:
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Qu Wenruo authored
[BUG] With experimental subpage compression enabled, a simple fsstress can lead to self deadlock on page 720896: mkfs.btrfs -f -s 4k $dev > /dev/null mount $dev -o compress $mnt $fsstress -p 1 -n 100 -w -d $mnt -v -s 1625511156 [CAUSE] If we have a file layout looks like below: 0 32K 64K 96K 128K |//| |///////////////| 4K Then we run delalloc range for the inode, it will: - Call find_lock_delalloc_range() with @delalloc_start = 0 Then we got a delalloc range [0, 4K). This range will be COWed. - Call find_lock_delalloc_range() again with @delalloc_start = 4K Since find_lock_delalloc_range() never cares whether the range is still inside page range [0, 64K), it will return range [64K, 128K). This range meets the condition for subpage compression, will go through async COW path. And async COW path will return @page_started. But that @page_started is now for range [64K, 128K), not for range [0, 64K). - writepage_dellloc() returned 1 for page [0, 64K) Thus page [0, 64K) will not be unlocked, nor its page dirty status will be cleared. Next time when we try to lock page [0, 64K) we will deadlock, as there is no one to release page [0, 64K). This problem will never happen for regular page size as one page only contains one sector. After the first find_lock_delalloc_range() call, the @delalloc_end will go beyond @page_end no matter if we found a delalloc range or not Thus this bug only happens for subpage, as now we need multiple runs to exhaust the delalloc range of a page. [FIX] Fix the problem by ensuring the delalloc range we ran at least started inside @locked_page. So that we will never get incorrect @page_started. And to prevent such problem from happening again: - Make find_lock_delalloc_range() return false if the found range is beyond @end value passed in. Since @end will be utilized now, add an ASSERT() to ensure we pass correct @end into find_lock_delalloc_range(). This also means, for selftests we needs to populate @end before calling find_lock_delalloc_range(). - New ASSERT() in find_lock_delalloc_range() Now we will make sure the @start/@end passed in at least covers part of the page. - New ASSERT() in run_delalloc_range() To make sure the range at least starts inside @locked page. - Use @delalloc_start as proper cursor, while @delalloc_end is always reset to @page_end. Signed-off-by: -
Qu Wenruo authored
There are several call sites of extent_clear_unlock_delalloc() which get @locked_page = NULL. So that extent_clear_unlock_delalloc() will try to call process_one_page() to unlock every page even the first page is not locked by btrfs_page_start_writer_lock(). This will trigger an ASSERT() in btrfs_subpage_end_and_test_writer() as previously we require every page passed to btrfs_subpage_end_and_test_writer() to be locked by btrfs_page_start_writer_lock(). But compression path doesn't go that way. Thankfully it's not hard to distinguish page locked by lock_page() and btrfs_page_start_writer_lock(). So do the check in btrfs_subpage_end_and_test_writer() so now it can handle both cases well. Signed-off-by:
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Qu Wenruo authored
Pages passed to __extent_writepage() are always locked, but they may be locked by different functions. There are two types of locked page for __extent_writepage(): - Page locked by plain lock_page() It should not have any subpage::writers count. Can be unlocked by unlock_page(). This is the most common locked page for __extent_writepage() called inside extent_write_cache_pages() or extent_write_full_page(). Rarer cases include the @locked_page from extent_write_locked_range(). - Page locked by lock_delalloc_pages() There is only one caller, all pages except @locked_page for extent_write_locked_range(). In this case, we have to call subpage helper to handle the case. So here we introduce a helper, btrfs_page_unlock_writer(), to allow __extent_writepage() to unlock different locked pages. And since for all other callers of __extent_writepage() their pages are ensured to be locked by lock_page(), also add an extra check for epd::extent_locked to unlock such pages directly. Signed-off-by:
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Qu Wenruo authored
There are several problems in lzo_compress_pages() preventing it from being subpage compatible: - No page offset is calculated when reading from inode pages For subpage case, we could have @start which is not aligned to PAGE_SIZE. Thus the destination where we read data from must take offset in page into consideration. - The padding for segment header is bound to PAGE_SIZE This means, for subpage case we can skip several corners where on x86 machines we need to add padding zeros. The rework will: - Update the comment to replace "page" with "sector" - Introduce a new helper, copy_compressed_data_to_page(), to do the copy So that we don't need to bother page switching for both input and output. Now in lzo_compress_pages() we only care about page switching for input, while in copy_compressed_data_to_page() we only care about the page switching for output. - Only one main cursor For lzo_compress_pages() we use @cur_in as main cursor. It will be the file offset we are currently at. All other helper variables will be only declared inside the loop. For copy_compressed_data_to_page() it's similar, we will have @cur_out at the main cursor, which records how many bytes are in the output. Signed-off-by:
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Qu Wenruo authored
Introduce a new helper, submit_uncompressed_range(), for async cow cases where we fallback to COW. There are some new updates introduced to the helper: - Proper locked_page detection It's possible that the async_extent range doesn't cover the locked page. In that case we shouldn't unlock the locked page. In the new helper, we will ensure that we only unlock the locked page when: * The locked page covers part of the async_extent range * The locked page is not unlocked by cow_file_range() nor extent_write_locked_range() This also means extra comments are added focusing on the page locking. - Add extra comment on some rare parameter used. We use @unlock_page = 0 for cow_file_range(), where only two call sites doing the same thing, including the new helper. It's definitely worth some comments. Signed-off-by: -
Qu Wenruo authored
There are two sites are not subpage compatible yet for extent_write_locked_range(): - How @nr_pages are calculated For subpage we can have the following range with 64K page size: 0 32K 64K 96K 128K | |////|/////| | In that case, although 96K - 32K == 64K, thus it looks like one page is enough, but the range spans two pages, not one. Fix it by doing proper round_up() and round_down() to calculate @nr_pages. Also add some extra ASSERT()s to ensure the range passed in is already aligned. - How the page end is calculated Currently we just use cur + PAGE_SIZE - 1 to calculate the page end. Which can't handle the above range layout, and will trigger ASSERT() in btrfs_writepage_endio_finish_ordered(), as the range is no longer covered by the page range. Fix it by taking page end into consideration. Signed-off-by:
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Qu Wenruo authored
In end_compressed_writeback() we just clear the full page writeback. For subpage case, if there are two delalloc ranges in the same page, the 2nd range will trigger a BUG_ON() as the page writeback is already cleared by previous range. Fix it by using btrfs_page_clamp_clear_writeback() helper. Signed-off-by:
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Qu Wenruo authored
There is a WARN_ON() checking if @start is aligned to PAGE_SIZE, not sectorsize, which will cause false alert for subpage. Fix it to check against sectorsize. Furthermore: - Use ASSERT() to do the check So that in the future we may skip the check for production build - Also check alignment for @len Signed-off-by:
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Qu Wenruo authored
In function compress_file_range(), when the compression is finished, the function just rounds up @total_in to PAGE_SIZE. This is fine for regular sectorsize == PAGE_SIZE case, but not for subpage. Just change the ALIGN(, PAGE_SIZE) to round_up(, sectorsize) so that both regular sectorsize and subpage sectorsize will be happy. Signed-off-by:
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Qu Wenruo authored
There are several cleanups for extent_write_locked_range(), most of them are pure cleanups, but with some preparation for future subpage support. - Add a proper comment for which call sites are suitable Unlike regular synchronized extent write back, if async COW or zoned COW happens, we have all pages in the range still locked. Thus for those (only) two call sites, we need this function to submit page content into bios and submit them. - Remove @mode parameter All the existing two call sites pass WB_SYNC_ALL. No need for @mode parameter. - Better error handling Currently if we hit an error during the page iteration loop, we overwrite @ret, causing only the last error can be recorded. Here we add @found_error and @first_error variable to record if we hit any error, and the first error we hit. So the first error won't get lost. - Don't reuse @start as the cursor We reuse the parameter @start as the cursor to iterate the range, not a big problem, but since we're here, introduce a proper @cur as the cursor. - Remove impossible branch Since all pages are still locked after the ordered extent is inserted, there is no way that pages can get its dirty bit cleared. Remove the branch where page is not dirty and replace it with an ASSERT(). Signed-off-by:
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Qu Wenruo authored
We have a big chunk of code inside a while() loop, with tons of strange jumps for error handling. It's definitely not to the code standard of today. Move the code into a new function, submit_one_async_extent(). Since we're here, also do the following changes: - Comment style change To follow the current scheme - Don't fallback to non-compressed write then hitting ENOSPC If we hit ENOSPC for compressed write, how could we reserve more space for non-compressed write? Thus we go error path directly. This removes the retry: label. - Add more comment for super long parameter list Explain which parameter is for, so we don't need to check the prototype. - Move the error handling to submit_one_async_extent() Thus no strange code like: out_free: ... goto again; Signed-off-by:
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Qu Wenruo authored
As the last caller in compression.c has been removed, we don't need that function anymore. Signed-off-by:
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Qu Wenruo authored
Currently btrfs_submit_compressed_write() will check btrfs_bio_fits_in_stripe() each time a new page is going to be added. Even if compressed extent is small, we don't really need to do that for every page. Align the behavior to extent_io.c, by determining the stripe boundary when allocating a bio. Unlike extent_io.c, in compressed.c we don't need to bother things like different bio flags, thus no need to re-use bio_ctrl. Here we just manually introduce new local variable, next_stripe_start, and use that value returned from alloc_compressed_bio() to calculate the stripe boundary. Then each time we add some page range into the bio, we check if we reached the boundary. And if reached, submit it. Also, since we have @cur_disk_bytenr to determine whether we're the last bio, we don't need a explicit last_bio: tag for error handling any more. And since we use @cur_disk_bytenr to wait, there is no need for pending_bios, also remove it to save some memory of compressed_bio. Signed-off-by:
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Qu Wenruo authored
Currently btrfs_submit_compressed_read() will check btrfs_bio_fits_in_stripe() each time a new page is going to be added. Even if compressed extent is small, we don't really need to do that for every page. This patch will align the behavior to extent_io.c, by determining the stripe boundary when allocating a bio. Unlike extent_io.c, in compressed.c we don't need to bother things like different bio flags, thus no need to re-use bio_ctrl. Here we just manually introduce new local variable, next_stripe_start, and teach alloc_compressed_bio() to calculate the stripe boundary. Then each time we add some page range into the bio, we check if we reached the boundary. And if reached, submit it. Also, since we have @cur_disk_byte to determine whether we're the last bio, we don't need a explicit last_bio: tag for error handling any more. And we can use @cur_disk_byte to track which range has been added to bio, we can also use @cur_disk_byte to calculate the wait condition, no need for @pending_bios. Signed-off-by:
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Qu Wenruo authored
Just aggregate the bio allocation code into one helper, so that we can replace 4 call sites. There is one special note for zoned write. Currently btrfs_submit_compressed_write() will only allocate the first bio using ZONE_APPEND. If we have to submit current bio due to stripe boundary, the new bio allocated will not use ZONE_APPEND. In theory this should be a bug, but considering zoned mode currently only support SINGLE profile, which doesn't have any stripe boundary limit, it should never be a problem and we have assertions in place. This function will provide a good entrance for any work which needs to be done at bio allocation time. Like determining the stripe boundary. Signed-off-by:
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Qu Wenruo authored
The new helper, submit_compressed_bio(), will aggregate the following work: - Increase compressed_bio::pending_bios - Remap the endio function - Map and submit the bio This slightly reorders calls to btrfs_csum_one_bio or btrfs_lookup_bio_sums but but none of them does anything regarding IO submission so this is effectively no change. We mainly care about order of - atomic_inc - btrfs_bio_wq_end_io - btrfs_map_bio Signed-off-by:
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Qu Wenruo authored
Just like btrfs_submit_compressed_read(), there are quite some BUG_ON()s inside btrfs_submit_compressed_write() for the bio submission path. Fix them using the same method: - For last bio, just endio the bio As in that case, one of the endio function of all these submitted bio will be able to free the compressed_bio - For half-submitted bio, wait and finish the compressed_bio manually In this case, as long as all other bio finish, we're the only one referring the compressed bio, and can manually finish it. Signed-off-by:
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Qu Wenruo authored
There are quite some BUG_ON()s inside btrfs_submit_compressed_read(), namely all errors inside the for() loop relies on BUG_ON() to handle -ENOMEM. Handle these errors properly by: - Wait for submitted bios to finish first Using wake_var_event() APIs to wait without introducing extra memory overhead inside compressed_bio. This allows us to wait for any submitted bio to finish, while still keeps the compressed_bio from being freed. - Introduce finish_compressed_bio_read() to finish the compressed_bio - Properly end the bio and finish compressed_bio when error happens Now in btrfs_submit_compressed_read() even when the bio submission failed, we can properly handle the error without triggering BUG_ON(). Signed-off-by:
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Qu Wenruo authored
Although in btrfs we have very limited usage of PageChecked flag, it's still some page flag not yet subpage compatible. Fix it by introducing btrfs_subpage::checked_offset to do the convert. For most call sites, especially for free-space cache, COW fixup and btrfs_invalidatepage(), they all work in full page mode anyway. For other call sites, they work as subpage compatible mode. Some call sites need extra modification: - btrfs_drop_pages() Needs extra parameter to get the real range we need to clear checked flag. Also since btrfs_drop_pages() will accept pages beyond the dirtied range, update btrfs_subpage_clamp_range() to handle such case by setting @len to 0 if the page is beyond target range. - btrfs_invalidatepage() We need to call subpage helper before calling __btrfs_releasepage(), or it will trigger ASSERT() as page->private will be cleared. - btrfs_verify_data_csum() In theory we don't need the io_bio->csum check anymore, but it's won't hurt. Just change the comment. Signed-off-by:
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Qu Wenruo authored
For btrfs_submit_compressed_read() and btrfs_submit_compressed_write(), we have a pretty weird dance around compressed_bio::pending_bios: btrfs_submit_compressed_read/write() { cb = kmalloc() refcount_set(&cb->pending_bios, 0); bio = btrfs_alloc_bio(); /* NOTE here, we haven't yet submitted any bio */ refcount_set(&cb->pending_bios, 1); for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) { if (submit) { /* Here we submit bio, but we always have one * extra pending_bios */ refcount_inc(&cb->pending_bios); ret = btrfs_map_bio(); } } /* Submit the last bio */ ret = btrfs_map_bio(); } There are two reasons why we do this: - compressed_bio::pending_bios is a refcount Thus if it's reduced to 0, it can not be increased again. - To ensure the compressed_bio is not freed by some submitted bios If the submitted bio is finished before the next bio submitted, we can free the compressed_bio completely. But the above code is sometimes confusing, and we can do it better by introducing a new member, compressed_bio::pending_sectors. Now we use compressed_bio::pending_sectors to indicate whether we have any pending sectors under IO or not yet submitted. If pending_sectors == 0, we're definitely the last bio of compressed_bio, and is OK to release the compressed bio. Now the workflow looks like this: btrfs_submit_compressed_read/write() { cb = kmalloc() atomic_set(&cb->pending_bios, 0); refcount_set(&cb->pending_sectors, compressed_len >> sectorsize_bits); bio = btrfs_alloc_bio(); for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) { if (submit) { refcount_inc(&cb->pending_bios); ret = btrfs_map_bio(); } } /* Submit the last bio */ refcount_inc(&cb->pending_bios); ret = btrfs_map_bio(); } For now we still need pending_bios for later error handling, but will remove pending_bios eventually after properly handling the errors. Signed-off-by: -
Qu Wenruo authored
[BUG] If we remove the subpage limitation in add_ra_bio_pages(), then read a compressed extent which has part of its range in next page, like the following inode layout: 0 32K 64K 96K 128K |<--------------|-------------->| Btrfs will trigger ASSERT() in endio function: assertion failed: atomic_read(&subpage->readers) >= nbits ------------[ cut here ]------------ kernel BUG at fs/btrfs/ctree.h:3431! Internal error: Oops - BUG: 0 [#1] SMP Workqueue: btrfs-endio btrfs_work_helper [btrfs] Call trace: assertfail.constprop.0+0x28/0x2c [btrfs] btrfs_subpage_end_reader+0x148/0x14c [btrfs] end_page_read+0x8c/0x100 [btrfs] end_bio_extent_readpage+0x320/0x6b0 [btrfs] bio_endio+0x15c/0x1dc end_workqueue_fn+0x44/0x64 [btrfs] btrfs_work_helper+0x74/0x250 [btrfs] process_one_work+0x1d4/0x47c worker_thread+0x180/0x400 kthread+0x11c/0x120 ret_from_fork+0x10/0x30 ---[ end trace c8b7b552d3bb408c ]--- [CAUSE] When we read the page range [0, 64K), we find it's a compressed extent, and we will try to add extra pages in add_ra_bio_pages() to avoid reading the same compressed extent. But when we add such page into the read bio, it doesn't follow the behavior of btrfs_do_readpage() to properly set subpage::readers. This means, for page [64K, 128K), its subpage::readers is still 0. And when endio is executed on both pages, since page [64K, 128K) has 0 subpage::readers, it triggers above ASSERT() [FIX] Function add_ra_bio_pages() is far from subpage compatible, it always assume PAGE_SIZE == sectorsize, thus when it skip to next range it always just skip PAGE_SIZE. Make it subpage compatible by: - Skip to next page properly when needed If we find there is already a page cache, we need to skip to next page. For that case, we shouldn't just skip PAGE_SIZE bytes, but use @pg_index to calculate the next bytenr and continue. - Only add the page range covered by current extent map We need to calculate which range is covered by current extent map and only add that part into the read bio. - Update subpage::readers before submitting the bio - Use proper cursor other than confusing @last_offset - Calculate the missed threshold based on sector size It's no longer using missed pages, as for 64K page size, we have at most 3 pages to skip. (If aligned only 2 pages) - Add ASSERT() to make sure our bytenr is always aligned - Add comment for the function Add a special note for subpage case, as the function won't really work well for subpage cases. Signed-off-by:
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Qu Wenruo authored
Since async_extent holds the compressed page, it would trigger the new ASSERT() in btrfs_mark_ordered_io_finished() which checks that the range is inside the page. Now btrfs_writepage_endio_finish_ordered() can accept @page == NULL, just pass NULL to btrfs_writepage_endio_finish_ordered(). Signed-off-by:
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Qu Wenruo authored
For structure async_chunk, we use a very strange member layout to grab structure async_cow who owns this async_chunk. At initialization, it goes like this: async_chunk[i].pending = &ctx->num_chunks; Then at async_cow_free() we do a super weird freeing: /* * Since the pointer to 'pending' is at the beginning of the array of * async_chunk's, freeing it ensures the whole array has been freed. */ if (atomic_dec_and_test(async_chunk->pending)) kvfree(async_chunk->pending); This is absolutely an abuse of kvfree(). Replace async_chunk::pending with async_chunk::async_cow, so that we can grab the async_cow structure directly, without this strange dancing. And with this change, there is no requirement for any specific member location. Reviewed-by:
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Qu Wenruo authored
In function __extent_writepage() we always pass page start to @delalloc_start for writepage_delalloc(). Thus we don't really need @delalloc_start parameter as we can extract it from @page. Remove @delalloc_start parameter and make __extent_writepage() to declare @page_start and @page_end as const. Signed-off-by:
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Qu Wenruo authored
Variable @nr_pages only gets increased but never used. Remove it. Signed-off-by:
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Filipe Manana authored
When logging a directory and inserting a batch of directory items, we are copying the data of each item from a leaf in the fs/subvolume tree to a leaf in a log tree, separately. This is not really needed, since we are copying from a contiguous memory area into another one, so we can use a single copy operation to copy all items at once. This patch is part of a small patchset that is comprised of the following patches: btrfs: loop only once over data sizes array when inserting an item batch btrfs: unexport setup_items_for_insert() btrfs: use single bulk copy operations when logging directories This is patch 3/3. The following test was used to compare performance of a branch without the patchset versus one branch that has the whole patchset applied: $ cat dir-fsync-test.sh #!/bin/bash DEV=/dev/nvme0n1 MNT=/mnt/nvme0n1 NUM_NEW_FILES=1000000 NUM_FILE_DELETES=1000 LEAF_SIZE=16K mkfs.btrfs -f -n $LEAF_SIZE $DEV mount -o ssd $DEV $MNT mkdir $MNT/testdir for ((i = 1; i <= $NUM_NEW_FILES; i++)); do echo -n > $MNT/testdir/file_$i done # Fsync the directory, this will log the new dir items and the inodes # they point to, because these are new inodes. start=$(date +%s%N) xfs_io -c "fsync" $MNT/testdir end=$(date +%s%N) dur=$(( (end - start) / 1000000 )) echo "dir fsync took $dur ms after adding $NUM_NEW_FILES files" # sync to force transaction commit and wipeout the log. sync del_inc=$(( $NUM_NEW_FILES / $NUM_FILE_DELETES )) for ((i = 1; i <= $NUM_NEW_FILES; i += $del_inc)); do rm -f $MNT/testdir/file_$i done # Fsync the directory, this will only log dir items, there are no # dentries pointing to new inodes. start=$(date +%s%N) xfs_io -c "fsync" $MNT/testdir end=$(date +%s%N) dur=$(( (end - start) / 1000000 )) echo "dir fsync took $dur ms after deleting $NUM_FILE_DELETES files" umount $MNT The tests were run on a non-debug kernel (Debian's default kernel config) and were the following: *** with a leaf size of 16K, before patchset *** dir fsync took 8482 ms after adding 1000000 files dir fsync took 166 ms after deleting 1000 files *** with a leaf size of 16K, after patchset *** dir fsync took 8196 ms after adding 1000000 files (-3.4%) dir fsync took 143 ms after deleting 1000 files (-14.9%) *** with a leaf size of 64K, before patchset *** dir fsync took 12851 ms after adding 1000000 files dir fsync took 466 ms after deleting 1000 files *** with a leaf size of 64K, after patchset *** dir fsync took 12287 ms after adding 1000000 files (-4.5%) dir fsync took 414 ms after deleting 1000 files (-11.8%) Signed-off-by:Filipe Manana <fdmanana@suse.com> Signed-off-by:
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Filipe Manana authored
Since setup_items_for_insert() is not used anymore outside of ctree.c, make it static and remove its prototype from ctree.h. This also requires to move the definition of setup_item_for_insert() from ctree.h to ctree.c and move down btrfs_duplicate_item() so that it's defined after setup_items_for_insert(). Further, since setup_item_for_insert() is used outside ctree.c, rename it to btrfs_setup_item_for_insert(). This patch is part of a small patchset that is comprised of the following patches: btrfs: loop only once over data sizes array when inserting an item batch btrfs: unexport setup_items_for_insert() btrfs: use single bulk copy operations when logging directories This is patch 2/3 and performance results, and the specific tests, are included in the changelog of patch 3/3. Signed-off-by:
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Filipe Manana authored
When inserting a batch of items into a btree, we end up looping over the data sizes array 3 times: 1) Once in the caller of btrfs_insert_empty_items(), when it populates the array with the data sizes for each item; 2) Once at btrfs_insert_empty_items() to sum the elements of the data sizes array and compute the total data size; 3) And then once again at setup_items_for_insert(), where we do exactly the same as what we do at btrfs_insert_empty_items(), to compute the total data size. That is not bad for small arrays, but when the arrays have hundreds of elements, the time spent on looping is not negligible. For example when doing batch inserts of delayed items for dir index items or when logging a directory, it's common to have 200 to 260 dir index items in a single batch when using a leaf size of 16K and using file names between 8 and 12 characters. For a 64K leaf size, multiply that by 4. Taking into account that during directory logging or when flushing delayed dir index items we can have many of those large batches, the time spent on the looping adds up quickly. It's also more important to avoid it at setup_items_for_insert(), since we are holding a write lock on a leaf and, in some cases, on upper nodes of the btree, which causes us to block other tasks that want to access the leaf and nodes for longer than necessary. So change the code so that setup_items_for_insert() and btrfs_insert_empty_items() no longer compute the total data size, and instead rely on the caller to supply it. This makes us loop over the array only once, where we can both populate the data size array and compute the total data size, taking advantage of spatial and temporal locality. To make this more manageable, use a structure to contain all the relevant details for a batch of items (keys array, data sizes array, total data size, number of items), and use it as an argument for btrfs_insert_empty_items() and setup_items_for_insert(). This patch is part of a small patchset that is comprised of the following patches: btrfs: loop only once over data sizes array when inserting an item batch btrfs: unexport setup_items_for_insert() btrfs: use single bulk copy operations when logging directories This is patch 1/3 and performance results, and the specific tests, are included in the changelog of patch 3/3. Signed-off-by:
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Qu Wenruo authored
We can grab fs_info reliably from btrfs_raid_bio::bioc, as the bioc is always passed into alloc_rbio(), and only get released when the raid bio is released. Remove btrfs_raid_bio::fs_info member, and cleanup all the @fs_info parameters for alloc_rbio() callers. Reviewed-by:
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Qu Wenruo authored
Currently btrfs_io_context::fs_info is only initialized in btrfs_map_bio, but there are call sites like btrfs_map_sblock() which calls __btrfs_map_block() directly, leaving bioc::fs_info uninitialized (NULL). Currently this is fine, but later cleanup will rely on bioc::fs_info to grab fs_info, and this can be a hidden problem for such usage. This patch will remove such hidden uninitialized member by always assigning bioc::fs_info at alloc_btrfs_io_context(). Reviewed-by:
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Filipe Manana authored
We currently use lockdep_assert_held() at btrfs_assert_tree_locked(), and that checks that we hold a lock either in read mode or write mode. However in all contexts we use btrfs_assert_tree_locked(), we actually want to check if we are holding a write lock on the extent buffer's rw semaphore - it would be a bug if in any of those contexts we were holding a read lock instead. So change btrfs_assert_tree_locked() to use lockdep_assert_held_write() instead and, to make it more explicit, rename btrfs_assert_tree_locked() to btrfs_assert_tree_write_locked(), so that it's clear we want to check we are holding a write lock. For now there are no contexts where we want to assert that we must have a read lock, but in case that is needed in the future, we can add a new helper function that just calls out lockdep_assert_held_read(). Signed-off-by:
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Josef Bacik authored
We got the following lockdep splat while running fstests (specifically btrfs/003 and btrfs/020 in a row) with the new rc. This was uncovered by 87579e9b ("loop: use worker per cgroup instead of kworker") which converted loop to using workqueues, which comes with lockdep annotations that don't exist with kworkers. The lockdep splat is as follows: WARNING: possible circular locking dependency detected 5.14.0-rc2-custom+ #34 Not tainted ------------------------------------------------------ losetup/156417 is trying to acquire lock: ffff9c7645b02d38 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x84/0x600 but task is already holding lock: ffff9c7647395468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x41/0x650 [loop] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&lo->lo_mutex){+.+.}-{3:3}: __mutex_lock+0xba/0x7c0 lo_open+0x28/0x60 [loop] blkdev_get_whole+0x28/0xf0 blkdev_get_by_dev.part.0+0x168/0x3c0 blkdev_open+0xd2/0xe0 do_dentry_open+0x163/0x3a0 path_openat+0x74d/0xa40 do_filp_open+0x9c/0x140 do_sys_openat2+0xb1/0x170 __x64_sys_openat+0x54/0x90 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #4 (&disk->open_mutex){+.+.}-{3:3}: __mutex_lock+0xba/0x7c0 blkdev_get_by_dev.part.0+0xd1/0x3c0 blkdev_get_by_path+0xc0/0xd0 btrfs_scan_one_device+0x52/0x1f0 [btrfs] btrfs_control_ioctl+0xac/0x170 [btrfs] __x64_sys_ioctl+0x83/0xb0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #3 (uuid_mutex){+.+.}-{3:3}: __mutex_lock+0xba/0x7c0 btrfs_rm_device+0x48/0x6a0 [btrfs] btrfs_ioctl+0x2d1c/0x3110 [btrfs] __x64_sys_ioctl+0x83/0xb0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #2 (sb_writers#11){.+.+}-{0:0}: lo_write_bvec+0x112/0x290 [loop] loop_process_work+0x25f/0xcb0 [loop] process_one_work+0x28f/0x5d0 worker_thread+0x55/0x3c0 kthread+0x140/0x170 ret_from_fork+0x22/0x30 -> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}: process_one_work+0x266/0x5d0 worker_thread+0x55/0x3c0 kthread+0x140/0x170 ret_from_fork+0x22/0x30 -> #0 ((wq_completion)loop0){+.+.}-{0:0}: __lock_acquire+0x1130/0x1dc0 lock_acquire+0xf5/0x320 flush_workqueue+0xae/0x600 drain_workqueue+0xa0/0x110 destroy_workqueue+0x36/0x250 __loop_clr_fd+0x9a/0x650 [loop] lo_ioctl+0x29d/0x780 [loop] block_ioctl+0x3f/0x50 __x64_sys_ioctl+0x83/0xb0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae other info that might help us debug this: Chain exists of: (wq_completion)loop0 --> &disk->open_mutex --> &lo->lo_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&lo->lo_mutex); lock(&disk->open_mutex); lock(&lo->lo_mutex); lock((wq_completion)loop0); *** DEADLOCK *** 1 lock held by losetup/156417: #0: ffff9c7647395468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x41/0x650 [loop] stack backtrace: CPU: 8 PID: 156417 Comm: losetup Not tainted 5.14.0-rc2-custom+ #34 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Call Trace: dump_stack_lvl+0x57/0x72 check_noncircular+0x10a/0x120 __lock_acquire+0x1130/0x1dc0 lock_acquire+0xf5/0x320 ? flush_workqueue+0x84/0x600 flush_workqueue+0xae/0x600 ? flush_workqueue+0x84/0x600 drain_workqueue+0xa0/0x110 destroy_workqueue+0x36/0x250 __loop_clr_fd+0x9a/0x650 [loop] lo_ioctl+0x29d/0x780 [loop] ? __lock_acquire+0x3a0/0x1dc0 ? update_dl_rq_load_avg+0x152/0x360 ? lock_is_held_type+0xa5/0x120 ? find_held_lock.constprop.0+0x2b/0x80 block_ioctl+0x3f/0x50 __x64_sys_ioctl+0x83/0xb0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f645884de6b Usually the uuid_mutex exists to protect the fs_devices that map together all of the devices that match a specific uuid. In rm_device we're messing with the uuid of a device, so it makes sense to protect that here. However in doing that it pulls in a whole host of lockdep dependencies, as we call mnt_may_write() on the sb before we grab the uuid_mutex, thus we end up with the dependency chain under the uuid_mutex being added under the normal sb write dependency chain, which causes problems with loop devices. We don't need the uuid mutex here however. If we call btrfs_scan_one_device() before we scratch the super block we will find the fs_devices and not find the device itself and return EBUSY because the fs_devices is open. If we call it after the scratch happens it will not appear to be a valid btrfs file system. We do not need to worry about other fs_devices modifying operations here because we're protected by the exclusive operations locking. So drop the uuid_mutex here in order to fix the lockdep splat. A more detailed explanation from the discussion: We are worried about rm and scan racing with each other, before this change we'll zero the device out under the UUID mutex so when scan does run it'll make sure that it can go through the whole device scan thing without rm messing with us. We aren't worried if the scratch happens first, because the result is we don't think this is a btrfs device and we bail out. The only case we are concerned with is we scratch _after_ scan is able to read the superblock and gets a seemingly valid super block, so lets consider this case. Scan will call device_list_add() with the device we're removing. We'll call find_fsid_with_metadata_uuid() and get our fs_devices for this UUID. At this point we lock the fs_devices->device_list_mutex. This is what protects us in this case, but we have two cases here. 1. We aren't to the device removal part of the RM. We found our device, and device name matches our path, we go down and we set total_devices to our super number of devices, which doesn't affect anything because we haven't done the remove yet. 2. We are past the device removal part, which is protected by the device_list_mutex. Scan doesn't find the device, it goes down and does the if (fs_devices->opened) return -EBUSY; check and we bail out. Nothing about this situation is ideal, but the lockdep splat is real, and the fix is safe, tho admittedly a bit scary looking. Reviewed-by:
Anand Jain <anand.jain@oracle.com> Signed-off-by:
Josef Bacik <josef@toxicpanda.com> Reviewed-by:
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Qu Wenruo authored
Previously we had "struct btrfs_bio", which records IO context for mirrored IO and RAID56, and "strcut btrfs_io_bio", which records extra btrfs specific info for logical bytenr bio. With "btrfs_bio" renamed to "btrfs_io_context", we are safe to rename "btrfs_io_bio" to "btrfs_bio" which is a more suitable name now. The struct btrfs_bio changes meaning by this commit. There was a suggested name like btrfs_logical_bio but it's a bit long and we'd prefer to use a shorter name. This could be a concern for backports to older kernels where the different meaning could possibly cause confusion or bugs. Comparing the new and old structures, there's no overlap among the struct members so a build would break in case of incorrect backport. We haven't had many backports to bio code anyway so this is more of a theoretical cause of bugs and a matter of precaution but we'll need to keep the semantic change in mind. Signed-off-by:
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Qu Wenruo authored
The helper btrfs_bio_alloc() is almost the same as btrfs_io_bio_alloc(), except it's allocating using BIO_MAX_VECS as @nr_iovecs, and initializes bio->bi_iter.bi_sector. However the naming itself is not using "btrfs_io_bio" to indicate its parameter is "strcut btrfs_io_bio" and can be easily confused with "struct btrfs_bio". Considering assigned bio->bi_iter.bi_sector is such a simple work and there are already tons of call sites doing that manually, there is no need to do that in a helper. Remove btrfs_bio_alloc() helper, and enhance btrfs_io_bio_alloc() function to provide a fail-safe value for its @nr_iovecs. And then replace all btrfs_bio_alloc() callers with btrfs_io_bio_alloc(). Signed-off-by:
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Qu Wenruo authored
The structure btrfs_bio is used by two different sites: - bio->bi_private for mirror based profiles For those profiles (SINGLE/DUP/RAID1*/RAID10), this structures records how many mirrors are still pending, and save the original endio function of the bio. - RAID56 code In that case, RAID56 only utilize the stripes info, and no long uses that to trace the pending mirrors. So btrfs_bio is not always bind to a bio, and contains more info for IO context, thus renaming it will make the naming less confusing. Signed-off-by:
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Filipe Manana authored
After the first time we log a directory in the current transaction, for each directory item in a changed leaf of the subvolume tree, we have to check if we previously logged the item, in order to overwrite it in case its data changed or skip it in case its data hasn't changed. Checking if we have logged each item before not only wastes times, but it also adds lock contention on the log tree. So in order to minimize the number of times we do such checks, keep track of the offset of the last key we logged for a directory and, on the next time we log the directory, skip the checks for any new keys that have an offset greater than the offset we have previously saved. This is specially effective for index keys, because the offset for these keys comes from a monotonically increasing counter. This patch is part of a patchset comprised of the following 5 patches: btrfs: remove root argument from btrfs_log_inode() and its callees btrfs: remove redundant log root assignment from log_dir_items() btrfs: factor out the copying loop of dir items from log_dir_items() btrfs: insert items in batches when logging a directory when possible btrfs: keep track of the last logged keys when logging a directory This is patch 5/5. The following test was used on a non-debug kernel to measure the impact it has on a directory fsync: $ cat test-dir-fsync.sh #!/bin/bash DEV=/dev/nvme0n1 MNT=/mnt/nvme0n1 NUM_NEW_FILES=100000 NUM_FILE_DELETES=1000 mkfs.btrfs -f $DEV mount -o ssd $DEV $MNT mkdir $MNT/testdir for ((i = 1; i <= $NUM_NEW_FILES; i++)); do echo -n > $MNT/testdir/file_$i done # fsync the directory, this will log the new dir items and the inodes # they point to, because these are new inodes. start=$(date +%s%N) xfs_io -c "fsync" $MNT/testdir end=$(date +%s%N) dur=$(( (end - start) / 1000000 )) echo "dir fsync took $dur ms after adding $NUM_NEW_FILES files" # sync to force transaction commit and wipeout the log. sync del_inc=$(( $NUM_NEW_FILES / $NUM_FILE_DELETES )) for ((i = 1; i <= $NUM_NEW_FILES; i += $del_inc)); do rm -f $MNT/testdir/file_$i done # fsync the directory, this will only log dir items, there are no # dentries pointing to new inodes. start=$(date +%s%N) xfs_io -c "fsync" $MNT/testdir end=$(date +%s%N) dur=$(( (end - start) / 1000000 )) echo "dir fsync took $dur ms after deleting $NUM_FILE_DELETES files" umount $MNT Test results with NUM_NEW_FILES set to 100 000 and 1 000 000: **** before patchset, 100 000 files, 1000 deletes **** dir fsync took 848 ms after adding 100000 files dir fsync took 175 ms after deleting 1000 files **** after patchset, 100 000 files, 1000 deletes **** dir fsync took 758 ms after adding 100000 files (-11.2%) dir fsync took 63 ms after deleting 1000 files (-94.1%) **** before patchset, 1 000 000 files, 1000 deletes **** dir fsync took 9945 ms after adding 1000000 files dir fsync took 473 ms after deleting 1000 files **** after patchset, 1 000 000 files, 1000 deletes **** dir fsync took 8677 ms after adding 1000000 files (-13.6%) dir fsync took 146 ms after deleting 1000 files (-105.6%) Signed-off-by: -
Filipe Manana authored
When logging a directory, we scan its directory items from the subvolume tree and then copy one by one into the log tree. This is not efficient since we generally are able to insert several items in a batch, using a single btree operation for adding several items at once. The reason we copy items one by one is that we must check if each item was previously logged in the current transaction, and if it was we either overwrite it or skip it in case its content did not change in the subvolume tree (this can happen only for dir item keys, but not for dir index keys), and doing such check makes it a bit cumbersome to attempt batch insertions. However the chances for doing batch insertions are very frequent and always happen when: 1) Logging the directory for the first time in the current transaction, as none of the items exist in the log tree yet; 2) Logging new dir index keys, because the offset for new dir index keys comes from a monotonically increasing counter. This means if we keep adding dentries to a directory, through creation of new files and sub-directories or by adding new links or renaming from some other directory into the one we are logging, all the new dir index keys have a new offset that is greater than the offset of any previously logged index keys, so we can insert them in batches into the log tree. For dir item keys, since their offset depends on the result of an hash function against the dentry's name, unless the directory is being logged for the first time in the current transaction, the chances being able to insert the items in the log using batches is pretty much random and not predictable, as it depends on the names of the dentries, but still happens often enough. So change directory logging to keep track of consecutive directory items that don't exist yet in the log and batch insert them. This patch is part of a patchset comprised of the following 5 patches: btrfs: remove root argument from btrfs_log_inode() and its callees btrfs: remove redundant log root assignment from log_dir_items() btrfs: factor out the copying loop of dir items from log_dir_items() btrfs: insert items in batches when logging a directory when possible btrfs: keep track of the last logged keys when logging a directory This is patch 4/5. The change log of the last patch (5/5) has performance results. Signed-off-by:
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Filipe Manana authored
In preparation for the next change, move the loop that processes a leaf and copies its directory items to the log, into a separate helper function. This makes the next change simpler and it also helps making log_dir_items() a bit shorter (specially after the next change). This patch is part of a patchset comprised of the following 5 patches: btrfs: remove root argument from btrfs_log_inode() and its callees btrfs: remove redundant log root assignment from log_dir_items() btrfs: factor out the copying loop of dir items from log_dir_items() btrfs: insert items in batches when logging a directory when possible btrfs: keep track of the last logged keys when logging a directory This is patch 3/5. The change log of the last patch (5/5) has performance results. Signed-off-by:
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