kernel.git/fs/btrfs/extent_map.c, branch linux-6.3.y

btrfs: fix extent map logging bit not cleared for split maps after dropping range

2023-03-06T18:28:19Z

At btrfs_drop_extent_map_range() we are clearing the EXTENT_FLAG_LOGGING bit on a 'flags' variable that was not initialized. This makes static checkers complain about it, so initialize the 'flags' variable before clearing the bit. In practice this has no consequences, because EXTENT_FLAG_LOGGING should not be set when btrfs_drop_extent_map_range() is called, as an fsync locks the inode in exclusive mode, locks the inode's mmap semaphore in exclusive mode too and it always flushes all delalloc. Also add a comment about why we clear EXTENT_FLAG_LOGGING on a copy of the flags of the split extent map. Reported-by: Dan Carpenter Link: https://lore.kernel.org/linux-btrfs/Y%2FyipSVozUDEZKow@kili/ Fixes: db21370bffbc ("btrfs: drop extent map range more efficiently") Signed-off-by: Filipe Manana Signed-off-by: David Sterba

btrfs: remove no longer used btrfs_next_extent_map()

2022-12-05T17:00:56Z

There are no more users of btrfs_next_extent_map(), the previous patch in the series ("btrfs: search for delalloc more efficiently during lseek/fiemap") removed the last usage of the function, so delete it. This change is part of a patchset that has the goal to make performance better for applications that use lseek's SEEK_HOLE and SEEK_DATA modes to iterate over the extents of a file. Two examples are the cp program from coreutils 9.0+ and the tar program (when using its --sparse / -S option). A sample test and results are listed in the changelog of the last patch in the series: 1/9 btrfs: remove leftover setting of EXTENT_UPTODATE state in an inode's io_tree 2/9 btrfs: add an early exit when searching for delalloc range for lseek/fiemap 3/9 btrfs: skip unnecessary delalloc searches during lseek/fiemap 4/9 btrfs: search for delalloc more efficiently during lseek/fiemap 5/9 btrfs: remove no longer used btrfs_next_extent_map() 6/9 btrfs: allow passing a cached state record to count_range_bits() 7/9 btrfs: update stale comment for count_range_bits() 8/9 btrfs: use cached state when looking for delalloc ranges with fiemap 9/9 btrfs: use cached state when looking for delalloc ranges with lseek Reported-by: Wang Yugui Link: https://lore.kernel.org/linux-btrfs/20221106073028.71F9.409509F4@e16-tech.com/ Link: https://lore.kernel.org/linux-btrfs/CAL3q7H5NSVicm7nYBJ7x8fFkDpno8z3PYt5aPU43Bajc1H0h1Q@mail.gmail.com/ Signed-off-by: Filipe Manana Signed-off-by: David Sterba

btrfs: selftests: remove impossible inline extent at non-zero file offset

2022-12-05T17:00:47Z

In our inode-tests.c, we create an inline offset at file offset 5, which is no longer possible since the introduction of tree-checker. Thus I don't think we should spend time maintaining some corner cases which are already ruled out by tree-checker. So this patch will: - Change the inline extent to start at file offset 0 Also change its length to 6 to cover the original length - Add an extra ASSERT() for btrfs_add_extent_mapping() This is to make sure tree-checker is working correctly. - Update the inode selftest Signed-off-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: update function comments

2022-12-05T17:00:45Z

Update, reformat or reword function comments. This also removes the kdoc marker so we don't get reports when the function name is missing. Changes made: - remove kdoc markers - reformat the brief description to be a proper sentence - reword to imperative voice - align parameter list - fix typos Signed-off-by: David Sterba

btrfs: move the printk helpers out of ctree.h

2022-12-05T17:00:41Z

We have a bunch of printk helpers that are in ctree.h. These have nothing to do with ctree.c, so move them into their own header. Subsequent patches will cleanup the printk helpers. Reviewed-by: Johannes Thumshirn Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: get the next extent map during fiemap/lseek more efficiently

2022-12-05T17:00:38Z

At find_delalloc_subrange(), when we need to get the next extent map, we do a full search on the extent map tree (a red black tree). This is fine but it's a lot more efficient to simply use rb_next(), which typically requires iterating over less nodes of the tree and never needs to compare the ranges of nodes with the one we are looking for. So add a public helper to extent_map.{h,c} to get the extent map that immediately follows another extent map, using rb_next(), and use that helper at find_delalloc_subrange(). Signed-off-by: Filipe Manana Signed-off-by: David Sterba

btrfs: drop extent map range more efficiently

2022-09-29T15:08:31Z

Currently when dropping extent maps for a file range, through btrfs_drop_extent_map_range(), we do the following non-optimal things: 1) We lookup for extent maps one by one, always starting the search from the root of the extent map tree. This is not efficient if we have multiple extent maps in the range; 2) We check on every iteration if we have the 'split' and 'split2' spare extent maps in case we need to split an extent map that intersects our range but also crosses its boundaries (to the left, to the right or both cases). If our target range is for example: [2M, 8M) And we have 3 extents maps in the range: [1M, 3M) [3M, 6M) [6M, 10M[ The on the first iteration we allocate two extent maps for 'split' and 'split2', and use the 'split' to split the first extent map, so after the split we set 'split' to 'split2' and then set 'split2' to NULL. On the second iteration, we don't need to split the second extent map, but because 'split2' is now NULL, we allocate a new extent map for 'split2'. On the third iteration we need to split the third extent map, so we use the extent map pointed by 'split'. So we ended up allocating 3 extent maps for splitting, but all we needed was 2 extent maps. We never need to allocate more than 2, because extent maps that need to be split are always the first one and the last one in the target range. Improve on this by: 1) Using rb_next() to move on to the next extent map. This results in iterating over less nodes of the tree and it does not require comparing the ranges of nodes to our start/end offset; 2) Allocate the 2 extent maps for splitting before entering the loop and never allocate more than 2. In practice it's very rare to have the combination of both extent map allocations fail, since we have a dedicated slab for extent maps, and also have the need to split two extent maps. This patch is part of a patchset comprised of the following patches: btrfs: fix missed extent on fsync after dropping extent maps btrfs: move btrfs_drop_extent_cache() to extent_map.c btrfs: use extent_map_end() at btrfs_drop_extent_map_range() btrfs: use cond_resched_rwlock_write() during inode eviction btrfs: move open coded extent map tree deletion out of inode eviction btrfs: add helper to replace extent map range with a new extent map btrfs: remove the refcount warning/check at free_extent_map() btrfs: remove unnecessary extent map initializations btrfs: assert tree is locked when clearing extent map from logging btrfs: remove unnecessary NULL pointer checks when searching extent maps btrfs: remove unnecessary next extent map search btrfs: avoid pointless extent map tree search when flushing delalloc btrfs: drop extent map range more efficiently And the following fio test was done before and after applying the whole patchset, on a non-debug kernel (Debian's default kernel config) on a 12 cores Intel box with 64G of ram: $ cat test.sh #!/bin/bash DEV=/dev/nvme0n1 MNT=/mnt/nvme0n1 MOUNT_OPTIONS="-o ssd" MKFS_OPTIONS="-R free-space-tree -O no-holes" cat < /tmp/fio-job.ini [writers] rw=randwrite fsync=8 fallocate=none group_reporting=1 direct=0 bssplit=4k/20:8k/20:16k/20:32k/10:64k/10:128k/5:256k/5:512k/5:1m/5 ioengine=psync filesize=2G runtime=300 time_based directory=$MNT numjobs=8 thread EOF echo performance | \ tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor echo echo "Using config:" echo cat /tmp/fio-job.ini echo umount $MNT &> /dev/null mkfs.btrfs -f $MKFS_OPTIONS $DEV mount $MOUNT_OPTIONS $DEV $MNT fio /tmp/fio-job.ini umount $MNT Result before applying the patchset: WRITE: bw=197MiB/s (206MB/s), 197MiB/s-197MiB/s (206MB/s-206MB/s), io=57.7GiB (61.9GB), run=300188-300188msec Result after applying the patchset: WRITE: bw=203MiB/s (213MB/s), 203MiB/s-203MiB/s (213MB/s-213MB/s), io=59.5GiB (63.9GB), run=300019-300019msec Signed-off-by: Filipe Manana Signed-off-by: David Sterba

btrfs: remove unnecessary next extent map search

2022-09-29T15:08:31Z

At __tree_search(), and its single caller __lookup_extent_mapping(), there is no point in finding the next extent map that starts after the search offset if we were able to find the previous extent map that ends before our search offset, because __lookup_extent_mapping() ignores the next acceptable extent map if we were able to find the previous one. So just return immediately if we were able to find the previous extent map, therefore avoiding wasting time iterating the tree looking for the next extent map which will not be used by __lookup_extent_mapping(). Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: remove unnecessary NULL pointer checks when searching extent maps

2022-09-29T15:08:31Z

The previous and next pointer arguments passed to __tree_search() are never NULL as the only caller of this function, __lookup_extent_mapping(), always passes the address of two on stack pointers. So remove the NULL checks and add assertions to verify the pointers. Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: assert tree is locked when clearing extent map from logging

2022-09-29T15:08:31Z

When calling clear_em_logging() we should have a write lock on the extent map tree, as we will try to merge the extent map with the previous and next ones in the tree. So assert that we have a write lock. Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba