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btrfs: use cached state when looking for delalloc ranges with fiemap
During fiemap, whenever we find a hole or prealloc extent, we will look for delalloc in that range, and one of the things we do for that is to find out ranges in the inode's io_tree marked with EXTENT_DELALLOC, using calls to count_range_bits(). Since we process file extents from left to right, if we have a file with several holes or prealloc extents, we benefit from keeping a cached extent state record for calls to count_range_bits(). Most of the time the last extent state record we visited in one call to count_range_bits() matches the first extent state record we will use in the next call to count_range_bits(), so there's a benefit here. So use an extent state record to cache results from count_range_bits() calls during fiemap. 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 <wangyugui@e16-tech.com> 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 <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
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@ -3698,6 +3698,7 @@ static int fiemap_search_slot(struct btrfs_inode *inode, struct btrfs_path *path
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static int fiemap_process_hole(struct btrfs_inode *inode,
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struct fiemap_extent_info *fieinfo,
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struct fiemap_cache *cache,
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struct extent_state **delalloc_cached_state,
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struct btrfs_backref_share_check_ctx *backref_ctx,
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u64 disk_bytenr, u64 extent_offset,
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u64 extent_gen,
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@ -3722,6 +3723,7 @@ static int fiemap_process_hole(struct btrfs_inode *inode,
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bool delalloc;
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delalloc = btrfs_find_delalloc_in_range(inode, cur_offset, end,
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delalloc_cached_state,
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&delalloc_start,
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&delalloc_end);
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if (!delalloc)
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@ -3892,6 +3894,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
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{
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const u64 ino = btrfs_ino(inode);
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struct extent_state *cached_state = NULL;
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struct extent_state *delalloc_cached_state = NULL;
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struct btrfs_path *path;
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struct fiemap_cache cache = { 0 };
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struct btrfs_backref_share_check_ctx *backref_ctx;
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@ -3966,6 +3969,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
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const u64 range_end = min(key.offset, lockend) - 1;
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ret = fiemap_process_hole(inode, fieinfo, &cache,
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&delalloc_cached_state,
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backref_ctx, 0, 0, 0,
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prev_extent_end, range_end);
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if (ret < 0) {
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@ -4006,6 +4010,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
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extent_len, flags);
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} else if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
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ret = fiemap_process_hole(inode, fieinfo, &cache,
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&delalloc_cached_state,
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backref_ctx,
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disk_bytenr, extent_offset,
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extent_gen, key.offset,
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@ -4013,6 +4018,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
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} else if (disk_bytenr == 0) {
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/* We have an explicit hole. */
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ret = fiemap_process_hole(inode, fieinfo, &cache,
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&delalloc_cached_state,
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backref_ctx, 0, 0, 0,
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key.offset, extent_end - 1);
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} else {
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@ -4070,7 +4076,8 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
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path = NULL;
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if (!stopped && prev_extent_end < lockend) {
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ret = fiemap_process_hole(inode, fieinfo, &cache, backref_ctx,
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ret = fiemap_process_hole(inode, fieinfo, &cache,
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&delalloc_cached_state, backref_ctx,
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0, 0, 0, prev_extent_end, lockend - 1);
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if (ret < 0)
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goto out_unlock;
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@ -4088,6 +4095,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
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delalloc = btrfs_find_delalloc_in_range(inode,
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prev_extent_end,
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i_size - 1,
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&delalloc_cached_state,
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&delalloc_start,
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&delalloc_end);
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if (!delalloc)
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@ -4102,6 +4110,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
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out_unlock:
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unlock_extent(&inode->io_tree, lockstart, lockend, &cached_state);
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out:
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free_extent_state(delalloc_cached_state);
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btrfs_free_backref_share_ctx(backref_ctx);
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btrfs_free_path(path);
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return ret;
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@ -3214,6 +3214,7 @@ static long btrfs_fallocate(struct file *file, int mode,
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* looping while it gets adjacent subranges, and merging them together.
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*/
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static bool find_delalloc_subrange(struct btrfs_inode *inode, u64 start, u64 end,
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struct extent_state **cached_state,
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bool *search_io_tree,
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u64 *delalloc_start_ret, u64 *delalloc_end_ret)
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{
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@ -3236,7 +3237,7 @@ static bool find_delalloc_subrange(struct btrfs_inode *inode, u64 start, u64 end
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delalloc_len = count_range_bits(&inode->io_tree,
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delalloc_start_ret, end,
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len, EXTENT_DELALLOC, 1,
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NULL);
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cached_state);
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} else {
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spin_unlock(&inode->lock);
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}
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@ -3324,6 +3325,8 @@ static bool find_delalloc_subrange(struct btrfs_inode *inode, u64 start, u64 end
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* sector size aligned.
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* @end: The end offset (inclusive value) of the search range.
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* It does not need to be sector size aligned.
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* @cached_state: Extent state record used for speeding up delalloc
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* searches in the inode's io_tree. Can be NULL.
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* @delalloc_start_ret: Output argument, set to the start offset of the
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* subrange found with delalloc (may not be sector size
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* aligned).
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@ -3335,6 +3338,7 @@ static bool find_delalloc_subrange(struct btrfs_inode *inode, u64 start, u64 end
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* end offsets of the subrange.
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*/
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bool btrfs_find_delalloc_in_range(struct btrfs_inode *inode, u64 start, u64 end,
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struct extent_state **cached_state,
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u64 *delalloc_start_ret, u64 *delalloc_end_ret)
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{
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u64 cur_offset = round_down(start, inode->root->fs_info->sectorsize);
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@ -3348,7 +3352,7 @@ bool btrfs_find_delalloc_in_range(struct btrfs_inode *inode, u64 start, u64 end,
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bool delalloc;
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delalloc = find_delalloc_subrange(inode, cur_offset, end,
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&search_io_tree,
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cached_state, &search_io_tree,
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&delalloc_start,
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&delalloc_end);
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if (!delalloc)
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@ -3400,7 +3404,7 @@ static bool find_desired_extent_in_hole(struct btrfs_inode *inode, int whence,
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u64 delalloc_end;
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bool delalloc;
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delalloc = btrfs_find_delalloc_in_range(inode, start, end,
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delalloc = btrfs_find_delalloc_in_range(inode, start, end, NULL,
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&delalloc_start, &delalloc_end);
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if (delalloc && whence == SEEK_DATA) {
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*start_ret = delalloc_start;
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@ -27,6 +27,7 @@ int btrfs_check_nocow_lock(struct btrfs_inode *inode, loff_t pos,
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size_t *write_bytes, bool nowait);
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void btrfs_check_nocow_unlock(struct btrfs_inode *inode);
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bool btrfs_find_delalloc_in_range(struct btrfs_inode *inode, u64 start, u64 end,
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struct extent_state **cached_state,
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u64 *delalloc_start_ret, u64 *delalloc_end_ret);
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#endif
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