From b3e744fe6d289bec77b138b6201201e4148dcb0e Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Fri, 11 Nov 2022 11:50:34 +0000 Subject: [PATCH] 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 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 --- fs/btrfs/extent_io.c | 11 ++++++++++- fs/btrfs/file.c | 10 +++++++--- fs/btrfs/file.h | 1 + 3 files changed, 18 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 33cc3a9a2b68..704ae7c08867 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3698,6 +3698,7 @@ static int fiemap_search_slot(struct btrfs_inode *inode, struct btrfs_path *path static int fiemap_process_hole(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo, struct fiemap_cache *cache, + struct extent_state **delalloc_cached_state, struct btrfs_backref_share_check_ctx *backref_ctx, u64 disk_bytenr, u64 extent_offset, u64 extent_gen, @@ -3722,6 +3723,7 @@ static int fiemap_process_hole(struct btrfs_inode *inode, bool delalloc; delalloc = btrfs_find_delalloc_in_range(inode, cur_offset, end, + delalloc_cached_state, &delalloc_start, &delalloc_end); if (!delalloc) @@ -3892,6 +3894,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo, { const u64 ino = btrfs_ino(inode); struct extent_state *cached_state = NULL; + struct extent_state *delalloc_cached_state = NULL; struct btrfs_path *path; struct fiemap_cache cache = { 0 }; struct btrfs_backref_share_check_ctx *backref_ctx; @@ -3966,6 +3969,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo, const u64 range_end = min(key.offset, lockend) - 1; ret = fiemap_process_hole(inode, fieinfo, &cache, + &delalloc_cached_state, backref_ctx, 0, 0, 0, prev_extent_end, range_end); if (ret < 0) { @@ -4006,6 +4010,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo, extent_len, flags); } else if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) { ret = fiemap_process_hole(inode, fieinfo, &cache, + &delalloc_cached_state, backref_ctx, disk_bytenr, extent_offset, extent_gen, key.offset, @@ -4013,6 +4018,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo, } else if (disk_bytenr == 0) { /* We have an explicit hole. */ ret = fiemap_process_hole(inode, fieinfo, &cache, + &delalloc_cached_state, backref_ctx, 0, 0, 0, key.offset, extent_end - 1); } else { @@ -4070,7 +4076,8 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo, path = NULL; if (!stopped && prev_extent_end < lockend) { - ret = fiemap_process_hole(inode, fieinfo, &cache, backref_ctx, + ret = fiemap_process_hole(inode, fieinfo, &cache, + &delalloc_cached_state, backref_ctx, 0, 0, 0, prev_extent_end, lockend - 1); if (ret < 0) goto out_unlock; @@ -4088,6 +4095,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo, delalloc = btrfs_find_delalloc_in_range(inode, prev_extent_end, i_size - 1, + &delalloc_cached_state, &delalloc_start, &delalloc_end); if (!delalloc) @@ -4102,6 +4110,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo, out_unlock: unlock_extent(&inode->io_tree, lockstart, lockend, &cached_state); out: + free_extent_state(delalloc_cached_state); btrfs_free_backref_share_ctx(backref_ctx); btrfs_free_path(path); return ret; diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index dc8399610ca3..da390f891220 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -3214,6 +3214,7 @@ static long btrfs_fallocate(struct file *file, int mode, * looping while it gets adjacent subranges, and merging them together. */ static bool find_delalloc_subrange(struct btrfs_inode *inode, u64 start, u64 end, + struct extent_state **cached_state, bool *search_io_tree, u64 *delalloc_start_ret, u64 *delalloc_end_ret) { @@ -3236,7 +3237,7 @@ static bool find_delalloc_subrange(struct btrfs_inode *inode, u64 start, u64 end delalloc_len = count_range_bits(&inode->io_tree, delalloc_start_ret, end, len, EXTENT_DELALLOC, 1, - NULL); + cached_state); } else { spin_unlock(&inode->lock); } @@ -3324,6 +3325,8 @@ static bool find_delalloc_subrange(struct btrfs_inode *inode, u64 start, u64 end * sector size aligned. * @end: The end offset (inclusive value) of the search range. * It does not need to be sector size aligned. + * @cached_state: Extent state record used for speeding up delalloc + * searches in the inode's io_tree. Can be NULL. * @delalloc_start_ret: Output argument, set to the start offset of the * subrange found with delalloc (may not be sector size * aligned). @@ -3335,6 +3338,7 @@ static bool find_delalloc_subrange(struct btrfs_inode *inode, u64 start, u64 end * end offsets of the subrange. */ bool btrfs_find_delalloc_in_range(struct btrfs_inode *inode, u64 start, u64 end, + struct extent_state **cached_state, u64 *delalloc_start_ret, u64 *delalloc_end_ret) { u64 cur_offset = round_down(start, inode->root->fs_info->sectorsize); @@ -3348,7 +3352,7 @@ bool btrfs_find_delalloc_in_range(struct btrfs_inode *inode, u64 start, u64 end, bool delalloc; delalloc = find_delalloc_subrange(inode, cur_offset, end, - &search_io_tree, + cached_state, &search_io_tree, &delalloc_start, &delalloc_end); if (!delalloc) @@ -3400,7 +3404,7 @@ static bool find_desired_extent_in_hole(struct btrfs_inode *inode, int whence, u64 delalloc_end; bool delalloc; - delalloc = btrfs_find_delalloc_in_range(inode, start, end, + delalloc = btrfs_find_delalloc_in_range(inode, start, end, NULL, &delalloc_start, &delalloc_end); if (delalloc && whence == SEEK_DATA) { *start_ret = delalloc_start; diff --git a/fs/btrfs/file.h b/fs/btrfs/file.h index f3d794e33d46..82b34fbb295f 100644 --- a/fs/btrfs/file.h +++ b/fs/btrfs/file.h @@ -27,6 +27,7 @@ int btrfs_check_nocow_lock(struct btrfs_inode *inode, loff_t pos, size_t *write_bytes, bool nowait); void btrfs_check_nocow_unlock(struct btrfs_inode *inode); bool btrfs_find_delalloc_in_range(struct btrfs_inode *inode, u64 start, u64 end, + struct extent_state **cached_state, u64 *delalloc_start_ret, u64 *delalloc_end_ret); #endif -- GitLab