mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-11-01 08:58:07 +00:00
Code Issues Releases Wiki Activity

btrfs: reuse cloned extent buffer during fiemap to avoid re-allocations

Browse source 
During fiemap we may have to visit multiple leaves of the subvolume's
inode tree, and each time we are freeing and allocating an extent buffer
to use as a clone of each visited leaf. Optimize this by reusing cloned
extent buffers, to avoid the freeing and re-allocation both of the extent
buffer structure itself and more importantly of the pages attached to the
extent buffer.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Filipe Manana 2024-02-28 14:36:33 +00:00 committed by David Sterba
parent 978b63f746
commit 1cab1375ba
1 changed files with 24 additions and 8 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

32
fs/btrfs/extent_io.c
View file

@ -2752,7 +2752,7 @@ static int emit_last_fiemap_cache(struct fiemap_extent_info *fieinfo,
static int fiemap_next_leaf_item(struct btrfs_inode *inode, struct btrfs_path *path) static int fiemap_next_leaf_item(struct btrfs_inode *inode, struct btrfs_path *path)
{ {
struct extent_buffer *clone; struct extent_buffer *clone = path->nodes[0];
struct btrfs_key key; struct btrfs_key key;
int slot; int slot;
int ret; int ret;
@ -2761,29 +2761,45 @@ static int fiemap_next_leaf_item(struct btrfs_inode *inode, struct btrfs_path *p
if (path->slots[0] < btrfs_header_nritems(path->nodes[0])) if (path->slots[0] < btrfs_header_nritems(path->nodes[0]))
return 0; return 0;
/*
* Add a temporary extra ref to an already cloned extent buffer to
* prevent btrfs_next_leaf() freeing it, we want to reuse it to avoid
* the cost of allocating a new one.
*/
ASSERT(test_bit(EXTENT_BUFFER_UNMAPPED, &clone->bflags));
atomic_inc(&clone->refs);
ret = btrfs_next_leaf(inode->root, path); ret = btrfs_next_leaf(inode->root, path);
if (ret != 0) if (ret != 0)
return ret; goto out;
/* /*
* Don't bother with cloning if there are no more file extent items for * Don't bother with cloning if there are no more file extent items for
* our inode. * our inode.
*/ */
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
if (key.objectid != btrfs_ino(inode) || key.type != BTRFS_EXTENT_DATA_KEY) if (key.objectid != btrfs_ino(inode) || key.type != BTRFS_EXTENT_DATA_KEY) {
return 1; ret = 1;
goto out;
}
/* See the comment at fiemap_search_slot() about why we clone. */ /* See the comment at fiemap_search_slot() about why we clone. */
clone = btrfs_clone_extent_buffer(path->nodes[0]); copy_extent_buffer_full(clone, path->nodes[0]);
if (!clone) /*
return -ENOMEM; * Important to preserve the start field, for the optimizations when
* checking if extents are shared (see extent_fiemap()).
*/
clone->start = path->nodes[0]->start;
slot = path->slots[0]; slot = path->slots[0];
btrfs_release_path(path); btrfs_release_path(path);
path->nodes[0] = clone; path->nodes[0] = clone;
path->slots[0] = slot; path->slots[0] = slot;
out:
if (ret)
free_extent_buffer(clone);
return 0; return ret;
} }
/* /*