From 2c463823cb897a8e1758518c911646f5605cdd82 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Sat, 31 May 2014 02:31:05 +0100 Subject: [PATCH] Btrfs: avoid visiting all extent items when cloning a range When cloning a range of a file, we were visiting all the extent items in the btree that belong to our source inode. We don't need to visit those extent items that don't overlap the range we are cloning, as doing so only makes us waste time and do unnecessary btree navigations (btrfs_next_leaf) for inodes that have a large number of file extent items in the btree. Signed-off-by: Filipe David Borba Manana Signed-off-by: Chris Mason --- fs/btrfs/ioctl.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 38f2169b73a4..f0b4237cedfc 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -3020,7 +3020,7 @@ static int btrfs_clone(struct inode *src, struct inode *inode, /* clone data */ key.objectid = btrfs_ino(src); key.type = BTRFS_EXTENT_DATA_KEY; - key.offset = 0; + key.offset = off; while (1) { /* @@ -3032,6 +3032,17 @@ static int btrfs_clone(struct inode *src, struct inode *inode, 0, 0); if (ret < 0) goto out; + /* + * First search, if no extent item that starts at offset off was + * found but the previous item is an extent item, it's possible + * it might overlap our target range, therefore process it. + */ + if (key.offset == off && ret > 0 && path->slots[0] > 0) { + btrfs_item_key_to_cpu(path->nodes[0], &key, + path->slots[0] - 1); + if (key.type == BTRFS_EXTENT_DATA_KEY) + path->slots[0]--; + } nritems = btrfs_header_nritems(path->nodes[0]); process_slot: @@ -3081,10 +3092,16 @@ process_slot: extent); } - if (key.offset + datal <= off || - key.offset >= off + len - 1) { + /* + * The first search might have left us at an extent + * item that ends before our target range's start, can + * happen if we have holes and NO_HOLES feature enabled. + */ + if (key.offset + datal <= off) { path->slots[0]++; goto process_slot; + } else if (key.offset >= off + len) { + break; } size = btrfs_item_size_nr(leaf, slot); @@ -3291,6 +3308,8 @@ process_slot: goto out; } ret = btrfs_end_transaction(trans, root); + if (new_key.offset + datal >= destoff + len) + break; } btrfs_release_path(path); key.offset++; @@ -3298,7 +3317,6 @@ process_slot: ret = 0; out: - btrfs_release_path(path); btrfs_free_path(path); vfree(buf); return ret; -- 2.20.1