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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 <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Filipe Manana 2014-05-31 02:31:05 +01:00 committed by Chris Mason
parent c55bfa67e9
commit 2c463823cb
1 changed files with 22 additions and 4 deletions
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26
fs/btrfs/ioctl.c
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@ -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;