Btrfs: free space cache cleanups
This patch cleans up the free space cache code a bit. It better documents the
idiosyncrasies of tree_search_offset and makes the code make a bit more sense.
I took out the info allocation at the start of __btrfs_add_free_space and put it
where it makes more sense. This was left over cruft from when alloc_mutex
existed. Also all of the re-searches we do to make sure we inserted properly.
Signed-off-by: Josef Bacik <jbacik@redhat.com>
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index d1e5f0e..69b023f 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -68,14 +68,24 @@
}
/*
- * searches the tree for the given offset. If contains is set we will return
- * the free space that contains the given offset. If contains is not set we
- * will return the free space that starts at or after the given offset and is
- * at least bytes long.
+ * searches the tree for the given offset.
+ *
+ * fuzzy == 1: this is used for allocations where we are given a hint of where
+ * to look for free space. Because the hint may not be completely on an offset
+ * mark, or the hint may no longer point to free space we need to fudge our
+ * results a bit. So we look for free space starting at or after offset with at
+ * least bytes size. We prefer to find as close to the given offset as we can.
+ * Also if the offset is within a free space range, then we will return the free
+ * space that contains the given offset, which means we can return a free space
+ * chunk with an offset before the provided offset.
+ *
+ * fuzzy == 0: this is just a normal tree search. Give us the free space that
+ * starts at the given offset which is at least bytes size, and if its not there
+ * return NULL.
*/
static struct btrfs_free_space *tree_search_offset(struct rb_root *root,
u64 offset, u64 bytes,
- int contains)
+ int fuzzy)
{
struct rb_node *n = root->rb_node;
struct btrfs_free_space *entry, *ret = NULL;
@@ -84,13 +94,14 @@
entry = rb_entry(n, struct btrfs_free_space, offset_index);
if (offset < entry->offset) {
- if (!contains &&
+ if (fuzzy &&
(!ret || entry->offset < ret->offset) &&
(bytes <= entry->bytes))
ret = entry;
n = n->rb_left;
} else if (offset > entry->offset) {
- if ((entry->offset + entry->bytes - 1) >= offset &&
+ if (fuzzy &&
+ (entry->offset + entry->bytes - 1) >= offset &&
bytes <= entry->bytes) {
ret = entry;
break;
@@ -190,55 +201,28 @@
struct btrfs_free_space *right_info;
struct btrfs_free_space *left_info;
struct btrfs_free_space *info = NULL;
- struct btrfs_free_space *alloc_info;
int ret = 0;
- alloc_info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);
- if (!alloc_info)
- return -ENOMEM;
-
/*
* first we want to see if there is free space adjacent to the range we
* are adding, if there is remove that struct and add a new one to
* cover the entire range
*/
right_info = tree_search_offset(&block_group->free_space_offset,
- offset+bytes, 0, 1);
+ offset+bytes, 0, 0);
left_info = tree_search_offset(&block_group->free_space_offset,
offset-1, 0, 1);
- if (right_info && right_info->offset == offset+bytes) {
+ if (right_info) {
unlink_free_space(block_group, right_info);
info = right_info;
info->offset = offset;
info->bytes += bytes;
- } else if (right_info && right_info->offset != offset+bytes) {
- printk(KERN_ERR "btrfs adding space in the middle of an "
- "existing free space area. existing: "
- "offset=%llu, bytes=%llu. new: offset=%llu, "
- "bytes=%llu\n", (unsigned long long)right_info->offset,
- (unsigned long long)right_info->bytes,
- (unsigned long long)offset,
- (unsigned long long)bytes);
- BUG();
}
- if (left_info) {
+ if (left_info && left_info->offset + left_info->bytes == offset) {
unlink_free_space(block_group, left_info);
- if (unlikely((left_info->offset + left_info->bytes) !=
- offset)) {
- printk(KERN_ERR "btrfs free space to the left "
- "of new free space isn't "
- "quite right. existing: offset=%llu, "
- "bytes=%llu. new: offset=%llu, bytes=%llu\n",
- (unsigned long long)left_info->offset,
- (unsigned long long)left_info->bytes,
- (unsigned long long)offset,
- (unsigned long long)bytes);
- BUG();
- }
-
if (info) {
info->offset = left_info->offset;
info->bytes += left_info->bytes;
@@ -251,13 +235,15 @@
if (info) {
ret = link_free_space(block_group, info);
- if (!ret)
- info = NULL;
+ if (ret)
+ kfree(info);
goto out;
}
- info = alloc_info;
- alloc_info = NULL;
+ info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);
+ if (!info)
+ return -ENOMEM;
+
info->offset = offset;
info->bytes = bytes;
@@ -271,8 +257,6 @@
BUG();
}
- kfree(alloc_info);
-
return ret;
}
@@ -283,6 +267,7 @@
struct btrfs_free_space *info;
int ret = 0;
+ BUG_ON(!block_group->cached);
info = tree_search_offset(&block_group->free_space_offset, offset, 0,
1);
@@ -341,6 +326,18 @@
offset - old_start);
BUG_ON(ret);
} else {
+ if (!info) {
+ printk(KERN_ERR "couldn't find space %llu to free\n",
+ (unsigned long long)offset);
+ printk(KERN_ERR "cached is %d, offset %llu bytes %llu\n",
+ block_group->cached, block_group->key.objectid,
+ block_group->key.offset);
+ btrfs_dump_free_space(block_group, bytes);
+ } else if (info) {
+ printk(KERN_ERR "hmm, found offset=%llu bytes=%llu, "
+ "but wanted offset=%llu bytes=%llu\n",
+ info->offset, info->bytes, offset, bytes);
+ }
WARN_ON(1);
}
out:
@@ -351,12 +348,9 @@
u64 offset, u64 bytes)
{
int ret;
- struct btrfs_free_space *sp;
mutex_lock(&block_group->alloc_mutex);
ret = __btrfs_add_free_space(block_group, offset, bytes);
- sp = tree_search_offset(&block_group->free_space_offset, offset, 0, 1);
- BUG_ON(!sp);
mutex_unlock(&block_group->alloc_mutex);
return ret;
@@ -366,11 +360,8 @@
u64 offset, u64 bytes)
{
int ret;
- struct btrfs_free_space *sp;
ret = __btrfs_add_free_space(block_group, offset, bytes);
- sp = tree_search_offset(&block_group->free_space_offset, offset, 0, 1);
- BUG_ON(!sp);
return ret;
}
@@ -408,6 +399,8 @@
info = rb_entry(n, struct btrfs_free_space, offset_index);
if (info->bytes >= bytes)
count++;
+ printk(KERN_ERR "entry offset %llu, bytes %llu\n", info->offset,
+ info->bytes);
}
printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
"\n", count);
@@ -486,7 +479,7 @@
struct btrfs_free_space *ret = NULL;
ret = tree_search_offset(&block_group->free_space_offset, offset,
- bytes, 0);
+ bytes, 1);
if (!ret)
ret = tree_search_bytes(&block_group->free_space_bytes,
offset, bytes);