Josef Bacik
2010-Dec-08 14:18 UTC
[PATCH] Btrfs: do not do fast caching if we are allocating blocks for tree_root
Since the fast caching uses normal tree locking, we can possibly deadlock if we
get to the caching via a btrfs_search_slot() on the tree_root. So just check to
see if the root we are on is the tree root, and just don''t do the fast
caching.
Reported-by: Sage Weil <sage@newdream.net>
Signed-off-by: Josef Bacik <josef@redhat.com>
---
fs/btrfs/extent-tree.c | 18 ++++++++++++------
1 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 03f4738..8aed05e 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -434,6 +434,7 @@ err:
static int cache_block_group(struct btrfs_block_group_cache *cache,
struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
int load_cache_only)
{
struct btrfs_fs_info *fs_info = cache->fs_info;
@@ -447,9 +448,12 @@ static int cache_block_group(struct btrfs_block_group_cache
*cache,
/*
* We can''t do the read from on-disk cache during a commit since we
need
- * to have the normal tree locking.
+ * to have the normal tree locking. Also if we are currently trying to
+ * allocate blocks for the tree root we can''t do the fast caching
since
+ * we likely hold important locks.
*/
- if (!trans->transaction->in_commit) {
+ if (!trans->transaction->in_commit &&
+ (root && root != root->fs_info->tree_root)) {
spin_lock(&cache->lock);
if (cache->cached != BTRFS_CACHE_NO) {
spin_unlock(&cache->lock);
@@ -4089,7 +4093,7 @@ static int update_block_group(struct btrfs_trans_handle
*trans,
* space back to the block group, otherwise we will leak space.
*/
if (!alloc && cache->cached == BTRFS_CACHE_NO)
- cache_block_group(cache, trans, 1);
+ cache_block_group(cache, trans, NULL, 1);
byte_in_group = bytenr - cache->key.objectid;
WARN_ON(byte_in_group > cache->key.offset);
@@ -4984,7 +4988,8 @@ have_block_group:
if (unlikely(block_group->cached == BTRFS_CACHE_NO)) {
u64 free_percent;
- ret = cache_block_group(block_group, trans, 1);
+ ret = cache_block_group(block_group, trans,
+ orig_root, 1);
if (block_group->cached == BTRFS_CACHE_FINISHED)
goto have_block_group;
@@ -5008,7 +5013,8 @@ have_block_group:
if (loop > LOOP_CACHING_NOWAIT ||
(loop > LOOP_FIND_IDEAL &&
atomic_read(&space_info->caching_threads) < 2)) {
- ret = cache_block_group(block_group, trans, 0);
+ ret = cache_block_group(block_group, trans,
+ orig_root, 0);
BUG_ON(ret);
}
found_uncached_bg = true;
@@ -5561,7 +5567,7 @@ int btrfs_alloc_logged_file_extent(struct
btrfs_trans_handle *trans,
u64 num_bytes = ins->offset;
block_group = btrfs_lookup_block_group(root->fs_info, ins->objectid);
- cache_block_group(block_group, trans, 0);
+ cache_block_group(block_group, trans, NULL, 0);
caching_ctl = get_caching_control(block_group);
if (!caching_ctl) {
--
1.6.6.1
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