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Btrfs: do not do fast caching if we are allocating blocks for tree_root

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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>
This commit is contained in:
Josef Bacik 2010-12-08 09:15:11 -05:00
parent 2b20982e31
commit b8399dee47
1 changed files with 12 additions and 6 deletions
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18
fs/btrfs/extent-tree.c
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@ -429,6 +429,7 @@ 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;
@ -442,9 +443,12 @@ 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);
@ -4083,7 +4087,7 @@ 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);
@ -4937,7 +4941,8 @@ 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;
@ -4961,7 +4966,8 @@ 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;
@ -5518,7 +5524,7 @@ 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) {