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author | Chris Mason <chris.mason@oracle.com> | 2008-06-25 20:01:30 (GMT) |
---|---|---|
committer | Chris Mason <chris.mason@oracle.com> | 2008-09-25 15:04:03 (GMT) |
commit | 5cd57b2cbbb06a350df2698314e4e6a80805fc2f (patch) | |
tree | cd20c904dd016ab031af582dadfbd6e04bf4df9e /fs/btrfs/ctree.c | |
parent | 168fd7d271d9d8e81ff0b03eb08c36d82670c8a9 (diff) | |
download | linux-fsl-qoriq-5cd57b2cbbb06a350df2698314e4e6a80805fc2f.tar.xz |
Btrfs: Add a skip_locking parameter to struct path, and make various funcs honor it
Allocations may need to read in block groups from the extent allocation tree,
which will require a tree search and take locks on the extent allocation
tree. But, those locks might already be held in other places, leading
to deadlocks.
Since the alloc_mutex serializes everything right now, it is safe to
skip the btree locking while caching block groups. A better fix will be
to either create a recursive lock or find a way to back off existing
locks while caching block groups.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/ctree.c')
-rw-r--r-- | fs/btrfs/ctree.c | 32 |
1 files changed, 18 insertions, 14 deletions
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index b8f7aec..fd68601 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -64,6 +64,7 @@ void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p) { int i; int keep = p->keep_locks; + int skip = p->skip_locking; for (i = 0; i < BTRFS_MAX_LEVEL; i++) { if (!p->nodes[i]) @@ -76,6 +77,7 @@ void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p) } memset(p, 0, sizeof(*p)); p->keep_locks = keep; + p->skip_locking = skip; } struct extent_buffer *btrfs_root_node(struct btrfs_root *root) @@ -1262,7 +1264,10 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root if (ins_len < 0) lowest_unlock = 2; again: - b = btrfs_lock_root_node(root); + if (p->skip_locking) + b = btrfs_root_node(root); + else + b = btrfs_lock_root_node(root); while (b) { level = btrfs_header_level(b); @@ -1282,7 +1287,8 @@ again: WARN_ON(1); level = btrfs_header_level(b); p->nodes[level] = b; - p->locks[level] = 1; + if (!p->skip_locking) + p->locks[level] = 1; ret = check_block(root, p, level); if (ret) return -1; @@ -1349,7 +1355,8 @@ again: b = read_node_slot(root, b, slot); } } - btrfs_tree_lock(b); + if (!p->skip_locking) + btrfs_tree_lock(b); unlock_up(p, level, lowest_unlock); } else { p->slots[level] = slot; @@ -1392,13 +1399,6 @@ static int fixup_low_keys(struct btrfs_trans_handle *trans, break; t = path->nodes[i]; btrfs_set_node_key(t, key, tslot); - if (!btrfs_tree_locked(path->nodes[i])) { - int ii; -printk("fixup without lock on level %d\n", btrfs_header_level(path->nodes[i])); - for (ii = 0; ii < BTRFS_MAX_LEVEL; ii++) { -printk("level %d slot %d\n", ii, path->slots[ii]); - } - } btrfs_mark_buffer_dirty(path->nodes[i]); if (tslot != 0) break; @@ -3033,8 +3033,10 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path) reada_for_search(root, path, level, slot, 0); next = read_node_slot(root, c, slot); - WARN_ON(!btrfs_tree_locked(c)); - btrfs_tree_lock(next); + if (!path->skip_locking) { + WARN_ON(!btrfs_tree_locked(c)); + btrfs_tree_lock(next); + } break; } path->slots[level] = slot; @@ -3052,8 +3054,10 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path) if (level == 1 && path->locks[1] && path->reada) reada_for_search(root, path, level, slot, 0); next = read_node_slot(root, next, 0); - WARN_ON(!btrfs_tree_locked(path->nodes[level])); - btrfs_tree_lock(next); + if (!path->skip_locking) { + WARN_ON(!btrfs_tree_locked(path->nodes[level])); + btrfs_tree_lock(next); + } } done: unlock_up(path, 0, 1); |